re PR go/65462 (Use of 'go get' with gccgo is not finding dependencies correctly)

	PR go/65462
cmd: Fix dependencies for 'go get' with gccgo

Problem described in GCC BZ 65462.
Generate the list of the standard GO package names based on what was built into libgo in the libgo Makefile.
Change the var name from reqPkgSrc to reqStdPkgSrc to clarify it only affects standard GO packages.
Skip the attempted loading of a package only if it is a standard GO package and the flag is set indicating its source is not required to be available.
This requires a corresponding change to gotools to build and link in the new file containing the list of standard GO package names that was generated by the libgo Makefile.

gotools/:
	PR go/65462
	* Makefile.am (go_cmd_go_files): Add $(libgodir)/zstdpkglist.go.
	* Makefile.in: Rebuild.

From-SVN: r221643

3 files changed, 20 insertions, 14 deletions

diff --git a/libgo/go/cmd/go/build.go b/libgo/go/cmd/go/build.go
index 95b9804..22d37f3 100644
--- a/libgo/go/cmd/go/build.go
+++ b/libgo/go/cmd/go/build.go
@@ -132,7 +132,8 @@ var buildLdflags []string    // -ldflags flag
 var buildGccgoflags []string // -gccgoflags flag
 var buildRace bool           // -race flag
 
-var reqPkgSrc bool // req src for Imports
+// Require the source for go std packages
+var reqStdPkgSrc bool
 var buildContext = build.Default
 var buildToolchain toolchain = noToolchain{}
 
@@ -187,9 +188,9 @@ func addBuildFlags(cmd *Command) {
 	cmd.Flag.BoolVar(&buildRace, "race", false, "")
 	switch build.Default.Compiler {
 	case "gc":
-		reqPkgSrc = true
+		reqStdPkgSrc = true
 	case "gccgo":
-		reqPkgSrc = false
+		reqStdPkgSrc = false
 	}
 }
 
@@ -579,7 +580,7 @@ func (b *builder) action(mode buildMode, depMode buildMode, p *Package) *action
 	// are writing is not the cgo we need to use.
 
 	if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace {
-		if reqPkgSrc {
+		if reqStdPkgSrc {
 			if len(p.CgoFiles) > 0 || p.Standard && p.ImportPath == "runtime/cgo" {
 				var stk importStack
 				p1 := loadPackage("cmd/cgo", &stk)
diff --git a/libgo/go/cmd/go/pkg.go b/libgo/go/cmd/go/pkg.go
index 621cb4b..62f6b4a 100644
--- a/libgo/go/cmd/go/pkg.go
+++ b/libgo/go/cmd/go/pkg.go
@@ -112,7 +112,11 @@ func (p *Package) copyBuild(pp *build.Package) {
 	p.ConflictDir = pp.ConflictDir
 	// TODO? Target
 	p.Goroot = pp.Goroot
-	p.Standard = p.Goroot && p.ImportPath != "" && !strings.Contains(p.ImportPath, ".")
+	if buildContext.Compiler == "gccgo" {
+		p.Standard = stdpkg[p.ImportPath]
+	} else {
+		p.Standard = p.Goroot && p.ImportPath != "" && !strings.Contains(p.ImportPath, ".")
+	}
 	p.GoFiles = pp.GoFiles
 	p.CgoFiles = pp.CgoFiles
 	p.IgnoredGoFiles = pp.IgnoredGoFiles
@@ -582,7 +586,7 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 			continue
 		}
 		p1 := loadImport(path, p.Dir, stk, p.build.ImportPos[path])
-		if !reqPkgSrc && p1.Root == "" {
+		if !reqStdPkgSrc && p1.Standard {
 			continue
 		}
 		if p1.local {
diff --git a/libgo/go/cmd/go/test.go b/libgo/go/cmd/go/test.go
index 28b46ff..cc0a9ac 100644
--- a/libgo/go/cmd/go/test.go
+++ b/libgo/go/cmd/go/test.go
@@ -384,17 +384,18 @@ func runTest(cmd *Command, args []string) {
 		delete(deps, "unsafe")
 
 		all := []string{}
-		if reqPkgSrc {
-			for path := range deps {
-				if !build.IsLocalImport(path) {
-					all = append(all, path)
-				}
+		for path := range deps {
+			if !build.IsLocalImport(path) {
+				all = append(all, path)
 			}
 		}
 		sort.Strings(all)
 
 		a := &action{}
 		for _, p := range packagesForBuild(all) {
+			if !reqStdPkgSrc && p.Standard {
+				continue
+			}
 			a.deps = append(a.deps, b.action(modeInstall, modeInstall, p))
 		}
 		b.do(a)
@@ -563,7 +564,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 	stk.push(p.ImportPath + " (test)")
 	for _, path := range p.TestImports {
 		p1 := loadImport(path, p.Dir, &stk, p.build.TestImportPos[path])
-		if !reqPkgSrc && p1.Root == "" {
+		if !reqStdPkgSrc && p1.Standard {
 			continue
 		}
 		if p1.Error != nil {
@@ -591,7 +592,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 			continue
 		}
 		p1 := loadImport(path, p.Dir, &stk, p.build.XTestImportPos[path])
-		if !reqPkgSrc && p1.Root == "" {
+		if !reqStdPkgSrc && p1.Standard {
 			continue
 		}
 		if p1.Error != nil {
@@ -722,7 +723,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 			pmain.imports = append(pmain.imports, ptest)
 		} else {
 			p1 := loadImport(dep, "", &stk, nil)
-			if !reqPkgSrc && p1.Root == "" {
+			if !reqStdPkgSrc && p1.Standard {
 				continue
 			}
 			if p1.Error != nil {