libgo: update to Go1.12beta2

    
    Reviewed-on: https://go-review.googlesource.com/c/158019

gotools/:
	* Makefile.am (go_cmd_vet_files): Update for Go1.12beta2 release.
	(GOTOOLS_TEST_TIMEOUT): Increase to 600.
	(check-runtime): Export LD_LIBRARY_PATH before computing GOARCH
	and GOOS.
	(check-vet): Copy golang.org/x/tools into check-vet-dir.
	* Makefile.in: Regenerate.

gcc/testsuite/:
	* go.go-torture/execute/names-1.go: Stop using debug/xcoff, which
	is no longer externally visible.

From-SVN: r268084

55 files changed, 11775 insertions, 0 deletions

diff --git a/libgo/go/golang.org/x/tools/LICENSE b/libgo/go/golang.org/x/tools/LICENSE
new file mode 100644
index 00000000000..6a66aea5eaf
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/libgo/go/golang.org/x/tools/PATENTS b/libgo/go/golang.org/x/tools/PATENTS
new file mode 100644
index 00000000000..733099041f8
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/PATENTS
@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.
diff --git a/libgo/go/golang.org/x/tools/go/analysis/analysis.go b/libgo/go/golang.org/x/tools/go/analysis/analysis.go
new file mode 100644
index 00000000000..21baa02a8de
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/analysis.go
@@ -0,0 +1,192 @@
+package analysis
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"reflect"
+)
+
+// An Analyzer describes an analysis function and its options.
+type Analyzer struct {
+	// The Name of the analyzer must be a valid Go identifier
+	// as it may appear in command-line flags, URLs, and so on.
+	Name string
+
+	// Doc is the documentation for the analyzer.
+	// The part before the first "\n\n" is the title
+	// (no capital or period, max ~60 letters).
+	Doc string
+
+	// Flags defines any flags accepted by the analyzer.
+	// The manner in which these flags are exposed to the user
+	// depends on the driver which runs the analyzer.
+	Flags flag.FlagSet
+
+	// Run applies the analyzer to a package.
+	// It returns an error if the analyzer failed.
+	//
+	// On success, the Run function may return a result
+	// computed by the Analyzer; its type must match ResultType.
+	// The driver makes this result available as an input to
+	// another Analyzer that depends directly on this one (see
+	// Requires) when it analyzes the same package.
+	//
+	// To pass analysis results between packages (and thus
+	// potentially between address spaces), use Facts, which are
+	// serializable.
+	Run func(*Pass) (interface{}, error)
+
+	// RunDespiteErrors allows the driver to invoke
+	// the Run method of this analyzer even on a
+	// package that contains parse or type errors.
+	RunDespiteErrors bool
+
+	// Requires is a set of analyzers that must run successfully
+	// before this one on a given package. This analyzer may inspect
+	// the outputs produced by each analyzer in Requires.
+	// The graph over analyzers implied by Requires edges must be acyclic.
+	//
+	// Requires establishes a "horizontal" dependency between
+	// analysis passes (different analyzers, same package).
+	Requires []*Analyzer
+
+	// ResultType is the type of the optional result of the Run function.
+	ResultType reflect.Type
+
+	// FactTypes indicates that this analyzer imports and exports
+	// Facts of the specified concrete types.
+	// An analyzer that uses facts may assume that its import
+	// dependencies have been similarly analyzed before it runs.
+	// Facts must be pointers.
+	//
+	// FactTypes establishes a "vertical" dependency between
+	// analysis passes (same analyzer, different packages).
+	FactTypes []Fact
+}
+
+func (a *Analyzer) String() string { return a.Name }
+
+// A Pass provides information to the Run function that
+// applies a specific analyzer to a single Go package.
+//
+// It forms the interface between the analysis logic and the driver
+// program, and has both input and an output components.
+//
+// As in a compiler, one pass may depend on the result computed by another.
+//
+// The Run function should not call any of the Pass functions concurrently.
+type Pass struct {
+	Analyzer *Analyzer // the identity of the current analyzer
+
+	// syntax and type information
+	Fset       *token.FileSet // file position information
+	Files      []*ast.File    // the abstract syntax tree of each file
+	OtherFiles []string       // names of non-Go files of this package
+	Pkg        *types.Package // type information about the package
+	TypesInfo  *types.Info    // type information about the syntax trees
+
+	// Report reports a Diagnostic, a finding about a specific location
+	// in the analyzed source code such as a potential mistake.
+	// It may be called by the Run function.
+	Report func(Diagnostic)
+
+	// ResultOf provides the inputs to this analysis pass, which are
+	// the corresponding results of its prerequisite analyzers.
+	// The map keys are the elements of Analysis.Required,
+	// and the type of each corresponding value is the required
+	// analysis's ResultType.
+	ResultOf map[*Analyzer]interface{}
+
+	// -- facts --
+
+	// ImportObjectFact retrieves a fact associated with obj.
+	// Given a value ptr of type *T, where *T satisfies Fact,
+	// ImportObjectFact copies the value to *ptr.
+	//
+	// ImportObjectFact panics if called after the pass is complete.
+	// ImportObjectFact is not concurrency-safe.
+	ImportObjectFact func(obj types.Object, fact Fact) bool
+
+	// ImportPackageFact retrieves a fact associated with package pkg,
+	// which must be this package or one of its dependencies.
+	// See comments for ImportObjectFact.
+	ImportPackageFact func(pkg *types.Package, fact Fact) bool
+
+	// ExportObjectFact associates a fact of type *T with the obj,
+	// replacing any previous fact of that type.
+	//
+	// ExportObjectFact panics if it is called after the pass is
+	// complete, or if obj does not belong to the package being analyzed.
+	// ExportObjectFact is not concurrency-safe.
+	ExportObjectFact func(obj types.Object, fact Fact)
+
+	// ExportPackageFact associates a fact with the current package.
+	// See comments for ExportObjectFact.
+	ExportPackageFact func(fact Fact)
+
+	/* Further fields may be added in future. */
+	// For example, suggested or applied refactorings.
+}
+
+// Reportf is a helper function that reports a Diagnostic using the
+// specified position and formatted error message.
+func (pass *Pass) Reportf(pos token.Pos, format string, args ...interface{}) {
+	msg := fmt.Sprintf(format, args...)
+	pass.Report(Diagnostic{Pos: pos, Message: msg})
+}
+
+func (pass *Pass) String() string {
+	return fmt.Sprintf("%s@%s", pass.Analyzer.Name, pass.Pkg.Path())
+}
+
+// A Fact is an intermediate fact produced during analysis.
+//
+// Each fact is associated with a named declaration (a types.Object) or
+// with a package as a whole. A single object or package may have
+// multiple associated facts, but only one of any particular fact type.
+//
+// A Fact represents a predicate such as "never returns", but does not
+// represent the subject of the predicate such as "function F" or "package P".
+//
+// Facts may be produced in one analysis pass and consumed by another
+// analysis pass even if these are in different address spaces.
+// If package P imports Q, all facts about Q produced during
+// analysis of that package will be available during later analysis of P.
+// Facts are analogous to type export data in a build system:
+// just as export data enables separate compilation of several passes,
+// facts enable "separate analysis".
+//
+// Each pass (a, p) starts with the set of facts produced by the
+// same analyzer a applied to the packages directly imported by p.
+// The analysis may add facts to the set, and they may be exported in turn.
+// An analysis's Run function may retrieve facts by calling
+// Pass.Import{Object,Package}Fact and update them using
+// Pass.Export{Object,Package}Fact.
+//
+// A fact is logically private to its Analysis. To pass values
+// between different analyzers, use the results mechanism;
+// see Analyzer.Requires, Analyzer.ResultType, and Pass.ResultOf.
+//
+// A Fact type must be a pointer.
+// Facts are encoded and decoded using encoding/gob.
+// A Fact may implement the GobEncoder/GobDecoder interfaces
+// to customize its encoding. Fact encoding should not fail.
+//
+// A Fact should not be modified once exported.
+type Fact interface {
+	AFact() // dummy method to avoid type errors
+}
+
+// A Diagnostic is a message associated with a source location.
+//
+// An Analyzer may return a variety of diagnostics; the optional Category,
+// which should be a constant, may be used to classify them.
+// It is primarily intended to make it easy to look up documentation.
+type Diagnostic struct {
+	Pos      token.Pos
+	Category string // optional
+	Message  string
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/doc.go b/libgo/go/golang.org/x/tools/go/analysis/doc.go
new file mode 100644
index 00000000000..f925849ab50
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/doc.go
@@ -0,0 +1,336 @@
+/*
+
+The analysis package defines the interface between a modular static
+analysis and an analysis driver program.
+
+Background
+
+A static analysis is a function that inspects a package of Go code and
+reports a set of diagnostics (typically mistakes in the code), and
+perhaps produces other results as well, such as suggested refactorings
+or other facts. An analysis that reports mistakes is informally called a
+"checker". For example, the printf checker reports mistakes in
+fmt.Printf format strings.
+
+A "modular" analysis is one that inspects one package at a time but can
+save information from a lower-level package and use it when inspecting a
+higher-level package, analogous to separate compilation in a toolchain.
+The printf checker is modular: when it discovers that a function such as
+log.Fatalf delegates to fmt.Printf, it records this fact, and checks
+calls to that function too, including calls made from another package.
+
+By implementing a common interface, checkers from a variety of sources
+can be easily selected, incorporated, and reused in a wide range of
+driver programs including command-line tools (such as vet), text editors and
+IDEs, build and test systems (such as go build, Bazel, or Buck), test
+frameworks, code review tools, code-base indexers (such as SourceGraph),
+documentation viewers (such as godoc), batch pipelines for large code
+bases, and so on.
+
+
+Analyzer
+
+The primary type in the API is Analyzer. An Analyzer statically
+describes an analysis function: its name, documentation, flags,
+relationship to other analyzers, and of course, its logic.
+
+To define an analysis, a user declares a (logically constant) variable
+of type Analyzer. Here is a typical example from one of the analyzers in
+the go/analysis/passes/ subdirectory:
+
+	package unusedresult
+
+	var Analyzer = &analysis.Analyzer{
+		Name:	"unusedresult",
+		Doc:	"check for unused results of calls to some functions",
+		Run:    run,
+		...
+	}
+
+	func run(pass *analysis.Pass) (interface{}, error) {
+		...
+	}
+
+
+An analysis driver is a program such as vet that runs a set of
+analyses and prints the diagnostics that they report.
+The driver program must import the list of Analyzers it needs.
+Typically each Analyzer resides in a separate package.
+To add a new Analyzer to an existing driver, add another item to the list:
+
+	import ( "unusedresult"; "nilness"; "printf" )
+
+	var analyses = []*analysis.Analyzer{
+		unusedresult.Analyzer,
+		nilness.Analyzer,
+		printf.Analyzer,
+	}
+
+A driver may use the name, flags, and documentation to provide on-line
+help that describes the analyses its performs.
+The doc comment contains a brief one-line summary,
+optionally followed by paragraphs of explanation.
+The vet command, shown below, is an example of a driver that runs
+multiple analyzers. It is based on the multichecker package
+(see the "Standalone commands" section for details).
+
+	$ go build golang.org/x/tools/go/analysis/cmd/vet
+	$ ./vet help
+	vet is a tool for static analysis of Go programs.
+
+	Usage: vet [-flag] [package]
+
+	Registered analyzers:
+
+	    asmdecl      report mismatches between assembly files and Go declarations
+	    assign       check for useless assignments
+	    atomic       check for common mistakes using the sync/atomic package
+	    ...
+	    unusedresult check for unused results of calls to some functions
+
+	$ ./vet help unusedresult
+	unusedresult: check for unused results of calls to some functions
+
+	Analyzer flags:
+
+	  -unusedresult.funcs value
+	        comma-separated list of functions whose results must be used (default Error,String)
+	  -unusedresult.stringmethods value
+	        comma-separated list of names of methods of type func() string whose results must be used
+
+	Some functions like fmt.Errorf return a result and have no side effects,
+	so it is always a mistake to discard the result. This analyzer reports
+	calls to certain functions in which the result of the call is ignored.
+
+	The set of functions may be controlled using flags.
+
+The Analyzer type has more fields besides those shown above:
+
+	type Analyzer struct {
+		Name			string
+		Doc			string
+		Flags			flag.FlagSet
+		Run			func(*Pass) (interface{}, error)
+		RunDespiteErrors	bool
+		ResultType		reflect.Type
+		Requires		[]*Analyzer
+		FactTypes		[]Fact
+	}
+
+The Flags field declares a set of named (global) flag variables that
+control analysis behavior. Unlike vet, analysis flags are not declared
+directly in the command line FlagSet; it is up to the driver to set the
+flag variables. A driver for a single analysis, a, might expose its flag
+f directly on the command line as -f, whereas a driver for multiple
+analyses might prefix the flag name by the analysis name (-a.f) to avoid
+ambiguity. An IDE might expose the flags through a graphical interface,
+and a batch pipeline might configure them from a config file.
+See the "findcall" analyzer for an example of flags in action.
+
+The RunDespiteErrors flag indicates whether the analysis is equipped to
+handle ill-typed code. If not, the driver will skip the analysis if
+there were parse or type errors.
+The optional ResultType field specifies the type of the result value
+computed by this analysis and made available to other analyses.
+The Requires field specifies a list of analyses upon which
+this one depends and whose results it may access, and it constrains the
+order in which a driver may run analyses.
+The FactTypes field is discussed in the section on Modularity.
+The analysis package provides a Validate function to perform basic
+sanity checks on an Analyzer, such as that its Requires graph is
+acyclic, its fact and result types are unique, and so on.
+
+Finally, the Run field contains a function to be called by the driver to
+execute the analysis on a single package. The driver passes it an
+instance of the Pass type.
+
+
+Pass
+
+A Pass describes a single unit of work: the application of a particular
+Analyzer to a particular package of Go code.
+The Pass provides information to the Analyzer's Run function about the
+package being analyzed, and provides operations to the Run function for
+reporting diagnostics and other information back to the driver.
+
+	type Pass struct {
+		Fset   		*token.FileSet
+		Files		[]*ast.File
+		OtherFiles	[]string
+		Pkg		*types.Package
+		TypesInfo	*types.Info
+		ResultOf	map[*Analyzer]interface{}
+		Report		func(Diagnostic)
+		...
+	}
+
+The Fset, Files, Pkg, and TypesInfo fields provide the syntax trees,
+type information, and source positions for a single package of Go code.
+
+The OtherFiles field provides the names, but not the contents, of non-Go
+files such as assembly that are part of this package. See the "asmdecl"
+or "buildtags" analyzers for examples of loading non-Go files and report
+diagnostics against them.
+
+The ResultOf field provides the results computed by the analyzers
+required by this one, as expressed in its Analyzer.Requires field. The
+driver runs the required analyzers first and makes their results
+available in this map. Each Analyzer must return a value of the type
+described in its Analyzer.ResultType field.
+For example, the "ctrlflow" analyzer returns a *ctrlflow.CFGs, which
+provides a control-flow graph for each function in the package (see
+golang.org/x/tools/go/cfg); the "inspect" analyzer returns a value that
+enables other Analyzers to traverse the syntax trees of the package more
+efficiently; and the "buildssa" analyzer constructs an SSA-form
+intermediate representation.
+Each of these Analyzers extends the capabilities of later Analyzers
+without adding a dependency to the core API, so an analysis tool pays
+only for the extensions it needs.
+
+The Report function emits a diagnostic, a message associated with a
+source position. For most analyses, diagnostics are their primary
+result.
+For convenience, Pass provides a helper method, Reportf, to report a new
+diagnostic by formatting a string.
+Diagnostic is defined as:
+
+	type Diagnostic struct {
+		Pos      token.Pos
+		Category string // optional
+		Message  string
+	}
+
+The optional Category field is a short identifier that classifies the
+kind of message when an analysis produces several kinds of diagnostic.
+
+Most Analyzers inspect typed Go syntax trees, but a few, such as asmdecl
+and buildtag, inspect the raw text of Go source files or even non-Go
+files such as assembly. To report a diagnostic against a line of a
+raw text file, use the following sequence:
+
+	content, err := ioutil.ReadFile(filename)
+	if err != nil { ... }
+	tf := fset.AddFile(filename, -1, len(content))
+	tf.SetLinesForContent(content)
+	...
+	pass.Reportf(tf.LineStart(line), "oops")
+
+
+Modular analysis with Facts
+
+To improve efficiency and scalability, large programs are routinely
+built using separate compilation: units of the program are compiled
+separately, and recompiled only when one of their dependencies changes;
+independent modules may be compiled in parallel. The same technique may
+be applied to static analyses, for the same benefits. Such analyses are
+described as "modular".
+
+A compiler’s type checker is an example of a modular static analysis.
+Many other checkers we would like to apply to Go programs can be
+understood as alternative or non-standard type systems. For example,
+vet's printf checker infers whether a function has the "printf wrapper"
+type, and it applies stricter checks to calls of such functions. In
+addition, it records which functions are printf wrappers for use by
+later analysis units to identify other printf wrappers by induction.
+A result such as “f is a printf wrapper” that is not interesting by
+itself but serves as a stepping stone to an interesting result (such as
+a diagnostic) is called a "fact".
+
+The analysis API allows an analysis to define new types of facts, to
+associate facts of these types with objects (named entities) declared
+within the current package, or with the package as a whole, and to query
+for an existing fact of a given type associated with an object or
+package.
+
+An Analyzer that uses facts must declare their types:
+
+	var Analyzer = &analysis.Analyzer{
+		Name:       "printf",
+		FactTypes: []reflect.Type{reflect.TypeOf(new(isWrapper))},
+		...
+	}
+
+	type isWrapper struct{} // => *types.Func f “is a printf wrapper”
+
+A driver program ensures that facts for a pass’s dependencies are
+generated before analyzing the pass and are responsible for propagating
+facts between from one pass to another, possibly across address spaces.
+Consequently, Facts must be serializable. The API requires that drivers
+use the gob encoding, an efficient, robust, self-describing binary
+protocol. A fact type may implement the GobEncoder/GobDecoder interfaces
+if the default encoding is unsuitable. Facts should be stateless.
+
+The Pass type has functions to import and export facts,
+associated either with an object or with a package:
+
+	type Pass struct {
+		...
+		ExportObjectFact func(types.Object, Fact)
+		ImportObjectFact func(types.Object, Fact) bool
+
+		ExportPackageFact func(fact Fact)
+		ImportPackageFact func(*types.Package, Fact) bool
+	}
+
+An Analyzer may only export facts associated with the current package or
+its objects, though it may import facts from any package or object that
+is an import dependency of the current package.
+
+Conceptually, ExportObjectFact(obj, fact) inserts fact into a hidden map keyed by
+the pair (obj, TypeOf(fact)), and the ImportObjectFact function
+retrieves the entry from this map and copies its value into the variable
+pointed to by fact. This scheme assumes that the concrete type of fact
+is a pointer; this assumption is checked by the Validate function.
+See the "printf" analyzer for an example of object facts in action.
+
+Some driver implementations (such as those based on Bazel and Blaze) do
+not currently apply analyzers to packages of the standard library.
+Therefore, for best results, analyzer authors should not rely on
+analysis facts being available for standard packages.
+For example, although the printf checker is capable of deducing during
+analysis of the log package that log.Printf is a printf-wrapper,
+this fact is built in to the analyzer so that it correctly checks
+calls to log.Printf even when run in a driver that does not apply
+it to standard packages. We plan to remove this limitation in future.
+
+
+Testing an Analyzer
+
+The analysistest subpackage provides utilities for testing an Analyzer.
+In a few lines of code, it is possible to run an analyzer on a package
+of testdata files and check that it reported all the expected
+diagnostics and facts (and no more). Expectations are expressed using
+"// want ..." comments in the input code.
+
+
+Standalone commands
+
+Analyzers are provided in the form of packages that a driver program is
+expected to import. The vet command imports a set of several analyzers,
+but users may wish to define their own analysis commands that perform
+additional checks. To simplify the task of creating an analysis command,
+either for a single analyzer or for a whole suite, we provide the
+singlechecker and multichecker subpackages.
+
+The singlechecker package provides the main function for a command that
+runs one analyzer. By convention, each analyzer such as
+go/passes/findcall should be accompanied by a singlechecker-based
+command such as go/analysis/passes/findcall/cmd/findcall, defined in its
+entirety as:
+
+	package main
+
+	import (
+		"golang.org/x/tools/go/analysis/passes/findcall"
+		"golang.org/x/tools/go/analysis/singlechecker"
+	)
+
+	func main() { singlechecker.Main(findcall.Analyzer) }
+
+A tool that provides multiple analyzers can use multichecker in a
+similar way, giving it the list of Analyzers.
+
+
+
+*/
+package analysis
diff --git a/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/flags.go b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/flags.go
new file mode 100644
index 00000000000..729ac3b4176
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/flags.go
@@ -0,0 +1,343 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package analysisflags defines helpers for processing flags of
+// analysis driver tools.
+package analysisflags
+
+import (
+	"crypto/sha256"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"go/token"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+// flags common to all {single,multi,unit}checkers.
+var (
+	JSON    = false // -json
+	Context = -1    // -c=N: if N>0, display offending line plus N lines of context
+)
+
+// Parse creates a flag for each of the analyzer's flags,
+// including (in multi mode) a flag named after the analyzer,
+// parses the flags, then filters and returns the list of
+// analyzers enabled by flags.
+func Parse(analyzers []*analysis.Analyzer, multi bool) []*analysis.Analyzer {
+	// Connect each analysis flag to the command line as -analysis.flag.
+	enabled := make(map[*analysis.Analyzer]*triState)
+	for _, a := range analyzers {
+		var prefix string
+
+		// Add -NAME flag to enable it.
+		if multi {
+			prefix = a.Name + "."
+
+			enable := new(triState)
+			enableUsage := "enable " + a.Name + " analysis"
+			flag.Var(enable, a.Name, enableUsage)
+			enabled[a] = enable
+		}
+
+		a.Flags.VisitAll(func(f *flag.Flag) {
+			if !multi && flag.Lookup(f.Name) != nil {
+				log.Printf("%s flag -%s would conflict with driver; skipping", a.Name, f.Name)
+				return
+			}
+
+			name := prefix + f.Name
+			flag.Var(f.Value, name, f.Usage)
+		})
+	}
+
+	// standard flags: -flags, -V.
+	printflags := flag.Bool("flags", false, "print analyzer flags in JSON")
+	addVersionFlag()
+
+	// flags common to all checkers
+	flag.BoolVar(&JSON, "json", JSON, "emit JSON output")
+	flag.IntVar(&Context, "c", Context, `display offending line with this many lines of context`)
+
+	// Add shims for legacy vet flags to enable existing
+	// scripts that run vet to continue to work.
+	_ = flag.Bool("source", false, "no effect (deprecated)")
+	_ = flag.Bool("v", false, "no effect (deprecated)")
+	_ = flag.Bool("all", false, "no effect (deprecated)")
+	_ = flag.String("tags", "", "no effect (deprecated)")
+	for old, new := range vetLegacyFlags {
+		newFlag := flag.Lookup(new)
+		if newFlag != nil && flag.Lookup(old) == nil {
+			flag.Var(newFlag.Value, old, "deprecated alias for -"+new)
+		}
+	}
+
+	flag.Parse() // (ExitOnError)
+
+	// -flags: print flags so that go vet knows which ones are legitimate.
+	if *printflags {
+		printFlags()
+		os.Exit(0)
+	}
+
+	// If any -NAME flag is true,  run only those analyzers. Otherwise,
+	// if any -NAME flag is false, run all but those analyzers.
+	if multi {
+		var hasTrue, hasFalse bool
+		for _, ts := range enabled {
+			switch *ts {
+			case setTrue:
+				hasTrue = true
+			case setFalse:
+				hasFalse = true
+			}
+		}
+
+		var keep []*analysis.Analyzer
+		if hasTrue {
+			for _, a := range analyzers {
+				if *enabled[a] == setTrue {
+					keep = append(keep, a)
+				}
+			}
+			analyzers = keep
+		} else if hasFalse {
+			for _, a := range analyzers {
+				if *enabled[a] != setFalse {
+					keep = append(keep, a)
+				}
+			}
+			analyzers = keep
+		}
+	}
+
+	return analyzers
+}
+
+func printFlags() {
+	type jsonFlag struct {
+		Name  string
+		Bool  bool
+		Usage string
+	}
+	var flags []jsonFlag = nil
+	flag.VisitAll(func(f *flag.Flag) {
+		// Don't report {single,multi}checker debugging
+		// flags as these have no effect on unitchecker
+		// (as invoked by 'go vet').
+		switch f.Name {
+		case "debug", "cpuprofile", "memprofile", "trace":
+			return
+		}
+
+		b, ok := f.Value.(interface{ IsBoolFlag() bool })
+		isBool := ok && b.IsBoolFlag()
+		flags = append(flags, jsonFlag{f.Name, isBool, f.Usage})
+	})
+	data, err := json.MarshalIndent(flags, "", "\t")
+	if err != nil {
+		log.Fatal(err)
+	}
+	os.Stdout.Write(data)
+}
+
+// addVersionFlag registers a -V flag that, if set,
+// prints the executable version and exits 0.
+//
+// It is a variable not a function to permit easy
+// overriding in the copy vendored in $GOROOT/src/cmd/vet:
+//
+// func init() { addVersionFlag = objabi.AddVersionFlag }
+var addVersionFlag = func() {
+	flag.Var(versionFlag{}, "V", "print version and exit")
+}
+
+// versionFlag minimally complies with the -V protocol required by "go vet".
+type versionFlag struct{}
+
+func (versionFlag) IsBoolFlag() bool { return true }
+func (versionFlag) Get() interface{} { return nil }
+func (versionFlag) String() string   { return "" }
+func (versionFlag) Set(s string) error {
+	if s != "full" {
+		log.Fatalf("unsupported flag value: -V=%s", s)
+	}
+
+	// This replicates the miminal subset of
+	// cmd/internal/objabi.AddVersionFlag, which is private to the
+	// go tool yet forms part of our command-line interface.
+	// TODO(adonovan): clarify the contract.
+
+	// Print the tool version so the build system can track changes.
+	// Formats:
+	//   $progname version devel ... buildID=...
+	//   $progname version go1.9.1
+	progname := os.Args[0]
+	f, err := os.Open(progname)
+	if err != nil {
+		log.Fatal(err)
+	}
+	h := sha256.New()
+	if _, err := io.Copy(h, f); err != nil {
+		log.Fatal(err)
+	}
+	f.Close()
+	fmt.Printf("%s version devel comments-go-here buildID=%02x\n",
+		progname, string(h.Sum(nil)))
+	os.Exit(0)
+	return nil
+}
+
+// A triState is a boolean that knows whether
+// it has been set to either true or false.
+// It is used to identify whether a flag appears;
+// the standard boolean flag cannot
+// distinguish missing from unset.
+// It also satisfies flag.Value.
+type triState int
+
+const (
+	unset triState = iota
+	setTrue
+	setFalse
+)
+
+func triStateFlag(name string, value triState, usage string) *triState {
+	flag.Var(&value, name, usage)
+	return &value
+}
+
+// triState implements flag.Value, flag.Getter, and flag.boolFlag.
+// They work like boolean flags: we can say vet -printf as well as vet -printf=true
+func (ts *triState) Get() interface{} {
+	return *ts == setTrue
+}
+
+func (ts triState) isTrue() bool {
+	return ts == setTrue
+}
+
+func (ts *triState) Set(value string) error {
+	b, err := strconv.ParseBool(value)
+	if err != nil {
+		// This error message looks poor but package "flag" adds
+		// "invalid boolean value %q for -NAME: %s"
+		return fmt.Errorf("want true or false")
+	}
+	if b {
+		*ts = setTrue
+	} else {
+		*ts = setFalse
+	}
+	return nil
+}
+
+func (ts *triState) String() string {
+	switch *ts {
+	case unset:
+		return "true"
+	case setTrue:
+		return "true"
+	case setFalse:
+		return "false"
+	}
+	panic("not reached")
+}
+
+func (ts triState) IsBoolFlag() bool {
+	return true
+}
+
+// Legacy flag support
+
+// vetLegacyFlags maps flags used by legacy vet to their corresponding
+// new names. The old names will continue to work.
+var vetLegacyFlags = map[string]string{
+	// Analyzer name changes
+	"bool":       "bools",
+	"buildtags":  "buildtag",
+	"methods":    "stdmethods",
+	"rangeloops": "loopclosure",
+
+	// Analyzer flags
+	"compositewhitelist":  "composites.whitelist",
+	"printfuncs":          "printf.funcs",
+	"shadowstrict":        "shadow.strict",
+	"unusedfuncs":         "unusedresult.funcs",
+	"unusedstringmethods": "unusedresult.stringmethods",
+}
+
+// ---- output helpers common to all drivers ----
+
+// PrintPlain prints a diagnostic in plain text form,
+// with context specified by the -c flag.
+func PrintPlain(fset *token.FileSet, diag analysis.Diagnostic) {
+	posn := fset.Position(diag.Pos)
+	fmt.Fprintf(os.Stderr, "%s: %s\n", posn, diag.Message)
+
+	// -c=N: show offending line plus N lines of context.
+	if Context >= 0 {
+		data, _ := ioutil.ReadFile(posn.Filename)
+		lines := strings.Split(string(data), "\n")
+		for i := posn.Line - Context; i <= posn.Line+Context; i++ {
+			if 1 <= i && i <= len(lines) {
+				fmt.Fprintf(os.Stderr, "%d\t%s\n", i, lines[i-1])
+			}
+		}
+	}
+}
+
+// A JSONTree is a mapping from package ID to analysis name to result.
+// Each result is either a jsonError or a list of jsonDiagnostic.
+type JSONTree map[string]map[string]interface{}
+
+// Add adds the result of analysis 'name' on package 'id'.
+// The result is either a list of diagnostics or an error.
+func (tree JSONTree) Add(fset *token.FileSet, id, name string, diags []analysis.Diagnostic, err error) {
+	var v interface{}
+	if err != nil {
+		type jsonError struct {
+			Err string `json:"error"`
+		}
+		v = jsonError{err.Error()}
+	} else if len(diags) > 0 {
+		type jsonDiagnostic struct {
+			Category string `json:"category,omitempty"`
+			Posn     string `json:"posn"`
+			Message  string `json:"message"`
+		}
+		var diagnostics []jsonDiagnostic
+		for _, f := range diags {
+			diagnostics = append(diagnostics, jsonDiagnostic{
+				Category: f.Category,
+				Posn:     fset.Position(f.Pos).String(),
+				Message:  f.Message,
+			})
+		}
+		v = diagnostics
+	}
+	if v != nil {
+		m, ok := tree[id]
+		if !ok {
+			m = make(map[string]interface{})
+			tree[id] = m
+		}
+		m[name] = v
+	}
+}
+
+func (tree JSONTree) Print() {
+	data, err := json.MarshalIndent(tree, "", "\t")
+	if err != nil {
+		log.Panicf("internal error: JSON marshalling failed: %v", err)
+	}
+	fmt.Printf("%s\n", data)
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/help.go b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/help.go
new file mode 100644
index 00000000000..043b97896dd
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/help.go
@@ -0,0 +1,89 @@
+package analysisflags
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"sort"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+const help = `PROGNAME is a tool for static analysis of Go programs.
+
+PROGNAME examines Go source code and reports suspicious constructs,
+such as Printf calls whose arguments do not align with the format
+string. It uses heuristics that do not guarantee all reports are
+genuine problems, but it can find errors not caught by the compilers.
+`
+
+// Help implements the help subcommand for a multichecker or unitchecker
+// style command. The optional args specify the analyzers to describe.
+// Help calls log.Fatal if no such analyzer exists.
+func Help(progname string, analyzers []*analysis.Analyzer, args []string) {
+	// No args: show summary of all analyzers.
+	if len(args) == 0 {
+		fmt.Println(strings.Replace(help, "PROGNAME", progname, -1))
+		fmt.Println("Registered analyzers:")
+		fmt.Println()
+		sort.Slice(analyzers, func(i, j int) bool {
+			return analyzers[i].Name < analyzers[j].Name
+		})
+		for _, a := range analyzers {
+			title := strings.Split(a.Doc, "\n\n")[0]
+			fmt.Printf("    %-12s %s\n", a.Name, title)
+		}
+		fmt.Println("\nBy default all analyzers are run.")
+		fmt.Println("To select specific analyzers, use the -NAME flag for each one,")
+		fmt.Println(" or -NAME=false to run all analyzers not explicitly disabled.")
+
+		// Show only the core command-line flags.
+		fmt.Println("\nCore flags:")
+		fmt.Println()
+		fs := flag.NewFlagSet("", flag.ExitOnError)
+		flag.VisitAll(func(f *flag.Flag) {
+			if !strings.Contains(f.Name, ".") {
+				fs.Var(f.Value, f.Name, f.Usage)
+			}
+		})
+		fs.PrintDefaults()
+
+		fmt.Printf("\nTo see details and flags of a specific analyzer, run '%s help name'.\n", progname)
+
+		return
+	}
+
+	// Show help on specific analyzer(s).
+outer:
+	for _, arg := range args {
+		for _, a := range analyzers {
+			if a.Name == arg {
+				paras := strings.Split(a.Doc, "\n\n")
+				title := paras[0]
+				fmt.Printf("%s: %s\n", a.Name, title)
+
+				// Show only the flags relating to this analysis,
+				// properly prefixed.
+				first := true
+				fs := flag.NewFlagSet(a.Name, flag.ExitOnError)
+				a.Flags.VisitAll(func(f *flag.Flag) {
+					if first {
+						first = false
+						fmt.Println("\nAnalyzer flags:")
+						fmt.Println()
+					}
+					fs.Var(f.Value, a.Name+"."+f.Name, f.Usage)
+				})
+				fs.PrintDefaults()
+
+				if len(paras) > 1 {
+					fmt.Printf("\n%s\n", strings.Join(paras[1:], "\n\n"))
+				}
+
+				continue outer
+			}
+		}
+		log.Fatalf("Analyzer %q not registered", arg)
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/patch.go b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/patch.go
new file mode 100644
index 00000000000..8f9741055cb
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/internal/analysisflags/patch.go
@@ -0,0 +1,7 @@
+package analysisflags
+
+import "cmd/internal/objabi"
+
+// This additional file changes the behavior of the vendored code.
+
+func init() { addVersionFlag = objabi.AddVersionFlag }
diff --git a/libgo/go/golang.org/x/tools/go/analysis/internal/facts/facts.go b/libgo/go/golang.org/x/tools/go/analysis/internal/facts/facts.go
new file mode 100644
index 00000000000..468f148900f
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/internal/facts/facts.go
@@ -0,0 +1,299 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package facts defines a serializable set of analysis.Fact.
+//
+// It provides a partial implementation of the Fact-related parts of the
+// analysis.Pass interface for use in analysis drivers such as "go vet"
+// and other build systems.
+//
+// The serial format is unspecified and may change, so the same version
+// of this package must be used for reading and writing serialized facts.
+//
+// The handling of facts in the analysis system parallels the handling
+// of type information in the compiler: during compilation of package P,
+// the compiler emits an export data file that describes the type of
+// every object (named thing) defined in package P, plus every object
+// indirectly reachable from one of those objects. Thus the downstream
+// compiler of package Q need only load one export data file per direct
+// import of Q, and it will learn everything about the API of package P
+// and everything it needs to know about the API of P's dependencies.
+//
+// Similarly, analysis of package P emits a fact set containing facts
+// about all objects exported from P, plus additional facts about only
+// those objects of P's dependencies that are reachable from the API of
+// package P; the downstream analysis of Q need only load one fact set
+// per direct import of Q.
+//
+// The notion of "exportedness" that matters here is that of the
+// compiler. According to the language spec, a method pkg.T.f is
+// unexported simply because its name starts with lowercase. But the
+// compiler must nonethless export f so that downstream compilations can
+// accurately ascertain whether pkg.T implements an interface pkg.I
+// defined as interface{f()}. Exported thus means "described in export
+// data".
+//
+package facts
+
+import (
+	"bytes"
+	"encoding/gob"
+	"fmt"
+	"go/types"
+	"io/ioutil"
+	"log"
+	"reflect"
+	"sort"
+	"sync"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/types/objectpath"
+)
+
+const debug = false
+
+// A Set is a set of analysis.Facts.
+//
+// Decode creates a Set of facts by reading from the imports of a given
+// package, and Encode writes out the set. Between these operation,
+// the Import and Export methods will query and update the set.
+//
+// All of Set's methods except String are safe to call concurrently.
+type Set struct {
+	pkg *types.Package
+	mu  sync.Mutex
+	m   map[key]analysis.Fact
+}
+
+type key struct {
+	pkg *types.Package
+	obj types.Object // (object facts only)
+	t   reflect.Type
+}
+
+// ImportObjectFact implements analysis.Pass.ImportObjectFact.
+func (s *Set) ImportObjectFact(obj types.Object, ptr analysis.Fact) bool {
+	if obj == nil {
+		panic("nil object")
+	}
+	key := key{pkg: obj.Pkg(), obj: obj, t: reflect.TypeOf(ptr)}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if v, ok := s.m[key]; ok {
+		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
+		return true
+	}
+	return false
+}
+
+// ExportObjectFact implements analysis.Pass.ExportObjectFact.
+func (s *Set) ExportObjectFact(obj types.Object, fact analysis.Fact) {
+	if obj.Pkg() != s.pkg {
+		log.Panicf("in package %s: ExportObjectFact(%s, %T): can't set fact on object belonging another package",
+			s.pkg, obj, fact)
+	}
+	key := key{pkg: obj.Pkg(), obj: obj, t: reflect.TypeOf(fact)}
+	s.mu.Lock()
+	s.m[key] = fact // clobber any existing entry
+	s.mu.Unlock()
+}
+
+// ImportPackageFact implements analysis.Pass.ImportPackageFact.
+func (s *Set) ImportPackageFact(pkg *types.Package, ptr analysis.Fact) bool {
+	if pkg == nil {
+		panic("nil package")
+	}
+	key := key{pkg: pkg, t: reflect.TypeOf(ptr)}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if v, ok := s.m[key]; ok {
+		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
+		return true
+	}
+	return false
+}
+
+// ExportPackageFact implements analysis.Pass.ExportPackageFact.
+func (s *Set) ExportPackageFact(fact analysis.Fact) {
+	key := key{pkg: s.pkg, t: reflect.TypeOf(fact)}
+	s.mu.Lock()
+	s.m[key] = fact // clobber any existing entry
+	s.mu.Unlock()
+}
+
+// gobFact is the Gob declaration of a serialized fact.
+type gobFact struct {
+	PkgPath string          // path of package
+	Object  objectpath.Path // optional path of object relative to package itself
+	Fact    analysis.Fact   // type and value of user-defined Fact
+}
+
+// Decode decodes all the facts relevant to the analysis of package pkg.
+// The read function reads serialized fact data from an external source
+// for one of of pkg's direct imports. The empty file is a valid
+// encoding of an empty fact set.
+//
+// It is the caller's responsibility to call gob.Register on all
+// necessary fact types.
+func Decode(pkg *types.Package, read func(packagePath string) ([]byte, error)) (*Set, error) {
+	// Compute the import map for this package.
+	// See the package doc comment.
+	packages := importMap(pkg.Imports())
+
+	// Read facts from imported packages.
+	// Facts may describe indirectly imported packages, or their objects.
+	m := make(map[key]analysis.Fact) // one big bucket
+	for _, imp := range pkg.Imports() {
+		logf := func(format string, args ...interface{}) {
+			if debug {
+				prefix := fmt.Sprintf("in %s, importing %s: ",
+					pkg.Path(), imp.Path())
+				log.Print(prefix, fmt.Sprintf(format, args...))
+			}
+		}
+
+		// Read the gob-encoded facts.
+		data, err := read(imp.Path())
+		if err != nil {
+			return nil, fmt.Errorf("in %s, can't import facts for package %q: %v",
+				pkg.Path(), imp.Path(), err)
+		}
+		if len(data) == 0 {
+			continue // no facts
+		}
+		var gobFacts []gobFact
+		if err := gob.NewDecoder(bytes.NewReader(data)).Decode(&gobFacts); err != nil {
+			return nil, fmt.Errorf("decoding facts for %q: %v", imp.Path(), err)
+		}
+		if debug {
+			logf("decoded %d facts: %v", len(gobFacts), gobFacts)
+		}
+
+		// Parse each one into a key and a Fact.
+		for _, f := range gobFacts {
+			factPkg := packages[f.PkgPath]
+			if factPkg == nil {
+				// Fact relates to a dependency that was
+				// unused in this translation unit. Skip.
+				logf("no package %q; discarding %v", f.PkgPath, f.Fact)
+				continue
+			}
+			key := key{pkg: factPkg, t: reflect.TypeOf(f.Fact)}
+			if f.Object != "" {
+				// object fact
+				obj, err := objectpath.Object(factPkg, f.Object)
+				if err != nil {
+					// (most likely due to unexported object)
+					// TODO(adonovan): audit for other possibilities.
+					logf("no object for path: %v; discarding %s", err, f.Fact)
+					continue
+				}
+				key.obj = obj
+				logf("read %T fact %s for %v", f.Fact, f.Fact, key.obj)
+			} else {
+				// package fact
+				logf("read %T fact %s for %v", f.Fact, f.Fact, factPkg)
+			}
+			m[key] = f.Fact
+		}
+	}
+
+	return &Set{pkg: pkg, m: m}, nil
+}
+
+// Encode encodes a set of facts to a memory buffer.
+//
+// It may fail if one of the Facts could not be gob-encoded, but this is
+// a sign of a bug in an Analyzer.
+func (s *Set) Encode() []byte {
+
+	// TODO(adonovan): opt: use a more efficient encoding
+	// that avoids repeating PkgPath for each fact.
+
+	// Gather all facts, including those from imported packages.
+	var gobFacts []gobFact
+
+	s.mu.Lock()
+	for k, fact := range s.m {
+		if debug {
+			log.Printf("%v => %s\n", k, fact)
+		}
+		var object objectpath.Path
+		if k.obj != nil {
+			path, err := objectpath.For(k.obj)
+			if err != nil {
+				if debug {
+					log.Printf("discarding fact %s about %s\n", fact, k.obj)
+				}
+				continue // object not accessible from package API; discard fact
+			}
+			object = path
+		}
+		gobFacts = append(gobFacts, gobFact{
+			PkgPath: k.pkg.Path(),
+			Object:  object,
+			Fact:    fact,
+		})
+	}
+	s.mu.Unlock()
+
+	// Sort facts by (package, object, type) for determinism.
+	sort.Slice(gobFacts, func(i, j int) bool {
+		x, y := gobFacts[i], gobFacts[j]
+		if x.PkgPath != y.PkgPath {
+			return x.PkgPath < y.PkgPath
+		}
+		if x.Object != y.Object {
+			return x.Object < y.Object
+		}
+		tx := reflect.TypeOf(x.Fact)
+		ty := reflect.TypeOf(y.Fact)
+		if tx != ty {
+			return tx.String() < ty.String()
+		}
+		return false // equal
+	})
+
+	var buf bytes.Buffer
+	if len(gobFacts) > 0 {
+		if err := gob.NewEncoder(&buf).Encode(gobFacts); err != nil {
+			// Fact encoding should never fail. Identify the culprit.
+			for _, gf := range gobFacts {
+				if err := gob.NewEncoder(ioutil.Discard).Encode(gf); err != nil {
+					fact := gf.Fact
+					pkgpath := reflect.TypeOf(fact).Elem().PkgPath()
+					log.Panicf("internal error: gob encoding of analysis fact %s failed: %v; please report a bug against fact %T in package %q",
+						fact, err, fact, pkgpath)
+				}
+			}
+		}
+	}
+
+	if debug {
+		log.Printf("package %q: encode %d facts, %d bytes\n",
+			s.pkg.Path(), len(gobFacts), buf.Len())
+	}
+
+	return buf.Bytes()
+}
+
+// String is provided only for debugging, and must not be called
+// concurrent with any Import/Export method.
+func (s *Set) String() string {
+	var buf bytes.Buffer
+	buf.WriteString("{")
+	for k, f := range s.m {
+		if buf.Len() > 1 {
+			buf.WriteString(", ")
+		}
+		if k.obj != nil {
+			buf.WriteString(k.obj.String())
+		} else {
+			buf.WriteString(k.pkg.Path())
+		}
+		fmt.Fprintf(&buf, ": %v", f)
+	}
+	buf.WriteString("}")
+	return buf.String()
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/internal/facts/imports.go b/libgo/go/golang.org/x/tools/go/analysis/internal/facts/imports.go
new file mode 100644
index 00000000000..34740f48e04
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/internal/facts/imports.go
@@ -0,0 +1,88 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package facts
+
+import "go/types"
+
+// importMap computes the import map for a package by traversing the
+// entire exported API each of its imports.
+//
+// This is a workaround for the fact that we cannot access the map used
+// internally by the types.Importer returned by go/importer. The entries
+// in this map are the packages and objects that may be relevant to the
+// current analysis unit.
+//
+// Packages in the map that are only indirectly imported may be
+// incomplete (!pkg.Complete()).
+//
+func importMap(imports []*types.Package) map[string]*types.Package {
+	objects := make(map[types.Object]bool)
+	packages := make(map[string]*types.Package)
+
+	var addObj func(obj types.Object) bool
+	var addType func(T types.Type)
+
+	addObj = func(obj types.Object) bool {
+		if !objects[obj] {
+			objects[obj] = true
+			addType(obj.Type())
+			if pkg := obj.Pkg(); pkg != nil {
+				packages[pkg.Path()] = pkg
+			}
+			return true
+		}
+		return false
+	}
+
+	addType = func(T types.Type) {
+		switch T := T.(type) {
+		case *types.Basic:
+			// nop
+		case *types.Named:
+			if addObj(T.Obj()) {
+				for i := 0; i < T.NumMethods(); i++ {
+					addObj(T.Method(i))
+				}
+			}
+		case *types.Pointer:
+			addType(T.Elem())
+		case *types.Slice:
+			addType(T.Elem())
+		case *types.Array:
+			addType(T.Elem())
+		case *types.Chan:
+			addType(T.Elem())
+		case *types.Map:
+			addType(T.Key())
+			addType(T.Elem())
+		case *types.Signature:
+			addType(T.Params())
+			addType(T.Results())
+		case *types.Struct:
+			for i := 0; i < T.NumFields(); i++ {
+				addObj(T.Field(i))
+			}
+		case *types.Tuple:
+			for i := 0; i < T.Len(); i++ {
+				addObj(T.At(i))
+			}
+		case *types.Interface:
+			for i := 0; i < T.NumMethods(); i++ {
+				addObj(T.Method(i))
+			}
+		}
+	}
+
+	for _, imp := range imports {
+		packages[imp.Path()] = imp
+
+		scope := imp.Scope()
+		for _, name := range scope.Names() {
+			addObj(scope.Lookup(name))
+		}
+	}
+
+	return packages
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go b/libgo/go/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
new file mode 100644
index 00000000000..dce1ef7bd5e
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
@@ -0,0 +1,760 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package asmdecl defines an Analyzer that reports mismatches between
+// assembly files and Go declarations.
+package asmdecl
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/token"
+	"go/types"
+	"log"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name: "asmdecl",
+	Doc:  "report mismatches between assembly files and Go declarations",
+	Run:  run,
+}
+
+// 'kind' is a kind of assembly variable.
+// The kinds 1, 2, 4, 8 stand for values of that size.
+type asmKind int
+
+// These special kinds are not valid sizes.
+const (
+	asmString asmKind = 100 + iota
+	asmSlice
+	asmArray
+	asmInterface
+	asmEmptyInterface
+	asmStruct
+	asmComplex
+)
+
+// An asmArch describes assembly parameters for an architecture
+type asmArch struct {
+	name      string
+	bigEndian bool
+	stack     string
+	lr        bool
+	// calculated during initialization
+	sizes    types.Sizes
+	intSize  int
+	ptrSize  int
+	maxAlign int
+}
+
+// An asmFunc describes the expected variables for a function on a given architecture.
+type asmFunc struct {
+	arch        *asmArch
+	size        int // size of all arguments
+	vars        map[string]*asmVar
+	varByOffset map[int]*asmVar
+}
+
+// An asmVar describes a single assembly variable.
+type asmVar struct {
+	name  string
+	kind  asmKind
+	typ   string
+	off   int
+	size  int
+	inner []*asmVar
+}
+
+var (
+	asmArch386      = asmArch{name: "386", bigEndian: false, stack: "SP", lr: false}
+	asmArchArm      = asmArch{name: "arm", bigEndian: false, stack: "R13", lr: true}
+	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true}
+	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false}
+	asmArchAmd64p32 = asmArch{name: "amd64p32", bigEndian: false, stack: "SP", lr: false}
+	asmArchMips     = asmArch{name: "mips", bigEndian: true, stack: "R29", lr: true}
+	asmArchMipsLE   = asmArch{name: "mipsle", bigEndian: false, stack: "R29", lr: true}
+	asmArchMips64   = asmArch{name: "mips64", bigEndian: true, stack: "R29", lr: true}
+	asmArchMips64LE = asmArch{name: "mips64le", bigEndian: false, stack: "R29", lr: true}
+	asmArchPpc64    = asmArch{name: "ppc64", bigEndian: true, stack: "R1", lr: true}
+	asmArchPpc64LE  = asmArch{name: "ppc64le", bigEndian: false, stack: "R1", lr: true}
+	asmArchS390X    = asmArch{name: "s390x", bigEndian: true, stack: "R15", lr: true}
+	asmArchWasm     = asmArch{name: "wasm", bigEndian: false, stack: "SP", lr: false}
+
+	arches = []*asmArch{
+		&asmArch386,
+		&asmArchArm,
+		&asmArchArm64,
+		&asmArchAmd64,
+		&asmArchAmd64p32,
+		&asmArchMips,
+		&asmArchMipsLE,
+		&asmArchMips64,
+		&asmArchMips64LE,
+		&asmArchPpc64,
+		&asmArchPpc64LE,
+		&asmArchS390X,
+		&asmArchWasm,
+	}
+)
+
+func init() {
+	for _, arch := range arches {
+		arch.sizes = types.SizesFor("gc", arch.name)
+		if arch.sizes == nil {
+			// TODO(adonovan): fix: now that asmdecl is not in the standard
+			// library we cannot assume types.SizesFor is consistent with arches.
+			// For now, assume 64-bit norms and print a warning.
+			// But this warning should really be deferred until we attempt to use
+			// arch, which is very unlikely.
+			arch.sizes = types.SizesFor("gc", "amd64")
+			log.Printf("unknown architecture %s", arch.name)
+		}
+		arch.intSize = int(arch.sizes.Sizeof(types.Typ[types.Int]))
+		arch.ptrSize = int(arch.sizes.Sizeof(types.Typ[types.UnsafePointer]))
+		arch.maxAlign = int(arch.sizes.Alignof(types.Typ[types.Int64]))
+	}
+}
+
+var (
+	re           = regexp.MustCompile
+	asmPlusBuild = re(`//\s+\+build\s+([^\n]+)`)
+	asmTEXT      = re(`\bTEXT\b(.*)·([^\(]+)\(SB\)(?:\s*,\s*([0-9A-Z|+()]+))?(?:\s*,\s*\$(-?[0-9]+)(?:-([0-9]+))?)?`)
+	asmDATA      = re(`\b(DATA|GLOBL)\b`)
+	asmNamedFP   = re(`([a-zA-Z0-9_\xFF-\x{10FFFF}]+)(?:\+([0-9]+))\(FP\)`)
+	asmUnnamedFP = re(`[^+\-0-9](([0-9]+)\(FP\))`)
+	asmSP        = re(`[^+\-0-9](([0-9]+)\(([A-Z0-9]+)\))`)
+	asmOpcode    = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
+	ppc64Suff    = re(`([BHWD])(ZU|Z|U|BR)?$`)
+)
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	// No work if no assembly files.
+	var sfiles []string
+	for _, fname := range pass.OtherFiles {
+		if strings.HasSuffix(fname, ".s") {
+			sfiles = append(sfiles, fname)
+		}
+	}
+	if sfiles == nil {
+		return nil, nil
+	}
+
+	// Gather declarations. knownFunc[name][arch] is func description.
+	knownFunc := make(map[string]map[string]*asmFunc)
+
+	for _, f := range pass.Files {
+		for _, decl := range f.Decls {
+			if decl, ok := decl.(*ast.FuncDecl); ok && decl.Body == nil {
+				knownFunc[decl.Name.Name] = asmParseDecl(pass, decl)
+			}
+		}
+	}
+
+Files:
+	for _, fname := range sfiles {
+		content, tf, err := analysisutil.ReadFile(pass.Fset, fname)
+		if err != nil {
+			return nil, err
+		}
+
+		// Determine architecture from file name if possible.
+		var arch string
+		var archDef *asmArch
+		for _, a := range arches {
+			if strings.HasSuffix(fname, "_"+a.name+".s") {
+				arch = a.name
+				archDef = a
+				break
+			}
+		}
+
+		lines := strings.SplitAfter(string(content), "\n")
+		var (
+			fn                 *asmFunc
+			fnName             string
+			localSize, argSize int
+			wroteSP            bool
+			haveRetArg         bool
+			retLine            []int
+		)
+
+		flushRet := func() {
+			if fn != nil && fn.vars["ret"] != nil && !haveRetArg && len(retLine) > 0 {
+				v := fn.vars["ret"]
+				for _, line := range retLine {
+					pass.Reportf(analysisutil.LineStart(tf, line), "[%s] %s: RET without writing to %d-byte ret+%d(FP)", arch, fnName, v.size, v.off)
+				}
+			}
+			retLine = nil
+		}
+		for lineno, line := range lines {
+			lineno++
+
+			badf := func(format string, args ...interface{}) {
+				pass.Reportf(analysisutil.LineStart(tf, lineno), "[%s] %s: %s", arch, fnName, fmt.Sprintf(format, args...))
+			}
+
+			if arch == "" {
+				// Determine architecture from +build line if possible.
+				if m := asmPlusBuild.FindStringSubmatch(line); m != nil {
+					// There can be multiple architectures in a single +build line,
+					// so accumulate them all and then prefer the one that
+					// matches build.Default.GOARCH.
+					var archCandidates []*asmArch
+					for _, fld := range strings.Fields(m[1]) {
+						for _, a := range arches {
+							if a.name == fld {
+								archCandidates = append(archCandidates, a)
+							}
+						}
+					}
+					for _, a := range archCandidates {
+						if a.name == build.Default.GOARCH {
+							archCandidates = []*asmArch{a}
+							break
+						}
+					}
+					if len(archCandidates) > 0 {
+						arch = archCandidates[0].name
+						archDef = archCandidates[0]
+					}
+				}
+			}
+
+			if m := asmTEXT.FindStringSubmatch(line); m != nil {
+				flushRet()
+				if arch == "" {
+					// Arch not specified by filename or build tags.
+					// Fall back to build.Default.GOARCH.
+					for _, a := range arches {
+						if a.name == build.Default.GOARCH {
+							arch = a.name
+							archDef = a
+							break
+						}
+					}
+					if arch == "" {
+						log.Printf("%s: cannot determine architecture for assembly file", fname)
+						continue Files
+					}
+				}
+				fnName = m[2]
+				if pkgPath := strings.TrimSpace(m[1]); pkgPath != "" {
+					// The assembler uses Unicode division slash within
+					// identifiers to represent the directory separator.
+					pkgPath = strings.Replace(pkgPath, "∕", "/", -1)
+					if pkgPath != pass.Pkg.Path() {
+						log.Printf("%s:%d: [%s] cannot check cross-package assembly function: %s is in package %s", fname, lineno, arch, fnName, pkgPath)
+						fn = nil
+						fnName = ""
+						continue
+					}
+				}
+				flag := m[3]
+				fn = knownFunc[fnName][arch]
+				if fn != nil {
+					size, _ := strconv.Atoi(m[5])
+					if size != fn.size && (flag != "7" && !strings.Contains(flag, "NOSPLIT") || size != 0) {
+						badf("wrong argument size %d; expected $...-%d", size, fn.size)
+					}
+				}
+				localSize, _ = strconv.Atoi(m[4])
+				localSize += archDef.intSize
+				if archDef.lr && !strings.Contains(flag, "NOFRAME") {
+					// Account for caller's saved LR
+					localSize += archDef.intSize
+				}
+				argSize, _ = strconv.Atoi(m[5])
+				if fn == nil && !strings.Contains(fnName, "<>") {
+					badf("function %s missing Go declaration", fnName)
+				}
+				wroteSP = false
+				haveRetArg = false
+				continue
+			} else if strings.Contains(line, "TEXT") && strings.Contains(line, "SB") {
+				// function, but not visible from Go (didn't match asmTEXT), so stop checking
+				flushRet()
+				fn = nil
+				fnName = ""
+				continue
+			}
+
+			if strings.Contains(line, "RET") {
+				retLine = append(retLine, lineno)
+			}
+
+			if fnName == "" {
+				continue
+			}
+
+			if asmDATA.FindStringSubmatch(line) != nil {
+				fn = nil
+			}
+
+			if archDef == nil {
+				continue
+			}
+
+			if strings.Contains(line, ", "+archDef.stack) || strings.Contains(line, ",\t"+archDef.stack) {
+				wroteSP = true
+				continue
+			}
+
+			for _, m := range asmSP.FindAllStringSubmatch(line, -1) {
+				if m[3] != archDef.stack || wroteSP {
+					continue
+				}
+				off := 0
+				if m[1] != "" {
+					off, _ = strconv.Atoi(m[2])
+				}
+				if off >= localSize {
+					if fn != nil {
+						v := fn.varByOffset[off-localSize]
+						if v != nil {
+							badf("%s should be %s+%d(FP)", m[1], v.name, off-localSize)
+							continue
+						}
+					}
+					if off >= localSize+argSize {
+						badf("use of %s points beyond argument frame", m[1])
+						continue
+					}
+					badf("use of %s to access argument frame", m[1])
+				}
+			}
+
+			if fn == nil {
+				continue
+			}
+
+			for _, m := range asmUnnamedFP.FindAllStringSubmatch(line, -1) {
+				off, _ := strconv.Atoi(m[2])
+				v := fn.varByOffset[off]
+				if v != nil {
+					badf("use of unnamed argument %s; offset %d is %s+%d(FP)", m[1], off, v.name, v.off)
+				} else {
+					badf("use of unnamed argument %s", m[1])
+				}
+			}
+
+			for _, m := range asmNamedFP.FindAllStringSubmatch(line, -1) {
+				name := m[1]
+				off := 0
+				if m[2] != "" {
+					off, _ = strconv.Atoi(m[2])
+				}
+				if name == "ret" || strings.HasPrefix(name, "ret_") {
+					haveRetArg = true
+				}
+				v := fn.vars[name]
+				if v == nil {
+					// Allow argframe+0(FP).
+					if name == "argframe" && off == 0 {
+						continue
+					}
+					v = fn.varByOffset[off]
+					if v != nil {
+						badf("unknown variable %s; offset %d is %s+%d(FP)", name, off, v.name, v.off)
+					} else {
+						badf("unknown variable %s", name)
+					}
+					continue
+				}
+				asmCheckVar(badf, fn, line, m[0], off, v)
+			}
+		}
+		flushRet()
+	}
+	return nil, nil
+}
+
+func asmKindForType(t types.Type, size int) asmKind {
+	switch t := t.Underlying().(type) {
+	case *types.Basic:
+		switch t.Kind() {
+		case types.String:
+			return asmString
+		case types.Complex64, types.Complex128:
+			return asmComplex
+		}
+		return asmKind(size)
+	case *types.Pointer, *types.Chan, *types.Map, *types.Signature:
+		return asmKind(size)
+	case *types.Struct:
+		return asmStruct
+	case *types.Interface:
+		if t.Empty() {
+			return asmEmptyInterface
+		}
+		return asmInterface
+	case *types.Array:
+		return asmArray
+	case *types.Slice:
+		return asmSlice
+	}
+	panic("unreachable")
+}
+
+// A component is an assembly-addressable component of a composite type,
+// or a composite type itself.
+type component struct {
+	size   int
+	offset int
+	kind   asmKind
+	typ    string
+	suffix string // Such as _base for string base, _0_lo for lo half of first element of [1]uint64 on 32 bit machine.
+	outer  string // The suffix for immediately containing composite type.
+}
+
+func newComponent(suffix string, kind asmKind, typ string, offset, size int, outer string) component {
+	return component{suffix: suffix, kind: kind, typ: typ, offset: offset, size: size, outer: outer}
+}
+
+// componentsOfType generates a list of components of type t.
+// For example, given string, the components are the string itself, the base, and the length.
+func componentsOfType(arch *asmArch, t types.Type) []component {
+	return appendComponentsRecursive(arch, t, nil, "", 0)
+}
+
+// appendComponentsRecursive implements componentsOfType.
+// Recursion is required to correct handle structs and arrays,
+// which can contain arbitrary other types.
+func appendComponentsRecursive(arch *asmArch, t types.Type, cc []component, suffix string, off int) []component {
+	s := t.String()
+	size := int(arch.sizes.Sizeof(t))
+	kind := asmKindForType(t, size)
+	cc = append(cc, newComponent(suffix, kind, s, off, size, suffix))
+
+	switch kind {
+	case 8:
+		if arch.ptrSize == 4 {
+			w1, w2 := "lo", "hi"
+			if arch.bigEndian {
+				w1, w2 = w2, w1
+			}
+			cc = append(cc, newComponent(suffix+"_"+w1, 4, "half "+s, off, 4, suffix))
+			cc = append(cc, newComponent(suffix+"_"+w2, 4, "half "+s, off+4, 4, suffix))
+		}
+
+	case asmEmptyInterface:
+		cc = append(cc, newComponent(suffix+"_type", asmKind(arch.ptrSize), "interface type", off, arch.ptrSize, suffix))
+		cc = append(cc, newComponent(suffix+"_data", asmKind(arch.ptrSize), "interface data", off+arch.ptrSize, arch.ptrSize, suffix))
+
+	case asmInterface:
+		cc = append(cc, newComponent(suffix+"_itable", asmKind(arch.ptrSize), "interface itable", off, arch.ptrSize, suffix))
+		cc = append(cc, newComponent(suffix+"_data", asmKind(arch.ptrSize), "interface data", off+arch.ptrSize, arch.ptrSize, suffix))
+
+	case asmSlice:
+		cc = append(cc, newComponent(suffix+"_base", asmKind(arch.ptrSize), "slice base", off, arch.ptrSize, suffix))
+		cc = append(cc, newComponent(suffix+"_len", asmKind(arch.intSize), "slice len", off+arch.ptrSize, arch.intSize, suffix))
+		cc = append(cc, newComponent(suffix+"_cap", asmKind(arch.intSize), "slice cap", off+arch.ptrSize+arch.intSize, arch.intSize, suffix))
+
+	case asmString:
+		cc = append(cc, newComponent(suffix+"_base", asmKind(arch.ptrSize), "string base", off, arch.ptrSize, suffix))
+		cc = append(cc, newComponent(suffix+"_len", asmKind(arch.intSize), "string len", off+arch.ptrSize, arch.intSize, suffix))
+
+	case asmComplex:
+		fsize := size / 2
+		cc = append(cc, newComponent(suffix+"_real", asmKind(fsize), fmt.Sprintf("real(complex%d)", size*8), off, fsize, suffix))
+		cc = append(cc, newComponent(suffix+"_imag", asmKind(fsize), fmt.Sprintf("imag(complex%d)", size*8), off+fsize, fsize, suffix))
+
+	case asmStruct:
+		tu := t.Underlying().(*types.Struct)
+		fields := make([]*types.Var, tu.NumFields())
+		for i := 0; i < tu.NumFields(); i++ {
+			fields[i] = tu.Field(i)
+		}
+		offsets := arch.sizes.Offsetsof(fields)
+		for i, f := range fields {
+			cc = appendComponentsRecursive(arch, f.Type(), cc, suffix+"_"+f.Name(), off+int(offsets[i]))
+		}
+
+	case asmArray:
+		tu := t.Underlying().(*types.Array)
+		elem := tu.Elem()
+		// Calculate offset of each element array.
+		fields := []*types.Var{
+			types.NewVar(token.NoPos, nil, "fake0", elem),
+			types.NewVar(token.NoPos, nil, "fake1", elem),
+		}
+		offsets := arch.sizes.Offsetsof(fields)
+		elemoff := int(offsets[1])
+		for i := 0; i < int(tu.Len()); i++ {
+			cc = appendComponentsRecursive(arch, elem, cc, suffix+"_"+strconv.Itoa(i), off+i*elemoff)
+		}
+	}
+
+	return cc
+}
+
+// asmParseDecl parses a function decl for expected assembly variables.
+func asmParseDecl(pass *analysis.Pass, decl *ast.FuncDecl) map[string]*asmFunc {
+	var (
+		arch   *asmArch
+		fn     *asmFunc
+		offset int
+	)
+
+	// addParams adds asmVars for each of the parameters in list.
+	// isret indicates whether the list are the arguments or the return values.
+	// TODO(adonovan): simplify by passing (*types.Signature).{Params,Results}
+	// instead of list.
+	addParams := func(list []*ast.Field, isret bool) {
+		argnum := 0
+		for _, fld := range list {
+			t := pass.TypesInfo.Types[fld.Type].Type
+
+			// Work around https://golang.org/issue/28277.
+			if t == nil {
+				if ell, ok := fld.Type.(*ast.Ellipsis); ok {
+					t = types.NewSlice(pass.TypesInfo.Types[ell.Elt].Type)
+				}
+			}
+
+			align := int(arch.sizes.Alignof(t))
+			size := int(arch.sizes.Sizeof(t))
+			offset += -offset & (align - 1)
+			cc := componentsOfType(arch, t)
+
+			// names is the list of names with this type.
+			names := fld.Names
+			if len(names) == 0 {
+				// Anonymous args will be called arg, arg1, arg2, ...
+				// Similarly so for return values: ret, ret1, ret2, ...
+				name := "arg"
+				if isret {
+					name = "ret"
+				}
+				if argnum > 0 {
+					name += strconv.Itoa(argnum)
+				}
+				names = []*ast.Ident{ast.NewIdent(name)}
+			}
+			argnum += len(names)
+
+			// Create variable for each name.
+			for _, id := range names {
+				name := id.Name
+				for _, c := range cc {
+					outer := name + c.outer
+					v := asmVar{
+						name: name + c.suffix,
+						kind: c.kind,
+						typ:  c.typ,
+						off:  offset + c.offset,
+						size: c.size,
+					}
+					if vo := fn.vars[outer]; vo != nil {
+						vo.inner = append(vo.inner, &v)
+					}
+					fn.vars[v.name] = &v
+					for i := 0; i < v.size; i++ {
+						fn.varByOffset[v.off+i] = &v
+					}
+				}
+				offset += size
+			}
+		}
+	}
+
+	m := make(map[string]*asmFunc)
+	for _, arch = range arches {
+		fn = &asmFunc{
+			arch:        arch,
+			vars:        make(map[string]*asmVar),
+			varByOffset: make(map[int]*asmVar),
+		}
+		offset = 0
+		addParams(decl.Type.Params.List, false)
+		if decl.Type.Results != nil && len(decl.Type.Results.List) > 0 {
+			offset += -offset & (arch.maxAlign - 1)
+			addParams(decl.Type.Results.List, true)
+		}
+		fn.size = offset
+		m[arch.name] = fn
+	}
+
+	return m
+}
+
+// asmCheckVar checks a single variable reference.
+func asmCheckVar(badf func(string, ...interface{}), fn *asmFunc, line, expr string, off int, v *asmVar) {
+	m := asmOpcode.FindStringSubmatch(line)
+	if m == nil {
+		if !strings.HasPrefix(strings.TrimSpace(line), "//") {
+			badf("cannot find assembly opcode")
+		}
+		return
+	}
+
+	// Determine operand sizes from instruction.
+	// Typically the suffix suffices, but there are exceptions.
+	var src, dst, kind asmKind
+	op := m[1]
+	switch fn.arch.name + "." + op {
+	case "386.FMOVLP":
+		src, dst = 8, 4
+	case "arm.MOVD":
+		src = 8
+	case "arm.MOVW":
+		src = 4
+	case "arm.MOVH", "arm.MOVHU":
+		src = 2
+	case "arm.MOVB", "arm.MOVBU":
+		src = 1
+	// LEA* opcodes don't really read the second arg.
+	// They just take the address of it.
+	case "386.LEAL":
+		dst = 4
+	case "amd64.LEAQ":
+		dst = 8
+	case "amd64p32.LEAL":
+		dst = 4
+	default:
+		switch fn.arch.name {
+		case "386", "amd64":
+			if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "D") || strings.HasSuffix(op, "DP")) {
+				// FMOVDP, FXCHD, etc
+				src = 8
+				break
+			}
+			if strings.HasPrefix(op, "P") && strings.HasSuffix(op, "RD") {
+				// PINSRD, PEXTRD, etc
+				src = 4
+				break
+			}
+			if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "F") || strings.HasSuffix(op, "FP")) {
+				// FMOVFP, FXCHF, etc
+				src = 4
+				break
+			}
+			if strings.HasSuffix(op, "SD") {
+				// MOVSD, SQRTSD, etc
+				src = 8
+				break
+			}
+			if strings.HasSuffix(op, "SS") {
+				// MOVSS, SQRTSS, etc
+				src = 4
+				break
+			}
+			if strings.HasPrefix(op, "SET") {
+				// SETEQ, etc
+				src = 1
+				break
+			}
+			switch op[len(op)-1] {
+			case 'B':
+				src = 1
+			case 'W':
+				src = 2
+			case 'L':
+				src = 4
+			case 'D', 'Q':
+				src = 8
+			}
+		case "ppc64", "ppc64le":
+			// Strip standard suffixes to reveal size letter.
+			m := ppc64Suff.FindStringSubmatch(op)
+			if m != nil {
+				switch m[1][0] {
+				case 'B':
+					src = 1
+				case 'H':
+					src = 2
+				case 'W':
+					src = 4
+				case 'D':
+					src = 8
+				}
+			}
+		case "mips", "mipsle", "mips64", "mips64le":
+			switch op {
+			case "MOVB", "MOVBU":
+				src = 1
+			case "MOVH", "MOVHU":
+				src = 2
+			case "MOVW", "MOVWU", "MOVF":
+				src = 4
+			case "MOVV", "MOVD":
+				src = 8
+			}
+		case "s390x":
+			switch op {
+			case "MOVB", "MOVBZ":
+				src = 1
+			case "MOVH", "MOVHZ":
+				src = 2
+			case "MOVW", "MOVWZ", "FMOVS":
+				src = 4
+			case "MOVD", "FMOVD":
+				src = 8
+			}
+		}
+	}
+	if dst == 0 {
+		dst = src
+	}
+
+	// Determine whether the match we're holding
+	// is the first or second argument.
+	if strings.Index(line, expr) > strings.Index(line, ",") {
+		kind = dst
+	} else {
+		kind = src
+	}
+
+	vk := v.kind
+	vs := v.size
+	vt := v.typ
+	switch vk {
+	case asmInterface, asmEmptyInterface, asmString, asmSlice:
+		// allow reference to first word (pointer)
+		vk = v.inner[0].kind
+		vs = v.inner[0].size
+		vt = v.inner[0].typ
+	}
+
+	if off != v.off {
+		var inner bytes.Buffer
+		for i, vi := range v.inner {
+			if len(v.inner) > 1 {
+				fmt.Fprintf(&inner, ",")
+			}
+			fmt.Fprintf(&inner, " ")
+			if i == len(v.inner)-1 {
+				fmt.Fprintf(&inner, "or ")
+			}
+			fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
+		}
+		badf("invalid offset %s; expected %s+%d(FP)%s", expr, v.name, v.off, inner.String())
+		return
+	}
+	if kind != 0 && kind != vk {
+		var inner bytes.Buffer
+		if len(v.inner) > 0 {
+			fmt.Fprintf(&inner, " containing")
+			for i, vi := range v.inner {
+				if i > 0 && len(v.inner) > 2 {
+					fmt.Fprintf(&inner, ",")
+				}
+				fmt.Fprintf(&inner, " ")
+				if i > 0 && i == len(v.inner)-1 {
+					fmt.Fprintf(&inner, "and ")
+				}
+				fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
+			}
+		}
+		badf("invalid %s of %s; %s is %d-byte value%s", op, expr, vt, vs, inner.String())
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/assign/assign.go b/libgo/go/golang.org/x/tools/go/analysis/passes/assign/assign.go
new file mode 100644
index 00000000000..4dff2908c32
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/assign/assign.go
@@ -0,0 +1,68 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package assign defines an Analyzer that detects useless assignments.
+package assign
+
+// TODO(adonovan): check also for assignments to struct fields inside
+// methods that are on T instead of *T.
+
+import (
+	"go/ast"
+	"go/token"
+	"reflect"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for useless assignments
+
+This checker reports assignments of the form x = x or a[i] = a[i].
+These are almost always useless, and even when they aren't they are
+usually a mistake.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "assign",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.AssignStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		stmt := n.(*ast.AssignStmt)
+		if stmt.Tok != token.ASSIGN {
+			return // ignore :=
+		}
+		if len(stmt.Lhs) != len(stmt.Rhs) {
+			// If LHS and RHS have different cardinality, they can't be the same.
+			return
+		}
+		for i, lhs := range stmt.Lhs {
+			rhs := stmt.Rhs[i]
+			if analysisutil.HasSideEffects(pass.TypesInfo, lhs) ||
+				analysisutil.HasSideEffects(pass.TypesInfo, rhs) {
+				continue // expressions may not be equal
+			}
+			if reflect.TypeOf(lhs) != reflect.TypeOf(rhs) {
+				continue // short-circuit the heavy-weight gofmt check
+			}
+			le := analysisutil.Format(pass.Fset, lhs)
+			re := analysisutil.Format(pass.Fset, rhs)
+			if le == re {
+				pass.Reportf(stmt.Pos(), "self-assignment of %s to %s", re, le)
+			}
+		}
+	})
+
+	return nil, nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/atomic/atomic.go b/libgo/go/golang.org/x/tools/go/analysis/passes/atomic/atomic.go
new file mode 100644
index 00000000000..45243d6f8c0
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/atomic/atomic.go
@@ -0,0 +1,96 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package atomic defines an Analyzer that checks for common mistakes
+// using the sync/atomic package.
+package atomic
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for common mistakes using the sync/atomic package
+
+The atomic checker looks for assignment statements of the form:
+
+	x = atomic.AddUint64(&x, 1)
+
+which are not atomic.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "atomic",
+	Doc:              Doc,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.AssignStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(node ast.Node) {
+		n := node.(*ast.AssignStmt)
+		if len(n.Lhs) != len(n.Rhs) {
+			return
+		}
+		if len(n.Lhs) == 1 && n.Tok == token.DEFINE {
+			return
+		}
+
+		for i, right := range n.Rhs {
+			call, ok := right.(*ast.CallExpr)
+			if !ok {
+				continue
+			}
+			sel, ok := call.Fun.(*ast.SelectorExpr)
+			if !ok {
+				continue
+			}
+			pkgIdent, _ := sel.X.(*ast.Ident)
+			pkgName, ok := pass.TypesInfo.Uses[pkgIdent].(*types.PkgName)
+			if !ok || pkgName.Imported().Path() != "sync/atomic" {
+				continue
+			}
+
+			switch sel.Sel.Name {
+			case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr":
+				checkAtomicAddAssignment(pass, n.Lhs[i], call)
+			}
+		}
+	})
+	return nil, nil
+}
+
+// checkAtomicAddAssignment walks the atomic.Add* method calls checking
+// for assigning the return value to the same variable being used in the
+// operation
+func checkAtomicAddAssignment(pass *analysis.Pass, left ast.Expr, call *ast.CallExpr) {
+	if len(call.Args) != 2 {
+		return
+	}
+	arg := call.Args[0]
+	broken := false
+
+	gofmt := func(e ast.Expr) string { return analysisutil.Format(pass.Fset, e) }
+
+	if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
+		broken = gofmt(left) == gofmt(uarg.X)
+	} else if star, ok := left.(*ast.StarExpr); ok {
+		broken = gofmt(star.X) == gofmt(arg)
+	}
+
+	if broken {
+		pass.Reportf(left.Pos(), "direct assignment to atomic value")
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/bools/bools.go b/libgo/go/golang.org/x/tools/go/analysis/passes/bools/bools.go
new file mode 100644
index 00000000000..833c9d7aae1
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/bools/bools.go
@@ -0,0 +1,214 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package bools defines an Analyzer that detects common mistakes
+// involving boolean operators.
+package bools
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "bools",
+	Doc:      "check for common mistakes involving boolean operators",
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.BinaryExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		e := n.(*ast.BinaryExpr)
+
+		var op boolOp
+		switch e.Op {
+		case token.LOR:
+			op = or
+		case token.LAND:
+			op = and
+		default:
+			return
+		}
+
+		// TODO(adonovan): this reports n(n-1)/2 errors for an
+		// expression e||...||e of depth n. Fix.
+		// See https://golang.org/issue/28086.
+		comm := op.commutativeSets(pass.TypesInfo, e)
+		for _, exprs := range comm {
+			op.checkRedundant(pass, exprs)
+			op.checkSuspect(pass, exprs)
+		}
+	})
+	return nil, nil
+}
+
+type boolOp struct {
+	name  string
+	tok   token.Token // token corresponding to this operator
+	badEq token.Token // token corresponding to the equality test that should not be used with this operator
+}
+
+var (
+	or  = boolOp{"or", token.LOR, token.NEQ}
+	and = boolOp{"and", token.LAND, token.EQL}
+)
+
+// commutativeSets returns all side effect free sets of
+// expressions in e that are connected by op.
+// For example, given 'a || b || f() || c || d' with the or op,
+// commutativeSets returns {{b, a}, {d, c}}.
+func (op boolOp) commutativeSets(info *types.Info, e *ast.BinaryExpr) [][]ast.Expr {
+	exprs := op.split(e)
+
+	// Partition the slice of expressions into commutative sets.
+	i := 0
+	var sets [][]ast.Expr
+	for j := 0; j <= len(exprs); j++ {
+		if j == len(exprs) || hasSideEffects(info, exprs[j]) {
+			if i < j {
+				sets = append(sets, exprs[i:j])
+			}
+			i = j + 1
+		}
+	}
+
+	return sets
+}
+
+// checkRedundant checks for expressions of the form
+//   e && e
+//   e || e
+// Exprs must contain only side effect free expressions.
+func (op boolOp) checkRedundant(pass *analysis.Pass, exprs []ast.Expr) {
+	seen := make(map[string]bool)
+	for _, e := range exprs {
+		efmt := analysisutil.Format(pass.Fset, e)
+		if seen[efmt] {
+			pass.Reportf(e.Pos(), "redundant %s: %s %s %s", op.name, efmt, op.tok, efmt)
+		} else {
+			seen[efmt] = true
+		}
+	}
+}
+
+// checkSuspect checks for expressions of the form
+//   x != c1 || x != c2
+//   x == c1 && x == c2
+// where c1 and c2 are constant expressions.
+// If c1 and c2 are the same then it's redundant;
+// if c1 and c2 are different then it's always true or always false.
+// Exprs must contain only side effect free expressions.
+func (op boolOp) checkSuspect(pass *analysis.Pass, exprs []ast.Expr) {
+	// seen maps from expressions 'x' to equality expressions 'x != c'.
+	seen := make(map[string]string)
+
+	for _, e := range exprs {
+		bin, ok := e.(*ast.BinaryExpr)
+		if !ok || bin.Op != op.badEq {
+			continue
+		}
+
+		// In order to avoid false positives, restrict to cases
+		// in which one of the operands is constant. We're then
+		// interested in the other operand.
+		// In the rare case in which both operands are constant
+		// (e.g. runtime.GOOS and "windows"), we'll only catch
+		// mistakes if the LHS is repeated, which is how most
+		// code is written.
+		var x ast.Expr
+		switch {
+		case pass.TypesInfo.Types[bin.Y].Value != nil:
+			x = bin.X
+		case pass.TypesInfo.Types[bin.X].Value != nil:
+			x = bin.Y
+		default:
+			continue
+		}
+
+		// e is of the form 'x != c' or 'x == c'.
+		xfmt := analysisutil.Format(pass.Fset, x)
+		efmt := analysisutil.Format(pass.Fset, e)
+		if prev, found := seen[xfmt]; found {
+			// checkRedundant handles the case in which efmt == prev.
+			if efmt != prev {
+				pass.Reportf(e.Pos(), "suspect %s: %s %s %s", op.name, efmt, op.tok, prev)
+			}
+		} else {
+			seen[xfmt] = efmt
+		}
+	}
+}
+
+// hasSideEffects reports whether evaluation of e has side effects.
+func hasSideEffects(info *types.Info, e ast.Expr) bool {
+	safe := true
+	ast.Inspect(e, func(node ast.Node) bool {
+		switch n := node.(type) {
+		case *ast.CallExpr:
+			typVal := info.Types[n.Fun]
+			switch {
+			case typVal.IsType():
+				// Type conversion, which is safe.
+			case typVal.IsBuiltin():
+				// Builtin func, conservatively assumed to not
+				// be safe for now.
+				safe = false
+				return false
+			default:
+				// A non-builtin func or method call.
+				// Conservatively assume that all of them have
+				// side effects for now.
+				safe = false
+				return false
+			}
+		case *ast.UnaryExpr:
+			if n.Op == token.ARROW {
+				safe = false
+				return false
+			}
+		}
+		return true
+	})
+	return !safe
+}
+
+// split returns a slice of all subexpressions in e that are connected by op.
+// For example, given 'a || (b || c) || d' with the or op,
+// split returns []{d, c, b, a}.
+func (op boolOp) split(e ast.Expr) (exprs []ast.Expr) {
+	for {
+		e = unparen(e)
+		if b, ok := e.(*ast.BinaryExpr); ok && b.Op == op.tok {
+			exprs = append(exprs, op.split(b.Y)...)
+			e = b.X
+		} else {
+			exprs = append(exprs, e)
+			break
+		}
+	}
+	return
+}
+
+// unparen returns e with any enclosing parentheses stripped.
+func unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/buildtag/buildtag.go b/libgo/go/golang.org/x/tools/go/analysis/passes/buildtag/buildtag.go
new file mode 100644
index 00000000000..5a441e609b6
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/buildtag/buildtag.go
@@ -0,0 +1,159 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package buildtag defines an Analyzer that checks build tags.
+package buildtag
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"strings"
+	"unicode"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name: "buildtag",
+	Doc:  "check that +build tags are well-formed and correctly located",
+	Run:  runBuildTag,
+}
+
+func runBuildTag(pass *analysis.Pass) (interface{}, error) {
+	for _, f := range pass.Files {
+		checkGoFile(pass, f)
+	}
+	for _, name := range pass.OtherFiles {
+		if err := checkOtherFile(pass, name); err != nil {
+			return nil, err
+		}
+	}
+	return nil, nil
+}
+
+func checkGoFile(pass *analysis.Pass, f *ast.File) {
+	pastCutoff := false
+	for _, group := range f.Comments {
+		// A +build comment is ignored after or adjoining the package declaration.
+		if group.End()+1 >= f.Package {
+			pastCutoff = true
+		}
+
+		// "+build" is ignored within or after a /*...*/ comment.
+		if !strings.HasPrefix(group.List[0].Text, "//") {
+			pastCutoff = true
+			continue
+		}
+
+		// Check each line of a //-comment.
+		for _, c := range group.List {
+			if !strings.Contains(c.Text, "+build") {
+				continue
+			}
+			if err := checkLine(c.Text, pastCutoff); err != nil {
+				pass.Reportf(c.Pos(), "%s", err)
+			}
+		}
+	}
+}
+
+func checkOtherFile(pass *analysis.Pass, filename string) error {
+	content, tf, err := analysisutil.ReadFile(pass.Fset, filename)
+	if err != nil {
+		return err
+	}
+
+	// We must look at the raw lines, as build tags may appear in non-Go
+	// files such as assembly files.
+	lines := bytes.SplitAfter(content, nl)
+
+	// Determine cutpoint where +build comments are no longer valid.
+	// They are valid in leading // comments in the file followed by
+	// a blank line.
+	//
+	// This must be done as a separate pass because of the
+	// requirement that the comment be followed by a blank line.
+	var cutoff int
+	for i, line := range lines {
+		line = bytes.TrimSpace(line)
+		if !bytes.HasPrefix(line, slashSlash) {
+			if len(line) > 0 {
+				break
+			}
+			cutoff = i
+		}
+	}
+
+	for i, line := range lines {
+		line = bytes.TrimSpace(line)
+		if !bytes.HasPrefix(line, slashSlash) {
+			continue
+		}
+		if !bytes.Contains(line, []byte("+build")) {
+			continue
+		}
+		if err := checkLine(string(line), i >= cutoff); err != nil {
+			pass.Reportf(analysisutil.LineStart(tf, i+1), "%s", err)
+			continue
+		}
+	}
+	return nil
+}
+
+// checkLine checks a line that starts with "//" and contains "+build".
+func checkLine(line string, pastCutoff bool) error {
+	line = strings.TrimPrefix(line, "//")
+	line = strings.TrimSpace(line)
+
+	if strings.HasPrefix(line, "+build") {
+		fields := strings.Fields(line)
+		if fields[0] != "+build" {
+			// Comment is something like +buildasdf not +build.
+			return fmt.Errorf("possible malformed +build comment")
+		}
+		if pastCutoff {
+			return fmt.Errorf("+build comment must appear before package clause and be followed by a blank line")
+		}
+		if err := checkArguments(fields); err != nil {
+			return err
+		}
+	} else {
+		// Comment with +build but not at beginning.
+		if !pastCutoff {
+			return fmt.Errorf("possible malformed +build comment")
+		}
+	}
+	return nil
+}
+
+func checkArguments(fields []string) error {
+	// The original version of this checker in vet could examine
+	// files with malformed build tags that would cause the file to
+	// be always ignored by "go build". However, drivers for the new
+	// analysis API will analyze only the files selected to form a
+	// package, so these checks will never fire.
+	// TODO(adonovan): rethink this.
+
+	for _, arg := range fields[1:] {
+		for _, elem := range strings.Split(arg, ",") {
+			if strings.HasPrefix(elem, "!!") {
+				return fmt.Errorf("invalid double negative in build constraint: %s", arg)
+			}
+			elem = strings.TrimPrefix(elem, "!")
+			for _, c := range elem {
+				if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
+					return fmt.Errorf("invalid non-alphanumeric build constraint: %s", arg)
+				}
+			}
+		}
+	}
+	return nil
+}
+
+var (
+	nl         = []byte("\n")
+	slashSlash = []byte("//")
+)
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/cgocall/cgocall.go b/libgo/go/golang.org/x/tools/go/analysis/passes/cgocall/cgocall.go
new file mode 100644
index 00000000000..f2e8949f607
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/cgocall/cgocall.go
@@ -0,0 +1,391 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cgocall defines an Analyzer that detects some violations of
+// the cgo pointer passing rules.
+package cgocall
+
+import (
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+	"runtime"
+	"strconv"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+)
+
+const debug = false
+
+const doc = `detect some violations of the cgo pointer passing rules
+
+Check for invalid cgo pointer passing.
+This looks for code that uses cgo to call C code passing values
+whose types are almost always invalid according to the cgo pointer
+sharing rules.
+Specifically, it warns about attempts to pass a Go chan, map, func,
+or slice to C, either directly, or via a pointer, array, or struct.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "cgocall",
+	Doc:              doc,
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	if runtime.Compiler != "gccgo" && imports(pass.Pkg, "runtime/cgo") == nil {
+		return nil, nil // doesn't use cgo
+	}
+
+	cgofiles, info, err := typeCheckCgoSourceFiles(pass.Fset, pass.Pkg, pass.Files, pass.TypesInfo)
+	if err != nil {
+		return nil, err
+	}
+	for _, f := range cgofiles {
+		checkCgo(pass.Fset, f, info, pass.Reportf)
+	}
+	return nil, nil
+}
+
+func checkCgo(fset *token.FileSet, f *ast.File, info *types.Info, reportf func(token.Pos, string, ...interface{})) {
+	ast.Inspect(f, func(n ast.Node) bool {
+		call, ok := n.(*ast.CallExpr)
+		if !ok {
+			return true
+		}
+
+		// Is this a C.f() call?
+		var name string
+		if sel, ok := analysisutil.Unparen(call.Fun).(*ast.SelectorExpr); ok {
+			if id, ok := sel.X.(*ast.Ident); ok && id.Name == "C" {
+				name = sel.Sel.Name
+			}
+		}
+		if name == "" {
+			return true // not a call we need to check
+		}
+
+		// A call to C.CBytes passes a pointer but is always safe.
+		if name == "CBytes" {
+			return true
+		}
+
+		if debug {
+			log.Printf("%s: call to C.%s", fset.Position(call.Lparen), name)
+		}
+
+		for _, arg := range call.Args {
+			if !typeOKForCgoCall(cgoBaseType(info, arg), make(map[types.Type]bool)) {
+				reportf(arg.Pos(), "possibly passing Go type with embedded pointer to C")
+				break
+			}
+
+			// Check for passing the address of a bad type.
+			if conv, ok := arg.(*ast.CallExpr); ok && len(conv.Args) == 1 &&
+				isUnsafePointer(info, conv.Fun) {
+				arg = conv.Args[0]
+			}
+			if u, ok := arg.(*ast.UnaryExpr); ok && u.Op == token.AND {
+				if !typeOKForCgoCall(cgoBaseType(info, u.X), make(map[types.Type]bool)) {
+					reportf(arg.Pos(), "possibly passing Go type with embedded pointer to C")
+					break
+				}
+			}
+		}
+		return true
+	})
+}
+
+// typeCheckCgoSourceFiles returns type-checked syntax trees for the raw
+// cgo files of a package (those that import "C"). Such files are not
+// Go, so there may be gaps in type information around C.f references.
+//
+// This checker was initially written in vet to inpect raw cgo source
+// files using partial type information. However, Analyzers in the new
+// analysis API are presented with the type-checked, "cooked" Go ASTs
+// resulting from cgo-processing files, so we must choose between
+// working with the cooked file generated by cgo (which was tried but
+// proved fragile) or locating the raw cgo file (e.g. from //line
+// directives) and working with that, as we now do.
+//
+// Specifically, we must type-check the raw cgo source files (or at
+// least the subtrees needed for this analyzer) in an environment that
+// simulates the rest of the already type-checked package.
+//
+// For example, for each raw cgo source file in the original package,
+// such as this one:
+//
+// 	package p
+// 	import "C"
+//	import "fmt"
+//	type T int
+//	const k = 3
+//	var x, y = fmt.Println()
+//	func f() { ... }
+//	func g() { ... C.malloc(k) ... }
+//	func (T) f(int) string { ... }
+//
+// we synthesize a new ast.File, shown below, that dot-imports the
+// orginal "cooked" package using a special name ("·this·"), so that all
+// references to package members resolve correctly. (References to
+// unexported names cause an "unexported" error, which we ignore.)
+//
+// To avoid shadowing names imported from the cooked package,
+// package-level declarations in the new source file are modified so
+// that they do not declare any names.
+// (The cgocall analysis is concerned with uses, not declarations.)
+// Specifically, type declarations are discarded;
+// all names in each var and const declaration are blanked out;
+// each method is turned into a regular function by turning
+// the receiver into the first parameter;
+// and all functions are renamed to "_".
+//
+// 	package p
+// 	import . "·this·" // declares T, k, x, y, f, g, T.f
+// 	import "C"
+//	import "fmt"
+//	const _ = 3
+//	var _, _ = fmt.Println()
+//	func _() { ... }
+//	func _() { ... C.malloc(k) ... }
+//	func _(T, int) string { ... }
+//
+// In this way, the raw function bodies and const/var initializer
+// expressions are preserved but refer to the "cooked" objects imported
+// from "·this·", and none of the transformed package-level declarations
+// actually declares anything. In the example above, the reference to k
+// in the argument of the call to C.malloc resolves to "·this·".k, which
+// has an accurate type.
+//
+// This approach could in principle be generalized to more complex
+// analyses on raw cgo files. One could synthesize a "C" package so that
+// C.f would resolve to "·this·"._C_func_f, for example. But we have
+// limited ourselves here to preserving function bodies and initializer
+// expressions since that is all that the cgocall analyzer needs.
+//
+func typeCheckCgoSourceFiles(fset *token.FileSet, pkg *types.Package, files []*ast.File, info *types.Info) ([]*ast.File, *types.Info, error) {
+	const thispkg = "·this·"
+
+	// Which files are cgo files?
+	var cgoFiles []*ast.File
+	importMap := map[string]*types.Package{thispkg: pkg}
+	for _, raw := range files {
+		// If f is a cgo-generated file, Position reports
+		// the original file, honoring //line directives.
+		filename := fset.Position(raw.Pos()).Filename
+		f, err := parser.ParseFile(fset, filename, nil, parser.Mode(0))
+		if err != nil {
+			return nil, nil, fmt.Errorf("can't parse raw cgo file: %v", err)
+		}
+		found := false
+		for _, spec := range f.Imports {
+			if spec.Path.Value == `"C"` {
+				found = true
+				break
+			}
+		}
+		if !found {
+			continue // not a cgo file
+		}
+
+		// Record the original import map.
+		for _, spec := range raw.Imports {
+			path, _ := strconv.Unquote(spec.Path.Value)
+			importMap[path] = imported(info, spec)
+		}
+
+		// Add special dot-import declaration:
+		//    import . "·this·"
+		var decls []ast.Decl
+		decls = append(decls, &ast.GenDecl{
+			Tok: token.IMPORT,
+			Specs: []ast.Spec{
+				&ast.ImportSpec{
+					Name: &ast.Ident{Name: "."},
+					Path: &ast.BasicLit{
+						Kind:  token.STRING,
+						Value: strconv.Quote(thispkg),
+					},
+				},
+			},
+		})
+
+		// Transform declarations from the raw cgo file.
+		for _, decl := range f.Decls {
+			switch decl := decl.(type) {
+			case *ast.GenDecl:
+				switch decl.Tok {
+				case token.TYPE:
+					// Discard type declarations.
+					continue
+				case token.IMPORT:
+					// Keep imports.
+				case token.VAR, token.CONST:
+					// Blank the declared var/const names.
+					for _, spec := range decl.Specs {
+						spec := spec.(*ast.ValueSpec)
+						for i := range spec.Names {
+							spec.Names[i].Name = "_"
+						}
+					}
+				}
+			case *ast.FuncDecl:
+				// Blank the declared func name.
+				decl.Name.Name = "_"
+
+				// Turn a method receiver:  func (T) f(P) R {...}
+				// into regular parameter:  func _(T, P) R {...}
+				if decl.Recv != nil {
+					var params []*ast.Field
+					params = append(params, decl.Recv.List...)
+					params = append(params, decl.Type.Params.List...)
+					decl.Type.Params.List = params
+					decl.Recv = nil
+				}
+			}
+			decls = append(decls, decl)
+		}
+		f.Decls = decls
+		if debug {
+			format.Node(os.Stderr, fset, f) // debugging
+		}
+		cgoFiles = append(cgoFiles, f)
+	}
+	if cgoFiles == nil {
+		return nil, nil, nil // nothing to do (can't happen?)
+	}
+
+	// Type-check the synthetic files.
+	tc := &types.Config{
+		FakeImportC: true,
+		Importer: importerFunc(func(path string) (*types.Package, error) {
+			return importMap[path], nil
+		}),
+		// TODO(adonovan): Sizes should probably be provided by analysis.Pass.
+		Sizes: types.SizesFor("gc", build.Default.GOARCH),
+		Error: func(error) {}, // ignore errors (e.g. unused import)
+	}
+
+	// It's tempting to record the new types in the
+	// existing pass.TypesInfo, but we don't own it.
+	altInfo := &types.Info{
+		Types: make(map[ast.Expr]types.TypeAndValue),
+	}
+	tc.Check(pkg.Path(), fset, cgoFiles, altInfo)
+
+	return cgoFiles, altInfo, nil
+}
+
+// cgoBaseType tries to look through type conversions involving
+// unsafe.Pointer to find the real type. It converts:
+//   unsafe.Pointer(x) => x
+//   *(*unsafe.Pointer)(unsafe.Pointer(&x)) => x
+func cgoBaseType(info *types.Info, arg ast.Expr) types.Type {
+	switch arg := arg.(type) {
+	case *ast.CallExpr:
+		if len(arg.Args) == 1 && isUnsafePointer(info, arg.Fun) {
+			return cgoBaseType(info, arg.Args[0])
+		}
+	case *ast.StarExpr:
+		call, ok := arg.X.(*ast.CallExpr)
+		if !ok || len(call.Args) != 1 {
+			break
+		}
+		// Here arg is *f(v).
+		t := info.Types[call.Fun].Type
+		if t == nil {
+			break
+		}
+		ptr, ok := t.Underlying().(*types.Pointer)
+		if !ok {
+			break
+		}
+		// Here arg is *(*p)(v)
+		elem, ok := ptr.Elem().Underlying().(*types.Basic)
+		if !ok || elem.Kind() != types.UnsafePointer {
+			break
+		}
+		// Here arg is *(*unsafe.Pointer)(v)
+		call, ok = call.Args[0].(*ast.CallExpr)
+		if !ok || len(call.Args) != 1 {
+			break
+		}
+		// Here arg is *(*unsafe.Pointer)(f(v))
+		if !isUnsafePointer(info, call.Fun) {
+			break
+		}
+		// Here arg is *(*unsafe.Pointer)(unsafe.Pointer(v))
+		u, ok := call.Args[0].(*ast.UnaryExpr)
+		if !ok || u.Op != token.AND {
+			break
+		}
+		// Here arg is *(*unsafe.Pointer)(unsafe.Pointer(&v))
+		return cgoBaseType(info, u.X)
+	}
+
+	return info.Types[arg].Type
+}
+
+// typeOKForCgoCall reports whether the type of arg is OK to pass to a
+// C function using cgo. This is not true for Go types with embedded
+// pointers. m is used to avoid infinite recursion on recursive types.
+func typeOKForCgoCall(t types.Type, m map[types.Type]bool) bool {
+	if t == nil || m[t] {
+		return true
+	}
+	m[t] = true
+	switch t := t.Underlying().(type) {
+	case *types.Chan, *types.Map, *types.Signature, *types.Slice:
+		return false
+	case *types.Pointer:
+		return typeOKForCgoCall(t.Elem(), m)
+	case *types.Array:
+		return typeOKForCgoCall(t.Elem(), m)
+	case *types.Struct:
+		for i := 0; i < t.NumFields(); i++ {
+			if !typeOKForCgoCall(t.Field(i).Type(), m) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+func isUnsafePointer(info *types.Info, e ast.Expr) bool {
+	t := info.Types[e].Type
+	return t != nil && t.Underlying() == types.Typ[types.UnsafePointer]
+}
+
+type importerFunc func(path string) (*types.Package, error)
+
+func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }
+
+// TODO(adonovan): make this a library function or method of Info.
+func imported(info *types.Info, spec *ast.ImportSpec) *types.Package {
+	obj, ok := info.Implicits[spec]
+	if !ok {
+		obj = info.Defs[spec.Name] // renaming import
+	}
+	return obj.(*types.PkgName).Imported()
+}
+
+// imports reports whether pkg has path among its direct imports.
+// It returns the imported package if so, or nil if not.
+// TODO(adonovan): move to analysisutil.
+func imports(pkg *types.Package, path string) *types.Package {
+	for _, imp := range pkg.Imports() {
+		if imp.Path() == path {
+			return imp
+		}
+	}
+	return nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/composite/composite.go b/libgo/go/golang.org/x/tools/go/analysis/passes/composite/composite.go
new file mode 100644
index 00000000000..9cca7781d00
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/composite/composite.go
@@ -0,0 +1,108 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package composite defines an Analyzer that checks for unkeyed
+// composite literals.
+package composite
+
+import (
+	"go/ast"
+	"go/types"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for unkeyed composite literals
+
+This analyzer reports a diagnostic for composite literals of struct
+types imported from another package that do not use the field-keyed
+syntax. Such literals are fragile because the addition of a new field
+(even if unexported) to the struct will cause compilation to fail.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "composites",
+	Doc:              Doc,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+var whitelist = true
+
+func init() {
+	Analyzer.Flags.BoolVar(&whitelist, "whitelist", whitelist, "use composite white list; for testing only")
+}
+
+// runUnkeyedLiteral checks if a composite literal is a struct literal with
+// unkeyed fields.
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.CompositeLit)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		cl := n.(*ast.CompositeLit)
+
+		typ := pass.TypesInfo.Types[cl].Type
+		if typ == nil {
+			// cannot determine composite literals' type, skip it
+			return
+		}
+		typeName := typ.String()
+		if whitelist && unkeyedLiteral[typeName] {
+			// skip whitelisted types
+			return
+		}
+		under := typ.Underlying()
+		for {
+			ptr, ok := under.(*types.Pointer)
+			if !ok {
+				break
+			}
+			under = ptr.Elem().Underlying()
+		}
+		if _, ok := under.(*types.Struct); !ok {
+			// skip non-struct composite literals
+			return
+		}
+		if isLocalType(pass, typ) {
+			// allow unkeyed locally defined composite literal
+			return
+		}
+
+		// check if the CompositeLit contains an unkeyed field
+		allKeyValue := true
+		for _, e := range cl.Elts {
+			if _, ok := e.(*ast.KeyValueExpr); !ok {
+				allKeyValue = false
+				break
+			}
+		}
+		if allKeyValue {
+			// all the composite literal fields are keyed
+			return
+		}
+
+		pass.Reportf(cl.Pos(), "%s composite literal uses unkeyed fields", typeName)
+	})
+	return nil, nil
+}
+
+func isLocalType(pass *analysis.Pass, typ types.Type) bool {
+	switch x := typ.(type) {
+	case *types.Struct:
+		// struct literals are local types
+		return true
+	case *types.Pointer:
+		return isLocalType(pass, x.Elem())
+	case *types.Named:
+		// names in package foo are local to foo_test too
+		return strings.TrimSuffix(x.Obj().Pkg().Path(), "_test") == strings.TrimSuffix(pass.Pkg.Path(), "_test")
+	}
+	return false
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/composite/whitelist.go b/libgo/go/golang.org/x/tools/go/analysis/passes/composite/whitelist.go
new file mode 100644
index 00000000000..ab609f279bc
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/composite/whitelist.go
@@ -0,0 +1,33 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package composite
+
+// unkeyedLiteral is a white list of types in the standard packages
+// that are used with unkeyed literals we deem to be acceptable.
+var unkeyedLiteral = map[string]bool{
+	// These image and image/color struct types are frozen. We will never add fields to them.
+	"image/color.Alpha16": true,
+	"image/color.Alpha":   true,
+	"image/color.CMYK":    true,
+	"image/color.Gray16":  true,
+	"image/color.Gray":    true,
+	"image/color.NRGBA64": true,
+	"image/color.NRGBA":   true,
+	"image/color.NYCbCrA": true,
+	"image/color.RGBA64":  true,
+	"image/color.RGBA":    true,
+	"image/color.YCbCr":   true,
+	"image.Point":         true,
+	"image.Rectangle":     true,
+	"image.Uniform":       true,
+
+	"unicode.Range16": true,
+
+	// These three structs are used in generated test main files,
+	// but the generator can be trusted.
+	"testing.InternalBenchmark": true,
+	"testing.InternalExample":   true,
+	"testing.InternalTest":      true,
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/copylock/copylock.go b/libgo/go/golang.org/x/tools/go/analysis/passes/copylock/copylock.go
new file mode 100644
index 00000000000..067aed57df3
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/copylock/copylock.go
@@ -0,0 +1,300 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package copylock defines an Analyzer that checks for locks
+// erroneously passed by value.
+package copylock
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for locks erroneously passed by value
+
+Inadvertently copying a value containing a lock, such as sync.Mutex or
+sync.WaitGroup, may cause both copies to malfunction. Generally such
+values should be referred to through a pointer.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "copylocks",
+	Doc:              Doc,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.AssignStmt)(nil),
+		(*ast.CallExpr)(nil),
+		(*ast.CompositeLit)(nil),
+		(*ast.FuncDecl)(nil),
+		(*ast.FuncLit)(nil),
+		(*ast.GenDecl)(nil),
+		(*ast.RangeStmt)(nil),
+		(*ast.ReturnStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(node ast.Node) {
+		switch node := node.(type) {
+		case *ast.RangeStmt:
+			checkCopyLocksRange(pass, node)
+		case *ast.FuncDecl:
+			checkCopyLocksFunc(pass, node.Name.Name, node.Recv, node.Type)
+		case *ast.FuncLit:
+			checkCopyLocksFunc(pass, "func", nil, node.Type)
+		case *ast.CallExpr:
+			checkCopyLocksCallExpr(pass, node)
+		case *ast.AssignStmt:
+			checkCopyLocksAssign(pass, node)
+		case *ast.GenDecl:
+			checkCopyLocksGenDecl(pass, node)
+		case *ast.CompositeLit:
+			checkCopyLocksCompositeLit(pass, node)
+		case *ast.ReturnStmt:
+			checkCopyLocksReturnStmt(pass, node)
+		}
+	})
+	return nil, nil
+}
+
+// checkCopyLocksAssign checks whether an assignment
+// copies a lock.
+func checkCopyLocksAssign(pass *analysis.Pass, as *ast.AssignStmt) {
+	for i, x := range as.Rhs {
+		if path := lockPathRhs(pass, x); path != nil {
+			pass.Reportf(x.Pos(), "assignment copies lock value to %v: %v", analysisutil.Format(pass.Fset, as.Lhs[i]), path)
+		}
+	}
+}
+
+// checkCopyLocksGenDecl checks whether lock is copied
+// in variable declaration.
+func checkCopyLocksGenDecl(pass *analysis.Pass, gd *ast.GenDecl) {
+	if gd.Tok != token.VAR {
+		return
+	}
+	for _, spec := range gd.Specs {
+		valueSpec := spec.(*ast.ValueSpec)
+		for i, x := range valueSpec.Values {
+			if path := lockPathRhs(pass, x); path != nil {
+				pass.Reportf(x.Pos(), "variable declaration copies lock value to %v: %v", valueSpec.Names[i].Name, path)
+			}
+		}
+	}
+}
+
+// checkCopyLocksCompositeLit detects lock copy inside a composite literal
+func checkCopyLocksCompositeLit(pass *analysis.Pass, cl *ast.CompositeLit) {
+	for _, x := range cl.Elts {
+		if node, ok := x.(*ast.KeyValueExpr); ok {
+			x = node.Value
+		}
+		if path := lockPathRhs(pass, x); path != nil {
+			pass.Reportf(x.Pos(), "literal copies lock value from %v: %v", analysisutil.Format(pass.Fset, x), path)
+		}
+	}
+}
+
+// checkCopyLocksReturnStmt detects lock copy in return statement
+func checkCopyLocksReturnStmt(pass *analysis.Pass, rs *ast.ReturnStmt) {
+	for _, x := range rs.Results {
+		if path := lockPathRhs(pass, x); path != nil {
+			pass.Reportf(x.Pos(), "return copies lock value: %v", path)
+		}
+	}
+}
+
+// checkCopyLocksCallExpr detects lock copy in the arguments to a function call
+func checkCopyLocksCallExpr(pass *analysis.Pass, ce *ast.CallExpr) {
+	var id *ast.Ident
+	switch fun := ce.Fun.(type) {
+	case *ast.Ident:
+		id = fun
+	case *ast.SelectorExpr:
+		id = fun.Sel
+	}
+	if fun, ok := pass.TypesInfo.Uses[id].(*types.Builtin); ok {
+		switch fun.Name() {
+		case "new", "len", "cap", "Sizeof":
+			return
+		}
+	}
+	for _, x := range ce.Args {
+		if path := lockPathRhs(pass, x); path != nil {
+			pass.Reportf(x.Pos(), "call of %s copies lock value: %v", analysisutil.Format(pass.Fset, ce.Fun), path)
+		}
+	}
+}
+
+// checkCopyLocksFunc checks whether a function might
+// inadvertently copy a lock, by checking whether
+// its receiver, parameters, or return values
+// are locks.
+func checkCopyLocksFunc(pass *analysis.Pass, name string, recv *ast.FieldList, typ *ast.FuncType) {
+	if recv != nil && len(recv.List) > 0 {
+		expr := recv.List[0].Type
+		if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
+			pass.Reportf(expr.Pos(), "%s passes lock by value: %v", name, path)
+		}
+	}
+
+	if typ.Params != nil {
+		for _, field := range typ.Params.List {
+			expr := field.Type
+			if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type); path != nil {
+				pass.Reportf(expr.Pos(), "%s passes lock by value: %v", name, path)
+			}
+		}
+	}
+
+	// Don't check typ.Results. If T has a Lock field it's OK to write
+	//     return T{}
+	// because that is returning the zero value. Leave result checking
+	// to the return statement.
+}
+
+// checkCopyLocksRange checks whether a range statement
+// might inadvertently copy a lock by checking whether
+// any of the range variables are locks.
+func checkCopyLocksRange(pass *analysis.Pass, r *ast.RangeStmt) {
+	checkCopyLocksRangeVar(pass, r.Tok, r.Key)
+	checkCopyLocksRangeVar(pass, r.Tok, r.Value)
+}
+
+func checkCopyLocksRangeVar(pass *analysis.Pass, rtok token.Token, e ast.Expr) {
+	if e == nil {
+		return
+	}
+	id, isId := e.(*ast.Ident)
+	if isId && id.Name == "_" {
+		return
+	}
+
+	var typ types.Type
+	if rtok == token.DEFINE {
+		if !isId {
+			return
+		}
+		obj := pass.TypesInfo.Defs[id]
+		if obj == nil {
+			return
+		}
+		typ = obj.Type()
+	} else {
+		typ = pass.TypesInfo.Types[e].Type
+	}
+
+	if typ == nil {
+		return
+	}
+	if path := lockPath(pass.Pkg, typ); path != nil {
+		pass.Reportf(e.Pos(), "range var %s copies lock: %v", analysisutil.Format(pass.Fset, e), path)
+	}
+}
+
+type typePath []types.Type
+
+// String pretty-prints a typePath.
+func (path typePath) String() string {
+	n := len(path)
+	var buf bytes.Buffer
+	for i := range path {
+		if i > 0 {
+			fmt.Fprint(&buf, " contains ")
+		}
+		// The human-readable path is in reverse order, outermost to innermost.
+		fmt.Fprint(&buf, path[n-i-1].String())
+	}
+	return buf.String()
+}
+
+func lockPathRhs(pass *analysis.Pass, x ast.Expr) typePath {
+	if _, ok := x.(*ast.CompositeLit); ok {
+		return nil
+	}
+	if _, ok := x.(*ast.CallExpr); ok {
+		// A call may return a zero value.
+		return nil
+	}
+	if star, ok := x.(*ast.StarExpr); ok {
+		if _, ok := star.X.(*ast.CallExpr); ok {
+			// A call may return a pointer to a zero value.
+			return nil
+		}
+	}
+	return lockPath(pass.Pkg, pass.TypesInfo.Types[x].Type)
+}
+
+// lockPath returns a typePath describing the location of a lock value
+// contained in typ. If there is no contained lock, it returns nil.
+func lockPath(tpkg *types.Package, typ types.Type) typePath {
+	if typ == nil {
+		return nil
+	}
+
+	for {
+		atyp, ok := typ.Underlying().(*types.Array)
+		if !ok {
+			break
+		}
+		typ = atyp.Elem()
+	}
+
+	// We're only interested in the case in which the underlying
+	// type is a struct. (Interfaces and pointers are safe to copy.)
+	styp, ok := typ.Underlying().(*types.Struct)
+	if !ok {
+		return nil
+	}
+
+	// We're looking for cases in which a pointer to this type
+	// is a sync.Locker, but a value is not. This differentiates
+	// embedded interfaces from embedded values.
+	if types.Implements(types.NewPointer(typ), lockerType) && !types.Implements(typ, lockerType) {
+		return []types.Type{typ}
+	}
+
+	// In go1.10, sync.noCopy did not implement Locker.
+	// (The Unlock method was added only in CL 121876.)
+	// TODO(adonovan): remove workaround when we drop go1.10.
+	if named, ok := typ.(*types.Named); ok &&
+		named.Obj().Name() == "noCopy" &&
+		named.Obj().Pkg().Path() == "sync" {
+		return []types.Type{typ}
+	}
+
+	nfields := styp.NumFields()
+	for i := 0; i < nfields; i++ {
+		ftyp := styp.Field(i).Type()
+		subpath := lockPath(tpkg, ftyp)
+		if subpath != nil {
+			return append(subpath, typ)
+		}
+	}
+
+	return nil
+}
+
+var lockerType *types.Interface
+
+// Construct a sync.Locker interface type.
+func init() {
+	nullary := types.NewSignature(nil, nil, nil, false) // func()
+	methods := []*types.Func{
+		types.NewFunc(token.NoPos, nil, "Lock", nullary),
+		types.NewFunc(token.NoPos, nil, "Unlock", nullary),
+	}
+	lockerType = types.NewInterface(methods, nil).Complete()
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/ctrlflow/ctrlflow.go b/libgo/go/golang.org/x/tools/go/analysis/passes/ctrlflow/ctrlflow.go
new file mode 100644
index 00000000000..75655c5bad4
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/ctrlflow/ctrlflow.go
@@ -0,0 +1,225 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ctrlflow is an analysis that provides a syntactic
+// control-flow graph (CFG) for the body of a function.
+// It records whether a function cannot return.
+// By itself, it does not report any diagnostics.
+package ctrlflow
+
+import (
+	"go/ast"
+	"go/types"
+	"log"
+	"reflect"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/go/cfg"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name:       "ctrlflow",
+	Doc:        "build a control-flow graph",
+	Run:        run,
+	ResultType: reflect.TypeOf(new(CFGs)),
+	FactTypes:  []analysis.Fact{new(noReturn)},
+	Requires:   []*analysis.Analyzer{inspect.Analyzer},
+}
+
+// noReturn is a fact indicating that a function does not return.
+type noReturn struct{}
+
+func (*noReturn) AFact() {}
+
+func (*noReturn) String() string { return "noReturn" }
+
+// A CFGs holds the control-flow graphs
+// for all the functions of the current package.
+type CFGs struct {
+	defs      map[*ast.Ident]types.Object // from Pass.TypesInfo.Defs
+	funcDecls map[*types.Func]*declInfo
+	funcLits  map[*ast.FuncLit]*litInfo
+	pass      *analysis.Pass // transient; nil after construction
+}
+
+// CFGs has two maps: funcDecls for named functions and funcLits for
+// unnamed ones. Unlike funcLits, the funcDecls map is not keyed by its
+// syntax node, *ast.FuncDecl, because callMayReturn needs to do a
+// look-up by *types.Func, and you can get from an *ast.FuncDecl to a
+// *types.Func but not the other way.
+
+type declInfo struct {
+	decl     *ast.FuncDecl
+	cfg      *cfg.CFG // iff decl.Body != nil
+	started  bool     // to break cycles
+	noReturn bool
+}
+
+type litInfo struct {
+	cfg      *cfg.CFG
+	noReturn bool
+}
+
+// FuncDecl returns the control-flow graph for a named function.
+// It returns nil if decl.Body==nil.
+func (c *CFGs) FuncDecl(decl *ast.FuncDecl) *cfg.CFG {
+	if decl.Body == nil {
+		return nil
+	}
+	fn := c.defs[decl.Name].(*types.Func)
+	return c.funcDecls[fn].cfg
+}
+
+// FuncLit returns the control-flow graph for a literal function.
+func (c *CFGs) FuncLit(lit *ast.FuncLit) *cfg.CFG {
+	return c.funcLits[lit].cfg
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	// Because CFG construction consumes and produces noReturn
+	// facts, CFGs for exported FuncDecls must be built before 'run'
+	// returns; we cannot construct them lazily.
+	// (We could build CFGs for FuncLits lazily,
+	// but the benefit is marginal.)
+
+	// Pass 1. Map types.Funcs to ast.FuncDecls in this package.
+	funcDecls := make(map[*types.Func]*declInfo) // functions and methods
+	funcLits := make(map[*ast.FuncLit]*litInfo)
+
+	var decls []*types.Func // keys(funcDecls), in order
+	var lits []*ast.FuncLit // keys(funcLits), in order
+
+	nodeFilter := []ast.Node{
+		(*ast.FuncDecl)(nil),
+		(*ast.FuncLit)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		switch n := n.(type) {
+		case *ast.FuncDecl:
+			fn := pass.TypesInfo.Defs[n.Name].(*types.Func)
+			funcDecls[fn] = &declInfo{decl: n}
+			decls = append(decls, fn)
+
+		case *ast.FuncLit:
+			funcLits[n] = new(litInfo)
+			lits = append(lits, n)
+		}
+	})
+
+	c := &CFGs{
+		defs:      pass.TypesInfo.Defs,
+		funcDecls: funcDecls,
+		funcLits:  funcLits,
+		pass:      pass,
+	}
+
+	// Pass 2. Build CFGs.
+
+	// Build CFGs for named functions.
+	// Cycles in the static call graph are broken
+	// arbitrarily but deterministically.
+	// We create noReturn facts as discovered.
+	for _, fn := range decls {
+		c.buildDecl(fn, funcDecls[fn])
+	}
+
+	// Build CFGs for literal functions.
+	// These aren't relevant to facts (since they aren't named)
+	// but are required for the CFGs.FuncLit API.
+	for _, lit := range lits {
+		li := funcLits[lit]
+		if li.cfg == nil {
+			li.cfg = cfg.New(lit.Body, c.callMayReturn)
+			if !hasReachableReturn(li.cfg) {
+				li.noReturn = true
+			}
+		}
+	}
+
+	// All CFGs are now built.
+	c.pass = nil
+
+	return c, nil
+}
+
+// di.cfg may be nil on return.
+func (c *CFGs) buildDecl(fn *types.Func, di *declInfo) {
+	// buildDecl may call itself recursively for the same function,
+	// because cfg.New is passed the callMayReturn method, which
+	// builds the CFG of the callee, leading to recursion.
+	// The buildDecl call tree thus resembles the static call graph.
+	// We mark each node when we start working on it to break cycles.
+
+	if !di.started { // break cycle
+		di.started = true
+
+		if isIntrinsicNoReturn(fn) {
+			di.noReturn = true
+		}
+		if di.decl.Body != nil {
+			di.cfg = cfg.New(di.decl.Body, c.callMayReturn)
+			if !hasReachableReturn(di.cfg) {
+				di.noReturn = true
+			}
+		}
+		if di.noReturn {
+			c.pass.ExportObjectFact(fn, new(noReturn))
+		}
+
+		// debugging
+		if false {
+			log.Printf("CFG for %s:\n%s (noreturn=%t)\n", fn, di.cfg.Format(c.pass.Fset), di.noReturn)
+		}
+	}
+}
+
+// callMayReturn reports whether the called function may return.
+// It is passed to the CFG builder.
+func (c *CFGs) callMayReturn(call *ast.CallExpr) (r bool) {
+	if id, ok := call.Fun.(*ast.Ident); ok && c.pass.TypesInfo.Uses[id] == panicBuiltin {
+		return false // panic never returns
+	}
+
+	// Is this a static call?
+	fn := typeutil.StaticCallee(c.pass.TypesInfo, call)
+	if fn == nil {
+		return true // callee not statically known; be conservative
+	}
+
+	// Function or method declared in this package?
+	if di, ok := c.funcDecls[fn]; ok {
+		c.buildDecl(fn, di)
+		return !di.noReturn
+	}
+
+	// Not declared in this package.
+	// Is there a fact from another package?
+	return !c.pass.ImportObjectFact(fn, new(noReturn))
+}
+
+var panicBuiltin = types.Universe.Lookup("panic").(*types.Builtin)
+
+func hasReachableReturn(g *cfg.CFG) bool {
+	for _, b := range g.Blocks {
+		if b.Live && b.Return() != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// isIntrinsicNoReturn reports whether a function intrinsically never
+// returns because it stops execution of the calling thread.
+// It is the base case in the recursion.
+func isIntrinsicNoReturn(fn *types.Func) bool {
+	// Add functions here as the need arises, but don't allocate memory.
+	path, name := fn.Pkg().Path(), fn.Name()
+	return path == "syscall" && (name == "Exit" || name == "ExitProcess" || name == "ExitThread") ||
+		path == "runtime" && name == "Goexit"
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/httpresponse/httpresponse.go b/libgo/go/golang.org/x/tools/go/analysis/passes/httpresponse/httpresponse.go
new file mode 100644
index 00000000000..0cf21b8cd1e
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/httpresponse/httpresponse.go
@@ -0,0 +1,177 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package httpresponse defines an Analyzer that checks for mistakes
+// using HTTP responses.
+package httpresponse
+
+import (
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for mistakes using HTTP responses
+
+A common mistake when using the net/http package is to defer a function
+call to close the http.Response Body before checking the error that
+determines whether the response is valid:
+
+	resp, err := http.Head(url)
+	defer resp.Body.Close()
+	if err != nil {
+		log.Fatal(err)
+	}
+	// (defer statement belongs here)
+
+This checker helps uncover latent nil dereference bugs by reporting a
+diagnostic for such mistakes.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "httpresponse",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	// Fast path: if the package doesn't import net/http,
+	// skip the traversal.
+	if !imports(pass.Pkg, "net/http") {
+		return nil, nil
+	}
+
+	nodeFilter := []ast.Node{
+		(*ast.CallExpr)(nil),
+	}
+	inspect.WithStack(nodeFilter, func(n ast.Node, push bool, stack []ast.Node) bool {
+		if !push {
+			return true
+		}
+		call := n.(*ast.CallExpr)
+		if !isHTTPFuncOrMethodOnClient(pass.TypesInfo, call) {
+			return true // the function call is not related to this check.
+		}
+
+		// Find the innermost containing block, and get the list
+		// of statements starting with the one containing call.
+		stmts := restOfBlock(stack)
+		if len(stmts) < 2 {
+			return true // the call to the http function is the last statement of the block.
+		}
+
+		asg, ok := stmts[0].(*ast.AssignStmt)
+		if !ok {
+			return true // the first statement is not assignment.
+		}
+		resp := rootIdent(asg.Lhs[0])
+		if resp == nil {
+			return true // could not find the http.Response in the assignment.
+		}
+
+		def, ok := stmts[1].(*ast.DeferStmt)
+		if !ok {
+			return true // the following statement is not a defer.
+		}
+		root := rootIdent(def.Call.Fun)
+		if root == nil {
+			return true // could not find the receiver of the defer call.
+		}
+
+		if resp.Obj == root.Obj {
+			pass.Reportf(root.Pos(), "using %s before checking for errors", resp.Name)
+		}
+		return true
+	})
+	return nil, nil
+}
+
+// isHTTPFuncOrMethodOnClient checks whether the given call expression is on
+// either a function of the net/http package or a method of http.Client that
+// returns (*http.Response, error).
+func isHTTPFuncOrMethodOnClient(info *types.Info, expr *ast.CallExpr) bool {
+	fun, _ := expr.Fun.(*ast.SelectorExpr)
+	sig, _ := info.Types[fun].Type.(*types.Signature)
+	if sig == nil {
+		return false // the call is not of the form x.f()
+	}
+
+	res := sig.Results()
+	if res.Len() != 2 {
+		return false // the function called does not return two values.
+	}
+	if ptr, ok := res.At(0).Type().(*types.Pointer); !ok || !isNamedType(ptr.Elem(), "net/http", "Response") {
+		return false // the first return type is not *http.Response.
+	}
+
+	errorType := types.Universe.Lookup("error").Type()
+	if !types.Identical(res.At(1).Type(), errorType) {
+		return false // the second return type is not error
+	}
+
+	typ := info.Types[fun.X].Type
+	if typ == nil {
+		id, ok := fun.X.(*ast.Ident)
+		return ok && id.Name == "http" // function in net/http package.
+	}
+
+	if isNamedType(typ, "net/http", "Client") {
+		return true // method on http.Client.
+	}
+	ptr, ok := typ.(*types.Pointer)
+	return ok && isNamedType(ptr.Elem(), "net/http", "Client") // method on *http.Client.
+}
+
+// restOfBlock, given a traversal stack, finds the innermost containing
+// block and returns the suffix of its statements starting with the
+// current node (the last element of stack).
+func restOfBlock(stack []ast.Node) []ast.Stmt {
+	for i := len(stack) - 1; i >= 0; i-- {
+		if b, ok := stack[i].(*ast.BlockStmt); ok {
+			for j, v := range b.List {
+				if v == stack[i+1] {
+					return b.List[j:]
+				}
+			}
+			break
+		}
+	}
+	return nil
+}
+
+// rootIdent finds the root identifier x in a chain of selections x.y.z, or nil if not found.
+func rootIdent(n ast.Node) *ast.Ident {
+	switch n := n.(type) {
+	case *ast.SelectorExpr:
+		return rootIdent(n.X)
+	case *ast.Ident:
+		return n
+	default:
+		return nil
+	}
+}
+
+// isNamedType reports whether t is the named type path.name.
+func isNamedType(t types.Type, path, name string) bool {
+	n, ok := t.(*types.Named)
+	if !ok {
+		return false
+	}
+	obj := n.Obj()
+	return obj.Name() == name && obj.Pkg() != nil && obj.Pkg().Path() == path
+}
+
+func imports(pkg *types.Package, path string) bool {
+	for _, imp := range pkg.Imports() {
+		if imp.Path() == path {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/inspect/inspect.go b/libgo/go/golang.org/x/tools/go/analysis/passes/inspect/inspect.go
new file mode 100644
index 00000000000..bd06549984a
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/inspect/inspect.go
@@ -0,0 +1,45 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package inspect defines an Analyzer that provides an AST inspector
+// (golang.org/x/tools/go/ast/inspect.Inspect) for the syntax trees of a
+// package. It is only a building block for other analyzers.
+//
+// Example of use in another analysis:
+//
+//	import "golang.org/x/tools/go/analysis/passes/inspect"
+//
+//	var Analyzer = &analysis.Analyzer{
+//		...
+//		Requires:       reflect.TypeOf(new(inspect.Analyzer)),
+//	}
+//
+// 	func run(pass *analysis.Pass) (interface{}, error) {
+// 		inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+// 		inspect.Preorder(nil, func(n ast.Node) {
+// 			...
+// 		})
+// 		return nil
+// 	}
+//
+package inspect
+
+import (
+	"reflect"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "inspect",
+	Doc:              "optimize AST traversal for later passes",
+	Run:              run,
+	RunDespiteErrors: true,
+	ResultType:       reflect.TypeOf(new(inspector.Inspector)),
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	return inspector.New(pass.Files), nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/internal/analysisutil/util.go b/libgo/go/golang.org/x/tools/go/analysis/passes/internal/analysisutil/util.go
new file mode 100644
index 00000000000..13a458d9d6b
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/internal/analysisutil/util.go
@@ -0,0 +1,106 @@
+// Package analysisutil defines various helper functions
+// used by two or more packages beneath go/analysis.
+package analysisutil
+
+import (
+	"bytes"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"go/types"
+	"io/ioutil"
+)
+
+// Format returns a string representation of the expression.
+func Format(fset *token.FileSet, x ast.Expr) string {
+	var b bytes.Buffer
+	printer.Fprint(&b, fset, x)
+	return b.String()
+}
+
+// HasSideEffects reports whether evaluation of e has side effects.
+func HasSideEffects(info *types.Info, e ast.Expr) bool {
+	safe := true
+	ast.Inspect(e, func(node ast.Node) bool {
+		switch n := node.(type) {
+		case *ast.CallExpr:
+			typVal := info.Types[n.Fun]
+			switch {
+			case typVal.IsType():
+				// Type conversion, which is safe.
+			case typVal.IsBuiltin():
+				// Builtin func, conservatively assumed to not
+				// be safe for now.
+				safe = false
+				return false
+			default:
+				// A non-builtin func or method call.
+				// Conservatively assume that all of them have
+				// side effects for now.
+				safe = false
+				return false
+			}
+		case *ast.UnaryExpr:
+			if n.Op == token.ARROW {
+				safe = false
+				return false
+			}
+		}
+		return true
+	})
+	return !safe
+}
+
+// Unparen returns e with any enclosing parentheses stripped.
+func Unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}
+
+// ReadFile reads a file and adds it to the FileSet
+// so that we can report errors against it using lineStart.
+func ReadFile(fset *token.FileSet, filename string) ([]byte, *token.File, error) {
+	content, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, nil, err
+	}
+	tf := fset.AddFile(filename, -1, len(content))
+	tf.SetLinesForContent(content)
+	return content, tf, nil
+}
+
+// LineStart returns the position of the start of the specified line
+// within file f, or NoPos if there is no line of that number.
+func LineStart(f *token.File, line int) token.Pos {
+	// Use binary search to find the start offset of this line.
+	//
+	// TODO(adonovan): eventually replace this function with the
+	// simpler and more efficient (*go/token.File).LineStart, added
+	// in go1.12.
+
+	min := 0        // inclusive
+	max := f.Size() // exclusive
+	for {
+		offset := (min + max) / 2
+		pos := f.Pos(offset)
+		posn := f.Position(pos)
+		if posn.Line == line {
+			return pos - (token.Pos(posn.Column) - 1)
+		}
+
+		if min+1 >= max {
+			return token.NoPos
+		}
+
+		if posn.Line < line {
+			min = offset
+		} else {
+			max = offset
+		}
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/loopclosure/loopclosure.go b/libgo/go/golang.org/x/tools/go/analysis/passes/loopclosure/loopclosure.go
new file mode 100644
index 00000000000..da0714069f7
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/loopclosure/loopclosure.go
@@ -0,0 +1,130 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package loopclosure defines an Analyzer that checks for references to
+// enclosing loop variables from within nested functions.
+package loopclosure
+
+import (
+	"go/ast"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+// TODO(adonovan): also report an error for the following structure,
+// which is often used to ensure that deferred calls do not accumulate
+// in a loop:
+//
+//	for i, x := range c {
+//		func() {
+//			...reference to i or x...
+//		}()
+//	}
+
+const Doc = `check references to loop variables from within nested functions
+
+This analyzer checks for references to loop variables from within a
+function literal inside the loop body. It checks only instances where
+the function literal is called in a defer or go statement that is the
+last statement in the loop body, as otherwise we would need whole
+program analysis.
+
+For example:
+
+	for i, v := range s {
+		go func() {
+			println(i, v) // not what you might expect
+		}()
+	}
+
+See: https://golang.org/doc/go_faq.html#closures_and_goroutines`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "loopclosure",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.RangeStmt)(nil),
+		(*ast.ForStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		// Find the variables updated by the loop statement.
+		var vars []*ast.Ident
+		addVar := func(expr ast.Expr) {
+			if id, ok := expr.(*ast.Ident); ok {
+				vars = append(vars, id)
+			}
+		}
+		var body *ast.BlockStmt
+		switch n := n.(type) {
+		case *ast.RangeStmt:
+			body = n.Body
+			addVar(n.Key)
+			addVar(n.Value)
+		case *ast.ForStmt:
+			body = n.Body
+			switch post := n.Post.(type) {
+			case *ast.AssignStmt:
+				// e.g. for p = head; p != nil; p = p.next
+				for _, lhs := range post.Lhs {
+					addVar(lhs)
+				}
+			case *ast.IncDecStmt:
+				// e.g. for i := 0; i < n; i++
+				addVar(post.X)
+			}
+		}
+		if vars == nil {
+			return
+		}
+
+		// Inspect a go or defer statement
+		// if it's the last one in the loop body.
+		// (We give up if there are following statements,
+		// because it's hard to prove go isn't followed by wait,
+		// or defer by return.)
+		if len(body.List) == 0 {
+			return
+		}
+		var last *ast.CallExpr
+		switch s := body.List[len(body.List)-1].(type) {
+		case *ast.GoStmt:
+			last = s.Call
+		case *ast.DeferStmt:
+			last = s.Call
+		default:
+			return
+		}
+		lit, ok := last.Fun.(*ast.FuncLit)
+		if !ok {
+			return
+		}
+		ast.Inspect(lit.Body, func(n ast.Node) bool {
+			id, ok := n.(*ast.Ident)
+			if !ok || id.Obj == nil {
+				return true
+			}
+			if pass.TypesInfo.Types[id].Type == nil {
+				// Not referring to a variable (e.g. struct field name)
+				return true
+			}
+			for _, v := range vars {
+				if v.Obj == id.Obj {
+					pass.Reportf(id.Pos(), "loop variable %s captured by func literal",
+						id.Name)
+				}
+			}
+			return true
+		})
+	})
+	return nil, nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/lostcancel/lostcancel.go b/libgo/go/golang.org/x/tools/go/analysis/passes/lostcancel/lostcancel.go
new file mode 100644
index 00000000000..b5161836a57
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/lostcancel/lostcancel.go
@@ -0,0 +1,315 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package lostcancel defines an Analyzer that checks for failure to
+// call a context cancelation function.
+package lostcancel
+
+import (
+	"fmt"
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/ctrlflow"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/go/cfg"
+)
+
+const Doc = `check cancel func returned by context.WithCancel is called
+
+The cancelation function returned by context.WithCancel, WithTimeout,
+and WithDeadline must be called or the new context will remain live
+until its parent context is cancelled.
+(The background context is never cancelled.)`
+
+var Analyzer = &analysis.Analyzer{
+	Name: "lostcancel",
+	Doc:  Doc,
+	Run:  run,
+	Requires: []*analysis.Analyzer{
+		inspect.Analyzer,
+		ctrlflow.Analyzer,
+	},
+}
+
+const debug = false
+
+var contextPackage = "context"
+
+// checkLostCancel reports a failure to the call the cancel function
+// returned by context.WithCancel, either because the variable was
+// assigned to the blank identifier, or because there exists a
+// control-flow path from the call to a return statement and that path
+// does not "use" the cancel function.  Any reference to the variable
+// counts as a use, even within a nested function literal.
+//
+// checkLostCancel analyzes a single named or literal function.
+func run(pass *analysis.Pass) (interface{}, error) {
+	// Fast path: bypass check if file doesn't use context.WithCancel.
+	if !hasImport(pass.Pkg, contextPackage) {
+		return nil, nil
+	}
+
+	// Call runFunc for each Func{Decl,Lit}.
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+	nodeTypes := []ast.Node{
+		(*ast.FuncLit)(nil),
+		(*ast.FuncDecl)(nil),
+	}
+	inspect.Preorder(nodeTypes, func(n ast.Node) {
+		runFunc(pass, n)
+	})
+	return nil, nil
+}
+
+func runFunc(pass *analysis.Pass, node ast.Node) {
+	// Maps each cancel variable to its defining ValueSpec/AssignStmt.
+	cancelvars := make(map[*types.Var]ast.Node)
+
+	// TODO(adonovan): opt: refactor to make a single pass
+	// over the AST using inspect.WithStack and node types
+	// {FuncDecl,FuncLit,CallExpr,SelectorExpr}.
+
+	// Find the set of cancel vars to analyze.
+	stack := make([]ast.Node, 0, 32)
+	ast.Inspect(node, func(n ast.Node) bool {
+		switch n.(type) {
+		case *ast.FuncLit:
+			if len(stack) > 0 {
+				return false // don't stray into nested functions
+			}
+		case nil:
+			stack = stack[:len(stack)-1] // pop
+			return true
+		}
+		stack = append(stack, n) // push
+
+		// Look for [{AssignStmt,ValueSpec} CallExpr SelectorExpr]:
+		//
+		//   ctx, cancel    := context.WithCancel(...)
+		//   ctx, cancel     = context.WithCancel(...)
+		//   var ctx, cancel = context.WithCancel(...)
+		//
+		if !isContextWithCancel(pass.TypesInfo, n) || !isCall(stack[len(stack)-2]) {
+			return true
+		}
+		var id *ast.Ident // id of cancel var
+		stmt := stack[len(stack)-3]
+		switch stmt := stmt.(type) {
+		case *ast.ValueSpec:
+			if len(stmt.Names) > 1 {
+				id = stmt.Names[1]
+			}
+		case *ast.AssignStmt:
+			if len(stmt.Lhs) > 1 {
+				id, _ = stmt.Lhs[1].(*ast.Ident)
+			}
+		}
+		if id != nil {
+			if id.Name == "_" {
+				pass.Reportf(id.Pos(),
+					"the cancel function returned by context.%s should be called, not discarded, to avoid a context leak",
+					n.(*ast.SelectorExpr).Sel.Name)
+			} else if v, ok := pass.TypesInfo.Uses[id].(*types.Var); ok {
+				cancelvars[v] = stmt
+			} else if v, ok := pass.TypesInfo.Defs[id].(*types.Var); ok {
+				cancelvars[v] = stmt
+			}
+		}
+		return true
+	})
+
+	if len(cancelvars) == 0 {
+		return // no need to inspect CFG
+	}
+
+	// Obtain the CFG.
+	cfgs := pass.ResultOf[ctrlflow.Analyzer].(*ctrlflow.CFGs)
+	var g *cfg.CFG
+	var sig *types.Signature
+	switch node := node.(type) {
+	case *ast.FuncDecl:
+		sig, _ = pass.TypesInfo.Defs[node.Name].Type().(*types.Signature)
+		if node.Name.Name == "main" && sig.Recv() == nil && pass.Pkg.Name() == "main" {
+			// Returning from main.main terminates the process,
+			// so there's no need to cancel contexts.
+			return
+		}
+		g = cfgs.FuncDecl(node)
+
+	case *ast.FuncLit:
+		sig, _ = pass.TypesInfo.Types[node.Type].Type.(*types.Signature)
+		g = cfgs.FuncLit(node)
+	}
+	if sig == nil {
+		return // missing type information
+	}
+
+	// Print CFG.
+	if debug {
+		fmt.Println(g.Format(pass.Fset))
+	}
+
+	// Examine the CFG for each variable in turn.
+	// (It would be more efficient to analyze all cancelvars in a
+	// single pass over the AST, but seldom is there more than one.)
+	for v, stmt := range cancelvars {
+		if ret := lostCancelPath(pass, g, v, stmt, sig); ret != nil {
+			lineno := pass.Fset.Position(stmt.Pos()).Line
+			pass.Reportf(stmt.Pos(), "the %s function is not used on all paths (possible context leak)", v.Name())
+			pass.Reportf(ret.Pos(), "this return statement may be reached without using the %s var defined on line %d", v.Name(), lineno)
+		}
+	}
+}
+
+func isCall(n ast.Node) bool { _, ok := n.(*ast.CallExpr); return ok }
+
+func hasImport(pkg *types.Package, path string) bool {
+	for _, imp := range pkg.Imports() {
+		if imp.Path() == path {
+			return true
+		}
+	}
+	return false
+}
+
+// isContextWithCancel reports whether n is one of the qualified identifiers
+// context.With{Cancel,Timeout,Deadline}.
+func isContextWithCancel(info *types.Info, n ast.Node) bool {
+	sel, ok := n.(*ast.SelectorExpr)
+	if !ok {
+		return false
+	}
+	switch sel.Sel.Name {
+	case "WithCancel", "WithTimeout", "WithDeadline":
+	default:
+		return false
+	}
+	if x, ok := sel.X.(*ast.Ident); ok {
+		if pkgname, ok := info.Uses[x].(*types.PkgName); ok {
+			return pkgname.Imported().Path() == contextPackage
+		}
+		// Import failed, so we can't check package path.
+		// Just check the local package name (heuristic).
+		return x.Name == "context"
+	}
+	return false
+}
+
+// lostCancelPath finds a path through the CFG, from stmt (which defines
+// the 'cancel' variable v) to a return statement, that doesn't "use" v.
+// If it finds one, it returns the return statement (which may be synthetic).
+// sig is the function's type, if known.
+func lostCancelPath(pass *analysis.Pass, g *cfg.CFG, v *types.Var, stmt ast.Node, sig *types.Signature) *ast.ReturnStmt {
+	vIsNamedResult := sig != nil && tupleContains(sig.Results(), v)
+
+	// uses reports whether stmts contain a "use" of variable v.
+	uses := func(pass *analysis.Pass, v *types.Var, stmts []ast.Node) bool {
+		found := false
+		for _, stmt := range stmts {
+			ast.Inspect(stmt, func(n ast.Node) bool {
+				switch n := n.(type) {
+				case *ast.Ident:
+					if pass.TypesInfo.Uses[n] == v {
+						found = true
+					}
+				case *ast.ReturnStmt:
+					// A naked return statement counts as a use
+					// of the named result variables.
+					if n.Results == nil && vIsNamedResult {
+						found = true
+					}
+				}
+				return !found
+			})
+		}
+		return found
+	}
+
+	// blockUses computes "uses" for each block, caching the result.
+	memo := make(map[*cfg.Block]bool)
+	blockUses := func(pass *analysis.Pass, v *types.Var, b *cfg.Block) bool {
+		res, ok := memo[b]
+		if !ok {
+			res = uses(pass, v, b.Nodes)
+			memo[b] = res
+		}
+		return res
+	}
+
+	// Find the var's defining block in the CFG,
+	// plus the rest of the statements of that block.
+	var defblock *cfg.Block
+	var rest []ast.Node
+outer:
+	for _, b := range g.Blocks {
+		for i, n := range b.Nodes {
+			if n == stmt {
+				defblock = b
+				rest = b.Nodes[i+1:]
+				break outer
+			}
+		}
+	}
+	if defblock == nil {
+		panic("internal error: can't find defining block for cancel var")
+	}
+
+	// Is v "used" in the remainder of its defining block?
+	if uses(pass, v, rest) {
+		return nil
+	}
+
+	// Does the defining block return without using v?
+	if ret := defblock.Return(); ret != nil {
+		return ret
+	}
+
+	// Search the CFG depth-first for a path, from defblock to a
+	// return block, in which v is never "used".
+	seen := make(map[*cfg.Block]bool)
+	var search func(blocks []*cfg.Block) *ast.ReturnStmt
+	search = func(blocks []*cfg.Block) *ast.ReturnStmt {
+		for _, b := range blocks {
+			if seen[b] {
+				continue
+			}
+			seen[b] = true
+
+			// Prune the search if the block uses v.
+			if blockUses(pass, v, b) {
+				continue
+			}
+
+			// Found path to return statement?
+			if ret := b.Return(); ret != nil {
+				if debug {
+					fmt.Printf("found path to return in block %s\n", b)
+				}
+				return ret // found
+			}
+
+			// Recur
+			if ret := search(b.Succs); ret != nil {
+				if debug {
+					fmt.Printf(" from block %s\n", b)
+				}
+				return ret
+			}
+		}
+		return nil
+	}
+	return search(defblock.Succs)
+}
+
+func tupleContains(tuple *types.Tuple, v *types.Var) bool {
+	for i := 0; i < tuple.Len(); i++ {
+		if tuple.At(i) == v {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/nilfunc/nilfunc.go b/libgo/go/golang.org/x/tools/go/analysis/passes/nilfunc/nilfunc.go
new file mode 100644
index 00000000000..9c2d4df20a0
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/nilfunc/nilfunc.go
@@ -0,0 +1,74 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package nilfunc defines an Analyzer that checks for useless
+// comparisons against nil.
+package nilfunc
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for useless comparisons between functions and nil
+
+A useless comparison is one like f == nil as opposed to f() == nil.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "nilfunc",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.BinaryExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		e := n.(*ast.BinaryExpr)
+
+		// Only want == or != comparisons.
+		if e.Op != token.EQL && e.Op != token.NEQ {
+			return
+		}
+
+		// Only want comparisons with a nil identifier on one side.
+		var e2 ast.Expr
+		switch {
+		case pass.TypesInfo.Types[e.X].IsNil():
+			e2 = e.Y
+		case pass.TypesInfo.Types[e.Y].IsNil():
+			e2 = e.X
+		default:
+			return
+		}
+
+		// Only want identifiers or selector expressions.
+		var obj types.Object
+		switch v := e2.(type) {
+		case *ast.Ident:
+			obj = pass.TypesInfo.Uses[v]
+		case *ast.SelectorExpr:
+			obj = pass.TypesInfo.Uses[v.Sel]
+		default:
+			return
+		}
+
+		// Only want functions.
+		if _, ok := obj.(*types.Func); !ok {
+			return
+		}
+
+		pass.Reportf(e.Pos(), "comparison of function %v %v nil is always %v", obj.Name(), e.Op, e.Op == token.NEQ)
+	})
+	return nil, nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/pkgfact/pkgfact.go b/libgo/go/golang.org/x/tools/go/analysis/passes/pkgfact/pkgfact.go
new file mode 100644
index 00000000000..e0530867329
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/pkgfact/pkgfact.go
@@ -0,0 +1,127 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The pkgfact package is a demonstration and test of the package fact
+// mechanism.
+//
+// The output of the pkgfact analysis is a set of key/values pairs
+// gathered from the analyzed package and its imported dependencies.
+// Each key/value pair comes from a top-level constant declaration
+// whose name starts and ends with "_".  For example:
+//
+//      package p
+//
+// 	const _greeting_  = "hello"
+// 	const _audience_  = "world"
+//
+// the pkgfact analysis output for package p would be:
+//
+//   {"greeting": "hello", "audience": "world"}.
+//
+// In addition, the analysis reports a diagnostic at each import
+// showing which key/value pairs it contributes.
+package pkgfact
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"reflect"
+	"sort"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name:       "pkgfact",
+	Doc:        "gather name/value pairs from constant declarations",
+	Run:        run,
+	FactTypes:  []analysis.Fact{new(pairsFact)},
+	ResultType: reflect.TypeOf(map[string]string{}),
+}
+
+// A pairsFact is a package-level fact that records
+// an set of key=value strings accumulated from constant
+// declarations in this package and its dependencies.
+// Elements are ordered by keys, which are unique.
+type pairsFact []string
+
+func (f *pairsFact) AFact()         {}
+func (f *pairsFact) String() string { return "pairs(" + strings.Join(*f, ", ") + ")" }
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	result := make(map[string]string)
+
+	// At each import, print the fact from the imported
+	// package and accumulate its information into the result.
+	// (Warning: accumulation leads to quadratic growth of work.)
+	doImport := func(spec *ast.ImportSpec) {
+		pkg := imported(pass.TypesInfo, spec)
+		var fact pairsFact
+		if pass.ImportPackageFact(pkg, &fact) {
+			for _, pair := range fact {
+				eq := strings.IndexByte(pair, '=')
+				result[pair[:eq]] = pair[1+eq:]
+			}
+			pass.Reportf(spec.Pos(), "%s", strings.Join(fact, " "))
+		}
+	}
+
+	// At each "const _name_ = value", add a fact into env.
+	doConst := func(spec *ast.ValueSpec) {
+		if len(spec.Names) == len(spec.Values) {
+			for i := range spec.Names {
+				name := spec.Names[i].Name
+				if strings.HasPrefix(name, "_") && strings.HasSuffix(name, "_") {
+
+					if key := strings.Trim(name, "_"); key != "" {
+						value := pass.TypesInfo.Types[spec.Values[i]].Value.String()
+						result[key] = value
+					}
+				}
+			}
+		}
+	}
+
+	for _, f := range pass.Files {
+		for _, decl := range f.Decls {
+			if decl, ok := decl.(*ast.GenDecl); ok {
+				for _, spec := range decl.Specs {
+					switch decl.Tok {
+					case token.IMPORT:
+						doImport(spec.(*ast.ImportSpec))
+					case token.CONST:
+						doConst(spec.(*ast.ValueSpec))
+					}
+				}
+			}
+		}
+	}
+
+	// Sort/deduplicate the result and save it as a package fact.
+	keys := make([]string, 0, len(result))
+	for key := range result {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	var fact pairsFact
+	for _, key := range keys {
+		fact = append(fact, fmt.Sprintf("%s=%s", key, result[key]))
+	}
+	if len(fact) > 0 {
+		pass.ExportPackageFact(&fact)
+	}
+
+	return result, nil
+}
+
+func imported(info *types.Info, spec *ast.ImportSpec) *types.Package {
+	obj, ok := info.Implicits[spec]
+	if !ok {
+		obj = info.Defs[spec.Name] // renaming import
+	}
+	return obj.(*types.PkgName).Imported()
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/printf/printf.go b/libgo/go/golang.org/x/tools/go/analysis/passes/printf/printf.go
new file mode 100644
index 00000000000..c0265aafeee
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/printf/printf.go
@@ -0,0 +1,1017 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the printf-checker.
+
+package printf
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"unicode/utf8"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+func init() {
+	Analyzer.Flags.Var(isPrint, "funcs", "comma-separated list of print function names to check")
+}
+
+var Analyzer = &analysis.Analyzer{
+	Name:      "printf",
+	Doc:       doc,
+	Requires:  []*analysis.Analyzer{inspect.Analyzer},
+	Run:       run,
+	FactTypes: []analysis.Fact{new(isWrapper)},
+}
+
+const doc = `check consistency of Printf format strings and arguments
+
+The check applies to known functions (for example, those in package fmt)
+as well as any detected wrappers of known functions.
+
+A function that wants to avail itself of printf checking but is not
+found by this analyzer's heuristics (for example, due to use of
+dynamic calls) can insert a bogus call:
+
+	if false {
+		_ = fmt.Sprintf(format, args...) // enable printf checking
+	}
+
+The -funcs flag specifies a comma-separated list of names of additional
+known formatting functions or methods. If the name contains a period,
+it must denote a specific function using one of the following forms:
+
+	dir/pkg.Function
+	dir/pkg.Type.Method
+	(*dir/pkg.Type).Method
+
+Otherwise the name is interpreted as a case-insensitive unqualified
+identifier such as "errorf". Either way, if a listed name ends in f, the
+function is assumed to be Printf-like, taking a format string before the
+argument list. Otherwise it is assumed to be Print-like, taking a list
+of arguments with no format string.
+`
+
+// isWrapper is a fact indicating that a function is a print or printf wrapper.
+type isWrapper struct{ Printf bool }
+
+func (f *isWrapper) AFact() {}
+
+func (f *isWrapper) String() string {
+	if f.Printf {
+		return "printfWrapper"
+	} else {
+		return "printWrapper"
+	}
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	findPrintfLike(pass)
+	checkCall(pass)
+	return nil, nil
+}
+
+type printfWrapper struct {
+	obj     *types.Func
+	fdecl   *ast.FuncDecl
+	format  *types.Var
+	args    *types.Var
+	callers []printfCaller
+	failed  bool // if true, not a printf wrapper
+}
+
+type printfCaller struct {
+	w    *printfWrapper
+	call *ast.CallExpr
+}
+
+// maybePrintfWrapper decides whether decl (a declared function) may be a wrapper
+// around a fmt.Printf or fmt.Print function. If so it returns a printfWrapper
+// function describing the declaration. Later processing will analyze the
+// graph of potential printf wrappers to pick out the ones that are true wrappers.
+// A function may be a Printf or Print wrapper if its last argument is ...interface{}.
+// If the next-to-last argument is a string, then this may be a Printf wrapper.
+// Otherwise it may be a Print wrapper.
+func maybePrintfWrapper(info *types.Info, decl ast.Decl) *printfWrapper {
+	// Look for functions with final argument type ...interface{}.
+	fdecl, ok := decl.(*ast.FuncDecl)
+	if !ok || fdecl.Body == nil {
+		return nil
+	}
+	fn := info.Defs[fdecl.Name].(*types.Func)
+
+	sig := fn.Type().(*types.Signature)
+	if !sig.Variadic() {
+		return nil // not variadic
+	}
+
+	params := sig.Params()
+	nparams := params.Len() // variadic => nonzero
+
+	args := params.At(nparams - 1)
+	iface, ok := args.Type().(*types.Slice).Elem().(*types.Interface)
+	if !ok || !iface.Empty() {
+		return nil // final (args) param is not ...interface{}
+	}
+
+	// Is second last param 'format string'?
+	var format *types.Var
+	if nparams >= 2 {
+		if p := params.At(nparams - 2); p.Type() == types.Typ[types.String] {
+			format = p
+		}
+	}
+
+	return &printfWrapper{
+		obj:    fn,
+		fdecl:  fdecl,
+		format: format,
+		args:   args,
+	}
+}
+
+// findPrintfLike scans the entire package to find printf-like functions.
+func findPrintfLike(pass *analysis.Pass) (interface{}, error) {
+	// Gather potential wrappers and call graph between them.
+	byObj := make(map[*types.Func]*printfWrapper)
+	var wrappers []*printfWrapper
+	for _, file := range pass.Files {
+		for _, decl := range file.Decls {
+			w := maybePrintfWrapper(pass.TypesInfo, decl)
+			if w == nil {
+				continue
+			}
+			byObj[w.obj] = w
+			wrappers = append(wrappers, w)
+		}
+	}
+
+	// Walk the graph to figure out which are really printf wrappers.
+	for _, w := range wrappers {
+		// Scan function for calls that could be to other printf-like functions.
+		ast.Inspect(w.fdecl.Body, func(n ast.Node) bool {
+			if w.failed {
+				return false
+			}
+
+			// TODO: Relax these checks; issue 26555.
+			if assign, ok := n.(*ast.AssignStmt); ok {
+				for _, lhs := range assign.Lhs {
+					if match(pass.TypesInfo, lhs, w.format) ||
+						match(pass.TypesInfo, lhs, w.args) {
+						// Modifies the format
+						// string or args in
+						// some way, so not a
+						// simple wrapper.
+						w.failed = true
+						return false
+					}
+				}
+			}
+			if un, ok := n.(*ast.UnaryExpr); ok && un.Op == token.AND {
+				if match(pass.TypesInfo, un.X, w.format) ||
+					match(pass.TypesInfo, un.X, w.args) {
+					// Taking the address of the
+					// format string or args,
+					// so not a simple wrapper.
+					w.failed = true
+					return false
+				}
+			}
+
+			call, ok := n.(*ast.CallExpr)
+			if !ok || len(call.Args) == 0 || !match(pass.TypesInfo, call.Args[len(call.Args)-1], w.args) {
+				return true
+			}
+
+			fn, kind := printfNameAndKind(pass, call)
+			if kind != 0 {
+				checkPrintfFwd(pass, w, call, kind)
+				return true
+			}
+
+			// If the call is to another function in this package,
+			// maybe we will find out it is printf-like later.
+			// Remember this call for later checking.
+			if fn != nil && fn.Pkg() == pass.Pkg && byObj[fn] != nil {
+				callee := byObj[fn]
+				callee.callers = append(callee.callers, printfCaller{w, call})
+			}
+
+			return true
+		})
+	}
+	return nil, nil
+}
+
+func match(info *types.Info, arg ast.Expr, param *types.Var) bool {
+	id, ok := arg.(*ast.Ident)
+	return ok && info.ObjectOf(id) == param
+}
+
+const (
+	kindPrintf = 1
+	kindPrint  = 2
+)
+
+// checkPrintfFwd checks that a printf-forwarding wrapper is forwarding correctly.
+// It diagnoses writing fmt.Printf(format, args) instead of fmt.Printf(format, args...).
+func checkPrintfFwd(pass *analysis.Pass, w *printfWrapper, call *ast.CallExpr, kind int) {
+	matched := kind == kindPrint ||
+		kind == kindPrintf && len(call.Args) >= 2 && match(pass.TypesInfo, call.Args[len(call.Args)-2], w.format)
+	if !matched {
+		return
+	}
+
+	if !call.Ellipsis.IsValid() {
+		typ, ok := pass.TypesInfo.Types[call.Fun].Type.(*types.Signature)
+		if !ok {
+			return
+		}
+		if len(call.Args) > typ.Params().Len() {
+			// If we're passing more arguments than what the
+			// print/printf function can take, adding an ellipsis
+			// would break the program. For example:
+			//
+			//   func foo(arg1 string, arg2 ...interface{} {
+			//       fmt.Printf("%s %v", arg1, arg2)
+			//   }
+			return
+		}
+		desc := "printf"
+		if kind == kindPrint {
+			desc = "print"
+		}
+		pass.Reportf(call.Pos(), "missing ... in args forwarded to %s-like function", desc)
+		return
+	}
+	fn := w.obj
+	var fact isWrapper
+	if !pass.ImportObjectFact(fn, &fact) {
+		fact.Printf = kind == kindPrintf
+		pass.ExportObjectFact(fn, &fact)
+		for _, caller := range w.callers {
+			checkPrintfFwd(pass, caller.w, caller.call, kind)
+		}
+	}
+}
+
+// isPrint records the print functions.
+// If a key ends in 'f' then it is assumed to be a formatted print.
+//
+// Keys are either values returned by (*types.Func).FullName,
+// or case-insensitive identifiers such as "errorf".
+//
+// The -funcs flag adds to this set.
+//
+// The set below includes facts for many important standard library
+// functions, even though the analysis is capable of deducing that, for
+// example, fmt.Printf forwards to fmt.Fprintf. We avoid relying on the
+// driver applying analyzers to standard packages because "go vet" does
+// not do so with gccgo, and nor do some other build systems.
+// TODO(adonovan): eliminate the redundant facts once this restriction
+// is lifted.
+//
+var isPrint = stringSet{
+	"fmt.Errorf":   true,
+	"fmt.Fprint":   true,
+	"fmt.Fprintf":  true,
+	"fmt.Fprintln": true,
+	"fmt.Print":    true,
+	"fmt.Printf":   true,
+	"fmt.Println":  true,
+	"fmt.Sprint":   true,
+	"fmt.Sprintf":  true,
+	"fmt.Sprintln": true,
+
+	"runtime/trace.Logf": true,
+
+	"log.Print":             true,
+	"log.Printf":            true,
+	"log.Println":           true,
+	"log.Fatal":             true,
+	"log.Fatalf":            true,
+	"log.Fatalln":           true,
+	"log.Panic":             true,
+	"log.Panicf":            true,
+	"log.Panicln":           true,
+	"(*log.Logger).Fatal":   true,
+	"(*log.Logger).Fatalf":  true,
+	"(*log.Logger).Fatalln": true,
+	"(*log.Logger).Panic":   true,
+	"(*log.Logger).Panicf":  true,
+	"(*log.Logger).Panicln": true,
+	"(*log.Logger).Print":   true,
+	"(*log.Logger).Printf":  true,
+	"(*log.Logger).Println": true,
+
+	"(*testing.common).Error":  true,
+	"(*testing.common).Errorf": true,
+	"(*testing.common).Fatal":  true,
+	"(*testing.common).Fatalf": true,
+	"(*testing.common).Log":    true,
+	"(*testing.common).Logf":   true,
+	"(*testing.common).Skip":   true,
+	"(*testing.common).Skipf":  true,
+	// *testing.T and B are detected by induction, but testing.TB is
+	// an interface and the inference can't follow dynamic calls.
+	"(testing.TB).Error":  true,
+	"(testing.TB).Errorf": true,
+	"(testing.TB).Fatal":  true,
+	"(testing.TB).Fatalf": true,
+	"(testing.TB).Log":    true,
+	"(testing.TB).Logf":   true,
+	"(testing.TB).Skip":   true,
+	"(testing.TB).Skipf":  true,
+}
+
+// formatString returns the format string argument and its index within
+// the given printf-like call expression.
+//
+// The last parameter before variadic arguments is assumed to be
+// a format string.
+//
+// The first string literal or string constant is assumed to be a format string
+// if the call's signature cannot be determined.
+//
+// If it cannot find any format string parameter, it returns ("", -1).
+func formatString(pass *analysis.Pass, call *ast.CallExpr) (format string, idx int) {
+	typ := pass.TypesInfo.Types[call.Fun].Type
+	if typ != nil {
+		if sig, ok := typ.(*types.Signature); ok {
+			if !sig.Variadic() {
+				// Skip checking non-variadic functions.
+				return "", -1
+			}
+			idx := sig.Params().Len() - 2
+			if idx < 0 {
+				// Skip checking variadic functions without
+				// fixed arguments.
+				return "", -1
+			}
+			s, ok := stringConstantArg(pass, call, idx)
+			if !ok {
+				// The last argument before variadic args isn't a string.
+				return "", -1
+			}
+			return s, idx
+		}
+	}
+
+	// Cannot determine call's signature. Fall back to scanning for the first
+	// string constant in the call.
+	for idx := range call.Args {
+		if s, ok := stringConstantArg(pass, call, idx); ok {
+			return s, idx
+		}
+		if pass.TypesInfo.Types[call.Args[idx]].Type == types.Typ[types.String] {
+			// Skip checking a call with a non-constant format
+			// string argument, since its contents are unavailable
+			// for validation.
+			return "", -1
+		}
+	}
+	return "", -1
+}
+
+// stringConstantArg returns call's string constant argument at the index idx.
+//
+// ("", false) is returned if call's argument at the index idx isn't a string
+// constant.
+func stringConstantArg(pass *analysis.Pass, call *ast.CallExpr, idx int) (string, bool) {
+	if idx >= len(call.Args) {
+		return "", false
+	}
+	arg := call.Args[idx]
+	lit := pass.TypesInfo.Types[arg].Value
+	if lit != nil && lit.Kind() == constant.String {
+		return constant.StringVal(lit), true
+	}
+	return "", false
+}
+
+// checkCall triggers the print-specific checks if the call invokes a print function.
+func checkCall(pass *analysis.Pass) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+	nodeFilter := []ast.Node{
+		(*ast.CallExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		call := n.(*ast.CallExpr)
+		fn, kind := printfNameAndKind(pass, call)
+		switch kind {
+		case kindPrintf:
+			checkPrintf(pass, call, fn)
+		case kindPrint:
+			checkPrint(pass, call, fn)
+		}
+	})
+}
+
+func printfNameAndKind(pass *analysis.Pass, call *ast.CallExpr) (fn *types.Func, kind int) {
+	fn, _ = typeutil.Callee(pass.TypesInfo, call).(*types.Func)
+	if fn == nil {
+		return nil, 0
+	}
+
+	var fact isWrapper
+	if pass.ImportObjectFact(fn, &fact) {
+		if fact.Printf {
+			return fn, kindPrintf
+		} else {
+			return fn, kindPrint
+		}
+	}
+
+	_, ok := isPrint[fn.FullName()]
+	if !ok {
+		// Next look up just "printf", for use with -printf.funcs.
+		_, ok = isPrint[strings.ToLower(fn.Name())]
+	}
+	if ok {
+		if strings.HasSuffix(fn.Name(), "f") {
+			kind = kindPrintf
+		} else {
+			kind = kindPrint
+		}
+	}
+	return fn, kind
+}
+
+// isFormatter reports whether t satisfies fmt.Formatter.
+// Unlike fmt.Stringer, it's impossible to satisfy fmt.Formatter without importing fmt.
+func isFormatter(pass *analysis.Pass, t types.Type) bool {
+	for _, imp := range pass.Pkg.Imports() {
+		if imp.Path() == "fmt" {
+			formatter := imp.Scope().Lookup("Formatter").Type().Underlying().(*types.Interface)
+			return types.Implements(t, formatter)
+		}
+	}
+	return false
+}
+
+// formatState holds the parsed representation of a printf directive such as "%3.*[4]d".
+// It is constructed by parsePrintfVerb.
+type formatState struct {
+	verb     rune   // the format verb: 'd' for "%d"
+	format   string // the full format directive from % through verb, "%.3d".
+	name     string // Printf, Sprintf etc.
+	flags    []byte // the list of # + etc.
+	argNums  []int  // the successive argument numbers that are consumed, adjusted to refer to actual arg in call
+	firstArg int    // Index of first argument after the format in the Printf call.
+	// Used only during parse.
+	pass         *analysis.Pass
+	call         *ast.CallExpr
+	argNum       int  // Which argument we're expecting to format now.
+	hasIndex     bool // Whether the argument is indexed.
+	indexPending bool // Whether we have an indexed argument that has not resolved.
+	nbytes       int  // number of bytes of the format string consumed.
+}
+
+// checkPrintf checks a call to a formatted print routine such as Printf.
+func checkPrintf(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
+	format, idx := formatString(pass, call)
+	if idx < 0 {
+		if false {
+			pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.Name())
+		}
+		return
+	}
+
+	firstArg := idx + 1 // Arguments are immediately after format string.
+	if !strings.Contains(format, "%") {
+		if len(call.Args) > firstArg {
+			pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.Name())
+		}
+		return
+	}
+	// Hard part: check formats against args.
+	argNum := firstArg
+	maxArgNum := firstArg
+	anyIndex := false
+	for i, w := 0, 0; i < len(format); i += w {
+		w = 1
+		if format[i] != '%' {
+			continue
+		}
+		state := parsePrintfVerb(pass, call, fn.Name(), format[i:], firstArg, argNum)
+		if state == nil {
+			return
+		}
+		w = len(state.format)
+		if !okPrintfArg(pass, call, state) { // One error per format is enough.
+			return
+		}
+		if state.hasIndex {
+			anyIndex = true
+		}
+		if len(state.argNums) > 0 {
+			// Continue with the next sequential argument.
+			argNum = state.argNums[len(state.argNums)-1] + 1
+		}
+		for _, n := range state.argNums {
+			if n >= maxArgNum {
+				maxArgNum = n + 1
+			}
+		}
+	}
+	// Dotdotdot is hard.
+	if call.Ellipsis.IsValid() && maxArgNum >= len(call.Args)-1 {
+		return
+	}
+	// If any formats are indexed, extra arguments are ignored.
+	if anyIndex {
+		return
+	}
+	// There should be no leftover arguments.
+	if maxArgNum != len(call.Args) {
+		expect := maxArgNum - firstArg
+		numArgs := len(call.Args) - firstArg
+		pass.Reportf(call.Pos(), "%s call needs %v but has %v", fn.Name(), count(expect, "arg"), count(numArgs, "arg"))
+	}
+}
+
+// parseFlags accepts any printf flags.
+func (s *formatState) parseFlags() {
+	for s.nbytes < len(s.format) {
+		switch c := s.format[s.nbytes]; c {
+		case '#', '0', '+', '-', ' ':
+			s.flags = append(s.flags, c)
+			s.nbytes++
+		default:
+			return
+		}
+	}
+}
+
+// scanNum advances through a decimal number if present.
+func (s *formatState) scanNum() {
+	for ; s.nbytes < len(s.format); s.nbytes++ {
+		c := s.format[s.nbytes]
+		if c < '0' || '9' < c {
+			return
+		}
+	}
+}
+
+// parseIndex scans an index expression. It returns false if there is a syntax error.
+func (s *formatState) parseIndex() bool {
+	if s.nbytes == len(s.format) || s.format[s.nbytes] != '[' {
+		return true
+	}
+	// Argument index present.
+	s.nbytes++ // skip '['
+	start := s.nbytes
+	s.scanNum()
+	ok := true
+	if s.nbytes == len(s.format) || s.nbytes == start || s.format[s.nbytes] != ']' {
+		ok = false
+		s.nbytes = strings.Index(s.format, "]")
+		if s.nbytes < 0 {
+			s.pass.Reportf(s.call.Pos(), "%s format %s is missing closing ]", s.name, s.format)
+			return false
+		}
+	}
+	arg32, err := strconv.ParseInt(s.format[start:s.nbytes], 10, 32)
+	if err != nil || !ok || arg32 <= 0 || arg32 > int64(len(s.call.Args)-s.firstArg) {
+		s.pass.Reportf(s.call.Pos(), "%s format has invalid argument index [%s]", s.name, s.format[start:s.nbytes])
+		return false
+	}
+	s.nbytes++ // skip ']'
+	arg := int(arg32)
+	arg += s.firstArg - 1 // We want to zero-index the actual arguments.
+	s.argNum = arg
+	s.hasIndex = true
+	s.indexPending = true
+	return true
+}
+
+// parseNum scans a width or precision (or *). It returns false if there's a bad index expression.
+func (s *formatState) parseNum() bool {
+	if s.nbytes < len(s.format) && s.format[s.nbytes] == '*' {
+		if s.indexPending { // Absorb it.
+			s.indexPending = false
+		}
+		s.nbytes++
+		s.argNums = append(s.argNums, s.argNum)
+		s.argNum++
+	} else {
+		s.scanNum()
+	}
+	return true
+}
+
+// parsePrecision scans for a precision. It returns false if there's a bad index expression.
+func (s *formatState) parsePrecision() bool {
+	// If there's a period, there may be a precision.
+	if s.nbytes < len(s.format) && s.format[s.nbytes] == '.' {
+		s.flags = append(s.flags, '.') // Treat precision as a flag.
+		s.nbytes++
+		if !s.parseIndex() {
+			return false
+		}
+		if !s.parseNum() {
+			return false
+		}
+	}
+	return true
+}
+
+// parsePrintfVerb looks the formatting directive that begins the format string
+// and returns a formatState that encodes what the directive wants, without looking
+// at the actual arguments present in the call. The result is nil if there is an error.
+func parsePrintfVerb(pass *analysis.Pass, call *ast.CallExpr, name, format string, firstArg, argNum int) *formatState {
+	state := &formatState{
+		format:   format,
+		name:     name,
+		flags:    make([]byte, 0, 5),
+		argNum:   argNum,
+		argNums:  make([]int, 0, 1),
+		nbytes:   1, // There's guaranteed to be a percent sign.
+		firstArg: firstArg,
+		pass:     pass,
+		call:     call,
+	}
+	// There may be flags.
+	state.parseFlags()
+	// There may be an index.
+	if !state.parseIndex() {
+		return nil
+	}
+	// There may be a width.
+	if !state.parseNum() {
+		return nil
+	}
+	// There may be a precision.
+	if !state.parsePrecision() {
+		return nil
+	}
+	// Now a verb, possibly prefixed by an index (which we may already have).
+	if !state.indexPending && !state.parseIndex() {
+		return nil
+	}
+	if state.nbytes == len(state.format) {
+		pass.Reportf(call.Pos(), "%s format %s is missing verb at end of string", name, state.format)
+		return nil
+	}
+	verb, w := utf8.DecodeRuneInString(state.format[state.nbytes:])
+	state.verb = verb
+	state.nbytes += w
+	if verb != '%' {
+		state.argNums = append(state.argNums, state.argNum)
+	}
+	state.format = state.format[:state.nbytes]
+	return state
+}
+
+// printfArgType encodes the types of expressions a printf verb accepts. It is a bitmask.
+type printfArgType int
+
+const (
+	argBool printfArgType = 1 << iota
+	argInt
+	argRune
+	argString
+	argFloat
+	argComplex
+	argPointer
+	anyType printfArgType = ^0
+)
+
+type printVerb struct {
+	verb  rune   // User may provide verb through Formatter; could be a rune.
+	flags string // known flags are all ASCII
+	typ   printfArgType
+}
+
+// Common flag sets for printf verbs.
+const (
+	noFlag       = ""
+	numFlag      = " -+.0"
+	sharpNumFlag = " -+.0#"
+	allFlags     = " -+.0#"
+)
+
+// printVerbs identifies which flags are known to printf for each verb.
+var printVerbs = []printVerb{
+	// '-' is a width modifier, always valid.
+	// '.' is a precision for float, max width for strings.
+	// '+' is required sign for numbers, Go format for %v.
+	// '#' is alternate format for several verbs.
+	// ' ' is spacer for numbers
+	{'%', noFlag, 0},
+	{'b', numFlag, argInt | argFloat | argComplex | argPointer},
+	{'c', "-", argRune | argInt},
+	{'d', numFlag, argInt | argPointer},
+	{'e', sharpNumFlag, argFloat | argComplex},
+	{'E', sharpNumFlag, argFloat | argComplex},
+	{'f', sharpNumFlag, argFloat | argComplex},
+	{'F', sharpNumFlag, argFloat | argComplex},
+	{'g', sharpNumFlag, argFloat | argComplex},
+	{'G', sharpNumFlag, argFloat | argComplex},
+	{'o', sharpNumFlag, argInt | argPointer},
+	{'p', "-#", argPointer},
+	{'q', " -+.0#", argRune | argInt | argString},
+	{'s', " -+.0", argString},
+	{'t', "-", argBool},
+	{'T', "-", anyType},
+	{'U', "-#", argRune | argInt},
+	{'v', allFlags, anyType},
+	{'x', sharpNumFlag, argRune | argInt | argString | argPointer},
+	{'X', sharpNumFlag, argRune | argInt | argString | argPointer},
+}
+
+// okPrintfArg compares the formatState to the arguments actually present,
+// reporting any discrepancies it can discern. If the final argument is ellipsissed,
+// there's little it can do for that.
+func okPrintfArg(pass *analysis.Pass, call *ast.CallExpr, state *formatState) (ok bool) {
+	var v printVerb
+	found := false
+	// Linear scan is fast enough for a small list.
+	for _, v = range printVerbs {
+		if v.verb == state.verb {
+			found = true
+			break
+		}
+	}
+
+	// Does current arg implement fmt.Formatter?
+	formatter := false
+	if state.argNum < len(call.Args) {
+		if tv, ok := pass.TypesInfo.Types[call.Args[state.argNum]]; ok {
+			formatter = isFormatter(pass, tv.Type)
+		}
+	}
+
+	if !formatter {
+		if !found {
+			pass.Reportf(call.Pos(), "%s format %s has unknown verb %c", state.name, state.format, state.verb)
+			return false
+		}
+		for _, flag := range state.flags {
+			// TODO: Disable complaint about '0' for Go 1.10. To be fixed properly in 1.11.
+			// See issues 23598 and 23605.
+			if flag == '0' {
+				continue
+			}
+			if !strings.ContainsRune(v.flags, rune(flag)) {
+				pass.Reportf(call.Pos(), "%s format %s has unrecognized flag %c", state.name, state.format, flag)
+				return false
+			}
+		}
+	}
+	// Verb is good. If len(state.argNums)>trueArgs, we have something like %.*s and all
+	// but the final arg must be an integer.
+	trueArgs := 1
+	if state.verb == '%' {
+		trueArgs = 0
+	}
+	nargs := len(state.argNums)
+	for i := 0; i < nargs-trueArgs; i++ {
+		argNum := state.argNums[i]
+		if !argCanBeChecked(pass, call, i, state) {
+			return
+		}
+		arg := call.Args[argNum]
+		if !matchArgType(pass, argInt, nil, arg) {
+			pass.Reportf(call.Pos(), "%s format %s uses non-int %s as argument of *", state.name, state.format, analysisutil.Format(pass.Fset, arg))
+			return false
+		}
+	}
+
+	if state.verb == '%' || formatter {
+		return true
+	}
+	argNum := state.argNums[len(state.argNums)-1]
+	if !argCanBeChecked(pass, call, len(state.argNums)-1, state) {
+		return false
+	}
+	arg := call.Args[argNum]
+	if isFunctionValue(pass, arg) && state.verb != 'p' && state.verb != 'T' {
+		pass.Reportf(call.Pos(), "%s format %s arg %s is a func value, not called", state.name, state.format, analysisutil.Format(pass.Fset, arg))
+		return false
+	}
+	if !matchArgType(pass, v.typ, nil, arg) {
+		typeString := ""
+		if typ := pass.TypesInfo.Types[arg].Type; typ != nil {
+			typeString = typ.String()
+		}
+		pass.Reportf(call.Pos(), "%s format %s has arg %s of wrong type %s", state.name, state.format, analysisutil.Format(pass.Fset, arg), typeString)
+		return false
+	}
+	if v.typ&argString != 0 && v.verb != 'T' && !bytes.Contains(state.flags, []byte{'#'}) && recursiveStringer(pass, arg) {
+		pass.Reportf(call.Pos(), "%s format %s with arg %s causes recursive String method call", state.name, state.format, analysisutil.Format(pass.Fset, arg))
+		return false
+	}
+	return true
+}
+
+// recursiveStringer reports whether the argument e is a potential
+// recursive call to stringer, such as t and &t in these examples:
+//
+// 	func (t *T) String() string { printf("%s",  t) }
+// 	func (t  T) String() string { printf("%s",  t) }
+// 	func (t  T) String() string { printf("%s", &t) }
+//
+func recursiveStringer(pass *analysis.Pass, e ast.Expr) bool {
+	typ := pass.TypesInfo.Types[e].Type
+
+	// It's unlikely to be a recursive stringer if it has a Format method.
+	if isFormatter(pass, typ) {
+		return false
+	}
+
+	// Does e allow e.String()?
+	obj, _, _ := types.LookupFieldOrMethod(typ, false, pass.Pkg, "String")
+	stringMethod, ok := obj.(*types.Func)
+	if !ok {
+		return false
+	}
+
+	// Is the expression e within the body of that String method?
+	if stringMethod.Pkg() != pass.Pkg || !stringMethod.Scope().Contains(e.Pos()) {
+		return false
+	}
+
+	// Is it the receiver r, or &r?
+	recv := stringMethod.Type().(*types.Signature).Recv()
+	if recv == nil {
+		return false
+	}
+	if u, ok := e.(*ast.UnaryExpr); ok && u.Op == token.AND {
+		e = u.X // strip off & from &r
+	}
+	if id, ok := e.(*ast.Ident); ok {
+		return pass.TypesInfo.Uses[id] == recv
+	}
+	return false
+}
+
+// isFunctionValue reports whether the expression is a function as opposed to a function call.
+// It is almost always a mistake to print a function value.
+func isFunctionValue(pass *analysis.Pass, e ast.Expr) bool {
+	if typ := pass.TypesInfo.Types[e].Type; typ != nil {
+		_, ok := typ.(*types.Signature)
+		return ok
+	}
+	return false
+}
+
+// argCanBeChecked reports whether the specified argument is statically present;
+// it may be beyond the list of arguments or in a terminal slice... argument, which
+// means we can't see it.
+func argCanBeChecked(pass *analysis.Pass, call *ast.CallExpr, formatArg int, state *formatState) bool {
+	argNum := state.argNums[formatArg]
+	if argNum <= 0 {
+		// Shouldn't happen, so catch it with prejudice.
+		panic("negative arg num")
+	}
+	if argNum < len(call.Args)-1 {
+		return true // Always OK.
+	}
+	if call.Ellipsis.IsValid() {
+		return false // We just can't tell; there could be many more arguments.
+	}
+	if argNum < len(call.Args) {
+		return true
+	}
+	// There are bad indexes in the format or there are fewer arguments than the format needs.
+	// This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi".
+	arg := argNum - state.firstArg + 1 // People think of arguments as 1-indexed.
+	pass.Reportf(call.Pos(), "%s format %s reads arg #%d, but call has %v", state.name, state.format, arg, count(len(call.Args)-state.firstArg, "arg"))
+	return false
+}
+
+// printFormatRE is the regexp we match and report as a possible format string
+// in the first argument to unformatted prints like fmt.Print.
+// We exclude the space flag, so that printing a string like "x % y" is not reported as a format.
+var printFormatRE = regexp.MustCompile(`%` + flagsRE + numOptRE + `\.?` + numOptRE + indexOptRE + verbRE)
+
+const (
+	flagsRE    = `[+\-#]*`
+	indexOptRE = `(\[[0-9]+\])?`
+	numOptRE   = `([0-9]+|` + indexOptRE + `\*)?`
+	verbRE     = `[bcdefgopqstvxEFGTUX]`
+)
+
+// checkPrint checks a call to an unformatted print routine such as Println.
+func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
+	firstArg := 0
+	typ := pass.TypesInfo.Types[call.Fun].Type
+	if typ == nil {
+		// Skip checking functions with unknown type.
+		return
+	}
+	if sig, ok := typ.(*types.Signature); ok {
+		if !sig.Variadic() {
+			// Skip checking non-variadic functions.
+			return
+		}
+		params := sig.Params()
+		firstArg = params.Len() - 1
+
+		typ := params.At(firstArg).Type()
+		typ = typ.(*types.Slice).Elem()
+		it, ok := typ.(*types.Interface)
+		if !ok || !it.Empty() {
+			// Skip variadic functions accepting non-interface{} args.
+			return
+		}
+	}
+	args := call.Args
+	if len(args) <= firstArg {
+		// Skip calls without variadic args.
+		return
+	}
+	args = args[firstArg:]
+
+	if firstArg == 0 {
+		if sel, ok := call.Args[0].(*ast.SelectorExpr); ok {
+			if x, ok := sel.X.(*ast.Ident); ok {
+				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
+					pass.Reportf(call.Pos(), "%s does not take io.Writer but has first arg %s", fn.Name(), analysisutil.Format(pass.Fset, call.Args[0]))
+				}
+			}
+		}
+	}
+
+	arg := args[0]
+	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
+		// Ignore trailing % character in lit.Value.
+		// The % in "abc 0.0%" couldn't be a formatting directive.
+		s := strings.TrimSuffix(lit.Value, `%"`)
+		if strings.Contains(s, "%") {
+			m := printFormatRE.FindStringSubmatch(s)
+			if m != nil {
+				pass.Reportf(call.Pos(), "%s call has possible formatting directive %s", fn.Name(), m[0])
+			}
+		}
+	}
+	if strings.HasSuffix(fn.Name(), "ln") {
+		// The last item, if a string, should not have a newline.
+		arg = args[len(args)-1]
+		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
+			str, _ := strconv.Unquote(lit.Value)
+			if strings.HasSuffix(str, "\n") {
+				pass.Reportf(call.Pos(), "%s arg list ends with redundant newline", fn.Name())
+			}
+		}
+	}
+	for _, arg := range args {
+		if isFunctionValue(pass, arg) {
+			pass.Reportf(call.Pos(), "%s arg %s is a func value, not called", fn.Name(), analysisutil.Format(pass.Fset, arg))
+		}
+		if recursiveStringer(pass, arg) {
+			pass.Reportf(call.Pos(), "%s arg %s causes recursive call to String method", fn.Name(), analysisutil.Format(pass.Fset, arg))
+		}
+	}
+}
+
+// count(n, what) returns "1 what" or "N whats"
+// (assuming the plural of what is whats).
+func count(n int, what string) string {
+	if n == 1 {
+		return "1 " + what
+	}
+	return fmt.Sprintf("%d %ss", n, what)
+}
+
+// stringSet is a set-of-nonempty-strings-valued flag.
+// Note: elements without a '.' get lower-cased.
+type stringSet map[string]bool
+
+func (ss stringSet) String() string {
+	var list []string
+	for name := range ss {
+		list = append(list, name)
+	}
+	sort.Strings(list)
+	return strings.Join(list, ",")
+}
+
+func (ss stringSet) Set(flag string) error {
+	for _, name := range strings.Split(flag, ",") {
+		if len(name) == 0 {
+			return fmt.Errorf("empty string")
+		}
+		if !strings.Contains(name, ".") {
+			name = strings.ToLower(name)
+		}
+		ss[name] = true
+	}
+	return nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/printf/types.go b/libgo/go/golang.org/x/tools/go/analysis/passes/printf/types.go
new file mode 100644
index 00000000000..e8810464cd4
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/printf/types.go
@@ -0,0 +1,239 @@
+package printf
+
+import (
+	"go/ast"
+	"go/build"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+)
+
+var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)
+
+// matchArgType reports an error if printf verb t is not appropriate
+// for operand arg.
+//
+// typ is used only for recursive calls; external callers must supply nil.
+//
+// (Recursion arises from the compound types {map,chan,slice} which
+// may be printed with %d etc. if that is appropriate for their element
+// types.)
+func matchArgType(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr) bool {
+	return matchArgTypeInternal(pass, t, typ, arg, make(map[types.Type]bool))
+}
+
+// matchArgTypeInternal is the internal version of matchArgType. It carries a map
+// remembering what types are in progress so we don't recur when faced with recursive
+// types or mutually recursive types.
+func matchArgTypeInternal(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr, inProgress map[types.Type]bool) bool {
+	// %v, %T accept any argument type.
+	if t == anyType {
+		return true
+	}
+	if typ == nil {
+		// external call
+		typ = pass.TypesInfo.Types[arg].Type
+		if typ == nil {
+			return true // probably a type check problem
+		}
+	}
+	// If the type implements fmt.Formatter, we have nothing to check.
+	if isFormatter(pass, typ) {
+		return true
+	}
+	// If we can use a string, might arg (dynamically) implement the Stringer or Error interface?
+	if t&argString != 0 && isConvertibleToString(pass, typ) {
+		return true
+	}
+
+	typ = typ.Underlying()
+	if inProgress[typ] {
+		// We're already looking at this type. The call that started it will take care of it.
+		return true
+	}
+	inProgress[typ] = true
+
+	switch typ := typ.(type) {
+	case *types.Signature:
+		return t == argPointer
+
+	case *types.Map:
+		return t == argPointer ||
+			// Recur: map[int]int matches %d.
+			(matchArgTypeInternal(pass, t, typ.Key(), arg, inProgress) && matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress))
+
+	case *types.Chan:
+		return t&argPointer != 0
+
+	case *types.Array:
+		// Same as slice.
+		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
+			return true // %s matches []byte
+		}
+		// Recur: []int matches %d.
+		return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)
+
+	case *types.Slice:
+		// Same as array.
+		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
+			return true // %s matches []byte
+		}
+		if t == argPointer {
+			return true // %p prints a slice's 0th element
+		}
+		// Recur: []int matches %d. But watch out for
+		//	type T []T
+		// If the element is a pointer type (type T[]*T), it's handled fine by the Pointer case below.
+		return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)
+
+	case *types.Pointer:
+		// Ugly, but dealing with an edge case: a known pointer to an invalid type,
+		// probably something from a failed import.
+		if typ.Elem().String() == "invalid type" {
+			if false {
+				pass.Reportf(arg.Pos(), "printf argument %v is pointer to invalid or unknown type", analysisutil.Format(pass.Fset, arg))
+			}
+			return true // special case
+		}
+		// If it's actually a pointer with %p, it prints as one.
+		if t == argPointer {
+			return true
+		}
+
+		under := typ.Elem().Underlying()
+		switch under.(type) {
+		case *types.Struct: // see below
+		case *types.Array: // see below
+		case *types.Slice: // see below
+		case *types.Map: // see below
+		default:
+			// Check whether the rest can print pointers.
+			return t&argPointer != 0
+		}
+		// If it's a top-level pointer to a struct, array, slice, or
+		// map, that's equivalent in our analysis to whether we can
+		// print the type being pointed to. Pointers in nested levels
+		// are not supported to minimize fmt running into loops.
+		if len(inProgress) > 1 {
+			return false
+		}
+		return matchArgTypeInternal(pass, t, under, arg, inProgress)
+
+	case *types.Struct:
+		return matchStructArgType(pass, t, typ, arg, inProgress)
+
+	case *types.Interface:
+		// There's little we can do.
+		// Whether any particular verb is valid depends on the argument.
+		// The user may have reasonable prior knowledge of the contents of the interface.
+		return true
+
+	case *types.Basic:
+		switch typ.Kind() {
+		case types.UntypedBool,
+			types.Bool:
+			return t&argBool != 0
+
+		case types.UntypedInt,
+			types.Int,
+			types.Int8,
+			types.Int16,
+			types.Int32,
+			types.Int64,
+			types.Uint,
+			types.Uint8,
+			types.Uint16,
+			types.Uint32,
+			types.Uint64,
+			types.Uintptr:
+			return t&argInt != 0
+
+		case types.UntypedFloat,
+			types.Float32,
+			types.Float64:
+			return t&argFloat != 0
+
+		case types.UntypedComplex,
+			types.Complex64,
+			types.Complex128:
+			return t&argComplex != 0
+
+		case types.UntypedString,
+			types.String:
+			return t&argString != 0
+
+		case types.UnsafePointer:
+			return t&(argPointer|argInt) != 0
+
+		case types.UntypedRune:
+			return t&(argInt|argRune) != 0
+
+		case types.UntypedNil:
+			return false
+
+		case types.Invalid:
+			if false {
+				pass.Reportf(arg.Pos(), "printf argument %v has invalid or unknown type", analysisutil.Format(pass.Fset, arg))
+			}
+			return true // Probably a type check problem.
+		}
+		panic("unreachable")
+	}
+
+	return false
+}
+
+func isConvertibleToString(pass *analysis.Pass, typ types.Type) bool {
+	if bt, ok := typ.(*types.Basic); ok && bt.Kind() == types.UntypedNil {
+		// We explicitly don't want untyped nil, which is
+		// convertible to both of the interfaces below, as it
+		// would just panic anyway.
+		return false
+	}
+	if types.ConvertibleTo(typ, errorType) {
+		return true // via .Error()
+	}
+
+	// Does it implement fmt.Stringer?
+	if obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "String"); obj != nil {
+		if fn, ok := obj.(*types.Func); ok {
+			sig := fn.Type().(*types.Signature)
+			if sig.Params().Len() == 0 &&
+				sig.Results().Len() == 1 &&
+				sig.Results().At(0).Type() == types.Typ[types.String] {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+// hasBasicType reports whether x's type is a types.Basic with the given kind.
+func hasBasicType(pass *analysis.Pass, x ast.Expr, kind types.BasicKind) bool {
+	t := pass.TypesInfo.Types[x].Type
+	if t != nil {
+		t = t.Underlying()
+	}
+	b, ok := t.(*types.Basic)
+	return ok && b.Kind() == kind
+}
+
+// matchStructArgType reports whether all the elements of the struct match the expected
+// type. For instance, with "%d" all the elements must be printable with the "%d" format.
+func matchStructArgType(pass *analysis.Pass, t printfArgType, typ *types.Struct, arg ast.Expr, inProgress map[types.Type]bool) bool {
+	for i := 0; i < typ.NumFields(); i++ {
+		typf := typ.Field(i)
+		if !matchArgTypeInternal(pass, t, typf.Type(), arg, inProgress) {
+			return false
+		}
+		if t&argString != 0 && !typf.Exported() && isConvertibleToString(pass, typf.Type()) {
+			// Issue #17798: unexported Stringer or error cannot be properly fomatted.
+			return false
+		}
+	}
+	return true
+}
+
+var archSizes = types.SizesFor("gc", build.Default.GOARCH)
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/shift/dead.go b/libgo/go/golang.org/x/tools/go/analysis/passes/shift/dead.go
new file mode 100644
index 00000000000..43415a98d61
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/shift/dead.go
@@ -0,0 +1,101 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package shift
+
+// Simplified dead code detector.
+// Used for skipping shift checks on unreachable arch-specific code.
+
+import (
+	"go/ast"
+	"go/constant"
+	"go/types"
+)
+
+// updateDead puts unreachable "if" and "case" nodes into dead.
+func updateDead(info *types.Info, dead map[ast.Node]bool, node ast.Node) {
+	if dead[node] {
+		// The node is already marked as dead.
+		return
+	}
+
+	// setDead marks the node and all the children as dead.
+	setDead := func(n ast.Node) {
+		ast.Inspect(n, func(node ast.Node) bool {
+			if node != nil {
+				dead[node] = true
+			}
+			return true
+		})
+	}
+
+	switch stmt := node.(type) {
+	case *ast.IfStmt:
+		// "if" branch is dead if its condition evaluates
+		// to constant false.
+		v := info.Types[stmt.Cond].Value
+		if v == nil {
+			return
+		}
+		if !constant.BoolVal(v) {
+			setDead(stmt.Body)
+			return
+		}
+		if stmt.Else != nil {
+			setDead(stmt.Else)
+		}
+	case *ast.SwitchStmt:
+		// Case clause with empty switch tag is dead if it evaluates
+		// to constant false.
+		if stmt.Tag == nil {
+		BodyLoopBool:
+			for _, stmt := range stmt.Body.List {
+				cc := stmt.(*ast.CaseClause)
+				if cc.List == nil {
+					// Skip default case.
+					continue
+				}
+				for _, expr := range cc.List {
+					v := info.Types[expr].Value
+					if v == nil || v.Kind() != constant.Bool || constant.BoolVal(v) {
+						continue BodyLoopBool
+					}
+				}
+				setDead(cc)
+			}
+			return
+		}
+
+		// Case clause is dead if its constant value doesn't match
+		// the constant value from the switch tag.
+		// TODO: This handles integer comparisons only.
+		v := info.Types[stmt.Tag].Value
+		if v == nil || v.Kind() != constant.Int {
+			return
+		}
+		tagN, ok := constant.Uint64Val(v)
+		if !ok {
+			return
+		}
+	BodyLoopInt:
+		for _, x := range stmt.Body.List {
+			cc := x.(*ast.CaseClause)
+			if cc.List == nil {
+				// Skip default case.
+				continue
+			}
+			for _, expr := range cc.List {
+				v := info.Types[expr].Value
+				if v == nil {
+					continue BodyLoopInt
+				}
+				n, ok := constant.Uint64Val(v)
+				if !ok || tagN == n {
+					continue BodyLoopInt
+				}
+			}
+			setDead(cc)
+		}
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/shift/shift.go b/libgo/go/golang.org/x/tools/go/analysis/passes/shift/shift.go
new file mode 100644
index 00000000000..56b150b2b13
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/shift/shift.go
@@ -0,0 +1,128 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package shift defines an Analyzer that checks for shifts that exceed
+// the width of an integer.
+package shift
+
+// TODO(adonovan): integrate with ctrflow (CFG-based) dead code analysis. May
+// have impedance mismatch due to its (non-)treatment of constant
+// expressions (such as runtime.GOARCH=="386").
+
+import (
+	"go/ast"
+	"go/build"
+	"go/constant"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "shift",
+	Doc:      "check for shifts that equal or exceed the width of the integer",
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	// Do a complete pass to compute dead nodes.
+	dead := make(map[ast.Node]bool)
+	nodeFilter := []ast.Node{
+		(*ast.IfStmt)(nil),
+		(*ast.SwitchStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		// TODO(adonovan): move updateDead into this file.
+		updateDead(pass.TypesInfo, dead, n)
+	})
+
+	nodeFilter = []ast.Node{
+		(*ast.AssignStmt)(nil),
+		(*ast.BinaryExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(node ast.Node) {
+		if dead[node] {
+			// Skip shift checks on unreachable nodes.
+			return
+		}
+
+		switch node := node.(type) {
+		case *ast.BinaryExpr:
+			if node.Op == token.SHL || node.Op == token.SHR {
+				checkLongShift(pass, node, node.X, node.Y)
+			}
+		case *ast.AssignStmt:
+			if len(node.Lhs) != 1 || len(node.Rhs) != 1 {
+				return
+			}
+			if node.Tok == token.SHL_ASSIGN || node.Tok == token.SHR_ASSIGN {
+				checkLongShift(pass, node, node.Lhs[0], node.Rhs[0])
+			}
+		}
+	})
+	return nil, nil
+}
+
+// checkLongShift checks if shift or shift-assign operations shift by more than
+// the length of the underlying variable.
+func checkLongShift(pass *analysis.Pass, node ast.Node, x, y ast.Expr) {
+	if pass.TypesInfo.Types[x].Value != nil {
+		// Ignore shifts of constants.
+		// These are frequently used for bit-twiddling tricks
+		// like ^uint(0) >> 63 for 32/64 bit detection and compatibility.
+		return
+	}
+
+	v := pass.TypesInfo.Types[y].Value
+	if v == nil {
+		return
+	}
+	amt, ok := constant.Int64Val(v)
+	if !ok {
+		return
+	}
+	t := pass.TypesInfo.Types[x].Type
+	if t == nil {
+		return
+	}
+	b, ok := t.Underlying().(*types.Basic)
+	if !ok {
+		return
+	}
+	var size int64
+	switch b.Kind() {
+	case types.Uint8, types.Int8:
+		size = 8
+	case types.Uint16, types.Int16:
+		size = 16
+	case types.Uint32, types.Int32:
+		size = 32
+	case types.Uint64, types.Int64:
+		size = 64
+	case types.Int, types.Uint:
+		size = uintBitSize
+	case types.Uintptr:
+		size = uintptrBitSize
+	default:
+		return
+	}
+	if amt >= size {
+		ident := analysisutil.Format(pass.Fset, x)
+		pass.Reportf(node.Pos(), "%s (%d bits) too small for shift of %d", ident, size, amt)
+	}
+}
+
+var (
+	uintBitSize    = 8 * archSizes.Sizeof(types.Typ[types.Uint])
+	uintptrBitSize = 8 * archSizes.Sizeof(types.Typ[types.Uintptr])
+)
+
+var archSizes = types.SizesFor("gc", build.Default.GOARCH)
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/stdmethods/stdmethods.go b/libgo/go/golang.org/x/tools/go/analysis/passes/stdmethods/stdmethods.go
new file mode 100644
index 00000000000..83495112243
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/stdmethods/stdmethods.go
@@ -0,0 +1,186 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package stdmethods defines an Analyzer that checks for misspellings
+// in the signatures of methods similar to well-known interfaces.
+package stdmethods
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check signature of methods of well-known interfaces
+
+Sometimes a type may be intended to satisfy an interface but may fail to
+do so because of a mistake in its method signature.
+For example, the result of this WriteTo method should be (int64, error),
+not error, to satisfy io.WriterTo:
+
+	type myWriterTo struct{...}
+        func (myWriterTo) WriteTo(w io.Writer) error { ... }
+
+This check ensures that each method whose name matches one of several
+well-known interface methods from the standard library has the correct
+signature for that interface.
+
+Checked method names include:
+	Format GobEncode GobDecode MarshalJSON MarshalXML
+	Peek ReadByte ReadFrom ReadRune Scan Seek
+	UnmarshalJSON UnreadByte UnreadRune WriteByte
+	WriteTo
+`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "stdmethods",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+// canonicalMethods lists the input and output types for Go methods
+// that are checked using dynamic interface checks. Because the
+// checks are dynamic, such methods would not cause a compile error
+// if they have the wrong signature: instead the dynamic check would
+// fail, sometimes mysteriously. If a method is found with a name listed
+// here but not the input/output types listed here, vet complains.
+//
+// A few of the canonical methods have very common names.
+// For example, a type might implement a Scan method that
+// has nothing to do with fmt.Scanner, but we still want to check
+// the methods that are intended to implement fmt.Scanner.
+// To do that, the arguments that have a = prefix are treated as
+// signals that the canonical meaning is intended: if a Scan
+// method doesn't have a fmt.ScanState as its first argument,
+// we let it go. But if it does have a fmt.ScanState, then the
+// rest has to match.
+var canonicalMethods = map[string]struct{ args, results []string }{
+	// "Flush": {{}, {"error"}}, // http.Flusher and jpeg.writer conflict
+	"Format":        {[]string{"=fmt.State", "rune"}, []string{}},                      // fmt.Formatter
+	"GobDecode":     {[]string{"[]byte"}, []string{"error"}},                           // gob.GobDecoder
+	"GobEncode":     {[]string{}, []string{"[]byte", "error"}},                         // gob.GobEncoder
+	"MarshalJSON":   {[]string{}, []string{"[]byte", "error"}},                         // json.Marshaler
+	"MarshalXML":    {[]string{"*xml.Encoder", "xml.StartElement"}, []string{"error"}}, // xml.Marshaler
+	"ReadByte":      {[]string{}, []string{"byte", "error"}},                           // io.ByteReader
+	"ReadFrom":      {[]string{"=io.Reader"}, []string{"int64", "error"}},              // io.ReaderFrom
+	"ReadRune":      {[]string{}, []string{"rune", "int", "error"}},                    // io.RuneReader
+	"Scan":          {[]string{"=fmt.ScanState", "rune"}, []string{"error"}},           // fmt.Scanner
+	"Seek":          {[]string{"=int64", "int"}, []string{"int64", "error"}},           // io.Seeker
+	"UnmarshalJSON": {[]string{"[]byte"}, []string{"error"}},                           // json.Unmarshaler
+	"UnmarshalXML":  {[]string{"*xml.Decoder", "xml.StartElement"}, []string{"error"}}, // xml.Unmarshaler
+	"UnreadByte":    {[]string{}, []string{"error"}},
+	"UnreadRune":    {[]string{}, []string{"error"}},
+	"WriteByte":     {[]string{"byte"}, []string{"error"}},                // jpeg.writer (matching bufio.Writer)
+	"WriteTo":       {[]string{"=io.Writer"}, []string{"int64", "error"}}, // io.WriterTo
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.FuncDecl)(nil),
+		(*ast.InterfaceType)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		switch n := n.(type) {
+		case *ast.FuncDecl:
+			if n.Recv != nil {
+				canonicalMethod(pass, n.Name)
+			}
+		case *ast.InterfaceType:
+			for _, field := range n.Methods.List {
+				for _, id := range field.Names {
+					canonicalMethod(pass, id)
+				}
+			}
+		}
+	})
+	return nil, nil
+}
+
+func canonicalMethod(pass *analysis.Pass, id *ast.Ident) {
+	// Expected input/output.
+	expect, ok := canonicalMethods[id.Name]
+	if !ok {
+		return
+	}
+
+	// Actual input/output
+	sign := pass.TypesInfo.Defs[id].Type().(*types.Signature)
+	args := sign.Params()
+	results := sign.Results()
+
+	// Do the =s (if any) all match?
+	if !matchParams(pass, expect.args, args, "=") || !matchParams(pass, expect.results, results, "=") {
+		return
+	}
+
+	// Everything must match.
+	if !matchParams(pass, expect.args, args, "") || !matchParams(pass, expect.results, results, "") {
+		expectFmt := id.Name + "(" + argjoin(expect.args) + ")"
+		if len(expect.results) == 1 {
+			expectFmt += " " + argjoin(expect.results)
+		} else if len(expect.results) > 1 {
+			expectFmt += " (" + argjoin(expect.results) + ")"
+		}
+
+		actual := typeString(sign)
+		actual = strings.TrimPrefix(actual, "func")
+		actual = id.Name + actual
+
+		pass.Reportf(id.Pos(), "method %s should have signature %s", actual, expectFmt)
+	}
+}
+
+func typeString(typ types.Type) string {
+	return types.TypeString(typ, (*types.Package).Name)
+}
+
+func argjoin(x []string) string {
+	y := make([]string, len(x))
+	for i, s := range x {
+		if s[0] == '=' {
+			s = s[1:]
+		}
+		y[i] = s
+	}
+	return strings.Join(y, ", ")
+}
+
+// Does each type in expect with the given prefix match the corresponding type in actual?
+func matchParams(pass *analysis.Pass, expect []string, actual *types.Tuple, prefix string) bool {
+	for i, x := range expect {
+		if !strings.HasPrefix(x, prefix) {
+			continue
+		}
+		if i >= actual.Len() {
+			return false
+		}
+		if !matchParamType(pass.Fset, pass.Pkg, x, actual.At(i).Type()) {
+			return false
+		}
+	}
+	if prefix == "" && actual.Len() > len(expect) {
+		return false
+	}
+	return true
+}
+
+// Does this one type match?
+func matchParamType(fset *token.FileSet, pkg *types.Package, expect string, actual types.Type) bool {
+	expect = strings.TrimPrefix(expect, "=")
+	// Strip package name if we're in that package.
+	if n := len(pkg.Name()); len(expect) > n && expect[:n] == pkg.Name() && expect[n] == '.' {
+		expect = expect[n+1:]
+	}
+
+	// Overkill but easy.
+	return typeString(actual) == expect
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/structtag/structtag.go b/libgo/go/golang.org/x/tools/go/analysis/passes/structtag/structtag.go
new file mode 100644
index 00000000000..2b67c376bab
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/structtag/structtag.go
@@ -0,0 +1,273 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package structtag defines an Analyzer that checks struct field tags
+// are well formed.
+package structtag
+
+import (
+	"errors"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"path/filepath"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check that struct field tags conform to reflect.StructTag.Get
+
+Also report certain struct tags (json, xml) used with unexported fields.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "structtag",
+	Doc:              Doc,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.StructType)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		styp := pass.TypesInfo.Types[n.(*ast.StructType)].Type.(*types.Struct)
+		var seen map[[2]string]token.Pos
+		for i := 0; i < styp.NumFields(); i++ {
+			field := styp.Field(i)
+			tag := styp.Tag(i)
+			checkCanonicalFieldTag(pass, field, tag, &seen)
+		}
+	})
+	return nil, nil
+}
+
+var checkTagDups = []string{"json", "xml"}
+var checkTagSpaces = map[string]bool{"json": true, "xml": true, "asn1": true}
+
+// checkCanonicalFieldTag checks a single struct field tag.
+func checkCanonicalFieldTag(pass *analysis.Pass, field *types.Var, tag string, seen *map[[2]string]token.Pos) {
+	for _, key := range checkTagDups {
+		checkTagDuplicates(pass, tag, key, field, field, seen)
+	}
+
+	if err := validateStructTag(tag); err != nil {
+		pass.Reportf(field.Pos(), "struct field tag %#q not compatible with reflect.StructTag.Get: %s", tag, err)
+	}
+
+	// Check for use of json or xml tags with unexported fields.
+
+	// Embedded struct. Nothing to do for now, but that
+	// may change, depending on what happens with issue 7363.
+	// TODO(adonovan): investigate, now that that issue is fixed.
+	if field.Anonymous() {
+		return
+	}
+
+	if field.Exported() {
+		return
+	}
+
+	for _, enc := range [...]string{"json", "xml"} {
+		if reflect.StructTag(tag).Get(enc) != "" {
+			pass.Reportf(field.Pos(), "struct field %s has %s tag but is not exported", field.Name(), enc)
+			return
+		}
+	}
+}
+
+// checkTagDuplicates checks a single struct field tag to see if any tags are
+// duplicated. nearest is the field that's closest to the field being checked,
+// while still being part of the top-level struct type.
+func checkTagDuplicates(pass *analysis.Pass, tag, key string, nearest, field *types.Var, seen *map[[2]string]token.Pos) {
+	val := reflect.StructTag(tag).Get(key)
+	if val == "-" {
+		// Ignored, even if the field is anonymous.
+		return
+	}
+	if val == "" || val[0] == ',' {
+		if field.Anonymous() {
+			typ, ok := field.Type().Underlying().(*types.Struct)
+			if !ok {
+				return
+			}
+			for i := 0; i < typ.NumFields(); i++ {
+				field := typ.Field(i)
+				if !field.Exported() {
+					continue
+				}
+				tag := typ.Tag(i)
+				checkTagDuplicates(pass, tag, key, nearest, field, seen)
+			}
+		}
+		// Ignored if the field isn't anonymous.
+		return
+	}
+	if key == "xml" && field.Name() == "XMLName" {
+		// XMLName defines the XML element name of the struct being
+		// checked. That name cannot collide with element or attribute
+		// names defined on other fields of the struct. Vet does not have a
+		// check for untagged fields of type struct defining their own name
+		// by containing a field named XMLName; see issue 18256.
+		return
+	}
+	if i := strings.Index(val, ","); i >= 0 {
+		if key == "xml" {
+			// Use a separate namespace for XML attributes.
+			for _, opt := range strings.Split(val[i:], ",") {
+				if opt == "attr" {
+					key += " attribute" // Key is part of the error message.
+					break
+				}
+			}
+		}
+		val = val[:i]
+	}
+	if *seen == nil {
+		*seen = map[[2]string]token.Pos{}
+	}
+	if pos, ok := (*seen)[[2]string{key, val}]; ok {
+		alsoPos := pass.Fset.Position(pos)
+		alsoPos.Column = 0
+
+		// Make the "also at" position relative to the current position,
+		// to ensure that all warnings are unambiguous and correct. For
+		// example, via anonymous struct fields, it's possible for the
+		// two fields to be in different packages and directories.
+		thisPos := pass.Fset.Position(field.Pos())
+		rel, err := filepath.Rel(filepath.Dir(thisPos.Filename), alsoPos.Filename)
+		if err != nil {
+			// Possibly because the paths are relative; leave the
+			// filename alone.
+		} else {
+			alsoPos.Filename = rel
+		}
+
+		pass.Reportf(nearest.Pos(), "struct field %s repeats %s tag %q also at %s", field.Name(), key, val, alsoPos)
+	} else {
+		(*seen)[[2]string{key, val}] = field.Pos()
+	}
+}
+
+var (
+	errTagSyntax      = errors.New("bad syntax for struct tag pair")
+	errTagKeySyntax   = errors.New("bad syntax for struct tag key")
+	errTagValueSyntax = errors.New("bad syntax for struct tag value")
+	errTagValueSpace  = errors.New("suspicious space in struct tag value")
+	errTagSpace       = errors.New("key:\"value\" pairs not separated by spaces")
+)
+
+// validateStructTag parses the struct tag and returns an error if it is not
+// in the canonical format, which is a space-separated list of key:"value"
+// settings. The value may contain spaces.
+func validateStructTag(tag string) error {
+	// This code is based on the StructTag.Get code in package reflect.
+
+	n := 0
+	for ; tag != ""; n++ {
+		if n > 0 && tag != "" && tag[0] != ' ' {
+			// More restrictive than reflect, but catches likely mistakes
+			// like `x:"foo",y:"bar"`, which parses as `x:"foo" ,y:"bar"` with second key ",y".
+			return errTagSpace
+		}
+		// Skip leading space.
+		i := 0
+		for i < len(tag) && tag[i] == ' ' {
+			i++
+		}
+		tag = tag[i:]
+		if tag == "" {
+			break
+		}
+
+		// Scan to colon. A space, a quote or a control character is a syntax error.
+		// Strictly speaking, control chars include the range [0x7f, 0x9f], not just
+		// [0x00, 0x1f], but in practice, we ignore the multi-byte control characters
+		// as it is simpler to inspect the tag's bytes than the tag's runes.
+		i = 0
+		for i < len(tag) && tag[i] > ' ' && tag[i] != ':' && tag[i] != '"' && tag[i] != 0x7f {
+			i++
+		}
+		if i == 0 {
+			return errTagKeySyntax
+		}
+		if i+1 >= len(tag) || tag[i] != ':' {
+			return errTagSyntax
+		}
+		if tag[i+1] != '"' {
+			return errTagValueSyntax
+		}
+		key := tag[:i]
+		tag = tag[i+1:]
+
+		// Scan quoted string to find value.
+		i = 1
+		for i < len(tag) && tag[i] != '"' {
+			if tag[i] == '\\' {
+				i++
+			}
+			i++
+		}
+		if i >= len(tag) {
+			return errTagValueSyntax
+		}
+		qvalue := tag[:i+1]
+		tag = tag[i+1:]
+
+		value, err := strconv.Unquote(qvalue)
+		if err != nil {
+			return errTagValueSyntax
+		}
+
+		if !checkTagSpaces[key] {
+			continue
+		}
+
+		switch key {
+		case "xml":
+			// If the first or last character in the XML tag is a space, it is
+			// suspicious.
+			if strings.Trim(value, " ") != value {
+				return errTagValueSpace
+			}
+
+			// If there are multiple spaces, they are suspicious.
+			if strings.Count(value, " ") > 1 {
+				return errTagValueSpace
+			}
+
+			// If there is no comma, skip the rest of the checks.
+			comma := strings.IndexRune(value, ',')
+			if comma < 0 {
+				continue
+			}
+
+			// If the character before a comma is a space, this is suspicious.
+			if comma > 0 && value[comma-1] == ' ' {
+				return errTagValueSpace
+			}
+			value = value[comma+1:]
+		case "json":
+			// JSON allows using spaces in the name, so skip it.
+			comma := strings.IndexRune(value, ',')
+			if comma < 0 {
+				continue
+			}
+			value = value[comma+1:]
+		}
+
+		if strings.IndexByte(value, ' ') >= 0 {
+			return errTagValueSpace
+		}
+	}
+	return nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/tests/tests.go b/libgo/go/golang.org/x/tools/go/analysis/passes/tests/tests.go
new file mode 100644
index 00000000000..35b0a3e7cc2
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/tests/tests.go
@@ -0,0 +1,175 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package tests defines an Analyzer that checks for common mistaken
+// usages of tests and examples.
+package tests
+
+import (
+	"go/ast"
+	"go/types"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+const Doc = `check for common mistaken usages of tests and examples
+
+The tests checker walks Test, Benchmark and Example functions checking
+malformed names, wrong signatures and examples documenting non-existent
+identifiers.`
+
+var Analyzer = &analysis.Analyzer{
+	Name: "tests",
+	Doc:  Doc,
+	Run:  run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	for _, f := range pass.Files {
+		if !strings.HasSuffix(pass.Fset.File(f.Pos()).Name(), "_test.go") {
+			continue
+		}
+		for _, decl := range f.Decls {
+			fn, ok := decl.(*ast.FuncDecl)
+			if !ok || fn.Recv != nil {
+				// Ignore non-functions or functions with receivers.
+				continue
+			}
+
+			switch {
+			case strings.HasPrefix(fn.Name.Name, "Example"):
+				checkExample(pass, fn)
+			case strings.HasPrefix(fn.Name.Name, "Test"):
+				checkTest(pass, fn, "Test")
+			case strings.HasPrefix(fn.Name.Name, "Benchmark"):
+				checkTest(pass, fn, "Benchmark")
+			}
+		}
+	}
+	return nil, nil
+}
+
+func isExampleSuffix(s string) bool {
+	r, size := utf8.DecodeRuneInString(s)
+	return size > 0 && unicode.IsLower(r)
+}
+
+func isTestSuffix(name string) bool {
+	if len(name) == 0 {
+		// "Test" is ok.
+		return true
+	}
+	r, _ := utf8.DecodeRuneInString(name)
+	return !unicode.IsLower(r)
+}
+
+func isTestParam(typ ast.Expr, wantType string) bool {
+	ptr, ok := typ.(*ast.StarExpr)
+	if !ok {
+		// Not a pointer.
+		return false
+	}
+	// No easy way of making sure it's a *testing.T or *testing.B:
+	// ensure the name of the type matches.
+	if name, ok := ptr.X.(*ast.Ident); ok {
+		return name.Name == wantType
+	}
+	if sel, ok := ptr.X.(*ast.SelectorExpr); ok {
+		return sel.Sel.Name == wantType
+	}
+	return false
+}
+
+func lookup(pkg *types.Package, name string) types.Object {
+	if o := pkg.Scope().Lookup(name); o != nil {
+		return o
+	}
+
+	// If this package is ".../foo_test" and it imports a package
+	// ".../foo", try looking in the latter package.
+	// This heuristic should work even on build systems that do not
+	// record any special link between the packages.
+	if basePath := strings.TrimSuffix(pkg.Path(), "_test"); basePath != pkg.Path() {
+		for _, imp := range pkg.Imports() {
+			if imp.Path() == basePath {
+				return imp.Scope().Lookup(name)
+			}
+		}
+	}
+	return nil
+}
+
+func checkExample(pass *analysis.Pass, fn *ast.FuncDecl) {
+	fnName := fn.Name.Name
+	if params := fn.Type.Params; len(params.List) != 0 {
+		pass.Reportf(fn.Pos(), "%s should be niladic", fnName)
+	}
+	if results := fn.Type.Results; results != nil && len(results.List) != 0 {
+		pass.Reportf(fn.Pos(), "%s should return nothing", fnName)
+	}
+
+	if fnName == "Example" {
+		// Nothing more to do.
+		return
+	}
+
+	var (
+		exName = strings.TrimPrefix(fnName, "Example")
+		elems  = strings.SplitN(exName, "_", 3)
+		ident  = elems[0]
+		obj    = lookup(pass.Pkg, ident)
+	)
+	if ident != "" && obj == nil {
+		// Check ExampleFoo and ExampleBadFoo.
+		pass.Reportf(fn.Pos(), "%s refers to unknown identifier: %s", fnName, ident)
+		// Abort since obj is absent and no subsequent checks can be performed.
+		return
+	}
+	if len(elems) < 2 {
+		// Nothing more to do.
+		return
+	}
+
+	if ident == "" {
+		// Check Example_suffix and Example_BadSuffix.
+		if residual := strings.TrimPrefix(exName, "_"); !isExampleSuffix(residual) {
+			pass.Reportf(fn.Pos(), "%s has malformed example suffix: %s", fnName, residual)
+		}
+		return
+	}
+
+	mmbr := elems[1]
+	if !isExampleSuffix(mmbr) {
+		// Check ExampleFoo_Method and ExampleFoo_BadMethod.
+		if obj, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), mmbr); obj == nil {
+			pass.Reportf(fn.Pos(), "%s refers to unknown field or method: %s.%s", fnName, ident, mmbr)
+		}
+	}
+	if len(elems) == 3 && !isExampleSuffix(elems[2]) {
+		// Check ExampleFoo_Method_suffix and ExampleFoo_Method_Badsuffix.
+		pass.Reportf(fn.Pos(), "%s has malformed example suffix: %s", fnName, elems[2])
+	}
+}
+
+func checkTest(pass *analysis.Pass, fn *ast.FuncDecl, prefix string) {
+	// Want functions with 0 results and 1 parameter.
+	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
+		fn.Type.Params == nil ||
+		len(fn.Type.Params.List) != 1 ||
+		len(fn.Type.Params.List[0].Names) > 1 {
+		return
+	}
+
+	// The param must look like a *testing.T or *testing.B.
+	if !isTestParam(fn.Type.Params.List[0].Type, prefix[:1]) {
+		return
+	}
+
+	if !isTestSuffix(fn.Name.Name[len(prefix):]) {
+		pass.Reportf(fn.Pos(), "%s has malformed name: first letter after '%s' must not be lowercase", fn.Name.Name, prefix)
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/unmarshal/unmarshal.go b/libgo/go/golang.org/x/tools/go/analysis/passes/unmarshal/unmarshal.go
new file mode 100644
index 00000000000..6cf4358ab9a
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/unmarshal/unmarshal.go
@@ -0,0 +1,92 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The unmarshal package defines an Analyzer that checks for passing
+// non-pointer or non-interface types to unmarshal and decode functions.
+package unmarshal
+
+import (
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+const doc = `report passing non-pointer or non-interface values to unmarshal
+
+The unmarshal analysis reports calls to functions such as json.Unmarshal
+in which the argument type is not a pointer or an interface.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "unmarshal",
+	Doc:      doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.CallExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		call := n.(*ast.CallExpr)
+		fn := typeutil.StaticCallee(pass.TypesInfo, call)
+		if fn == nil {
+			return // not a static call
+		}
+
+		// Classify the callee (without allocating memory).
+		argidx := -1
+		recv := fn.Type().(*types.Signature).Recv()
+		if fn.Name() == "Unmarshal" && recv == nil {
+			// "encoding/json".Unmarshal
+			//  "encoding/xml".Unmarshal
+			switch fn.Pkg().Path() {
+			case "encoding/json", "encoding/xml":
+				argidx = 1 // func([]byte, interface{})
+			}
+		} else if fn.Name() == "Decode" && recv != nil {
+			// (*"encoding/json".Decoder).Decode
+			// (* "encoding/gob".Decoder).Decode
+			// (* "encoding/xml".Decoder).Decode
+			t := recv.Type()
+			if ptr, ok := t.(*types.Pointer); ok {
+				t = ptr.Elem()
+			}
+			tname := t.(*types.Named).Obj()
+			if tname.Name() == "Decoder" {
+				switch tname.Pkg().Path() {
+				case "encoding/json", "encoding/xml", "encoding/gob":
+					argidx = 0 // func(interface{})
+				}
+			}
+		}
+		if argidx < 0 {
+			return // not a function we are interested in
+		}
+
+		if len(call.Args) < argidx+1 {
+			return // not enough arguments, e.g. called with return values of another function
+		}
+
+		t := pass.TypesInfo.Types[call.Args[argidx]].Type
+		switch t.Underlying().(type) {
+		case *types.Pointer, *types.Interface:
+			return
+		}
+
+		switch argidx {
+		case 0:
+			pass.Reportf(call.Lparen, "call of %s passes non-pointer", fn.Name())
+		case 1:
+			pass.Reportf(call.Lparen, "call of %s passes non-pointer as second argument", fn.Name())
+		}
+	})
+	return nil, nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/unreachable/unreachable.go b/libgo/go/golang.org/x/tools/go/analysis/passes/unreachable/unreachable.go
new file mode 100644
index 00000000000..19bc9c2db98
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/unreachable/unreachable.go
@@ -0,0 +1,314 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package unreachable defines an Analyzer that checks for unreachable code.
+package unreachable
+
+// TODO(adonovan): use the new cfg package, which is more precise.
+
+import (
+	"go/ast"
+	"go/token"
+	"log"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for unreachable code
+
+The unreachable analyzer finds statements that execution can never reach
+because they are preceded by an return statement, a call to panic, an
+infinite loop, or similar constructs.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:             "unreachable",
+	Doc:              Doc,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.FuncDecl)(nil),
+		(*ast.FuncLit)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		var body *ast.BlockStmt
+		switch n := n.(type) {
+		case *ast.FuncDecl:
+			body = n.Body
+		case *ast.FuncLit:
+			body = n.Body
+		}
+		if body == nil {
+			return
+		}
+		d := &deadState{
+			pass:     pass,
+			hasBreak: make(map[ast.Stmt]bool),
+			hasGoto:  make(map[string]bool),
+			labels:   make(map[string]ast.Stmt),
+		}
+		d.findLabels(body)
+		d.reachable = true
+		d.findDead(body)
+	})
+	return nil, nil
+}
+
+type deadState struct {
+	pass        *analysis.Pass
+	hasBreak    map[ast.Stmt]bool
+	hasGoto     map[string]bool
+	labels      map[string]ast.Stmt
+	breakTarget ast.Stmt
+
+	reachable bool
+}
+
+// findLabels gathers information about the labels defined and used by stmt
+// and about which statements break, whether a label is involved or not.
+func (d *deadState) findLabels(stmt ast.Stmt) {
+	switch x := stmt.(type) {
+	default:
+		log.Fatalf("%s: internal error in findLabels: unexpected statement %T", d.pass.Fset.Position(x.Pos()), x)
+
+	case *ast.AssignStmt,
+		*ast.BadStmt,
+		*ast.DeclStmt,
+		*ast.DeferStmt,
+		*ast.EmptyStmt,
+		*ast.ExprStmt,
+		*ast.GoStmt,
+		*ast.IncDecStmt,
+		*ast.ReturnStmt,
+		*ast.SendStmt:
+		// no statements inside
+
+	case *ast.BlockStmt:
+		for _, stmt := range x.List {
+			d.findLabels(stmt)
+		}
+
+	case *ast.BranchStmt:
+		switch x.Tok {
+		case token.GOTO:
+			if x.Label != nil {
+				d.hasGoto[x.Label.Name] = true
+			}
+
+		case token.BREAK:
+			stmt := d.breakTarget
+			if x.Label != nil {
+				stmt = d.labels[x.Label.Name]
+			}
+			if stmt != nil {
+				d.hasBreak[stmt] = true
+			}
+		}
+
+	case *ast.IfStmt:
+		d.findLabels(x.Body)
+		if x.Else != nil {
+			d.findLabels(x.Else)
+		}
+
+	case *ast.LabeledStmt:
+		d.labels[x.Label.Name] = x.Stmt
+		d.findLabels(x.Stmt)
+
+	// These cases are all the same, but the x.Body only works
+	// when the specific type of x is known, so the cases cannot
+	// be merged.
+	case *ast.ForStmt:
+		outer := d.breakTarget
+		d.breakTarget = x
+		d.findLabels(x.Body)
+		d.breakTarget = outer
+
+	case *ast.RangeStmt:
+		outer := d.breakTarget
+		d.breakTarget = x
+		d.findLabels(x.Body)
+		d.breakTarget = outer
+
+	case *ast.SelectStmt:
+		outer := d.breakTarget
+		d.breakTarget = x
+		d.findLabels(x.Body)
+		d.breakTarget = outer
+
+	case *ast.SwitchStmt:
+		outer := d.breakTarget
+		d.breakTarget = x
+		d.findLabels(x.Body)
+		d.breakTarget = outer
+
+	case *ast.TypeSwitchStmt:
+		outer := d.breakTarget
+		d.breakTarget = x
+		d.findLabels(x.Body)
+		d.breakTarget = outer
+
+	case *ast.CommClause:
+		for _, stmt := range x.Body {
+			d.findLabels(stmt)
+		}
+
+	case *ast.CaseClause:
+		for _, stmt := range x.Body {
+			d.findLabels(stmt)
+		}
+	}
+}
+
+// findDead walks the statement looking for dead code.
+// If d.reachable is false on entry, stmt itself is dead.
+// When findDead returns, d.reachable tells whether the
+// statement following stmt is reachable.
+func (d *deadState) findDead(stmt ast.Stmt) {
+	// Is this a labeled goto target?
+	// If so, assume it is reachable due to the goto.
+	// This is slightly conservative, in that we don't
+	// check that the goto is reachable, so
+	//	L: goto L
+	// will not provoke a warning.
+	// But it's good enough.
+	if x, isLabel := stmt.(*ast.LabeledStmt); isLabel && d.hasGoto[x.Label.Name] {
+		d.reachable = true
+	}
+
+	if !d.reachable {
+		switch stmt.(type) {
+		case *ast.EmptyStmt:
+			// do not warn about unreachable empty statements
+		default:
+			d.pass.Reportf(stmt.Pos(), "unreachable code")
+			d.reachable = true // silence error about next statement
+		}
+	}
+
+	switch x := stmt.(type) {
+	default:
+		log.Fatalf("%s: internal error in findDead: unexpected statement %T", d.pass.Fset.Position(x.Pos()), x)
+
+	case *ast.AssignStmt,
+		*ast.BadStmt,
+		*ast.DeclStmt,
+		*ast.DeferStmt,
+		*ast.EmptyStmt,
+		*ast.GoStmt,
+		*ast.IncDecStmt,
+		*ast.SendStmt:
+		// no control flow
+
+	case *ast.BlockStmt:
+		for _, stmt := range x.List {
+			d.findDead(stmt)
+		}
+
+	case *ast.BranchStmt:
+		switch x.Tok {
+		case token.BREAK, token.GOTO, token.FALLTHROUGH:
+			d.reachable = false
+		case token.CONTINUE:
+			// NOTE: We accept "continue" statements as terminating.
+			// They are not necessary in the spec definition of terminating,
+			// because a continue statement cannot be the final statement
+			// before a return. But for the more general problem of syntactically
+			// identifying dead code, continue redirects control flow just
+			// like the other terminating statements.
+			d.reachable = false
+		}
+
+	case *ast.ExprStmt:
+		// Call to panic?
+		call, ok := x.X.(*ast.CallExpr)
+		if ok {
+			name, ok := call.Fun.(*ast.Ident)
+			if ok && name.Name == "panic" && name.Obj == nil {
+				d.reachable = false
+			}
+		}
+
+	case *ast.ForStmt:
+		d.findDead(x.Body)
+		d.reachable = x.Cond != nil || d.hasBreak[x]
+
+	case *ast.IfStmt:
+		d.findDead(x.Body)
+		if x.Else != nil {
+			r := d.reachable
+			d.reachable = true
+			d.findDead(x.Else)
+			d.reachable = d.reachable || r
+		} else {
+			// might not have executed if statement
+			d.reachable = true
+		}
+
+	case *ast.LabeledStmt:
+		d.findDead(x.Stmt)
+
+	case *ast.RangeStmt:
+		d.findDead(x.Body)
+		d.reachable = true
+
+	case *ast.ReturnStmt:
+		d.reachable = false
+
+	case *ast.SelectStmt:
+		// NOTE: Unlike switch and type switch below, we don't care
+		// whether a select has a default, because a select without a
+		// default blocks until one of the cases can run. That's different
+		// from a switch without a default, which behaves like it has
+		// a default with an empty body.
+		anyReachable := false
+		for _, comm := range x.Body.List {
+			d.reachable = true
+			for _, stmt := range comm.(*ast.CommClause).Body {
+				d.findDead(stmt)
+			}
+			anyReachable = anyReachable || d.reachable
+		}
+		d.reachable = anyReachable || d.hasBreak[x]
+
+	case *ast.SwitchStmt:
+		anyReachable := false
+		hasDefault := false
+		for _, cas := range x.Body.List {
+			cc := cas.(*ast.CaseClause)
+			if cc.List == nil {
+				hasDefault = true
+			}
+			d.reachable = true
+			for _, stmt := range cc.Body {
+				d.findDead(stmt)
+			}
+			anyReachable = anyReachable || d.reachable
+		}
+		d.reachable = anyReachable || d.hasBreak[x] || !hasDefault
+
+	case *ast.TypeSwitchStmt:
+		anyReachable := false
+		hasDefault := false
+		for _, cas := range x.Body.List {
+			cc := cas.(*ast.CaseClause)
+			if cc.List == nil {
+				hasDefault = true
+			}
+			d.reachable = true
+			for _, stmt := range cc.Body {
+				d.findDead(stmt)
+			}
+			anyReachable = anyReachable || d.reachable
+		}
+		d.reachable = anyReachable || d.hasBreak[x] || !hasDefault
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/unsafeptr/unsafeptr.go b/libgo/go/golang.org/x/tools/go/analysis/passes/unsafeptr/unsafeptr.go
new file mode 100644
index 00000000000..308bfc69cb4
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/unsafeptr/unsafeptr.go
@@ -0,0 +1,130 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package unsafeptr defines an Analyzer that checks for invalid
+// conversions of uintptr to unsafe.Pointer.
+package unsafeptr
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for invalid conversions of uintptr to unsafe.Pointer
+
+The unsafeptr analyzer reports likely incorrect uses of unsafe.Pointer
+to convert integers to pointers. A conversion from uintptr to
+unsafe.Pointer is invalid if it implies that there is a uintptr-typed
+word in memory that holds a pointer value, because that word will be
+invisible to stack copying and to the garbage collector.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "unsafeptr",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.CallExpr)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		x := n.(*ast.CallExpr)
+		if len(x.Args) != 1 {
+			return
+		}
+		if hasBasicType(pass.TypesInfo, x.Fun, types.UnsafePointer) &&
+			hasBasicType(pass.TypesInfo, x.Args[0], types.Uintptr) &&
+			!isSafeUintptr(pass.TypesInfo, x.Args[0]) {
+			pass.Reportf(x.Pos(), "possible misuse of unsafe.Pointer")
+		}
+	})
+	return nil, nil
+}
+
+// isSafeUintptr reports whether x - already known to be a uintptr -
+// is safe to convert to unsafe.Pointer. It is safe if x is itself derived
+// directly from an unsafe.Pointer via conversion and pointer arithmetic
+// or if x is the result of reflect.Value.Pointer or reflect.Value.UnsafeAddr
+// or obtained from the Data field of a *reflect.SliceHeader or *reflect.StringHeader.
+func isSafeUintptr(info *types.Info, x ast.Expr) bool {
+	switch x := x.(type) {
+	case *ast.ParenExpr:
+		return isSafeUintptr(info, x.X)
+
+	case *ast.SelectorExpr:
+		if x.Sel.Name != "Data" {
+			break
+		}
+		// reflect.SliceHeader and reflect.StringHeader are okay,
+		// but only if they are pointing at a real slice or string.
+		// It's not okay to do:
+		//	var x SliceHeader
+		//	x.Data = uintptr(unsafe.Pointer(...))
+		//	... use x ...
+		//	p := unsafe.Pointer(x.Data)
+		// because in the middle the garbage collector doesn't
+		// see x.Data as a pointer and so x.Data may be dangling
+		// by the time we get to the conversion at the end.
+		// For now approximate by saying that *Header is okay
+		// but Header is not.
+		pt, ok := info.Types[x.X].Type.(*types.Pointer)
+		if ok {
+			t, ok := pt.Elem().(*types.Named)
+			if ok && t.Obj().Pkg().Path() == "reflect" {
+				switch t.Obj().Name() {
+				case "StringHeader", "SliceHeader":
+					return true
+				}
+			}
+		}
+
+	case *ast.CallExpr:
+		switch len(x.Args) {
+		case 0:
+			// maybe call to reflect.Value.Pointer or reflect.Value.UnsafeAddr.
+			sel, ok := x.Fun.(*ast.SelectorExpr)
+			if !ok {
+				break
+			}
+			switch sel.Sel.Name {
+			case "Pointer", "UnsafeAddr":
+				t, ok := info.Types[sel.X].Type.(*types.Named)
+				if ok && t.Obj().Pkg().Path() == "reflect" && t.Obj().Name() == "Value" {
+					return true
+				}
+			}
+
+		case 1:
+			// maybe conversion of uintptr to unsafe.Pointer
+			return hasBasicType(info, x.Fun, types.Uintptr) &&
+				hasBasicType(info, x.Args[0], types.UnsafePointer)
+		}
+
+	case *ast.BinaryExpr:
+		switch x.Op {
+		case token.ADD, token.SUB, token.AND_NOT:
+			return isSafeUintptr(info, x.X) && !isSafeUintptr(info, x.Y)
+		}
+	}
+	return false
+}
+
+// hasBasicType reports whether x's type is a types.Basic with the given kind.
+func hasBasicType(info *types.Info, x ast.Expr, kind types.BasicKind) bool {
+	t := info.Types[x].Type
+	if t != nil {
+		t = t.Underlying()
+	}
+	b, ok := t.(*types.Basic)
+	return ok && b.Kind() == kind
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/passes/unusedresult/unusedresult.go b/libgo/go/golang.org/x/tools/go/analysis/passes/unusedresult/unusedresult.go
new file mode 100644
index 00000000000..76d4ab23827
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/passes/unusedresult/unusedresult.go
@@ -0,0 +1,131 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package unusedresult defines an analyzer that checks for unused
+// results of calls to certain pure functions.
+package unusedresult
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+	"sort"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+// TODO(adonovan): make this analysis modular: export a mustUseResult
+// fact for each function that tail-calls one of the functions that we
+// check, and check those functions too.
+
+const Doc = `check for unused results of calls to some functions
+
+Some functions like fmt.Errorf return a result and have no side effects,
+so it is always a mistake to discard the result. This analyzer reports
+calls to certain functions in which the result of the call is ignored.
+
+The set of functions may be controlled using flags.`
+
+var Analyzer = &analysis.Analyzer{
+	Name:     "unusedresult",
+	Doc:      Doc,
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	Run:      run,
+}
+
+// flags
+var funcs, stringMethods stringSetFlag
+
+func init() {
+	// TODO(adonovan): provide a comment syntax to allow users to
+	// add their functions to this set using facts.
+	funcs.Set("errors.New,fmt.Errorf,fmt.Sprintf,fmt.Sprint,sort.Reverse")
+	Analyzer.Flags.Var(&funcs, "funcs",
+		"comma-separated list of functions whose results must be used")
+
+	stringMethods.Set("Error,String")
+	Analyzer.Flags.Var(&stringMethods, "stringmethods",
+		"comma-separated list of names of methods of type func() string whose results must be used")
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.ExprStmt)(nil),
+	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		call, ok := analysisutil.Unparen(n.(*ast.ExprStmt).X).(*ast.CallExpr)
+		if !ok {
+			return // not a call statement
+		}
+		fun := analysisutil.Unparen(call.Fun)
+
+		if pass.TypesInfo.Types[fun].IsType() {
+			return // a conversion, not a call
+		}
+
+		selector, ok := fun.(*ast.SelectorExpr)
+		if !ok {
+			return // neither a method call nor a qualified ident
+		}
+
+		sel, ok := pass.TypesInfo.Selections[selector]
+		if ok && sel.Kind() == types.MethodVal {
+			// method (e.g. foo.String())
+			obj := sel.Obj().(*types.Func)
+			sig := sel.Type().(*types.Signature)
+			if types.Identical(sig, sigNoArgsStringResult) {
+				if stringMethods[obj.Name()] {
+					pass.Reportf(call.Lparen, "result of (%s).%s call not used",
+						sig.Recv().Type(), obj.Name())
+				}
+			}
+		} else if !ok {
+			// package-qualified function (e.g. fmt.Errorf)
+			obj := pass.TypesInfo.Uses[selector.Sel]
+			if obj, ok := obj.(*types.Func); ok {
+				qname := obj.Pkg().Path() + "." + obj.Name()
+				if funcs[qname] {
+					pass.Reportf(call.Lparen, "result of %v call not used", qname)
+				}
+			}
+		}
+	})
+	return nil, nil
+}
+
+// func() string
+var sigNoArgsStringResult = types.NewSignature(nil, nil,
+	types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.String])),
+	false)
+
+type stringSetFlag map[string]bool
+
+func (ss *stringSetFlag) String() string {
+	var items []string
+	for item := range *ss {
+		items = append(items, item)
+	}
+	sort.Strings(items)
+	return strings.Join(items, ",")
+}
+
+func (ss *stringSetFlag) Set(s string) error {
+	m := make(map[string]bool) // clobber previous value
+	if s != "" {
+		for _, name := range strings.Split(s, ",") {
+			if name == "" {
+				continue // TODO: report error? proceed?
+			}
+			m[name] = true
+		}
+	}
+	*ss = m
+	return nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/unitchecker/main.go b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/main.go
new file mode 100644
index 00000000000..844e8f3dac2
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/main.go
@@ -0,0 +1,64 @@
+// +build ignore
+
+// This file provides an example command for static checkers
+// conforming to the golang.org/x/tools/go/analysis API.
+// It serves as a model for the behavior of the cmd/vet tool in $GOROOT.
+// Being based on the unitchecker driver, it must be run by go vet:
+//
+//   $ go build -o unitchecker main.go
+//   $ go vet -vettool=unitchecker my/project/...
+//
+// For a checker also capable of running standalone, use multichecker.
+package main
+
+import (
+	"golang.org/x/tools/go/analysis/unitchecker"
+
+	"golang.org/x/tools/go/analysis/passes/asmdecl"
+	"golang.org/x/tools/go/analysis/passes/assign"
+	"golang.org/x/tools/go/analysis/passes/atomic"
+	"golang.org/x/tools/go/analysis/passes/bools"
+	"golang.org/x/tools/go/analysis/passes/buildtag"
+	"golang.org/x/tools/go/analysis/passes/cgocall"
+	"golang.org/x/tools/go/analysis/passes/composite"
+	"golang.org/x/tools/go/analysis/passes/copylock"
+	"golang.org/x/tools/go/analysis/passes/httpresponse"
+	"golang.org/x/tools/go/analysis/passes/loopclosure"
+	"golang.org/x/tools/go/analysis/passes/lostcancel"
+	"golang.org/x/tools/go/analysis/passes/nilfunc"
+	"golang.org/x/tools/go/analysis/passes/printf"
+	"golang.org/x/tools/go/analysis/passes/shift"
+	"golang.org/x/tools/go/analysis/passes/stdmethods"
+	"golang.org/x/tools/go/analysis/passes/structtag"
+	"golang.org/x/tools/go/analysis/passes/tests"
+	"golang.org/x/tools/go/analysis/passes/unmarshal"
+	"golang.org/x/tools/go/analysis/passes/unreachable"
+	"golang.org/x/tools/go/analysis/passes/unsafeptr"
+	"golang.org/x/tools/go/analysis/passes/unusedresult"
+)
+
+func main() {
+	unitchecker.Main(
+		asmdecl.Analyzer,
+		assign.Analyzer,
+		atomic.Analyzer,
+		bools.Analyzer,
+		buildtag.Analyzer,
+		cgocall.Analyzer,
+		composite.Analyzer,
+		copylock.Analyzer,
+		httpresponse.Analyzer,
+		loopclosure.Analyzer,
+		lostcancel.Analyzer,
+		nilfunc.Analyzer,
+		printf.Analyzer,
+		shift.Analyzer,
+		stdmethods.Analyzer,
+		structtag.Analyzer,
+		tests.Analyzer,
+		unmarshal.Analyzer,
+		unreachable.Analyzer,
+		unsafeptr.Analyzer,
+		unusedresult.Analyzer,
+	)
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go
new file mode 100644
index 00000000000..76dabc28b90
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go
@@ -0,0 +1,387 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The unitchecker package defines the main function for an analysis
+// driver that analyzes a single compilation unit during a build.
+// It is invoked by a build system such as "go vet":
+//
+//   $ go vet -vettool=$(which vet)
+//
+// It supports the following command-line protocol:
+//
+//      -V=full         describe executable               (to the build tool)
+//      -flags          describe flags                    (to the build tool)
+//      foo.cfg         description of compilation unit (from the build tool)
+//
+// This package does not depend on go/packages.
+// If you need a standalone tool, use multichecker,
+// which supports this mode but can also load packages
+// from source using go/packages.
+package unitchecker
+
+// TODO(adonovan):
+// - with gccgo, go build does not build standard library,
+//   so we will not get to analyze it. Yet we must in order
+//   to create base facts for, say, the fmt package for the
+//   printf checker.
+
+import (
+	"encoding/gob"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/internal/analysisflags"
+	"golang.org/x/tools/go/analysis/internal/facts"
+)
+
+// A Config describes a compilation unit to be analyzed.
+// It is provided to the tool in a JSON-encoded file
+// whose name ends with ".cfg".
+type Config struct {
+	ID                        string // e.g. "fmt [fmt.test]"
+	Compiler                  string
+	Dir                       string
+	ImportPath                string
+	GoFiles                   []string
+	NonGoFiles                []string
+	ImportMap                 map[string]string
+	PackageFile               map[string]string
+	Standard                  map[string]bool
+	PackageVetx               map[string]string
+	VetxOnly                  bool
+	VetxOutput                string
+	SucceedOnTypecheckFailure bool
+}
+
+// Main is the main function of a vet-like analysis tool that must be
+// invoked by a build system to analyze a single package.
+//
+// The protocol required by 'go vet -vettool=...' is that the tool must support:
+//
+//      -flags          describe flags in JSON
+//      -V=full         describe executable for build caching
+//      foo.cfg         perform separate modular analyze on the single
+//                      unit described by a JSON config file foo.cfg.
+//
+func Main(analyzers ...*analysis.Analyzer) {
+	progname := filepath.Base(os.Args[0])
+	log.SetFlags(0)
+	log.SetPrefix(progname + ": ")
+
+	if err := analysis.Validate(analyzers); err != nil {
+		log.Fatal(err)
+	}
+
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, `%[1]s is a tool for static analysis of Go programs.
+
+Usage of %[1]s:
+	%.16[1]s unit.cfg	# execute analysis specified by config file
+	%.16[1]s help    	# general help
+	%.16[1]s help name	# help on specific analyzer and its flags
+`, progname)
+		os.Exit(1)
+	}
+
+	analyzers = analysisflags.Parse(analyzers, true)
+
+	args := flag.Args()
+	if len(args) == 0 {
+		flag.Usage()
+	}
+	if args[0] == "help" {
+		analysisflags.Help(progname, analyzers, args[1:])
+		os.Exit(0)
+	}
+	if len(args) != 1 || !strings.HasSuffix(args[0], ".cfg") {
+		log.Fatalf(`invoking "go tool vet" directly is unsupported; use "go vet"`)
+	}
+	Run(args[0], analyzers)
+}
+
+// Run reads the *.cfg file, runs the analysis,
+// and calls os.Exit with an appropriate error code.
+// It assumes flags have already been set.
+func Run(configFile string, analyzers []*analysis.Analyzer) {
+	cfg, err := readConfig(configFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fset := token.NewFileSet()
+	results, err := run(fset, cfg, analyzers)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// In VetxOnly mode, the analysis is run only for facts.
+	if !cfg.VetxOnly {
+		if analysisflags.JSON {
+			// JSON output
+			tree := make(analysisflags.JSONTree)
+			for _, res := range results {
+				tree.Add(fset, cfg.ID, res.a.Name, res.diagnostics, res.err)
+			}
+			tree.Print()
+		} else {
+			// plain text
+			exit := 0
+			for _, res := range results {
+				if res.err != nil {
+					log.Println(res.err)
+					exit = 1
+				}
+			}
+			for _, res := range results {
+				for _, diag := range res.diagnostics {
+					analysisflags.PrintPlain(fset, diag)
+					exit = 1
+				}
+			}
+			os.Exit(exit)
+		}
+	}
+
+	os.Exit(0)
+}
+
+func readConfig(filename string) (*Config, error) {
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	cfg := new(Config)
+	if err := json.Unmarshal(data, cfg); err != nil {
+		return nil, fmt.Errorf("cannot decode JSON config file %s: %v", filename, err)
+	}
+	if len(cfg.GoFiles) == 0 {
+		// The go command disallows packages with no files.
+		// The only exception is unsafe, but the go command
+		// doesn't call vet on it.
+		return nil, fmt.Errorf("package has no files: %s", cfg.ImportPath)
+	}
+	return cfg, nil
+}
+
+var importerForCompiler = func(_ *token.FileSet, compiler string, lookup importer.Lookup) types.Importer {
+	// broken legacy implementation (https://golang.org/issue/28995)
+	return importer.For(compiler, lookup)
+}
+
+func run(fset *token.FileSet, cfg *Config, analyzers []*analysis.Analyzer) ([]result, error) {
+	// Load, parse, typecheck.
+	var files []*ast.File
+	for _, name := range cfg.GoFiles {
+		f, err := parser.ParseFile(fset, name, nil, parser.ParseComments)
+		if err != nil {
+			if cfg.SucceedOnTypecheckFailure {
+				// Silently succeed; let the compiler
+				// report parse errors.
+				err = nil
+			}
+			return nil, err
+		}
+		files = append(files, f)
+	}
+	compilerImporter := importerForCompiler(fset, cfg.Compiler, func(path string) (io.ReadCloser, error) {
+		// path is a resolved package path, not an import path.
+		file, ok := cfg.PackageFile[path]
+		if !ok {
+			if cfg.Compiler == "gccgo" && cfg.Standard[path] {
+				return nil, nil // fall back to default gccgo lookup
+			}
+			return nil, fmt.Errorf("no package file for %q", path)
+		}
+		return os.Open(file)
+	})
+	importer := importerFunc(func(importPath string) (*types.Package, error) {
+		path, ok := cfg.ImportMap[importPath] // resolve vendoring, etc
+		if !ok {
+			return nil, fmt.Errorf("can't resolve import %q", path)
+		}
+		return compilerImporter.Import(path)
+	})
+	tc := &types.Config{
+		Importer: importer,
+		Sizes:    types.SizesFor("gc", build.Default.GOARCH), // assume gccgo ≡ gc?
+	}
+	info := &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Implicits:  make(map[ast.Node]types.Object),
+		Scopes:     make(map[ast.Node]*types.Scope),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	pkg, err := tc.Check(cfg.ImportPath, fset, files, info)
+	if err != nil {
+		if cfg.SucceedOnTypecheckFailure {
+			// Silently succeed; let the compiler
+			// report type errors.
+			err = nil
+		}
+		return nil, err
+	}
+
+	// Register fact types with gob.
+	// In VetxOnly mode, analyzers are only for their facts,
+	// so we can skip any analysis that neither produces facts
+	// nor depends on any analysis that produces facts.
+	// Also build a map to hold working state and result.
+	type action struct {
+		once        sync.Once
+		result      interface{}
+		err         error
+		usesFacts   bool // (transitively uses)
+		diagnostics []analysis.Diagnostic
+	}
+	actions := make(map[*analysis.Analyzer]*action)
+	var registerFacts func(a *analysis.Analyzer) bool
+	registerFacts = func(a *analysis.Analyzer) bool {
+		act, ok := actions[a]
+		if !ok {
+			act = new(action)
+			var usesFacts bool
+			for _, f := range a.FactTypes {
+				usesFacts = true
+				gob.Register(f)
+			}
+			for _, req := range a.Requires {
+				if registerFacts(req) {
+					usesFacts = true
+				}
+			}
+			act.usesFacts = usesFacts
+			actions[a] = act
+		}
+		return act.usesFacts
+	}
+	var filtered []*analysis.Analyzer
+	for _, a := range analyzers {
+		if registerFacts(a) || !cfg.VetxOnly {
+			filtered = append(filtered, a)
+		}
+	}
+	analyzers = filtered
+
+	// Read facts from imported packages.
+	read := func(path string) ([]byte, error) {
+		if vetx, ok := cfg.PackageVetx[path]; ok {
+			return ioutil.ReadFile(vetx)
+		}
+		return nil, nil // no .vetx file, no facts
+	}
+	facts, err := facts.Decode(pkg, read)
+	if err != nil {
+		return nil, err
+	}
+
+	// In parallel, execute the DAG of analyzers.
+	var exec func(a *analysis.Analyzer) *action
+	var execAll func(analyzers []*analysis.Analyzer)
+	exec = func(a *analysis.Analyzer) *action {
+		act := actions[a]
+		act.once.Do(func() {
+			execAll(a.Requires) // prefetch dependencies in parallel
+
+			// The inputs to this analysis are the
+			// results of its prerequisites.
+			inputs := make(map[*analysis.Analyzer]interface{})
+			var failed []string
+			for _, req := range a.Requires {
+				reqact := exec(req)
+				if reqact.err != nil {
+					failed = append(failed, req.String())
+					continue
+				}
+				inputs[req] = reqact.result
+			}
+
+			// Report an error if any dependency failed.
+			if failed != nil {
+				sort.Strings(failed)
+				act.err = fmt.Errorf("failed prerequisites: %s", strings.Join(failed, ", "))
+				return
+			}
+
+			pass := &analysis.Pass{
+				Analyzer:          a,
+				Fset:              fset,
+				Files:             files,
+				OtherFiles:        cfg.NonGoFiles,
+				Pkg:               pkg,
+				TypesInfo:         info,
+				ResultOf:          inputs,
+				Report:            func(d analysis.Diagnostic) { act.diagnostics = append(act.diagnostics, d) },
+				ImportObjectFact:  facts.ImportObjectFact,
+				ExportObjectFact:  facts.ExportObjectFact,
+				ImportPackageFact: facts.ImportPackageFact,
+				ExportPackageFact: facts.ExportPackageFact,
+			}
+
+			t0 := time.Now()
+			act.result, act.err = a.Run(pass)
+			if false {
+				log.Printf("analysis %s = %s", pass, time.Since(t0))
+			}
+		})
+		return act
+	}
+	execAll = func(analyzers []*analysis.Analyzer) {
+		var wg sync.WaitGroup
+		for _, a := range analyzers {
+			wg.Add(1)
+			go func(a *analysis.Analyzer) {
+				_ = exec(a)
+				wg.Done()
+			}(a)
+		}
+		wg.Wait()
+	}
+
+	execAll(analyzers)
+
+	// Return diagnostics and errors from root analyzers.
+	results := make([]result, len(analyzers))
+	for i, a := range analyzers {
+		act := actions[a]
+		results[i].a = a
+		results[i].err = act.err
+		results[i].diagnostics = act.diagnostics
+	}
+
+	data := facts.Encode()
+	if err := ioutil.WriteFile(cfg.VetxOutput, data, 0666); err != nil {
+		return nil, fmt.Errorf("failed to write analysis facts: %v", err)
+	}
+
+	return results, nil
+}
+
+type result struct {
+	a           *analysis.Analyzer
+	diagnostics []analysis.Diagnostic
+	err         error
+}
+
+type importerFunc func(path string) (*types.Package, error)
+
+func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }
diff --git a/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker112.go b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker112.go
new file mode 100644
index 00000000000..683b7e91d25
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/unitchecker/unitchecker112.go
@@ -0,0 +1,9 @@
+// +build go1.12
+
+package unitchecker
+
+import "go/importer"
+
+func init() {
+	importerForCompiler = importer.ForCompiler
+}
diff --git a/libgo/go/golang.org/x/tools/go/analysis/validate.go b/libgo/go/golang.org/x/tools/go/analysis/validate.go
new file mode 100644
index 00000000000..6e6cf4984fe
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/analysis/validate.go
@@ -0,0 +1,104 @@
+package analysis
+
+import (
+	"fmt"
+	"reflect"
+	"unicode"
+)
+
+// Validate reports an error if any of the analyzers are misconfigured.
+// Checks include:
+// that the name is a valid identifier;
+// that analyzer names are unique;
+// that the Requires graph is acylic;
+// that analyzer fact types are unique;
+// that each fact type is a pointer.
+func Validate(analyzers []*Analyzer) error {
+	names := make(map[string]bool)
+
+	// Map each fact type to its sole generating analyzer.
+	factTypes := make(map[reflect.Type]*Analyzer)
+
+	// Traverse the Requires graph, depth first.
+	const (
+		white = iota
+		grey
+		black
+		finished
+	)
+	color := make(map[*Analyzer]uint8)
+	var visit func(a *Analyzer) error
+	visit = func(a *Analyzer) error {
+		if a == nil {
+			return fmt.Errorf("nil *Analyzer")
+		}
+		if color[a] == white {
+			color[a] = grey
+
+			// names
+			if !validIdent(a.Name) {
+				return fmt.Errorf("invalid analyzer name %q", a)
+			}
+			if names[a.Name] {
+				return fmt.Errorf("duplicate analyzer name %q", a)
+			}
+			names[a.Name] = true
+
+			if a.Doc == "" {
+				return fmt.Errorf("analyzer %q is undocumented", a)
+			}
+
+			// fact types
+			for _, f := range a.FactTypes {
+				if f == nil {
+					return fmt.Errorf("analyzer %s has nil FactType", a)
+				}
+				t := reflect.TypeOf(f)
+				if prev := factTypes[t]; prev != nil {
+					return fmt.Errorf("fact type %s registered by two analyzers: %v, %v",
+						t, a, prev)
+				}
+				if t.Kind() != reflect.Ptr {
+					return fmt.Errorf("%s: fact type %s is not a pointer", a, t)
+				}
+				factTypes[t] = a
+			}
+
+			// recursion
+			for i, req := range a.Requires {
+				if err := visit(req); err != nil {
+					return fmt.Errorf("%s.Requires[%d]: %v", a.Name, i, err)
+				}
+			}
+			color[a] = black
+		}
+
+		return nil
+	}
+	for _, a := range analyzers {
+		if err := visit(a); err != nil {
+			return err
+		}
+	}
+
+	// Reject duplicates among analyzers.
+	// Precondition:  color[a] == black.
+	// Postcondition: color[a] == finished.
+	for _, a := range analyzers {
+		if color[a] == finished {
+			return fmt.Errorf("duplicate analyzer: %s", a.Name)
+		}
+		color[a] = finished
+	}
+
+	return nil
+}
+
+func validIdent(name string) bool {
+	for i, r := range name {
+		if !(r == '_' || unicode.IsLetter(r) || i > 0 && unicode.IsDigit(r)) {
+			return false
+		}
+	}
+	return name != ""
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/astutil/enclosing.go b/libgo/go/golang.org/x/tools/go/ast/astutil/enclosing.go
new file mode 100644
index 00000000000..6b7052b892c
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/astutil/enclosing.go
@@ -0,0 +1,627 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package astutil
+
+// This file defines utilities for working with source positions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"sort"
+)
+
+// PathEnclosingInterval returns the node that encloses the source
+// interval [start, end), and all its ancestors up to the AST root.
+//
+// The definition of "enclosing" used by this function considers
+// additional whitespace abutting a node to be enclosed by it.
+// In this example:
+//
+//              z := x + y // add them
+//                   <-A->
+//                  <----B----->
+//
+// the ast.BinaryExpr(+) node is considered to enclose interval B
+// even though its [Pos()..End()) is actually only interval A.
+// This behaviour makes user interfaces more tolerant of imperfect
+// input.
+//
+// This function treats tokens as nodes, though they are not included
+// in the result. e.g. PathEnclosingInterval("+") returns the
+// enclosing ast.BinaryExpr("x + y").
+//
+// If start==end, the 1-char interval following start is used instead.
+//
+// The 'exact' result is true if the interval contains only path[0]
+// and perhaps some adjacent whitespace.  It is false if the interval
+// overlaps multiple children of path[0], or if it contains only
+// interior whitespace of path[0].
+// In this example:
+//
+//              z := x + y // add them
+//                <--C-->     <---E-->
+//                  ^
+//                  D
+//
+// intervals C, D and E are inexact.  C is contained by the
+// z-assignment statement, because it spans three of its children (:=,
+// x, +).  So too is the 1-char interval D, because it contains only
+// interior whitespace of the assignment.  E is considered interior
+// whitespace of the BlockStmt containing the assignment.
+//
+// Precondition: [start, end) both lie within the same file as root.
+// TODO(adonovan): return (nil, false) in this case and remove precond.
+// Requires FileSet; see loader.tokenFileContainsPos.
+//
+// Postcondition: path is never nil; it always contains at least 'root'.
+//
+func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Node, exact bool) {
+	// fmt.Printf("EnclosingInterval %d %d\n", start, end) // debugging
+
+	// Precondition: node.[Pos..End) and adjoining whitespace contain [start, end).
+	var visit func(node ast.Node) bool
+	visit = func(node ast.Node) bool {
+		path = append(path, node)
+
+		nodePos := node.Pos()
+		nodeEnd := node.End()
+
+		// fmt.Printf("visit(%T, %d, %d)\n", node, nodePos, nodeEnd) // debugging
+
+		// Intersect [start, end) with interval of node.
+		if start < nodePos {
+			start = nodePos
+		}
+		if end > nodeEnd {
+			end = nodeEnd
+		}
+
+		// Find sole child that contains [start, end).
+		children := childrenOf(node)
+		l := len(children)
+		for i, child := range children {
+			// [childPos, childEnd) is unaugmented interval of child.
+			childPos := child.Pos()
+			childEnd := child.End()
+
+			// [augPos, augEnd) is whitespace-augmented interval of child.
+			augPos := childPos
+			augEnd := childEnd
+			if i > 0 {
+				augPos = children[i-1].End() // start of preceding whitespace
+			}
+			if i < l-1 {
+				nextChildPos := children[i+1].Pos()
+				// Does [start, end) lie between child and next child?
+				if start >= augEnd && end <= nextChildPos {
+					return false // inexact match
+				}
+				augEnd = nextChildPos // end of following whitespace
+			}
+
+			// fmt.Printf("\tchild %d: [%d..%d)\tcontains interval [%d..%d)?\n",
+			// 	i, augPos, augEnd, start, end) // debugging
+
+			// Does augmented child strictly contain [start, end)?
+			if augPos <= start && end <= augEnd {
+				_, isToken := child.(tokenNode)
+				return isToken || visit(child)
+			}
+
+			// Does [start, end) overlap multiple children?
+			// i.e. left-augmented child contains start
+			// but LR-augmented child does not contain end.
+			if start < childEnd && end > augEnd {
+				break
+			}
+		}
+
+		// No single child contained [start, end),
+		// so node is the result.  Is it exact?
+
+		// (It's tempting to put this condition before the
+		// child loop, but it gives the wrong result in the
+		// case where a node (e.g. ExprStmt) and its sole
+		// child have equal intervals.)
+		if start == nodePos && end == nodeEnd {
+			return true // exact match
+		}
+
+		return false // inexact: overlaps multiple children
+	}
+
+	if start > end {
+		start, end = end, start
+	}
+
+	if start < root.End() && end > root.Pos() {
+		if start == end {
+			end = start + 1 // empty interval => interval of size 1
+		}
+		exact = visit(root)
+
+		// Reverse the path:
+		for i, l := 0, len(path); i < l/2; i++ {
+			path[i], path[l-1-i] = path[l-1-i], path[i]
+		}
+	} else {
+		// Selection lies within whitespace preceding the
+		// first (or following the last) declaration in the file.
+		// The result nonetheless always includes the ast.File.
+		path = append(path, root)
+	}
+
+	return
+}
+
+// tokenNode is a dummy implementation of ast.Node for a single token.
+// They are used transiently by PathEnclosingInterval but never escape
+// this package.
+//
+type tokenNode struct {
+	pos token.Pos
+	end token.Pos
+}
+
+func (n tokenNode) Pos() token.Pos {
+	return n.pos
+}
+
+func (n tokenNode) End() token.Pos {
+	return n.end
+}
+
+func tok(pos token.Pos, len int) ast.Node {
+	return tokenNode{pos, pos + token.Pos(len)}
+}
+
+// childrenOf returns the direct non-nil children of ast.Node n.
+// It may include fake ast.Node implementations for bare tokens.
+// it is not safe to call (e.g.) ast.Walk on such nodes.
+//
+func childrenOf(n ast.Node) []ast.Node {
+	var children []ast.Node
+
+	// First add nodes for all true subtrees.
+	ast.Inspect(n, func(node ast.Node) bool {
+		if node == n { // push n
+			return true // recur
+		}
+		if node != nil { // push child
+			children = append(children, node)
+		}
+		return false // no recursion
+	})
+
+	// Then add fake Nodes for bare tokens.
+	switch n := n.(type) {
+	case *ast.ArrayType:
+		children = append(children,
+			tok(n.Lbrack, len("[")),
+			tok(n.Elt.End(), len("]")))
+
+	case *ast.AssignStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.BasicLit:
+		children = append(children,
+			tok(n.ValuePos, len(n.Value)))
+
+	case *ast.BinaryExpr:
+		children = append(children, tok(n.OpPos, len(n.Op.String())))
+
+	case *ast.BlockStmt:
+		children = append(children,
+			tok(n.Lbrace, len("{")),
+			tok(n.Rbrace, len("}")))
+
+	case *ast.BranchStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.CallExpr:
+		children = append(children,
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+		if n.Ellipsis != 0 {
+			children = append(children, tok(n.Ellipsis, len("...")))
+		}
+
+	case *ast.CaseClause:
+		if n.List == nil {
+			children = append(children,
+				tok(n.Case, len("default")))
+		} else {
+			children = append(children,
+				tok(n.Case, len("case")))
+		}
+		children = append(children, tok(n.Colon, len(":")))
+
+	case *ast.ChanType:
+		switch n.Dir {
+		case ast.RECV:
+			children = append(children, tok(n.Begin, len("<-chan")))
+		case ast.SEND:
+			children = append(children, tok(n.Begin, len("chan<-")))
+		case ast.RECV | ast.SEND:
+			children = append(children, tok(n.Begin, len("chan")))
+		}
+
+	case *ast.CommClause:
+		if n.Comm == nil {
+			children = append(children,
+				tok(n.Case, len("default")))
+		} else {
+			children = append(children,
+				tok(n.Case, len("case")))
+		}
+		children = append(children, tok(n.Colon, len(":")))
+
+	case *ast.Comment:
+		// nop
+
+	case *ast.CommentGroup:
+		// nop
+
+	case *ast.CompositeLit:
+		children = append(children,
+			tok(n.Lbrace, len("{")),
+			tok(n.Rbrace, len("{")))
+
+	case *ast.DeclStmt:
+		// nop
+
+	case *ast.DeferStmt:
+		children = append(children,
+			tok(n.Defer, len("defer")))
+
+	case *ast.Ellipsis:
+		children = append(children,
+			tok(n.Ellipsis, len("...")))
+
+	case *ast.EmptyStmt:
+		// nop
+
+	case *ast.ExprStmt:
+		// nop
+
+	case *ast.Field:
+		// TODO(adonovan): Field.{Doc,Comment,Tag}?
+
+	case *ast.FieldList:
+		children = append(children,
+			tok(n.Opening, len("(")),
+			tok(n.Closing, len(")")))
+
+	case *ast.File:
+		// TODO test: Doc
+		children = append(children,
+			tok(n.Package, len("package")))
+
+	case *ast.ForStmt:
+		children = append(children,
+			tok(n.For, len("for")))
+
+	case *ast.FuncDecl:
+		// TODO(adonovan): FuncDecl.Comment?
+
+		// Uniquely, FuncDecl breaks the invariant that
+		// preorder traversal yields tokens in lexical order:
+		// in fact, FuncDecl.Recv precedes FuncDecl.Type.Func.
+		//
+		// As a workaround, we inline the case for FuncType
+		// here and order things correctly.
+		//
+		children = nil // discard ast.Walk(FuncDecl) info subtrees
+		children = append(children, tok(n.Type.Func, len("func")))
+		if n.Recv != nil {
+			children = append(children, n.Recv)
+		}
+		children = append(children, n.Name)
+		if n.Type.Params != nil {
+			children = append(children, n.Type.Params)
+		}
+		if n.Type.Results != nil {
+			children = append(children, n.Type.Results)
+		}
+		if n.Body != nil {
+			children = append(children, n.Body)
+		}
+
+	case *ast.FuncLit:
+		// nop
+
+	case *ast.FuncType:
+		if n.Func != 0 {
+			children = append(children,
+				tok(n.Func, len("func")))
+		}
+
+	case *ast.GenDecl:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+		if n.Lparen != 0 {
+			children = append(children,
+				tok(n.Lparen, len("(")),
+				tok(n.Rparen, len(")")))
+		}
+
+	case *ast.GoStmt:
+		children = append(children,
+			tok(n.Go, len("go")))
+
+	case *ast.Ident:
+		children = append(children,
+			tok(n.NamePos, len(n.Name)))
+
+	case *ast.IfStmt:
+		children = append(children,
+			tok(n.If, len("if")))
+
+	case *ast.ImportSpec:
+		// TODO(adonovan): ImportSpec.{Doc,EndPos}?
+
+	case *ast.IncDecStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.IndexExpr:
+		children = append(children,
+			tok(n.Lbrack, len("{")),
+			tok(n.Rbrack, len("}")))
+
+	case *ast.InterfaceType:
+		children = append(children,
+			tok(n.Interface, len("interface")))
+
+	case *ast.KeyValueExpr:
+		children = append(children,
+			tok(n.Colon, len(":")))
+
+	case *ast.LabeledStmt:
+		children = append(children,
+			tok(n.Colon, len(":")))
+
+	case *ast.MapType:
+		children = append(children,
+			tok(n.Map, len("map")))
+
+	case *ast.ParenExpr:
+		children = append(children,
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+
+	case *ast.RangeStmt:
+		children = append(children,
+			tok(n.For, len("for")),
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.ReturnStmt:
+		children = append(children,
+			tok(n.Return, len("return")))
+
+	case *ast.SelectStmt:
+		children = append(children,
+			tok(n.Select, len("select")))
+
+	case *ast.SelectorExpr:
+		// nop
+
+	case *ast.SendStmt:
+		children = append(children,
+			tok(n.Arrow, len("<-")))
+
+	case *ast.SliceExpr:
+		children = append(children,
+			tok(n.Lbrack, len("[")),
+			tok(n.Rbrack, len("]")))
+
+	case *ast.StarExpr:
+		children = append(children, tok(n.Star, len("*")))
+
+	case *ast.StructType:
+		children = append(children, tok(n.Struct, len("struct")))
+
+	case *ast.SwitchStmt:
+		children = append(children, tok(n.Switch, len("switch")))
+
+	case *ast.TypeAssertExpr:
+		children = append(children,
+			tok(n.Lparen-1, len(".")),
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+
+	case *ast.TypeSpec:
+		// TODO(adonovan): TypeSpec.{Doc,Comment}?
+
+	case *ast.TypeSwitchStmt:
+		children = append(children, tok(n.Switch, len("switch")))
+
+	case *ast.UnaryExpr:
+		children = append(children, tok(n.OpPos, len(n.Op.String())))
+
+	case *ast.ValueSpec:
+		// TODO(adonovan): ValueSpec.{Doc,Comment}?
+
+	case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt:
+		// nop
+	}
+
+	// TODO(adonovan): opt: merge the logic of ast.Inspect() into
+	// the switch above so we can make interleaved callbacks for
+	// both Nodes and Tokens in the right order and avoid the need
+	// to sort.
+	sort.Sort(byPos(children))
+
+	return children
+}
+
+type byPos []ast.Node
+
+func (sl byPos) Len() int {
+	return len(sl)
+}
+func (sl byPos) Less(i, j int) bool {
+	return sl[i].Pos() < sl[j].Pos()
+}
+func (sl byPos) Swap(i, j int) {
+	sl[i], sl[j] = sl[j], sl[i]
+}
+
+// NodeDescription returns a description of the concrete type of n suitable
+// for a user interface.
+//
+// TODO(adonovan): in some cases (e.g. Field, FieldList, Ident,
+// StarExpr) we could be much more specific given the path to the AST
+// root.  Perhaps we should do that.
+//
+func NodeDescription(n ast.Node) string {
+	switch n := n.(type) {
+	case *ast.ArrayType:
+		return "array type"
+	case *ast.AssignStmt:
+		return "assignment"
+	case *ast.BadDecl:
+		return "bad declaration"
+	case *ast.BadExpr:
+		return "bad expression"
+	case *ast.BadStmt:
+		return "bad statement"
+	case *ast.BasicLit:
+		return "basic literal"
+	case *ast.BinaryExpr:
+		return fmt.Sprintf("binary %s operation", n.Op)
+	case *ast.BlockStmt:
+		return "block"
+	case *ast.BranchStmt:
+		switch n.Tok {
+		case token.BREAK:
+			return "break statement"
+		case token.CONTINUE:
+			return "continue statement"
+		case token.GOTO:
+			return "goto statement"
+		case token.FALLTHROUGH:
+			return "fall-through statement"
+		}
+	case *ast.CallExpr:
+		if len(n.Args) == 1 && !n.Ellipsis.IsValid() {
+			return "function call (or conversion)"
+		}
+		return "function call"
+	case *ast.CaseClause:
+		return "case clause"
+	case *ast.ChanType:
+		return "channel type"
+	case *ast.CommClause:
+		return "communication clause"
+	case *ast.Comment:
+		return "comment"
+	case *ast.CommentGroup:
+		return "comment group"
+	case *ast.CompositeLit:
+		return "composite literal"
+	case *ast.DeclStmt:
+		return NodeDescription(n.Decl) + " statement"
+	case *ast.DeferStmt:
+		return "defer statement"
+	case *ast.Ellipsis:
+		return "ellipsis"
+	case *ast.EmptyStmt:
+		return "empty statement"
+	case *ast.ExprStmt:
+		return "expression statement"
+	case *ast.Field:
+		// Can be any of these:
+		// struct {x, y int}  -- struct field(s)
+		// struct {T}         -- anon struct field
+		// interface {I}      -- interface embedding
+		// interface {f()}    -- interface method
+		// func (A) func(B) C -- receiver, param(s), result(s)
+		return "field/method/parameter"
+	case *ast.FieldList:
+		return "field/method/parameter list"
+	case *ast.File:
+		return "source file"
+	case *ast.ForStmt:
+		return "for loop"
+	case *ast.FuncDecl:
+		return "function declaration"
+	case *ast.FuncLit:
+		return "function literal"
+	case *ast.FuncType:
+		return "function type"
+	case *ast.GenDecl:
+		switch n.Tok {
+		case token.IMPORT:
+			return "import declaration"
+		case token.CONST:
+			return "constant declaration"
+		case token.TYPE:
+			return "type declaration"
+		case token.VAR:
+			return "variable declaration"
+		}
+	case *ast.GoStmt:
+		return "go statement"
+	case *ast.Ident:
+		return "identifier"
+	case *ast.IfStmt:
+		return "if statement"
+	case *ast.ImportSpec:
+		return "import specification"
+	case *ast.IncDecStmt:
+		if n.Tok == token.INC {
+			return "increment statement"
+		}
+		return "decrement statement"
+	case *ast.IndexExpr:
+		return "index expression"
+	case *ast.InterfaceType:
+		return "interface type"
+	case *ast.KeyValueExpr:
+		return "key/value association"
+	case *ast.LabeledStmt:
+		return "statement label"
+	case *ast.MapType:
+		return "map type"
+	case *ast.Package:
+		return "package"
+	case *ast.ParenExpr:
+		return "parenthesized " + NodeDescription(n.X)
+	case *ast.RangeStmt:
+		return "range loop"
+	case *ast.ReturnStmt:
+		return "return statement"
+	case *ast.SelectStmt:
+		return "select statement"
+	case *ast.SelectorExpr:
+		return "selector"
+	case *ast.SendStmt:
+		return "channel send"
+	case *ast.SliceExpr:
+		return "slice expression"
+	case *ast.StarExpr:
+		return "*-operation" // load/store expr or pointer type
+	case *ast.StructType:
+		return "struct type"
+	case *ast.SwitchStmt:
+		return "switch statement"
+	case *ast.TypeAssertExpr:
+		return "type assertion"
+	case *ast.TypeSpec:
+		return "type specification"
+	case *ast.TypeSwitchStmt:
+		return "type switch"
+	case *ast.UnaryExpr:
+		return fmt.Sprintf("unary %s operation", n.Op)
+	case *ast.ValueSpec:
+		return "value specification"
+
+	}
+	panic(fmt.Sprintf("unexpected node type: %T", n))
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/astutil/imports.go b/libgo/go/golang.org/x/tools/go/ast/astutil/imports.go
new file mode 100644
index 00000000000..3e4b195368b
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/astutil/imports.go
@@ -0,0 +1,481 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package astutil contains common utilities for working with the Go AST.
+package astutil // import "golang.org/x/tools/go/ast/astutil"
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"strconv"
+	"strings"
+)
+
+// AddImport adds the import path to the file f, if absent.
+func AddImport(fset *token.FileSet, f *ast.File, path string) (added bool) {
+	return AddNamedImport(fset, f, "", path)
+}
+
+// AddNamedImport adds the import with the given name and path to the file f, if absent.
+// If name is not empty, it is used to rename the import.
+//
+// For example, calling
+//	AddNamedImport(fset, f, "pathpkg", "path")
+// adds
+//	import pathpkg "path"
+func AddNamedImport(fset *token.FileSet, f *ast.File, name, path string) (added bool) {
+	if imports(f, name, path) {
+		return false
+	}
+
+	newImport := &ast.ImportSpec{
+		Path: &ast.BasicLit{
+			Kind:  token.STRING,
+			Value: strconv.Quote(path),
+		},
+	}
+	if name != "" {
+		newImport.Name = &ast.Ident{Name: name}
+	}
+
+	// Find an import decl to add to.
+	// The goal is to find an existing import
+	// whose import path has the longest shared
+	// prefix with path.
+	var (
+		bestMatch  = -1         // length of longest shared prefix
+		lastImport = -1         // index in f.Decls of the file's final import decl
+		impDecl    *ast.GenDecl // import decl containing the best match
+		impIndex   = -1         // spec index in impDecl containing the best match
+
+		isThirdPartyPath = isThirdParty(path)
+	)
+	for i, decl := range f.Decls {
+		gen, ok := decl.(*ast.GenDecl)
+		if ok && gen.Tok == token.IMPORT {
+			lastImport = i
+			// Do not add to import "C", to avoid disrupting the
+			// association with its doc comment, breaking cgo.
+			if declImports(gen, "C") {
+				continue
+			}
+
+			// Match an empty import decl if that's all that is available.
+			if len(gen.Specs) == 0 && bestMatch == -1 {
+				impDecl = gen
+			}
+
+			// Compute longest shared prefix with imports in this group and find best
+			// matched import spec.
+			// 1. Always prefer import spec with longest shared prefix.
+			// 2. While match length is 0,
+			// - for stdlib package: prefer first import spec.
+			// - for third party package: prefer first third party import spec.
+			// We cannot use last import spec as best match for third party package
+			// because grouped imports are usually placed last by goimports -local
+			// flag.
+			// See issue #19190.
+			seenAnyThirdParty := false
+			for j, spec := range gen.Specs {
+				impspec := spec.(*ast.ImportSpec)
+				p := importPath(impspec)
+				n := matchLen(p, path)
+				if n > bestMatch || (bestMatch == 0 && !seenAnyThirdParty && isThirdPartyPath) {
+					bestMatch = n
+					impDecl = gen
+					impIndex = j
+				}
+				seenAnyThirdParty = seenAnyThirdParty || isThirdParty(p)
+			}
+		}
+	}
+
+	// If no import decl found, add one after the last import.
+	if impDecl == nil {
+		impDecl = &ast.GenDecl{
+			Tok: token.IMPORT,
+		}
+		if lastImport >= 0 {
+			impDecl.TokPos = f.Decls[lastImport].End()
+		} else {
+			// There are no existing imports.
+			// Our new import, preceded by a blank line,  goes after the package declaration
+			// and after the comment, if any, that starts on the same line as the
+			// package declaration.
+			impDecl.TokPos = f.Package
+
+			file := fset.File(f.Package)
+			pkgLine := file.Line(f.Package)
+			for _, c := range f.Comments {
+				if file.Line(c.Pos()) > pkgLine {
+					break
+				}
+				// +2 for a blank line
+				impDecl.TokPos = c.End() + 2
+			}
+		}
+		f.Decls = append(f.Decls, nil)
+		copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
+		f.Decls[lastImport+1] = impDecl
+	}
+
+	// Insert new import at insertAt.
+	insertAt := 0
+	if impIndex >= 0 {
+		// insert after the found import
+		insertAt = impIndex + 1
+	}
+	impDecl.Specs = append(impDecl.Specs, nil)
+	copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
+	impDecl.Specs[insertAt] = newImport
+	pos := impDecl.Pos()
+	if insertAt > 0 {
+		// If there is a comment after an existing import, preserve the comment
+		// position by adding the new import after the comment.
+		if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil {
+			pos = spec.Comment.End()
+		} else {
+			// Assign same position as the previous import,
+			// so that the sorter sees it as being in the same block.
+			pos = impDecl.Specs[insertAt-1].Pos()
+		}
+	}
+	if newImport.Name != nil {
+		newImport.Name.NamePos = pos
+	}
+	newImport.Path.ValuePos = pos
+	newImport.EndPos = pos
+
+	// Clean up parens. impDecl contains at least one spec.
+	if len(impDecl.Specs) == 1 {
+		// Remove unneeded parens.
+		impDecl.Lparen = token.NoPos
+	} else if !impDecl.Lparen.IsValid() {
+		// impDecl needs parens added.
+		impDecl.Lparen = impDecl.Specs[0].Pos()
+	}
+
+	f.Imports = append(f.Imports, newImport)
+
+	if len(f.Decls) <= 1 {
+		return true
+	}
+
+	// Merge all the import declarations into the first one.
+	var first *ast.GenDecl
+	for i := 0; i < len(f.Decls); i++ {
+		decl := f.Decls[i]
+		gen, ok := decl.(*ast.GenDecl)
+		if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
+			continue
+		}
+		if first == nil {
+			first = gen
+			continue // Don't touch the first one.
+		}
+		// We now know there is more than one package in this import
+		// declaration. Ensure that it ends up parenthesized.
+		first.Lparen = first.Pos()
+		// Move the imports of the other import declaration to the first one.
+		for _, spec := range gen.Specs {
+			spec.(*ast.ImportSpec).Path.ValuePos = first.Pos()
+			first.Specs = append(first.Specs, spec)
+		}
+		f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
+		i--
+	}
+
+	return true
+}
+
+func isThirdParty(importPath string) bool {
+	// Third party package import path usually contains "." (".com", ".org", ...)
+	// This logic is taken from golang.org/x/tools/imports package.
+	return strings.Contains(importPath, ".")
+}
+
+// DeleteImport deletes the import path from the file f, if present.
+// If there are duplicate import declarations, all matching ones are deleted.
+func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) {
+	return DeleteNamedImport(fset, f, "", path)
+}
+
+// DeleteNamedImport deletes the import with the given name and path from the file f, if present.
+// If there are duplicate import declarations, all matching ones are deleted.
+func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) {
+	var delspecs []*ast.ImportSpec
+	var delcomments []*ast.CommentGroup
+
+	// Find the import nodes that import path, if any.
+	for i := 0; i < len(f.Decls); i++ {
+		decl := f.Decls[i]
+		gen, ok := decl.(*ast.GenDecl)
+		if !ok || gen.Tok != token.IMPORT {
+			continue
+		}
+		for j := 0; j < len(gen.Specs); j++ {
+			spec := gen.Specs[j]
+			impspec := spec.(*ast.ImportSpec)
+			if importName(impspec) != name || importPath(impspec) != path {
+				continue
+			}
+
+			// We found an import spec that imports path.
+			// Delete it.
+			delspecs = append(delspecs, impspec)
+			deleted = true
+			copy(gen.Specs[j:], gen.Specs[j+1:])
+			gen.Specs = gen.Specs[:len(gen.Specs)-1]
+
+			// If this was the last import spec in this decl,
+			// delete the decl, too.
+			if len(gen.Specs) == 0 {
+				copy(f.Decls[i:], f.Decls[i+1:])
+				f.Decls = f.Decls[:len(f.Decls)-1]
+				i--
+				break
+			} else if len(gen.Specs) == 1 {
+				if impspec.Doc != nil {
+					delcomments = append(delcomments, impspec.Doc)
+				}
+				if impspec.Comment != nil {
+					delcomments = append(delcomments, impspec.Comment)
+				}
+				for _, cg := range f.Comments {
+					// Found comment on the same line as the import spec.
+					if cg.End() < impspec.Pos() && fset.Position(cg.End()).Line == fset.Position(impspec.Pos()).Line {
+						delcomments = append(delcomments, cg)
+						break
+					}
+				}
+
+				spec := gen.Specs[0].(*ast.ImportSpec)
+
+				// Move the documentation right after the import decl.
+				if spec.Doc != nil {
+					for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Doc.Pos()).Line {
+						fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
+					}
+				}
+				for _, cg := range f.Comments {
+					if cg.End() < spec.Pos() && fset.Position(cg.End()).Line == fset.Position(spec.Pos()).Line {
+						for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Pos()).Line {
+							fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
+						}
+						break
+					}
+				}
+			}
+			if j > 0 {
+				lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
+				lastLine := fset.Position(lastImpspec.Path.ValuePos).Line
+				line := fset.Position(impspec.Path.ValuePos).Line
+
+				// We deleted an entry but now there may be
+				// a blank line-sized hole where the import was.
+				if line-lastLine > 1 {
+					// There was a blank line immediately preceding the deleted import,
+					// so there's no need to close the hole.
+					// Do nothing.
+				} else if line != fset.File(gen.Rparen).LineCount() {
+					// There was no blank line. Close the hole.
+					fset.File(gen.Rparen).MergeLine(line)
+				}
+			}
+			j--
+		}
+	}
+
+	// Delete imports from f.Imports.
+	for i := 0; i < len(f.Imports); i++ {
+		imp := f.Imports[i]
+		for j, del := range delspecs {
+			if imp == del {
+				copy(f.Imports[i:], f.Imports[i+1:])
+				f.Imports = f.Imports[:len(f.Imports)-1]
+				copy(delspecs[j:], delspecs[j+1:])
+				delspecs = delspecs[:len(delspecs)-1]
+				i--
+				break
+			}
+		}
+	}
+
+	// Delete comments from f.Comments.
+	for i := 0; i < len(f.Comments); i++ {
+		cg := f.Comments[i]
+		for j, del := range delcomments {
+			if cg == del {
+				copy(f.Comments[i:], f.Comments[i+1:])
+				f.Comments = f.Comments[:len(f.Comments)-1]
+				copy(delcomments[j:], delcomments[j+1:])
+				delcomments = delcomments[:len(delcomments)-1]
+				i--
+				break
+			}
+		}
+	}
+
+	if len(delspecs) > 0 {
+		panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
+	}
+
+	return
+}
+
+// RewriteImport rewrites any import of path oldPath to path newPath.
+func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) {
+	for _, imp := range f.Imports {
+		if importPath(imp) == oldPath {
+			rewrote = true
+			// record old End, because the default is to compute
+			// it using the length of imp.Path.Value.
+			imp.EndPos = imp.End()
+			imp.Path.Value = strconv.Quote(newPath)
+		}
+	}
+	return
+}
+
+// UsesImport reports whether a given import is used.
+func UsesImport(f *ast.File, path string) (used bool) {
+	spec := importSpec(f, path)
+	if spec == nil {
+		return
+	}
+
+	name := spec.Name.String()
+	switch name {
+	case "<nil>":
+		// If the package name is not explicitly specified,
+		// make an educated guess. This is not guaranteed to be correct.
+		lastSlash := strings.LastIndex(path, "/")
+		if lastSlash == -1 {
+			name = path
+		} else {
+			name = path[lastSlash+1:]
+		}
+	case "_", ".":
+		// Not sure if this import is used - err on the side of caution.
+		return true
+	}
+
+	ast.Walk(visitFn(func(n ast.Node) {
+		sel, ok := n.(*ast.SelectorExpr)
+		if ok && isTopName(sel.X, name) {
+			used = true
+		}
+	}), f)
+
+	return
+}
+
+type visitFn func(node ast.Node)
+
+func (fn visitFn) Visit(node ast.Node) ast.Visitor {
+	fn(node)
+	return fn
+}
+
+// imports reports whether f has an import with the specified name and path.
+func imports(f *ast.File, name, path string) bool {
+	for _, s := range f.Imports {
+		if importName(s) == name && importPath(s) == path {
+			return true
+		}
+	}
+	return false
+}
+
+// importSpec returns the import spec if f imports path,
+// or nil otherwise.
+func importSpec(f *ast.File, path string) *ast.ImportSpec {
+	for _, s := range f.Imports {
+		if importPath(s) == path {
+			return s
+		}
+	}
+	return nil
+}
+
+// importName returns the name of s,
+// or "" if the import is not named.
+func importName(s *ast.ImportSpec) string {
+	if s.Name == nil {
+		return ""
+	}
+	return s.Name.Name
+}
+
+// importPath returns the unquoted import path of s,
+// or "" if the path is not properly quoted.
+func importPath(s *ast.ImportSpec) string {
+	t, err := strconv.Unquote(s.Path.Value)
+	if err != nil {
+		return ""
+	}
+	return t
+}
+
+// declImports reports whether gen contains an import of path.
+func declImports(gen *ast.GenDecl, path string) bool {
+	if gen.Tok != token.IMPORT {
+		return false
+	}
+	for _, spec := range gen.Specs {
+		impspec := spec.(*ast.ImportSpec)
+		if importPath(impspec) == path {
+			return true
+		}
+	}
+	return false
+}
+
+// matchLen returns the length of the longest path segment prefix shared by x and y.
+func matchLen(x, y string) int {
+	n := 0
+	for i := 0; i < len(x) && i < len(y) && x[i] == y[i]; i++ {
+		if x[i] == '/' {
+			n++
+		}
+	}
+	return n
+}
+
+// isTopName returns true if n is a top-level unresolved identifier with the given name.
+func isTopName(n ast.Expr, name string) bool {
+	id, ok := n.(*ast.Ident)
+	return ok && id.Name == name && id.Obj == nil
+}
+
+// Imports returns the file imports grouped by paragraph.
+func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
+	var groups [][]*ast.ImportSpec
+
+	for _, decl := range f.Decls {
+		genDecl, ok := decl.(*ast.GenDecl)
+		if !ok || genDecl.Tok != token.IMPORT {
+			break
+		}
+
+		group := []*ast.ImportSpec{}
+
+		var lastLine int
+		for _, spec := range genDecl.Specs {
+			importSpec := spec.(*ast.ImportSpec)
+			pos := importSpec.Path.ValuePos
+			line := fset.Position(pos).Line
+			if lastLine > 0 && pos > 0 && line-lastLine > 1 {
+				groups = append(groups, group)
+				group = []*ast.ImportSpec{}
+			}
+			group = append(group, importSpec)
+			lastLine = line
+		}
+		groups = append(groups, group)
+	}
+
+	return groups
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/astutil/rewrite.go b/libgo/go/golang.org/x/tools/go/ast/astutil/rewrite.go
new file mode 100644
index 00000000000..cf72ea990bd
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/astutil/rewrite.go
@@ -0,0 +1,477 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package astutil
+
+import (
+	"fmt"
+	"go/ast"
+	"reflect"
+	"sort"
+)
+
+// An ApplyFunc is invoked by Apply for each node n, even if n is nil,
+// before and/or after the node's children, using a Cursor describing
+// the current node and providing operations on it.
+//
+// The return value of ApplyFunc controls the syntax tree traversal.
+// See Apply for details.
+type ApplyFunc func(*Cursor) bool
+
+// Apply traverses a syntax tree recursively, starting with root,
+// and calling pre and post for each node as described below.
+// Apply returns the syntax tree, possibly modified.
+//
+// If pre is not nil, it is called for each node before the node's
+// children are traversed (pre-order). If pre returns false, no
+// children are traversed, and post is not called for that node.
+//
+// If post is not nil, and a prior call of pre didn't return false,
+// post is called for each node after its children are traversed
+// (post-order). If post returns false, traversal is terminated and
+// Apply returns immediately.
+//
+// Only fields that refer to AST nodes are considered children;
+// i.e., token.Pos, Scopes, Objects, and fields of basic types
+// (strings, etc.) are ignored.
+//
+// Children are traversed in the order in which they appear in the
+// respective node's struct definition. A package's files are
+// traversed in the filenames' alphabetical order.
+//
+func Apply(root ast.Node, pre, post ApplyFunc) (result ast.Node) {
+	parent := &struct{ ast.Node }{root}
+	defer func() {
+		if r := recover(); r != nil && r != abort {
+			panic(r)
+		}
+		result = parent.Node
+	}()
+	a := &application{pre: pre, post: post}
+	a.apply(parent, "Node", nil, root)
+	return
+}
+
+var abort = new(int) // singleton, to signal termination of Apply
+
+// A Cursor describes a node encountered during Apply.
+// Information about the node and its parent is available
+// from the Node, Parent, Name, and Index methods.
+//
+// If p is a variable of type and value of the current parent node
+// c.Parent(), and f is the field identifier with name c.Name(),
+// the following invariants hold:
+//
+//   p.f            == c.Node()  if c.Index() <  0
+//   p.f[c.Index()] == c.Node()  if c.Index() >= 0
+//
+// The methods Replace, Delete, InsertBefore, and InsertAfter
+// can be used to change the AST without disrupting Apply.
+type Cursor struct {
+	parent ast.Node
+	name   string
+	iter   *iterator // valid if non-nil
+	node   ast.Node
+}
+
+// Node returns the current Node.
+func (c *Cursor) Node() ast.Node { return c.node }
+
+// Parent returns the parent of the current Node.
+func (c *Cursor) Parent() ast.Node { return c.parent }
+
+// Name returns the name of the parent Node field that contains the current Node.
+// If the parent is a *ast.Package and the current Node is a *ast.File, Name returns
+// the filename for the current Node.
+func (c *Cursor) Name() string { return c.name }
+
+// Index reports the index >= 0 of the current Node in the slice of Nodes that
+// contains it, or a value < 0 if the current Node is not part of a slice.
+// The index of the current node changes if InsertBefore is called while
+// processing the current node.
+func (c *Cursor) Index() int {
+	if c.iter != nil {
+		return c.iter.index
+	}
+	return -1
+}
+
+// field returns the current node's parent field value.
+func (c *Cursor) field() reflect.Value {
+	return reflect.Indirect(reflect.ValueOf(c.parent)).FieldByName(c.name)
+}
+
+// Replace replaces the current Node with n.
+// The replacement node is not walked by Apply.
+func (c *Cursor) Replace(n ast.Node) {
+	if _, ok := c.node.(*ast.File); ok {
+		file, ok := n.(*ast.File)
+		if !ok {
+			panic("attempt to replace *ast.File with non-*ast.File")
+		}
+		c.parent.(*ast.Package).Files[c.name] = file
+		return
+	}
+
+	v := c.field()
+	if i := c.Index(); i >= 0 {
+		v = v.Index(i)
+	}
+	v.Set(reflect.ValueOf(n))
+}
+
+// Delete deletes the current Node from its containing slice.
+// If the current Node is not part of a slice, Delete panics.
+// As a special case, if the current node is a package file,
+// Delete removes it from the package's Files map.
+func (c *Cursor) Delete() {
+	if _, ok := c.node.(*ast.File); ok {
+		delete(c.parent.(*ast.Package).Files, c.name)
+		return
+	}
+
+	i := c.Index()
+	if i < 0 {
+		panic("Delete node not contained in slice")
+	}
+	v := c.field()
+	l := v.Len()
+	reflect.Copy(v.Slice(i, l), v.Slice(i+1, l))
+	v.Index(l - 1).Set(reflect.Zero(v.Type().Elem()))
+	v.SetLen(l - 1)
+	c.iter.step--
+}
+
+// InsertAfter inserts n after the current Node in its containing slice.
+// If the current Node is not part of a slice, InsertAfter panics.
+// Apply does not walk n.
+func (c *Cursor) InsertAfter(n ast.Node) {
+	i := c.Index()
+	if i < 0 {
+		panic("InsertAfter node not contained in slice")
+	}
+	v := c.field()
+	v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
+	l := v.Len()
+	reflect.Copy(v.Slice(i+2, l), v.Slice(i+1, l))
+	v.Index(i + 1).Set(reflect.ValueOf(n))
+	c.iter.step++
+}
+
+// InsertBefore inserts n before the current Node in its containing slice.
+// If the current Node is not part of a slice, InsertBefore panics.
+// Apply will not walk n.
+func (c *Cursor) InsertBefore(n ast.Node) {
+	i := c.Index()
+	if i < 0 {
+		panic("InsertBefore node not contained in slice")
+	}
+	v := c.field()
+	v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
+	l := v.Len()
+	reflect.Copy(v.Slice(i+1, l), v.Slice(i, l))
+	v.Index(i).Set(reflect.ValueOf(n))
+	c.iter.index++
+}
+
+// application carries all the shared data so we can pass it around cheaply.
+type application struct {
+	pre, post ApplyFunc
+	cursor    Cursor
+	iter      iterator
+}
+
+func (a *application) apply(parent ast.Node, name string, iter *iterator, n ast.Node) {
+	// convert typed nil into untyped nil
+	if v := reflect.ValueOf(n); v.Kind() == reflect.Ptr && v.IsNil() {
+		n = nil
+	}
+
+	// avoid heap-allocating a new cursor for each apply call; reuse a.cursor instead
+	saved := a.cursor
+	a.cursor.parent = parent
+	a.cursor.name = name
+	a.cursor.iter = iter
+	a.cursor.node = n
+
+	if a.pre != nil && !a.pre(&a.cursor) {
+		a.cursor = saved
+		return
+	}
+
+	// walk children
+	// (the order of the cases matches the order of the corresponding node types in go/ast)
+	switch n := n.(type) {
+	case nil:
+		// nothing to do
+
+	// Comments and fields
+	case *ast.Comment:
+		// nothing to do
+
+	case *ast.CommentGroup:
+		if n != nil {
+			a.applyList(n, "List")
+		}
+
+	case *ast.Field:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.applyList(n, "Names")
+		a.apply(n, "Type", nil, n.Type)
+		a.apply(n, "Tag", nil, n.Tag)
+		a.apply(n, "Comment", nil, n.Comment)
+
+	case *ast.FieldList:
+		a.applyList(n, "List")
+
+	// Expressions
+	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
+		// nothing to do
+
+	case *ast.Ellipsis:
+		a.apply(n, "Elt", nil, n.Elt)
+
+	case *ast.FuncLit:
+		a.apply(n, "Type", nil, n.Type)
+		a.apply(n, "Body", nil, n.Body)
+
+	case *ast.CompositeLit:
+		a.apply(n, "Type", nil, n.Type)
+		a.applyList(n, "Elts")
+
+	case *ast.ParenExpr:
+		a.apply(n, "X", nil, n.X)
+
+	case *ast.SelectorExpr:
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Sel", nil, n.Sel)
+
+	case *ast.IndexExpr:
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Index", nil, n.Index)
+
+	case *ast.SliceExpr:
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Low", nil, n.Low)
+		a.apply(n, "High", nil, n.High)
+		a.apply(n, "Max", nil, n.Max)
+
+	case *ast.TypeAssertExpr:
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Type", nil, n.Type)
+
+	case *ast.CallExpr:
+		a.apply(n, "Fun", nil, n.Fun)
+		a.applyList(n, "Args")
+
+	case *ast.StarExpr:
+		a.apply(n, "X", nil, n.X)
+
+	case *ast.UnaryExpr:
+		a.apply(n, "X", nil, n.X)
+
+	case *ast.BinaryExpr:
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Y", nil, n.Y)
+
+	case *ast.KeyValueExpr:
+		a.apply(n, "Key", nil, n.Key)
+		a.apply(n, "Value", nil, n.Value)
+
+	// Types
+	case *ast.ArrayType:
+		a.apply(n, "Len", nil, n.Len)
+		a.apply(n, "Elt", nil, n.Elt)
+
+	case *ast.StructType:
+		a.apply(n, "Fields", nil, n.Fields)
+
+	case *ast.FuncType:
+		a.apply(n, "Params", nil, n.Params)
+		a.apply(n, "Results", nil, n.Results)
+
+	case *ast.InterfaceType:
+		a.apply(n, "Methods", nil, n.Methods)
+
+	case *ast.MapType:
+		a.apply(n, "Key", nil, n.Key)
+		a.apply(n, "Value", nil, n.Value)
+
+	case *ast.ChanType:
+		a.apply(n, "Value", nil, n.Value)
+
+	// Statements
+	case *ast.BadStmt:
+		// nothing to do
+
+	case *ast.DeclStmt:
+		a.apply(n, "Decl", nil, n.Decl)
+
+	case *ast.EmptyStmt:
+		// nothing to do
+
+	case *ast.LabeledStmt:
+		a.apply(n, "Label", nil, n.Label)
+		a.apply(n, "Stmt", nil, n.Stmt)
+
+	case *ast.ExprStmt:
+		a.apply(n, "X", nil, n.X)
+
+	case *ast.SendStmt:
+		a.apply(n, "Chan", nil, n.Chan)
+		a.apply(n, "Value", nil, n.Value)
+
+	case *ast.IncDecStmt:
+		a.apply(n, "X", nil, n.X)
+
+	case *ast.AssignStmt:
+		a.applyList(n, "Lhs")
+		a.applyList(n, "Rhs")
+
+	case *ast.GoStmt:
+		a.apply(n, "Call", nil, n.Call)
+
+	case *ast.DeferStmt:
+		a.apply(n, "Call", nil, n.Call)
+
+	case *ast.ReturnStmt:
+		a.applyList(n, "Results")
+
+	case *ast.BranchStmt:
+		a.apply(n, "Label", nil, n.Label)
+
+	case *ast.BlockStmt:
+		a.applyList(n, "List")
+
+	case *ast.IfStmt:
+		a.apply(n, "Init", nil, n.Init)
+		a.apply(n, "Cond", nil, n.Cond)
+		a.apply(n, "Body", nil, n.Body)
+		a.apply(n, "Else", nil, n.Else)
+
+	case *ast.CaseClause:
+		a.applyList(n, "List")
+		a.applyList(n, "Body")
+
+	case *ast.SwitchStmt:
+		a.apply(n, "Init", nil, n.Init)
+		a.apply(n, "Tag", nil, n.Tag)
+		a.apply(n, "Body", nil, n.Body)
+
+	case *ast.TypeSwitchStmt:
+		a.apply(n, "Init", nil, n.Init)
+		a.apply(n, "Assign", nil, n.Assign)
+		a.apply(n, "Body", nil, n.Body)
+
+	case *ast.CommClause:
+		a.apply(n, "Comm", nil, n.Comm)
+		a.applyList(n, "Body")
+
+	case *ast.SelectStmt:
+		a.apply(n, "Body", nil, n.Body)
+
+	case *ast.ForStmt:
+		a.apply(n, "Init", nil, n.Init)
+		a.apply(n, "Cond", nil, n.Cond)
+		a.apply(n, "Post", nil, n.Post)
+		a.apply(n, "Body", nil, n.Body)
+
+	case *ast.RangeStmt:
+		a.apply(n, "Key", nil, n.Key)
+		a.apply(n, "Value", nil, n.Value)
+		a.apply(n, "X", nil, n.X)
+		a.apply(n, "Body", nil, n.Body)
+
+	// Declarations
+	case *ast.ImportSpec:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.apply(n, "Name", nil, n.Name)
+		a.apply(n, "Path", nil, n.Path)
+		a.apply(n, "Comment", nil, n.Comment)
+
+	case *ast.ValueSpec:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.applyList(n, "Names")
+		a.apply(n, "Type", nil, n.Type)
+		a.applyList(n, "Values")
+		a.apply(n, "Comment", nil, n.Comment)
+
+	case *ast.TypeSpec:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.apply(n, "Name", nil, n.Name)
+		a.apply(n, "Type", nil, n.Type)
+		a.apply(n, "Comment", nil, n.Comment)
+
+	case *ast.BadDecl:
+		// nothing to do
+
+	case *ast.GenDecl:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.applyList(n, "Specs")
+
+	case *ast.FuncDecl:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.apply(n, "Recv", nil, n.Recv)
+		a.apply(n, "Name", nil, n.Name)
+		a.apply(n, "Type", nil, n.Type)
+		a.apply(n, "Body", nil, n.Body)
+
+	// Files and packages
+	case *ast.File:
+		a.apply(n, "Doc", nil, n.Doc)
+		a.apply(n, "Name", nil, n.Name)
+		a.applyList(n, "Decls")
+		// Don't walk n.Comments; they have either been walked already if
+		// they are Doc comments, or they can be easily walked explicitly.
+
+	case *ast.Package:
+		// collect and sort names for reproducible behavior
+		var names []string
+		for name := range n.Files {
+			names = append(names, name)
+		}
+		sort.Strings(names)
+		for _, name := range names {
+			a.apply(n, name, nil, n.Files[name])
+		}
+
+	default:
+		panic(fmt.Sprintf("Apply: unexpected node type %T", n))
+	}
+
+	if a.post != nil && !a.post(&a.cursor) {
+		panic(abort)
+	}
+
+	a.cursor = saved
+}
+
+// An iterator controls iteration over a slice of nodes.
+type iterator struct {
+	index, step int
+}
+
+func (a *application) applyList(parent ast.Node, name string) {
+	// avoid heap-allocating a new iterator for each applyList call; reuse a.iter instead
+	saved := a.iter
+	a.iter.index = 0
+	for {
+		// must reload parent.name each time, since cursor modifications might change it
+		v := reflect.Indirect(reflect.ValueOf(parent)).FieldByName(name)
+		if a.iter.index >= v.Len() {
+			break
+		}
+
+		// element x may be nil in a bad AST - be cautious
+		var x ast.Node
+		if e := v.Index(a.iter.index); e.IsValid() {
+			x = e.Interface().(ast.Node)
+		}
+
+		a.iter.step = 1
+		a.apply(parent, name, &a.iter, x)
+		a.iter.index += a.iter.step
+	}
+	a.iter = saved
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/astutil/util.go b/libgo/go/golang.org/x/tools/go/ast/astutil/util.go
new file mode 100644
index 00000000000..7630629824a
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/astutil/util.go
@@ -0,0 +1,14 @@
+package astutil
+
+import "go/ast"
+
+// Unparen returns e with any enclosing parentheses stripped.
+func Unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/inspector/inspector.go b/libgo/go/golang.org/x/tools/go/ast/inspector/inspector.go
new file mode 100644
index 00000000000..db88a951090
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/inspector/inspector.go
@@ -0,0 +1,182 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package inspector provides helper functions for traversal over the
+// syntax trees of a package, including node filtering by type, and
+// materialization of the traversal stack.
+//
+// During construction, the inspector does a complete traversal and
+// builds a list of push/pop events and their node type. Subsequent
+// method calls that request a traversal scan this list, rather than walk
+// the AST, and perform type filtering using efficient bit sets.
+//
+// Experiments suggest the inspector's traversals are about 2.5x faster
+// than ast.Inspect, but it may take around 5 traversals for this
+// benefit to amortize the inspector's construction cost.
+// If efficiency is the primary concern, do not use use Inspector for
+// one-off traversals.
+package inspector
+
+// There are four orthogonal features in a traversal:
+//  1 type filtering
+//  2 pruning
+//  3 postorder calls to f
+//  4 stack
+// Rather than offer all of them in the API,
+// only a few combinations are exposed:
+// - Preorder is the fastest and has fewest features,
+//   but is the most commonly needed traversal.
+// - Nodes and WithStack both provide pruning and postorder calls,
+//   even though few clients need it, because supporting two versions
+//   is not justified.
+// More combinations could be supported by expressing them as
+// wrappers around a more generic traversal, but this was measured
+// and found to degrade performance significantly (30%).
+
+import (
+	"go/ast"
+)
+
+// An Inspector provides methods for inspecting
+// (traversing) the syntax trees of a package.
+type Inspector struct {
+	events []event
+}
+
+// New returns an Inspector for the specified syntax trees.
+func New(files []*ast.File) *Inspector {
+	return &Inspector{traverse(files)}
+}
+
+// An event represents a push or a pop
+// of an ast.Node during a traversal.
+type event struct {
+	node  ast.Node
+	typ   uint64 // typeOf(node)
+	index int    // 1 + index of corresponding pop event, or 0 if this is a pop
+}
+
+// Preorder visits all the nodes of the files supplied to New in
+// depth-first order. It calls f(n) for each node n before it visits
+// n's children.
+//
+// The types argument, if non-empty, enables type-based filtering of
+// events. The function f if is called only for nodes whose type
+// matches an element of the types slice.
+func (in *Inspector) Preorder(types []ast.Node, f func(ast.Node)) {
+	// Because it avoids postorder calls to f, and the pruning
+	// check, Preorder is almost twice as fast as Nodes. The two
+	// features seem to contribute similar slowdowns (~1.4x each).
+
+	mask := maskOf(types)
+	for i := 0; i < len(in.events); {
+		ev := in.events[i]
+		if ev.typ&mask != 0 {
+			if ev.index > 0 {
+				f(ev.node)
+			}
+		}
+		i++
+	}
+}
+
+// Nodes visits the nodes of the files supplied to New in depth-first
+// order. It calls f(n, true) for each node n before it visits n's
+// children. If f returns true, Nodes invokes f recursively for each
+// of the non-nil children of the node, followed by a call of
+// f(n, false).
+//
+// The types argument, if non-empty, enables type-based filtering of
+// events. The function f if is called only for nodes whose type
+// matches an element of the types slice.
+func (in *Inspector) Nodes(types []ast.Node, f func(n ast.Node, push bool) (prune bool)) {
+	mask := maskOf(types)
+	for i := 0; i < len(in.events); {
+		ev := in.events[i]
+		if ev.typ&mask != 0 {
+			if ev.index > 0 {
+				// push
+				if !f(ev.node, true) {
+					i = ev.index // jump to corresponding pop + 1
+					continue
+				}
+			} else {
+				// pop
+				f(ev.node, false)
+			}
+		}
+		i++
+	}
+}
+
+// WithStack visits nodes in a similar manner to Nodes, but it
+// supplies each call to f an additional argument, the current
+// traversal stack. The stack's first element is the outermost node,
+// an *ast.File; its last is the innermost, n.
+func (in *Inspector) WithStack(types []ast.Node, f func(n ast.Node, push bool, stack []ast.Node) (prune bool)) {
+	mask := maskOf(types)
+	var stack []ast.Node
+	for i := 0; i < len(in.events); {
+		ev := in.events[i]
+		if ev.index > 0 {
+			// push
+			stack = append(stack, ev.node)
+			if ev.typ&mask != 0 {
+				if !f(ev.node, true, stack) {
+					i = ev.index
+					stack = stack[:len(stack)-1]
+					continue
+				}
+			}
+		} else {
+			// pop
+			if ev.typ&mask != 0 {
+				f(ev.node, false, stack)
+			}
+			stack = stack[:len(stack)-1]
+		}
+		i++
+	}
+}
+
+// traverse builds the table of events representing a traversal.
+func traverse(files []*ast.File) []event {
+	// Preallocate approximate number of events
+	// based on source file extent.
+	// This makes traverse faster by 4x (!).
+	var extent int
+	for _, f := range files {
+		extent += int(f.End() - f.Pos())
+	}
+	// This estimate is based on the net/http package.
+	events := make([]event, 0, extent*33/100)
+
+	var stack []event
+	for _, f := range files {
+		ast.Inspect(f, func(n ast.Node) bool {
+			if n != nil {
+				// push
+				ev := event{
+					node:  n,
+					typ:   typeOf(n),
+					index: len(events), // push event temporarily holds own index
+				}
+				stack = append(stack, ev)
+				events = append(events, ev)
+			} else {
+				// pop
+				ev := stack[len(stack)-1]
+				stack = stack[:len(stack)-1]
+
+				events[ev.index].index = len(events) + 1 // make push refer to pop
+
+				ev.index = 0 // turn ev into a pop event
+				events = append(events, ev)
+			}
+			return true
+		})
+	}
+
+	return events
+}
diff --git a/libgo/go/golang.org/x/tools/go/ast/inspector/typeof.go b/libgo/go/golang.org/x/tools/go/ast/inspector/typeof.go
new file mode 100644
index 00000000000..d61301b133d
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/ast/inspector/typeof.go
@@ -0,0 +1,216 @@
+package inspector
+
+// This file defines func typeOf(ast.Node) uint64.
+//
+// The initial map-based implementation was too slow;
+// see https://go-review.googlesource.com/c/tools/+/135655/1/go/ast/inspector/inspector.go#196
+
+import "go/ast"
+
+const (
+	nArrayType = iota
+	nAssignStmt
+	nBadDecl
+	nBadExpr
+	nBadStmt
+	nBasicLit
+	nBinaryExpr
+	nBlockStmt
+	nBranchStmt
+	nCallExpr
+	nCaseClause
+	nChanType
+	nCommClause
+	nComment
+	nCommentGroup
+	nCompositeLit
+	nDeclStmt
+	nDeferStmt
+	nEllipsis
+	nEmptyStmt
+	nExprStmt
+	nField
+	nFieldList
+	nFile
+	nForStmt
+	nFuncDecl
+	nFuncLit
+	nFuncType
+	nGenDecl
+	nGoStmt
+	nIdent
+	nIfStmt
+	nImportSpec
+	nIncDecStmt
+	nIndexExpr
+	nInterfaceType
+	nKeyValueExpr
+	nLabeledStmt
+	nMapType
+	nPackage
+	nParenExpr
+	nRangeStmt
+	nReturnStmt
+	nSelectStmt
+	nSelectorExpr
+	nSendStmt
+	nSliceExpr
+	nStarExpr
+	nStructType
+	nSwitchStmt
+	nTypeAssertExpr
+	nTypeSpec
+	nTypeSwitchStmt
+	nUnaryExpr
+	nValueSpec
+)
+
+// typeOf returns a distinct single-bit value that represents the type of n.
+//
+// Various implementations were benchmarked with BenchmarkNewInspector:
+//								GOGC=off
+// - type switch				4.9-5.5ms	2.1ms
+// - binary search over a sorted list of types  5.5-5.9ms	2.5ms
+// - linear scan, frequency-ordered list 	5.9-6.1ms	2.7ms
+// - linear scan, unordered list		6.4ms		2.7ms
+// - hash table					6.5ms		3.1ms
+// A perfect hash seemed like overkill.
+//
+// The compiler's switch statement is the clear winner
+// as it produces a binary tree in code,
+// with constant conditions and good branch prediction.
+// (Sadly it is the most verbose in source code.)
+// Binary search suffered from poor branch prediction.
+//
+func typeOf(n ast.Node) uint64 {
+	// Fast path: nearly half of all nodes are identifiers.
+	if _, ok := n.(*ast.Ident); ok {
+		return 1 << nIdent
+	}
+
+	// These cases include all nodes encountered by ast.Inspect.
+	switch n.(type) {
+	case *ast.ArrayType:
+		return 1 << nArrayType
+	case *ast.AssignStmt:
+		return 1 << nAssignStmt
+	case *ast.BadDecl:
+		return 1 << nBadDecl
+	case *ast.BadExpr:
+		return 1 << nBadExpr
+	case *ast.BadStmt:
+		return 1 << nBadStmt
+	case *ast.BasicLit:
+		return 1 << nBasicLit
+	case *ast.BinaryExpr:
+		return 1 << nBinaryExpr
+	case *ast.BlockStmt:
+		return 1 << nBlockStmt
+	case *ast.BranchStmt:
+		return 1 << nBranchStmt
+	case *ast.CallExpr:
+		return 1 << nCallExpr
+	case *ast.CaseClause:
+		return 1 << nCaseClause
+	case *ast.ChanType:
+		return 1 << nChanType
+	case *ast.CommClause:
+		return 1 << nCommClause
+	case *ast.Comment:
+		return 1 << nComment
+	case *ast.CommentGroup:
+		return 1 << nCommentGroup
+	case *ast.CompositeLit:
+		return 1 << nCompositeLit
+	case *ast.DeclStmt:
+		return 1 << nDeclStmt
+	case *ast.DeferStmt:
+		return 1 << nDeferStmt
+	case *ast.Ellipsis:
+		return 1 << nEllipsis
+	case *ast.EmptyStmt:
+		return 1 << nEmptyStmt
+	case *ast.ExprStmt:
+		return 1 << nExprStmt
+	case *ast.Field:
+		return 1 << nField
+	case *ast.FieldList:
+		return 1 << nFieldList
+	case *ast.File:
+		return 1 << nFile
+	case *ast.ForStmt:
+		return 1 << nForStmt
+	case *ast.FuncDecl:
+		return 1 << nFuncDecl
+	case *ast.FuncLit:
+		return 1 << nFuncLit
+	case *ast.FuncType:
+		return 1 << nFuncType
+	case *ast.GenDecl:
+		return 1 << nGenDecl
+	case *ast.GoStmt:
+		return 1 << nGoStmt
+	case *ast.Ident:
+		return 1 << nIdent
+	case *ast.IfStmt:
+		return 1 << nIfStmt
+	case *ast.ImportSpec:
+		return 1 << nImportSpec
+	case *ast.IncDecStmt:
+		return 1 << nIncDecStmt
+	case *ast.IndexExpr:
+		return 1 << nIndexExpr
+	case *ast.InterfaceType:
+		return 1 << nInterfaceType
+	case *ast.KeyValueExpr:
+		return 1 << nKeyValueExpr
+	case *ast.LabeledStmt:
+		return 1 << nLabeledStmt
+	case *ast.MapType:
+		return 1 << nMapType
+	case *ast.Package:
+		return 1 << nPackage
+	case *ast.ParenExpr:
+		return 1 << nParenExpr
+	case *ast.RangeStmt:
+		return 1 << nRangeStmt
+	case *ast.ReturnStmt:
+		return 1 << nReturnStmt
+	case *ast.SelectStmt:
+		return 1 << nSelectStmt
+	case *ast.SelectorExpr:
+		return 1 << nSelectorExpr
+	case *ast.SendStmt:
+		return 1 << nSendStmt
+	case *ast.SliceExpr:
+		return 1 << nSliceExpr
+	case *ast.StarExpr:
+		return 1 << nStarExpr
+	case *ast.StructType:
+		return 1 << nStructType
+	case *ast.SwitchStmt:
+		return 1 << nSwitchStmt
+	case *ast.TypeAssertExpr:
+		return 1 << nTypeAssertExpr
+	case *ast.TypeSpec:
+		return 1 << nTypeSpec
+	case *ast.TypeSwitchStmt:
+		return 1 << nTypeSwitchStmt
+	case *ast.UnaryExpr:
+		return 1 << nUnaryExpr
+	case *ast.ValueSpec:
+		return 1 << nValueSpec
+	}
+	return 0
+}
+
+func maskOf(nodes []ast.Node) uint64 {
+	if nodes == nil {
+		return 1<<64 - 1 // match all node types
+	}
+	var mask uint64
+	for _, n := range nodes {
+		mask |= typeOf(n)
+	}
+	return mask
+}
diff --git a/libgo/go/golang.org/x/tools/go/cfg/builder.go b/libgo/go/golang.org/x/tools/go/cfg/builder.go
new file mode 100644
index 00000000000..24e1aba0339
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/cfg/builder.go
@@ -0,0 +1,510 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cfg
+
+// This file implements the CFG construction pass.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+)
+
+type builder struct {
+	cfg       *CFG
+	mayReturn func(*ast.CallExpr) bool
+	current   *Block
+	lblocks   map[*ast.Object]*lblock // labeled blocks
+	targets   *targets                // linked stack of branch targets
+}
+
+func (b *builder) stmt(_s ast.Stmt) {
+	// The label of the current statement.  If non-nil, its _goto
+	// target is always set; its _break and _continue are set only
+	// within the body of switch/typeswitch/select/for/range.
+	// It is effectively an additional default-nil parameter of stmt().
+	var label *lblock
+start:
+	switch s := _s.(type) {
+	case *ast.BadStmt,
+		*ast.SendStmt,
+		*ast.IncDecStmt,
+		*ast.GoStmt,
+		*ast.DeferStmt,
+		*ast.EmptyStmt,
+		*ast.AssignStmt:
+		// No effect on control flow.
+		b.add(s)
+
+	case *ast.ExprStmt:
+		b.add(s)
+		if call, ok := s.X.(*ast.CallExpr); ok && !b.mayReturn(call) {
+			// Calls to panic, os.Exit, etc, never return.
+			b.current = b.newBlock("unreachable.call")
+		}
+
+	case *ast.DeclStmt:
+		// Treat each var ValueSpec as a separate statement.
+		d := s.Decl.(*ast.GenDecl)
+		if d.Tok == token.VAR {
+			for _, spec := range d.Specs {
+				if spec, ok := spec.(*ast.ValueSpec); ok {
+					b.add(spec)
+				}
+			}
+		}
+
+	case *ast.LabeledStmt:
+		label = b.labeledBlock(s.Label)
+		b.jump(label._goto)
+		b.current = label._goto
+		_s = s.Stmt
+		goto start // effectively: tailcall stmt(g, s.Stmt, label)
+
+	case *ast.ReturnStmt:
+		b.add(s)
+		b.current = b.newBlock("unreachable.return")
+
+	case *ast.BranchStmt:
+		b.branchStmt(s)
+
+	case *ast.BlockStmt:
+		b.stmtList(s.List)
+
+	case *ast.IfStmt:
+		if s.Init != nil {
+			b.stmt(s.Init)
+		}
+		then := b.newBlock("if.then")
+		done := b.newBlock("if.done")
+		_else := done
+		if s.Else != nil {
+			_else = b.newBlock("if.else")
+		}
+		b.add(s.Cond)
+		b.ifelse(then, _else)
+		b.current = then
+		b.stmt(s.Body)
+		b.jump(done)
+
+		if s.Else != nil {
+			b.current = _else
+			b.stmt(s.Else)
+			b.jump(done)
+		}
+
+		b.current = done
+
+	case *ast.SwitchStmt:
+		b.switchStmt(s, label)
+
+	case *ast.TypeSwitchStmt:
+		b.typeSwitchStmt(s, label)
+
+	case *ast.SelectStmt:
+		b.selectStmt(s, label)
+
+	case *ast.ForStmt:
+		b.forStmt(s, label)
+
+	case *ast.RangeStmt:
+		b.rangeStmt(s, label)
+
+	default:
+		panic(fmt.Sprintf("unexpected statement kind: %T", s))
+	}
+}
+
+func (b *builder) stmtList(list []ast.Stmt) {
+	for _, s := range list {
+		b.stmt(s)
+	}
+}
+
+func (b *builder) branchStmt(s *ast.BranchStmt) {
+	var block *Block
+	switch s.Tok {
+	case token.BREAK:
+		if s.Label != nil {
+			if lb := b.labeledBlock(s.Label); lb != nil {
+				block = lb._break
+			}
+		} else {
+			for t := b.targets; t != nil && block == nil; t = t.tail {
+				block = t._break
+			}
+		}
+
+	case token.CONTINUE:
+		if s.Label != nil {
+			if lb := b.labeledBlock(s.Label); lb != nil {
+				block = lb._continue
+			}
+		} else {
+			for t := b.targets; t != nil && block == nil; t = t.tail {
+				block = t._continue
+			}
+		}
+
+	case token.FALLTHROUGH:
+		for t := b.targets; t != nil; t = t.tail {
+			block = t._fallthrough
+		}
+
+	case token.GOTO:
+		if s.Label != nil {
+			block = b.labeledBlock(s.Label)._goto
+		}
+	}
+	if block == nil {
+		block = b.newBlock("undefined.branch")
+	}
+	b.jump(block)
+	b.current = b.newBlock("unreachable.branch")
+}
+
+func (b *builder) switchStmt(s *ast.SwitchStmt, label *lblock) {
+	if s.Init != nil {
+		b.stmt(s.Init)
+	}
+	if s.Tag != nil {
+		b.add(s.Tag)
+	}
+	done := b.newBlock("switch.done")
+	if label != nil {
+		label._break = done
+	}
+	// We pull the default case (if present) down to the end.
+	// But each fallthrough label must point to the next
+	// body block in source order, so we preallocate a
+	// body block (fallthru) for the next case.
+	// Unfortunately this makes for a confusing block order.
+	var defaultBody *[]ast.Stmt
+	var defaultFallthrough *Block
+	var fallthru, defaultBlock *Block
+	ncases := len(s.Body.List)
+	for i, clause := range s.Body.List {
+		body := fallthru
+		if body == nil {
+			body = b.newBlock("switch.body") // first case only
+		}
+
+		// Preallocate body block for the next case.
+		fallthru = done
+		if i+1 < ncases {
+			fallthru = b.newBlock("switch.body")
+		}
+
+		cc := clause.(*ast.CaseClause)
+		if cc.List == nil {
+			// Default case.
+			defaultBody = &cc.Body
+			defaultFallthrough = fallthru
+			defaultBlock = body
+			continue
+		}
+
+		var nextCond *Block
+		for _, cond := range cc.List {
+			nextCond = b.newBlock("switch.next")
+			b.add(cond) // one half of the tag==cond condition
+			b.ifelse(body, nextCond)
+			b.current = nextCond
+		}
+		b.current = body
+		b.targets = &targets{
+			tail:         b.targets,
+			_break:       done,
+			_fallthrough: fallthru,
+		}
+		b.stmtList(cc.Body)
+		b.targets = b.targets.tail
+		b.jump(done)
+		b.current = nextCond
+	}
+	if defaultBlock != nil {
+		b.jump(defaultBlock)
+		b.current = defaultBlock
+		b.targets = &targets{
+			tail:         b.targets,
+			_break:       done,
+			_fallthrough: defaultFallthrough,
+		}
+		b.stmtList(*defaultBody)
+		b.targets = b.targets.tail
+	}
+	b.jump(done)
+	b.current = done
+}
+
+func (b *builder) typeSwitchStmt(s *ast.TypeSwitchStmt, label *lblock) {
+	if s.Init != nil {
+		b.stmt(s.Init)
+	}
+	if s.Assign != nil {
+		b.add(s.Assign)
+	}
+
+	done := b.newBlock("typeswitch.done")
+	if label != nil {
+		label._break = done
+	}
+	var default_ *ast.CaseClause
+	for _, clause := range s.Body.List {
+		cc := clause.(*ast.CaseClause)
+		if cc.List == nil {
+			default_ = cc
+			continue
+		}
+		body := b.newBlock("typeswitch.body")
+		var next *Block
+		for _, casetype := range cc.List {
+			next = b.newBlock("typeswitch.next")
+			// casetype is a type, so don't call b.add(casetype).
+			// This block logically contains a type assertion,
+			// x.(casetype), but it's unclear how to represent x.
+			_ = casetype
+			b.ifelse(body, next)
+			b.current = next
+		}
+		b.current = body
+		b.typeCaseBody(cc, done)
+		b.current = next
+	}
+	if default_ != nil {
+		b.typeCaseBody(default_, done)
+	} else {
+		b.jump(done)
+	}
+	b.current = done
+}
+
+func (b *builder) typeCaseBody(cc *ast.CaseClause, done *Block) {
+	b.targets = &targets{
+		tail:   b.targets,
+		_break: done,
+	}
+	b.stmtList(cc.Body)
+	b.targets = b.targets.tail
+	b.jump(done)
+}
+
+func (b *builder) selectStmt(s *ast.SelectStmt, label *lblock) {
+	// First evaluate channel expressions.
+	// TODO(adonovan): fix: evaluate only channel exprs here.
+	for _, clause := range s.Body.List {
+		if comm := clause.(*ast.CommClause).Comm; comm != nil {
+			b.stmt(comm)
+		}
+	}
+
+	done := b.newBlock("select.done")
+	if label != nil {
+		label._break = done
+	}
+
+	var defaultBody *[]ast.Stmt
+	for _, cc := range s.Body.List {
+		clause := cc.(*ast.CommClause)
+		if clause.Comm == nil {
+			defaultBody = &clause.Body
+			continue
+		}
+		body := b.newBlock("select.body")
+		next := b.newBlock("select.next")
+		b.ifelse(body, next)
+		b.current = body
+		b.targets = &targets{
+			tail:   b.targets,
+			_break: done,
+		}
+		switch comm := clause.Comm.(type) {
+		case *ast.ExprStmt: // <-ch
+			// nop
+		case *ast.AssignStmt: // x := <-states[state].Chan
+			b.add(comm.Lhs[0])
+		}
+		b.stmtList(clause.Body)
+		b.targets = b.targets.tail
+		b.jump(done)
+		b.current = next
+	}
+	if defaultBody != nil {
+		b.targets = &targets{
+			tail:   b.targets,
+			_break: done,
+		}
+		b.stmtList(*defaultBody)
+		b.targets = b.targets.tail
+		b.jump(done)
+	}
+	b.current = done
+}
+
+func (b *builder) forStmt(s *ast.ForStmt, label *lblock) {
+	//	...init...
+	//      jump loop
+	// loop:
+	//      if cond goto body else done
+	// body:
+	//      ...body...
+	//      jump post
+	// post:				 (target of continue)
+	//      ...post...
+	//      jump loop
+	// done:                                 (target of break)
+	if s.Init != nil {
+		b.stmt(s.Init)
+	}
+	body := b.newBlock("for.body")
+	done := b.newBlock("for.done") // target of 'break'
+	loop := body                   // target of back-edge
+	if s.Cond != nil {
+		loop = b.newBlock("for.loop")
+	}
+	cont := loop // target of 'continue'
+	if s.Post != nil {
+		cont = b.newBlock("for.post")
+	}
+	if label != nil {
+		label._break = done
+		label._continue = cont
+	}
+	b.jump(loop)
+	b.current = loop
+	if loop != body {
+		b.add(s.Cond)
+		b.ifelse(body, done)
+		b.current = body
+	}
+	b.targets = &targets{
+		tail:      b.targets,
+		_break:    done,
+		_continue: cont,
+	}
+	b.stmt(s.Body)
+	b.targets = b.targets.tail
+	b.jump(cont)
+
+	if s.Post != nil {
+		b.current = cont
+		b.stmt(s.Post)
+		b.jump(loop) // back-edge
+	}
+	b.current = done
+}
+
+func (b *builder) rangeStmt(s *ast.RangeStmt, label *lblock) {
+	b.add(s.X)
+
+	if s.Key != nil {
+		b.add(s.Key)
+	}
+	if s.Value != nil {
+		b.add(s.Value)
+	}
+
+	//      ...
+	// loop:                                   (target of continue)
+	// 	if ... goto body else done
+	// body:
+	//      ...
+	// 	jump loop
+	// done:                                   (target of break)
+
+	loop := b.newBlock("range.loop")
+	b.jump(loop)
+	b.current = loop
+
+	body := b.newBlock("range.body")
+	done := b.newBlock("range.done")
+	b.ifelse(body, done)
+	b.current = body
+
+	if label != nil {
+		label._break = done
+		label._continue = loop
+	}
+	b.targets = &targets{
+		tail:      b.targets,
+		_break:    done,
+		_continue: loop,
+	}
+	b.stmt(s.Body)
+	b.targets = b.targets.tail
+	b.jump(loop) // back-edge
+	b.current = done
+}
+
+// -------- helpers --------
+
+// Destinations associated with unlabeled for/switch/select stmts.
+// We push/pop one of these as we enter/leave each construct and for
+// each BranchStmt we scan for the innermost target of the right type.
+//
+type targets struct {
+	tail         *targets // rest of stack
+	_break       *Block
+	_continue    *Block
+	_fallthrough *Block
+}
+
+// Destinations associated with a labeled block.
+// We populate these as labels are encountered in forward gotos or
+// labeled statements.
+//
+type lblock struct {
+	_goto     *Block
+	_break    *Block
+	_continue *Block
+}
+
+// labeledBlock returns the branch target associated with the
+// specified label, creating it if needed.
+//
+func (b *builder) labeledBlock(label *ast.Ident) *lblock {
+	lb := b.lblocks[label.Obj]
+	if lb == nil {
+		lb = &lblock{_goto: b.newBlock(label.Name)}
+		if b.lblocks == nil {
+			b.lblocks = make(map[*ast.Object]*lblock)
+		}
+		b.lblocks[label.Obj] = lb
+	}
+	return lb
+}
+
+// newBlock appends a new unconnected basic block to b.cfg's block
+// slice and returns it.
+// It does not automatically become the current block.
+// comment is an optional string for more readable debugging output.
+func (b *builder) newBlock(comment string) *Block {
+	g := b.cfg
+	block := &Block{
+		Index:   int32(len(g.Blocks)),
+		comment: comment,
+	}
+	block.Succs = block.succs2[:0]
+	g.Blocks = append(g.Blocks, block)
+	return block
+}
+
+func (b *builder) add(n ast.Node) {
+	b.current.Nodes = append(b.current.Nodes, n)
+}
+
+// jump adds an edge from the current block to the target block,
+// and sets b.current to nil.
+func (b *builder) jump(target *Block) {
+	b.current.Succs = append(b.current.Succs, target)
+	b.current = nil
+}
+
+// ifelse emits edges from the current block to the t and f blocks,
+// and sets b.current to nil.
+func (b *builder) ifelse(t, f *Block) {
+	b.current.Succs = append(b.current.Succs, t, f)
+	b.current = nil
+}
diff --git a/libgo/go/golang.org/x/tools/go/cfg/cfg.go b/libgo/go/golang.org/x/tools/go/cfg/cfg.go
new file mode 100644
index 00000000000..b075034bb45
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/cfg/cfg.go
@@ -0,0 +1,150 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This package constructs a simple control-flow graph (CFG) of the
+// statements and expressions within a single function.
+//
+// Use cfg.New to construct the CFG for a function body.
+//
+// The blocks of the CFG contain all the function's non-control
+// statements.  The CFG does not contain control statements such as If,
+// Switch, Select, and Branch, but does contain their subexpressions.
+// For example, this source code:
+//
+//	if x := f(); x != nil {
+//		T()
+//	} else {
+//		F()
+//	}
+//
+// produces this CFG:
+//
+//    1:  x := f()
+//        x != nil
+//        succs: 2, 3
+//    2:  T()
+//        succs: 4
+//    3:  F()
+//        succs: 4
+//    4:
+//
+// The CFG does contain Return statements; even implicit returns are
+// materialized (at the position of the function's closing brace).
+//
+// The CFG does not record conditions associated with conditional branch
+// edges, nor the short-circuit semantics of the && and || operators,
+// nor abnormal control flow caused by panic.  If you need this
+// information, use golang.org/x/tools/go/ssa instead.
+//
+package cfg
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/token"
+)
+
+// A CFG represents the control-flow graph of a single function.
+//
+// The entry point is Blocks[0]; there may be multiple return blocks.
+type CFG struct {
+	Blocks []*Block // block[0] is entry; order otherwise undefined
+}
+
+// A Block represents a basic block: a list of statements and
+// expressions that are always evaluated sequentially.
+//
+// A block may have 0-2 successors: zero for a return block or a block
+// that calls a function such as panic that never returns; one for a
+// normal (jump) block; and two for a conditional (if) block.
+type Block struct {
+	Nodes []ast.Node // statements, expressions, and ValueSpecs
+	Succs []*Block   // successor nodes in the graph
+	Index int32      // index within CFG.Blocks
+	Live  bool       // block is reachable from entry
+
+	comment string    // for debugging
+	succs2  [2]*Block // underlying array for Succs
+}
+
+// New returns a new control-flow graph for the specified function body,
+// which must be non-nil.
+//
+// The CFG builder calls mayReturn to determine whether a given function
+// call may return.  For example, calls to panic, os.Exit, and log.Fatal
+// do not return, so the builder can remove infeasible graph edges
+// following such calls.  The builder calls mayReturn only for a
+// CallExpr beneath an ExprStmt.
+func New(body *ast.BlockStmt, mayReturn func(*ast.CallExpr) bool) *CFG {
+	b := builder{
+		mayReturn: mayReturn,
+		cfg:       new(CFG),
+	}
+	b.current = b.newBlock("entry")
+	b.stmt(body)
+
+	// Compute liveness (reachability from entry point), breadth-first.
+	q := make([]*Block, 0, len(b.cfg.Blocks))
+	q = append(q, b.cfg.Blocks[0]) // entry point
+	for len(q) > 0 {
+		b := q[len(q)-1]
+		q = q[:len(q)-1]
+
+		if !b.Live {
+			b.Live = true
+			q = append(q, b.Succs...)
+		}
+	}
+
+	// Does control fall off the end of the function's body?
+	// Make implicit return explicit.
+	if b.current != nil && b.current.Live {
+		b.add(&ast.ReturnStmt{
+			Return: body.End() - 1,
+		})
+	}
+
+	return b.cfg
+}
+
+func (b *Block) String() string {
+	return fmt.Sprintf("block %d (%s)", b.Index, b.comment)
+}
+
+// Return returns the return statement at the end of this block if present, nil otherwise.
+func (b *Block) Return() (ret *ast.ReturnStmt) {
+	if len(b.Nodes) > 0 {
+		ret, _ = b.Nodes[len(b.Nodes)-1].(*ast.ReturnStmt)
+	}
+	return
+}
+
+// Format formats the control-flow graph for ease of debugging.
+func (g *CFG) Format(fset *token.FileSet) string {
+	var buf bytes.Buffer
+	for _, b := range g.Blocks {
+		fmt.Fprintf(&buf, ".%d: # %s\n", b.Index, b.comment)
+		for _, n := range b.Nodes {
+			fmt.Fprintf(&buf, "\t%s\n", formatNode(fset, n))
+		}
+		if len(b.Succs) > 0 {
+			fmt.Fprintf(&buf, "\tsuccs:")
+			for _, succ := range b.Succs {
+				fmt.Fprintf(&buf, " %d", succ.Index)
+			}
+			buf.WriteByte('\n')
+		}
+		buf.WriteByte('\n')
+	}
+	return buf.String()
+}
+
+func formatNode(fset *token.FileSet, n ast.Node) string {
+	var buf bytes.Buffer
+	format.Node(&buf, fset, n)
+	// Indent secondary lines by a tab.
+	return string(bytes.Replace(buf.Bytes(), []byte("\n"), []byte("\n\t"), -1))
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/objectpath/objectpath.go b/libgo/go/golang.org/x/tools/go/types/objectpath/objectpath.go
new file mode 100644
index 00000000000..0d85488efb6
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/objectpath/objectpath.go
@@ -0,0 +1,523 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package objectpath defines a naming scheme for types.Objects
+// (that is, named entities in Go programs) relative to their enclosing
+// package.
+//
+// Type-checker objects are canonical, so they are usually identified by
+// their address in memory (a pointer), but a pointer has meaning only
+// within one address space. By contrast, objectpath names allow the
+// identity of an object to be sent from one program to another,
+// establishing a correspondence between types.Object variables that are
+// distinct but logically equivalent.
+//
+// A single object may have multiple paths. In this example,
+//     type A struct{ X int }
+//     type B A
+// the field X has two paths due to its membership of both A and B.
+// The For(obj) function always returns one of these paths, arbitrarily
+// but consistently.
+package objectpath
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"go/types"
+)
+
+// A Path is an opaque name that identifies a types.Object
+// relative to its package. Conceptually, the name consists of a
+// sequence of destructuring operations applied to the package scope
+// to obtain the original object.
+// The name does not include the package itself.
+type Path string
+
+// Encoding
+//
+// An object path is a textual and (with training) human-readable encoding
+// of a sequence of destructuring operators, starting from a types.Package.
+// The sequences represent a path through the package/object/type graph.
+// We classify these operators by their type:
+//
+//   PO package->object	Package.Scope.Lookup
+//   OT  object->type 	Object.Type
+//   TT    type->type 	Type.{Elem,Key,Params,Results,Underlying} [EKPRU]
+//   TO   type->object	Type.{At,Field,Method,Obj} [AFMO]
+//
+// All valid paths start with a package and end at an object
+// and thus may be defined by the regular language:
+//
+//   objectpath = PO (OT TT* TO)*
+//
+// The concrete encoding follows directly:
+// - The only PO operator is Package.Scope.Lookup, which requires an identifier.
+// - The only OT operator is Object.Type,
+//   which we encode as '.' because dot cannot appear in an identifier.
+// - The TT operators are encoded as [EKPRU].
+// - The OT operators are encoded as [AFMO];
+//   three of these (At,Field,Method) require an integer operand,
+//   which is encoded as a string of decimal digits.
+//   These indices are stable across different representations
+//   of the same package, even source and export data.
+//
+// In the example below,
+//
+//	package p
+//
+//	type T interface {
+//		f() (a string, b struct{ X int })
+//	}
+//
+// field X has the path "T.UM0.RA1.F0",
+// representing the following sequence of operations:
+//
+//    p.Lookup("T")					T
+//    .Type().Underlying().Method(0).			f
+//    .Type().Results().At(1)				b
+//    .Type().Field(0)					X
+//
+// The encoding is not maximally compact---every R or P is
+// followed by an A, for example---but this simplifies the
+// encoder and decoder.
+//
+const (
+	// object->type operators
+	opType = '.' // .Type()		  (Object)
+
+	// type->type operators
+	opElem       = 'E' // .Elem()		(Pointer, Slice, Array, Chan, Map)
+	opKey        = 'K' // .Key()		(Map)
+	opParams     = 'P' // .Params()		(Signature)
+	opResults    = 'R' // .Results()	(Signature)
+	opUnderlying = 'U' // .Underlying()	(Named)
+
+	// type->object operators
+	opAt     = 'A' // .At(i)		(Tuple)
+	opField  = 'F' // .Field(i)		(Struct)
+	opMethod = 'M' // .Method(i)		(Named or Interface; not Struct: "promoted" names are ignored)
+	opObj    = 'O' // .Obj()		(Named)
+)
+
+// The For function returns the path to an object relative to its package,
+// or an error if the object is not accessible from the package's Scope.
+//
+// The For function guarantees to return a path only for the following objects:
+// - package-level types
+// - exported package-level non-types
+// - methods
+// - parameter and result variables
+// - struct fields
+// These objects are sufficient to define the API of their package.
+// The objects described by a package's export data are drawn from this set.
+//
+// For does not return a path for predeclared names, imported package
+// names, local names, and unexported package-level names (except
+// types).
+//
+// Example: given this definition,
+//
+//	package p
+//
+//	type T interface {
+//		f() (a string, b struct{ X int })
+//	}
+//
+// For(X) would return a path that denotes the following sequence of operations:
+//
+//    p.Scope().Lookup("T")				(TypeName T)
+//    .Type().Underlying().Method(0).			(method Func f)
+//    .Type().Results().At(1)				(field Var b)
+//    .Type().Field(0)					(field Var X)
+//
+// where p is the package (*types.Package) to which X belongs.
+func For(obj types.Object) (Path, error) {
+	pkg := obj.Pkg()
+
+	// This table lists the cases of interest.
+	//
+	// Object				Action
+	// ------                               ------
+	// nil					reject
+	// builtin				reject
+	// pkgname				reject
+	// label				reject
+	// var
+	//    package-level			accept
+	//    func param/result			accept
+	//    local				reject
+	//    struct field			accept
+	// const
+	//    package-level			accept
+	//    local				reject
+	// func
+	//    package-level			accept
+	//    init functions			reject
+	//    concrete method			accept
+	//    interface method			accept
+	// type
+	//    package-level			accept
+	//    local				reject
+	//
+	// The only accessible package-level objects are members of pkg itself.
+	//
+	// The cases are handled in four steps:
+	//
+	// 1. reject nil and builtin
+	// 2. accept package-level objects
+	// 3. reject obviously invalid objects
+	// 4. search the API for the path to the param/result/field/method.
+
+	// 1. reference to nil or builtin?
+	if pkg == nil {
+		return "", fmt.Errorf("predeclared %s has no path", obj)
+	}
+	scope := pkg.Scope()
+
+	// 2. package-level object?
+	if scope.Lookup(obj.Name()) == obj {
+		// Only exported objects (and non-exported types) have a path.
+		// Non-exported types may be referenced by other objects.
+		if _, ok := obj.(*types.TypeName); !ok && !obj.Exported() {
+			return "", fmt.Errorf("no path for non-exported %v", obj)
+		}
+		return Path(obj.Name()), nil
+	}
+
+	// 3. Not a package-level object.
+	//    Reject obviously non-viable cases.
+	switch obj := obj.(type) {
+	case *types.Const, // Only package-level constants have a path.
+		*types.TypeName, // Only package-level types have a path.
+		*types.Label,    // Labels are function-local.
+		*types.PkgName:  // PkgNames are file-local.
+		return "", fmt.Errorf("no path for %v", obj)
+
+	case *types.Var:
+		// Could be:
+		// - a field (obj.IsField())
+		// - a func parameter or result
+		// - a local var.
+		// Sadly there is no way to distinguish
+		// a param/result from a local
+		// so we must proceed to the find.
+
+	case *types.Func:
+		// A func, if not package-level, must be a method.
+		if recv := obj.Type().(*types.Signature).Recv(); recv == nil {
+			return "", fmt.Errorf("func is not a method: %v", obj)
+		}
+		// TODO(adonovan): opt: if the method is concrete,
+		// do a specialized version of the rest of this function so
+		// that it's O(1) not O(|scope|).  Basically 'find' is needed
+		// only for struct fields and interface methods.
+
+	default:
+		panic(obj)
+	}
+
+	// 4. Search the API for the path to the var (field/param/result) or method.
+
+	// First inspect package-level named types.
+	// In the presence of path aliases, these give
+	// the best paths because non-types may
+	// refer to types, but not the reverse.
+	empty := make([]byte, 0, 48) // initial space
+	for _, name := range scope.Names() {
+		o := scope.Lookup(name)
+		tname, ok := o.(*types.TypeName)
+		if !ok {
+			continue // handle non-types in second pass
+		}
+
+		path := append(empty, name...)
+		path = append(path, opType)
+
+		T := o.Type()
+
+		if tname.IsAlias() {
+			// type alias
+			if r := find(obj, T, path); r != nil {
+				return Path(r), nil
+			}
+		} else {
+			// defined (named) type
+			if r := find(obj, T.Underlying(), append(path, opUnderlying)); r != nil {
+				return Path(r), nil
+			}
+		}
+	}
+
+	// Then inspect everything else:
+	// non-types, and declared methods of defined types.
+	for _, name := range scope.Names() {
+		o := scope.Lookup(name)
+		path := append(empty, name...)
+		if _, ok := o.(*types.TypeName); !ok {
+			if o.Exported() {
+				// exported non-type (const, var, func)
+				if r := find(obj, o.Type(), append(path, opType)); r != nil {
+					return Path(r), nil
+				}
+			}
+			continue
+		}
+
+		// Inspect declared methods of defined types.
+		if T, ok := o.Type().(*types.Named); ok {
+			path = append(path, opType)
+			for i := 0; i < T.NumMethods(); i++ {
+				m := T.Method(i)
+				path2 := appendOpArg(path, opMethod, i)
+				if m == obj {
+					return Path(path2), nil // found declared method
+				}
+				if r := find(obj, m.Type(), append(path2, opType)); r != nil {
+					return Path(r), nil
+				}
+			}
+		}
+	}
+
+	return "", fmt.Errorf("can't find path for %v in %s", obj, pkg.Path())
+}
+
+func appendOpArg(path []byte, op byte, arg int) []byte {
+	path = append(path, op)
+	path = strconv.AppendInt(path, int64(arg), 10)
+	return path
+}
+
+// find finds obj within type T, returning the path to it, or nil if not found.
+func find(obj types.Object, T types.Type, path []byte) []byte {
+	switch T := T.(type) {
+	case *types.Basic, *types.Named:
+		// Named types belonging to pkg were handled already,
+		// so T must belong to another package. No path.
+		return nil
+	case *types.Pointer:
+		return find(obj, T.Elem(), append(path, opElem))
+	case *types.Slice:
+		return find(obj, T.Elem(), append(path, opElem))
+	case *types.Array:
+		return find(obj, T.Elem(), append(path, opElem))
+	case *types.Chan:
+		return find(obj, T.Elem(), append(path, opElem))
+	case *types.Map:
+		if r := find(obj, T.Key(), append(path, opKey)); r != nil {
+			return r
+		}
+		return find(obj, T.Elem(), append(path, opElem))
+	case *types.Signature:
+		if r := find(obj, T.Params(), append(path, opParams)); r != nil {
+			return r
+		}
+		return find(obj, T.Results(), append(path, opResults))
+	case *types.Struct:
+		for i := 0; i < T.NumFields(); i++ {
+			f := T.Field(i)
+			path2 := appendOpArg(path, opField, i)
+			if f == obj {
+				return path2 // found field var
+			}
+			if r := find(obj, f.Type(), append(path2, opType)); r != nil {
+				return r
+			}
+		}
+		return nil
+	case *types.Tuple:
+		for i := 0; i < T.Len(); i++ {
+			v := T.At(i)
+			path2 := appendOpArg(path, opAt, i)
+			if v == obj {
+				return path2 // found param/result var
+			}
+			if r := find(obj, v.Type(), append(path2, opType)); r != nil {
+				return r
+			}
+		}
+		return nil
+	case *types.Interface:
+		for i := 0; i < T.NumMethods(); i++ {
+			m := T.Method(i)
+			path2 := appendOpArg(path, opMethod, i)
+			if m == obj {
+				return path2 // found interface method
+			}
+			if r := find(obj, m.Type(), append(path2, opType)); r != nil {
+				return r
+			}
+		}
+		return nil
+	}
+	panic(T)
+}
+
+// Object returns the object denoted by path p within the package pkg.
+func Object(pkg *types.Package, p Path) (types.Object, error) {
+	if p == "" {
+		return nil, fmt.Errorf("empty path")
+	}
+
+	pathstr := string(p)
+	var pkgobj, suffix string
+	if dot := strings.IndexByte(pathstr, opType); dot < 0 {
+		pkgobj = pathstr
+	} else {
+		pkgobj = pathstr[:dot]
+		suffix = pathstr[dot:] // suffix starts with "."
+	}
+
+	obj := pkg.Scope().Lookup(pkgobj)
+	if obj == nil {
+		return nil, fmt.Errorf("package %s does not contain %q", pkg.Path(), pkgobj)
+	}
+
+	// abtraction of *types.{Pointer,Slice,Array,Chan,Map}
+	type hasElem interface {
+		Elem() types.Type
+	}
+	// abstraction of *types.{Interface,Named}
+	type hasMethods interface {
+		Method(int) *types.Func
+		NumMethods() int
+	}
+
+	// The loop state is the pair (t, obj),
+	// exactly one of which is non-nil, initially obj.
+	// All suffixes start with '.' (the only object->type operation),
+	// followed by optional type->type operations,
+	// then a type->object operation.
+	// The cycle then repeats.
+	var t types.Type
+	for suffix != "" {
+		code := suffix[0]
+		suffix = suffix[1:]
+
+		// Codes [AFM] have an integer operand.
+		var index int
+		switch code {
+		case opAt, opField, opMethod:
+			rest := strings.TrimLeft(suffix, "0123456789")
+			numerals := suffix[:len(suffix)-len(rest)]
+			suffix = rest
+			i, err := strconv.Atoi(numerals)
+			if err != nil {
+				return nil, fmt.Errorf("invalid path: bad numeric operand %q for code %q", numerals, code)
+			}
+			index = int(i)
+		case opObj:
+			// no operand
+		default:
+			// The suffix must end with a type->object operation.
+			if suffix == "" {
+				return nil, fmt.Errorf("invalid path: ends with %q, want [AFMO]", code)
+			}
+		}
+
+		if code == opType {
+			if t != nil {
+				return nil, fmt.Errorf("invalid path: unexpected %q in type context", opType)
+			}
+			t = obj.Type()
+			obj = nil
+			continue
+		}
+
+		if t == nil {
+			return nil, fmt.Errorf("invalid path: code %q in object context", code)
+		}
+
+		// Inv: t != nil, obj == nil
+
+		switch code {
+		case opElem:
+			hasElem, ok := t.(hasElem) // Pointer, Slice, Array, Chan, Map
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want pointer, slice, array, chan or map)", code, t, t)
+			}
+			t = hasElem.Elem()
+
+		case opKey:
+			mapType, ok := t.(*types.Map)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want map)", code, t, t)
+			}
+			t = mapType.Key()
+
+		case opParams:
+			sig, ok := t.(*types.Signature)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
+			}
+			t = sig.Params()
+
+		case opResults:
+			sig, ok := t.(*types.Signature)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
+			}
+			t = sig.Results()
+
+		case opUnderlying:
+			named, ok := t.(*types.Named)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %s, want named)", code, t, t)
+			}
+			t = named.Underlying()
+
+		case opAt:
+			tuple, ok := t.(*types.Tuple)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %s, want tuple)", code, t, t)
+			}
+			if n := tuple.Len(); index >= n {
+				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
+			}
+			obj = tuple.At(index)
+			t = nil
+
+		case opField:
+			structType, ok := t.(*types.Struct)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want struct)", code, t, t)
+			}
+			if n := structType.NumFields(); index >= n {
+				return nil, fmt.Errorf("field index %d out of range [0-%d)", index, n)
+			}
+			obj = structType.Field(index)
+			t = nil
+
+		case opMethod:
+			hasMethods, ok := t.(hasMethods) // Interface or Named
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %s, want interface or named)", code, t, t)
+			}
+			if n := hasMethods.NumMethods(); index >= n {
+				return nil, fmt.Errorf("method index %d out of range [0-%d)", index, n)
+			}
+			obj = hasMethods.Method(index)
+			t = nil
+
+		case opObj:
+			named, ok := t.(*types.Named)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %s, want named)", code, t, t)
+			}
+			obj = named.Obj()
+			t = nil
+
+		default:
+			return nil, fmt.Errorf("invalid path: unknown code %q", code)
+		}
+	}
+
+	if obj.Pkg() != pkg {
+		return nil, fmt.Errorf("path denotes %s, which belongs to a different package", obj)
+	}
+
+	return obj, nil // success
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/typeutil/callee.go b/libgo/go/golang.org/x/tools/go/types/typeutil/callee.go
new file mode 100644
index 00000000000..38f596daf9e
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/typeutil/callee.go
@@ -0,0 +1,46 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+import (
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// Callee returns the named target of a function call, if any:
+// a function, method, builtin, or variable.
+func Callee(info *types.Info, call *ast.CallExpr) types.Object {
+	var obj types.Object
+	switch fun := astutil.Unparen(call.Fun).(type) {
+	case *ast.Ident:
+		obj = info.Uses[fun] // type, var, builtin, or declared func
+	case *ast.SelectorExpr:
+		if sel, ok := info.Selections[fun]; ok {
+			obj = sel.Obj() // method or field
+		} else {
+			obj = info.Uses[fun.Sel] // qualified identifier?
+		}
+	}
+	if _, ok := obj.(*types.TypeName); ok {
+		return nil // T(x) is a conversion, not a call
+	}
+	return obj
+}
+
+// StaticCallee returns the target (function or method) of a static
+// function call, if any. It returns nil for calls to builtins.
+func StaticCallee(info *types.Info, call *ast.CallExpr) *types.Func {
+	if f, ok := Callee(info, call).(*types.Func); ok && !interfaceMethod(f) {
+		return f
+	}
+	return nil
+}
+
+func interfaceMethod(f *types.Func) bool {
+	recv := f.Type().(*types.Signature).Recv()
+	return recv != nil && types.IsInterface(recv.Type())
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/typeutil/imports.go b/libgo/go/golang.org/x/tools/go/types/typeutil/imports.go
new file mode 100644
index 00000000000..9c441dba9c0
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/typeutil/imports.go
@@ -0,0 +1,31 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+import "go/types"
+
+// Dependencies returns all dependencies of the specified packages.
+//
+// Dependent packages appear in topological order: if package P imports
+// package Q, Q appears earlier than P in the result.
+// The algorithm follows import statements in the order they
+// appear in the source code, so the result is a total order.
+//
+func Dependencies(pkgs ...*types.Package) []*types.Package {
+	var result []*types.Package
+	seen := make(map[*types.Package]bool)
+	var visit func(pkgs []*types.Package)
+	visit = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !seen[p] {
+				seen[p] = true
+				visit(p.Imports())
+				result = append(result, p)
+			}
+		}
+	}
+	visit(pkgs)
+	return result
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/typeutil/map.go b/libgo/go/golang.org/x/tools/go/types/typeutil/map.go
new file mode 100644
index 00000000000..c7f75450064
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/typeutil/map.go
@@ -0,0 +1,313 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package typeutil defines various utilities for types, such as Map,
+// a mapping from types.Type to interface{} values.
+package typeutil // import "golang.org/x/tools/go/types/typeutil"
+
+import (
+	"bytes"
+	"fmt"
+	"go/types"
+	"reflect"
+)
+
+// Map is a hash-table-based mapping from types (types.Type) to
+// arbitrary interface{} values.  The concrete types that implement
+// the Type interface are pointers.  Since they are not canonicalized,
+// == cannot be used to check for equivalence, and thus we cannot
+// simply use a Go map.
+//
+// Just as with map[K]V, a nil *Map is a valid empty map.
+//
+// Not thread-safe.
+//
+type Map struct {
+	hasher Hasher             // shared by many Maps
+	table  map[uint32][]entry // maps hash to bucket; entry.key==nil means unused
+	length int                // number of map entries
+}
+
+// entry is an entry (key/value association) in a hash bucket.
+type entry struct {
+	key   types.Type
+	value interface{}
+}
+
+// SetHasher sets the hasher used by Map.
+//
+// All Hashers are functionally equivalent but contain internal state
+// used to cache the results of hashing previously seen types.
+//
+// A single Hasher created by MakeHasher() may be shared among many
+// Maps.  This is recommended if the instances have many keys in
+// common, as it will amortize the cost of hash computation.
+//
+// A Hasher may grow without bound as new types are seen.  Even when a
+// type is deleted from the map, the Hasher never shrinks, since other
+// types in the map may reference the deleted type indirectly.
+//
+// Hashers are not thread-safe, and read-only operations such as
+// Map.Lookup require updates to the hasher, so a full Mutex lock (not a
+// read-lock) is require around all Map operations if a shared
+// hasher is accessed from multiple threads.
+//
+// If SetHasher is not called, the Map will create a private hasher at
+// the first call to Insert.
+//
+func (m *Map) SetHasher(hasher Hasher) {
+	m.hasher = hasher
+}
+
+// Delete removes the entry with the given key, if any.
+// It returns true if the entry was found.
+//
+func (m *Map) Delete(key types.Type) bool {
+	if m != nil && m.table != nil {
+		hash := m.hasher.Hash(key)
+		bucket := m.table[hash]
+		for i, e := range bucket {
+			if e.key != nil && types.Identical(key, e.key) {
+				// We can't compact the bucket as it
+				// would disturb iterators.
+				bucket[i] = entry{}
+				m.length--
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// At returns the map entry for the given key.
+// The result is nil if the entry is not present.
+//
+func (m *Map) At(key types.Type) interface{} {
+	if m != nil && m.table != nil {
+		for _, e := range m.table[m.hasher.Hash(key)] {
+			if e.key != nil && types.Identical(key, e.key) {
+				return e.value
+			}
+		}
+	}
+	return nil
+}
+
+// Set sets the map entry for key to val,
+// and returns the previous entry, if any.
+func (m *Map) Set(key types.Type, value interface{}) (prev interface{}) {
+	if m.table != nil {
+		hash := m.hasher.Hash(key)
+		bucket := m.table[hash]
+		var hole *entry
+		for i, e := range bucket {
+			if e.key == nil {
+				hole = &bucket[i]
+			} else if types.Identical(key, e.key) {
+				prev = e.value
+				bucket[i].value = value
+				return
+			}
+		}
+
+		if hole != nil {
+			*hole = entry{key, value} // overwrite deleted entry
+		} else {
+			m.table[hash] = append(bucket, entry{key, value})
+		}
+	} else {
+		if m.hasher.memo == nil {
+			m.hasher = MakeHasher()
+		}
+		hash := m.hasher.Hash(key)
+		m.table = map[uint32][]entry{hash: {entry{key, value}}}
+	}
+
+	m.length++
+	return
+}
+
+// Len returns the number of map entries.
+func (m *Map) Len() int {
+	if m != nil {
+		return m.length
+	}
+	return 0
+}
+
+// Iterate calls function f on each entry in the map in unspecified order.
+//
+// If f should mutate the map, Iterate provides the same guarantees as
+// Go maps: if f deletes a map entry that Iterate has not yet reached,
+// f will not be invoked for it, but if f inserts a map entry that
+// Iterate has not yet reached, whether or not f will be invoked for
+// it is unspecified.
+//
+func (m *Map) Iterate(f func(key types.Type, value interface{})) {
+	if m != nil {
+		for _, bucket := range m.table {
+			for _, e := range bucket {
+				if e.key != nil {
+					f(e.key, e.value)
+				}
+			}
+		}
+	}
+}
+
+// Keys returns a new slice containing the set of map keys.
+// The order is unspecified.
+func (m *Map) Keys() []types.Type {
+	keys := make([]types.Type, 0, m.Len())
+	m.Iterate(func(key types.Type, _ interface{}) {
+		keys = append(keys, key)
+	})
+	return keys
+}
+
+func (m *Map) toString(values bool) string {
+	if m == nil {
+		return "{}"
+	}
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, "{")
+	sep := ""
+	m.Iterate(func(key types.Type, value interface{}) {
+		fmt.Fprint(&buf, sep)
+		sep = ", "
+		fmt.Fprint(&buf, key)
+		if values {
+			fmt.Fprintf(&buf, ": %q", value)
+		}
+	})
+	fmt.Fprint(&buf, "}")
+	return buf.String()
+}
+
+// String returns a string representation of the map's entries.
+// Values are printed using fmt.Sprintf("%v", v).
+// Order is unspecified.
+//
+func (m *Map) String() string {
+	return m.toString(true)
+}
+
+// KeysString returns a string representation of the map's key set.
+// Order is unspecified.
+//
+func (m *Map) KeysString() string {
+	return m.toString(false)
+}
+
+////////////////////////////////////////////////////////////////////////
+// Hasher
+
+// A Hasher maps each type to its hash value.
+// For efficiency, a hasher uses memoization; thus its memory
+// footprint grows monotonically over time.
+// Hashers are not thread-safe.
+// Hashers have reference semantics.
+// Call MakeHasher to create a Hasher.
+type Hasher struct {
+	memo map[types.Type]uint32
+}
+
+// MakeHasher returns a new Hasher instance.
+func MakeHasher() Hasher {
+	return Hasher{make(map[types.Type]uint32)}
+}
+
+// Hash computes a hash value for the given type t such that
+// Identical(t, t') => Hash(t) == Hash(t').
+func (h Hasher) Hash(t types.Type) uint32 {
+	hash, ok := h.memo[t]
+	if !ok {
+		hash = h.hashFor(t)
+		h.memo[t] = hash
+	}
+	return hash
+}
+
+// hashString computes the Fowler–Noll–Vo hash of s.
+func hashString(s string) uint32 {
+	var h uint32
+	for i := 0; i < len(s); i++ {
+		h ^= uint32(s[i])
+		h *= 16777619
+	}
+	return h
+}
+
+// hashFor computes the hash of t.
+func (h Hasher) hashFor(t types.Type) uint32 {
+	// See Identical for rationale.
+	switch t := t.(type) {
+	case *types.Basic:
+		return uint32(t.Kind())
+
+	case *types.Array:
+		return 9043 + 2*uint32(t.Len()) + 3*h.Hash(t.Elem())
+
+	case *types.Slice:
+		return 9049 + 2*h.Hash(t.Elem())
+
+	case *types.Struct:
+		var hash uint32 = 9059
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			f := t.Field(i)
+			if f.Anonymous() {
+				hash += 8861
+			}
+			hash += hashString(t.Tag(i))
+			hash += hashString(f.Name()) // (ignore f.Pkg)
+			hash += h.Hash(f.Type())
+		}
+		return hash
+
+	case *types.Pointer:
+		return 9067 + 2*h.Hash(t.Elem())
+
+	case *types.Signature:
+		var hash uint32 = 9091
+		if t.Variadic() {
+			hash *= 8863
+		}
+		return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results())
+
+	case *types.Interface:
+		var hash uint32 = 9103
+		for i, n := 0, t.NumMethods(); i < n; i++ {
+			// See go/types.identicalMethods for rationale.
+			// Method order is not significant.
+			// Ignore m.Pkg().
+			m := t.Method(i)
+			hash += 3*hashString(m.Name()) + 5*h.Hash(m.Type())
+		}
+		return hash
+
+	case *types.Map:
+		return 9109 + 2*h.Hash(t.Key()) + 3*h.Hash(t.Elem())
+
+	case *types.Chan:
+		return 9127 + 2*uint32(t.Dir()) + 3*h.Hash(t.Elem())
+
+	case *types.Named:
+		// Not safe with a copying GC; objects may move.
+		return uint32(reflect.ValueOf(t.Obj()).Pointer())
+
+	case *types.Tuple:
+		return h.hashTuple(t)
+	}
+	panic(t)
+}
+
+func (h Hasher) hashTuple(tuple *types.Tuple) uint32 {
+	// See go/types.identicalTypes for rationale.
+	n := tuple.Len()
+	var hash uint32 = 9137 + 2*uint32(n)
+	for i := 0; i < n; i++ {
+		hash += 3 * h.Hash(tuple.At(i).Type())
+	}
+	return hash
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/typeutil/methodsetcache.go b/libgo/go/golang.org/x/tools/go/types/typeutil/methodsetcache.go
new file mode 100644
index 00000000000..32084610f49
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/typeutil/methodsetcache.go
@@ -0,0 +1,72 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements a cache of method sets.
+
+package typeutil
+
+import (
+	"go/types"
+	"sync"
+)
+
+// A MethodSetCache records the method set of each type T for which
+// MethodSet(T) is called so that repeat queries are fast.
+// The zero value is a ready-to-use cache instance.
+type MethodSetCache struct {
+	mu     sync.Mutex
+	named  map[*types.Named]struct{ value, pointer *types.MethodSet } // method sets for named N and *N
+	others map[types.Type]*types.MethodSet                            // all other types
+}
+
+// MethodSet returns the method set of type T.  It is thread-safe.
+//
+// If cache is nil, this function is equivalent to types.NewMethodSet(T).
+// Utility functions can thus expose an optional *MethodSetCache
+// parameter to clients that care about performance.
+//
+func (cache *MethodSetCache) MethodSet(T types.Type) *types.MethodSet {
+	if cache == nil {
+		return types.NewMethodSet(T)
+	}
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	switch T := T.(type) {
+	case *types.Named:
+		return cache.lookupNamed(T).value
+
+	case *types.Pointer:
+		if N, ok := T.Elem().(*types.Named); ok {
+			return cache.lookupNamed(N).pointer
+		}
+	}
+
+	// all other types
+	// (The map uses pointer equivalence, not type identity.)
+	mset := cache.others[T]
+	if mset == nil {
+		mset = types.NewMethodSet(T)
+		if cache.others == nil {
+			cache.others = make(map[types.Type]*types.MethodSet)
+		}
+		cache.others[T] = mset
+	}
+	return mset
+}
+
+func (cache *MethodSetCache) lookupNamed(named *types.Named) struct{ value, pointer *types.MethodSet } {
+	if cache.named == nil {
+		cache.named = make(map[*types.Named]struct{ value, pointer *types.MethodSet })
+	}
+	// Avoid recomputing mset(*T) for each distinct Pointer
+	// instance whose underlying type is a named type.
+	msets, ok := cache.named[named]
+	if !ok {
+		msets.value = types.NewMethodSet(named)
+		msets.pointer = types.NewMethodSet(types.NewPointer(named))
+		cache.named[named] = msets
+	}
+	return msets
+}
diff --git a/libgo/go/golang.org/x/tools/go/types/typeutil/ui.go b/libgo/go/golang.org/x/tools/go/types/typeutil/ui.go
new file mode 100644
index 00000000000..9849c24cef3
--- /dev/null
+++ b/libgo/go/golang.org/x/tools/go/types/typeutil/ui.go
@@ -0,0 +1,52 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+// This file defines utilities for user interfaces that display types.
+
+import "go/types"
+
+// IntuitiveMethodSet returns the intuitive method set of a type T,
+// which is the set of methods you can call on an addressable value of
+// that type.
+//
+// The result always contains MethodSet(T), and is exactly MethodSet(T)
+// for interface types and for pointer-to-concrete types.
+// For all other concrete types T, the result additionally
+// contains each method belonging to *T if there is no identically
+// named method on T itself.
+//
+// This corresponds to user intuition about method sets;
+// this function is intended only for user interfaces.
+//
+// The order of the result is as for types.MethodSet(T).
+//
+func IntuitiveMethodSet(T types.Type, msets *MethodSetCache) []*types.Selection {
+	isPointerToConcrete := func(T types.Type) bool {
+		ptr, ok := T.(*types.Pointer)
+		return ok && !types.IsInterface(ptr.Elem())
+	}
+
+	var result []*types.Selection
+	mset := msets.MethodSet(T)
+	if types.IsInterface(T) || isPointerToConcrete(T) {
+		for i, n := 0, mset.Len(); i < n; i++ {
+			result = append(result, mset.At(i))
+		}
+	} else {
+		// T is some other concrete type.
+		// Report methods of T and *T, preferring those of T.
+		pmset := msets.MethodSet(types.NewPointer(T))
+		for i, n := 0, pmset.Len(); i < n; i++ {
+			meth := pmset.At(i)
+			if m := mset.Lookup(meth.Obj().Pkg(), meth.Obj().Name()); m != nil {
+				meth = m
+			}
+			result = append(result, meth)
+		}
+
+	}
+	return result
+}