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// Copyright 2021 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 noder
import (
"fmt"
"internal/types/errors"
"regexp"
"sort"
"cmd/compile/internal/base"
"cmd/compile/internal/syntax"
"cmd/compile/internal/types2"
"cmd/internal/src"
)
var versionErrorRx = regexp.MustCompile(`requires go[0-9]+\.[0-9]+ or later`)
// checkFiles configures and runs the types2 checker on the given
// parsed source files and then returns the result.
func checkFiles(m posMap, noders []*noder) (*types2.Package, *types2.Info) {
if base.SyntaxErrors() != 0 {
base.ErrorExit()
}
// setup and syntax error reporting
files := make([]*syntax.File, len(noders))
for i, p := range noders {
files[i] = p.file
}
// typechecking
ctxt := types2.NewContext()
importer := gcimports{
ctxt: ctxt,
packages: make(map[string]*types2.Package),
}
conf := types2.Config{
Context: ctxt,
GoVersion: base.Flag.Lang,
IgnoreBranchErrors: true, // parser already checked via syntax.CheckBranches mode
Error: func(err error) {
terr := err.(types2.Error)
msg := terr.Msg
// if we have a version error, hint at the -lang setting
if versionErrorRx.MatchString(msg) {
msg = fmt.Sprintf("%s (-lang was set to %s; check go.mod)", msg, base.Flag.Lang)
}
base.ErrorfAt(m.makeXPos(terr.Pos), terr.Code, "%s", msg)
},
Importer: &importer,
Sizes: &gcSizes{},
}
info := &types2.Info{
StoreTypesInSyntax: true,
Defs: make(map[*syntax.Name]types2.Object),
Uses: make(map[*syntax.Name]types2.Object),
Selections: make(map[*syntax.SelectorExpr]*types2.Selection),
Implicits: make(map[syntax.Node]types2.Object),
Scopes: make(map[syntax.Node]*types2.Scope),
Instances: make(map[*syntax.Name]types2.Instance),
// expand as needed
}
pkg, err := conf.Check(base.Ctxt.Pkgpath, files, info)
// Check for anonymous interface cycles (#56103).
if base.Debug.InterfaceCycles == 0 {
var f cycleFinder
for _, file := range files {
syntax.Inspect(file, func(n syntax.Node) bool {
if n, ok := n.(*syntax.InterfaceType); ok {
if f.hasCycle(n.GetTypeInfo().Type.(*types2.Interface)) {
base.ErrorfAt(m.makeXPos(n.Pos()), errors.InvalidTypeCycle, "invalid recursive type: anonymous interface refers to itself (see https://go.dev/issue/56103)")
for typ := range f.cyclic {
f.cyclic[typ] = false // suppress duplicate errors
}
}
return false
}
return true
})
}
}
// Implementation restriction: we don't allow not-in-heap types to
// be used as type arguments (#54765).
{
type nihTarg struct {
pos src.XPos
typ types2.Type
}
var nihTargs []nihTarg
for name, inst := range info.Instances {
for i := 0; i < inst.TypeArgs.Len(); i++ {
if targ := inst.TypeArgs.At(i); isNotInHeap(targ) {
nihTargs = append(nihTargs, nihTarg{m.makeXPos(name.Pos()), targ})
}
}
}
sort.Slice(nihTargs, func(i, j int) bool {
ti, tj := nihTargs[i], nihTargs[j]
return ti.pos.Before(tj.pos)
})
for _, targ := range nihTargs {
base.ErrorfAt(targ.pos, 0, "cannot use incomplete (or unallocatable) type as a type argument: %v", targ.typ)
}
}
base.ExitIfErrors()
if err != nil {
base.FatalfAt(src.NoXPos, "conf.Check error: %v", err)
}
return pkg, info
}
// A cycleFinder detects anonymous interface cycles (go.dev/issue/56103).
type cycleFinder struct {
cyclic map[*types2.Interface]bool
}
// hasCycle reports whether typ is part of an anonymous interface cycle.
func (f *cycleFinder) hasCycle(typ *types2.Interface) bool {
// We use Method instead of ExplicitMethod to implicitly expand any
// embedded interfaces. Then we just need to walk any anonymous
// types, keeping track of *types2.Interface types we visit along
// the way.
for i := 0; i < typ.NumMethods(); i++ {
if f.visit(typ.Method(i).Type()) {
return true
}
}
return false
}
// visit recursively walks typ0 to check any referenced interface types.
func (f *cycleFinder) visit(typ0 types2.Type) bool {
for { // loop for tail recursion
switch typ := typ0.(type) {
default:
base.Fatalf("unexpected type: %T", typ)
case *types2.Basic, *types2.Named, *types2.TypeParam:
return false // named types cannot be part of an anonymous cycle
case *types2.Pointer:
typ0 = typ.Elem()
case *types2.Array:
typ0 = typ.Elem()
case *types2.Chan:
typ0 = typ.Elem()
case *types2.Map:
if f.visit(typ.Key()) {
return true
}
typ0 = typ.Elem()
case *types2.Slice:
typ0 = typ.Elem()
case *types2.Struct:
for i := 0; i < typ.NumFields(); i++ {
if f.visit(typ.Field(i).Type()) {
return true
}
}
return false
case *types2.Interface:
// The empty interface (e.g., "any") cannot be part of a cycle.
if typ.NumExplicitMethods() == 0 && typ.NumEmbeddeds() == 0 {
return false
}
// As an optimization, we wait to allocate cyclic here, after
// we've found at least one other (non-empty) anonymous
// interface. This means when a cycle is present, we need to
// make an extra recursive call to actually detect it. But for
// most packages, it allows skipping the map allocation
// entirely.
if x, ok := f.cyclic[typ]; ok {
return x
}
if f.cyclic == nil {
f.cyclic = make(map[*types2.Interface]bool)
}
f.cyclic[typ] = true
if f.hasCycle(typ) {
return true
}
f.cyclic[typ] = false
return false
case *types2.Signature:
return f.visit(typ.Params()) || f.visit(typ.Results())
case *types2.Tuple:
for i := 0; i < typ.Len(); i++ {
if f.visit(typ.At(i).Type()) {
return true
}
}
return false
}
}
}
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