libgo: update to Go 1.15.3 release

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/265717

7 files changed, 54 insertions, 21 deletions

diff --git a/libgo/go/cmd/cgo/gcc.go b/libgo/go/cmd/cgo/gcc.go
index f774cbb9353..37bafcf189e 100644
--- a/libgo/go/cmd/cgo/gcc.go
+++ b/libgo/go/cmd/cgo/gcc.go
@@ -2459,6 +2459,18 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 			tt := *t
 			tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}
 			tt.Go = c.Ident("struct{}")
+			if dt.Kind == "struct" {
+				// We don't know what the representation of this struct is, so don't let
+				// anyone allocate one on the Go side. As a side effect of this annotation,
+				// pointers to this type will not be considered pointers in Go. They won't
+				// get writebarrier-ed or adjusted during a stack copy. This should handle
+				// all the cases badPointerTypedef used to handle, but hopefully will
+				// continue to work going forward without any more need for cgo changes.
+				tt.NotInHeap = true
+				// TODO: we should probably do the same for unions. Unions can't live
+				// on the Go heap, right? It currently doesn't work for unions because
+				// they are defined as a type alias for struct{}, not a defined type.
+			}
 			typedef[name.Name] = &tt
 			break
 		}
@@ -2529,6 +2541,7 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 		}
 		t.Go = name
 		t.BadPointer = sub.BadPointer
+		t.NotInHeap = sub.NotInHeap
 		if unionWithPointer[sub.Go] {
 			unionWithPointer[t.Go] = true
 		}
@@ -2539,6 +2552,7 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
 			tt := *t
 			tt.Go = sub.Go
 			tt.BadPointer = sub.BadPointer
+			tt.NotInHeap = sub.NotInHeap
 			typedef[name.Name] = &tt
 		}
 
@@ -3047,6 +3061,7 @@ func (c *typeConv) anonymousStructTypedef(dt *dwarf.TypedefType) bool {
 // non-pointers in this type.
 // TODO: Currently our best solution is to find these manually and list them as
 // they come up. A better solution is desired.
+// Note: DEPRECATED. There is now a better solution. Search for NotInHeap in this file.
 func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
 	if c.badCFType(dt) {
 		return true
diff --git a/libgo/go/cmd/cgo/main.go b/libgo/go/cmd/cgo/main.go
index 6de6d69ce6c..7fc2508021b 100644
--- a/libgo/go/cmd/cgo/main.go
+++ b/libgo/go/cmd/cgo/main.go
@@ -151,7 +151,8 @@ type Type struct {
 	Go         ast.Expr
 	EnumValues map[string]int64
 	Typedef    string
-	BadPointer bool
+	BadPointer bool // this pointer type should be represented as a uintptr (deprecated)
+	NotInHeap  bool // this type should have a go:notinheap annotation
 }
 
 // A FuncType collects information about a function type in both the C and Go worlds.
diff --git a/libgo/go/cmd/cgo/out.go b/libgo/go/cmd/cgo/out.go
index 1d23fc1d255..dd03f7d67a5 100644
--- a/libgo/go/cmd/cgo/out.go
+++ b/libgo/go/cmd/cgo/out.go
@@ -113,6 +113,9 @@ func (p *Package) writeDefs() {
 	sort.Strings(typedefNames)
 	for _, name := range typedefNames {
 		def := typedef[name]
+		if def.NotInHeap {
+			fmt.Fprintf(fgo2, "//go:notinheap\n")
+		}
 		fmt.Fprintf(fgo2, "type %s ", name)
 		// We don't have source info for these types, so write them out without source info.
 		// Otherwise types would look like:
diff --git a/libgo/go/cmd/go/internal/base/goflags.go b/libgo/go/cmd/go/internal/base/goflags.go
index 34766134b09..f29cc3cf9a5 100644
--- a/libgo/go/cmd/go/internal/base/goflags.go
+++ b/libgo/go/cmd/go/internal/base/goflags.go
@@ -153,3 +153,20 @@ func SetFromGOFLAGS(flags *flag.FlagSet) {
 		}
 	}
 }
+
+// InGOFLAGS returns whether GOFLAGS contains the given flag, such as "-mod".
+func InGOFLAGS(flag string) bool {
+	for _, goflag := range GOFLAGS() {
+		name := goflag
+		if strings.HasPrefix(name, "--") {
+			name = name[1:]
+		}
+		if i := strings.Index(name, "="); i >= 0 {
+			name = name[:i]
+		}
+		if name == flag {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/cmd/go/internal/version/version.go b/libgo/go/cmd/go/internal/version/version.go
index ac2ae501552..a5b13653cd6 100644
--- a/libgo/go/cmd/go/internal/version/version.go
+++ b/libgo/go/cmd/go/internal/version/version.go
@@ -53,7 +53,14 @@ var (
 
 func runVersion(cmd *base.Command, args []string) {
 	if len(args) == 0 {
-		if *versionM || *versionV {
+		// If any of this command's flags were passed explicitly, error
+		// out, because they only make sense with arguments.
+		//
+		// Don't error if the flags came from GOFLAGS, since that can be
+		// a reasonable use case. For example, imagine GOFLAGS=-v to
+		// turn "verbose mode" on for all Go commands, which should not
+		// break "go version".
+		if (!base.InGOFLAGS("-m") && *versionM) || (!base.InGOFLAGS("-v") && *versionV) {
 			fmt.Fprintf(os.Stderr, "go version: flags can only be used with arguments\n")
 			base.SetExitStatus(2)
 			return
diff --git a/libgo/go/cmd/go/internal/work/init.go b/libgo/go/cmd/go/internal/work/init.go
index dad3b10111d..c168364cd17 100644
--- a/libgo/go/cmd/go/internal/work/init.go
+++ b/libgo/go/cmd/go/internal/work/init.go
@@ -254,34 +254,18 @@ func buildModeInit() {
 	case "":
 		// ok
 	case "readonly", "vendor", "mod":
-		if !cfg.ModulesEnabled && !inGOFLAGS("-mod") {
+		if !cfg.ModulesEnabled && !base.InGOFLAGS("-mod") {
 			base.Fatalf("build flag -mod=%s only valid when using modules", cfg.BuildMod)
 		}
 	default:
 		base.Fatalf("-mod=%s not supported (can be '', 'mod', 'readonly', or 'vendor')", cfg.BuildMod)
 	}
 	if !cfg.ModulesEnabled {
-		if cfg.ModCacheRW && !inGOFLAGS("-modcacherw") {
+		if cfg.ModCacheRW && !base.InGOFLAGS("-modcacherw") {
 			base.Fatalf("build flag -modcacherw only valid when using modules")
 		}
-		if cfg.ModFile != "" && !inGOFLAGS("-mod") {
+		if cfg.ModFile != "" && !base.InGOFLAGS("-mod") {
 			base.Fatalf("build flag -modfile only valid when using modules")
 		}
 	}
 }
-
-func inGOFLAGS(flag string) bool {
-	for _, goflag := range base.GOFLAGS() {
-		name := goflag
-		if strings.HasPrefix(name, "--") {
-			name = name[1:]
-		}
-		if i := strings.Index(name, "="); i >= 0 {
-			name = name[:i]
-		}
-		if name == flag {
-			return true
-		}
-	}
-	return false
-}
diff --git a/libgo/go/cmd/go/testdata/script/version.txt b/libgo/go/cmd/go/testdata/script/version.txt
index 0123ac6d53f..87cb6befe93 100644
--- a/libgo/go/cmd/go/testdata/script/version.txt
+++ b/libgo/go/cmd/go/testdata/script/version.txt
@@ -9,6 +9,12 @@ stderr 'with arguments'
 ! go version -v
 stderr 'with arguments'
 
+# Neither of the two flags above should be an issue via GOFLAGS.
+env GOFLAGS='-m -v'
+go version
+stdout '^go version'
+env GOFLAGS=
+
 env GO111MODULE=on
 # Skip the builds below if we are running in short mode.
 [short] skip