cmd/go: stop treating GOROOT binaries specially

This was for cmd/cgo, and cmd/cgo isn't special anymore.

Change-Id: I71efaf553b24798b523c7102859428d36b470698
Reviewed-on: https://go-review.googlesource.com/68530
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/go/internal/cfg/cfg.go

@@ -131,7 +131,7 @@ func isGOROOT(path string) bool {
 
 // ExternalLinkingForced reports whether external linking is being
 // forced even for programs that do not use cgo.
-func ExternalLinkingForced(inGoroot bool) bool {
+func ExternalLinkingForced() bool {
 	// Some targets must use external linking even inside GOROOT.
 	switch BuildContext.GOOS {
 	case "android":
@@ -143,12 +143,6 @@ func ExternalLinkingForced(inGoroot bool) bool {
 		}
 	}
 
-	// Otherwise we disable forcing of external linking for GOROOT binaries.
-	// This is primarily for cgo, so we will be able to relax this soon.
-	if inGoroot {
-		return false
-	}
-
 	if !BuildContext.CgoEnabled {
 		return false
 	}

src/cmd/go/internal/load/pkg.go

@@ -1124,16 +1124,7 @@ func LinkerDeps(p *Package) []string {
 	var deps []string
 
 	// External linking mode forces an import of runtime/cgo.
-	// TODO(rsc): The GOROOT exception here is mainly to avoid a circular
-	// dependency when building cmd/cgo, which the build of
-	// runtime/cgo needs, but as of CL 68338 we now build
-	// cmd/cgo during cmd/dist, so that exception is no longer
-	// needed. At some point it may be worthwhile to remove the
-	// GOROOT exception here.
-	// Note that the condition here should also match the condition
-	// in ../work/build.go's gcToolchain.ld that controls disabling
-	// external linking during the link step.
-	if cfg.ExternalLinkingForced(p.Goroot) {
+	if cfg.ExternalLinkingForced() {
 		deps = append(deps, "runtime/cgo")
 	}
 	// On ARM with GOARM=5, it forces an import of math, for soft floating point.

src/cmd/go/internal/work/build.go

@@ -2541,20 +2541,6 @@ func (gcToolchain) ld(b *Builder, root *Action, out, importcfg string, allaction
 		ldflags = append(ldflags, "-buildid="+root.Package.Internal.BuildID)
 	}
 	ldflags = append(ldflags, cfg.BuildLdflags...)
-	if root.Package.Goroot {
-		// Cannot force -linkmode=external inside GOROOT.
-		// cmd/cgo cannot be linkmode=external,
-		// because that implies having runtime/cgo available,
-		// and runtime/cgo is built using cmd/cgo.
-		// It's possible the restriction can be limited to just cmd/cgo,
-		// but the whole-GOROOT prohibition matches the similar
-		// logic in ../load/pkg.go that decides whether to add an
-		// implicit runtime/cgo dependency.
-		// TODO(rsc): We may be able to remove this exception
-		// now that CL 68338 has made cmd/cgo not a special case.
-		// See the longer comment in ../load/pkg.go.
-		ldflags = removeLinkmodeExternal(ldflags)
-	}
 	ldflags = setextld(ldflags, compiler)
 
 	// On OS X when using external linking to build a shared library,
@@ -2572,27 +2558,6 @@ func (gcToolchain) ld(b *Builder, root *Action, out, importcfg string, allaction
 	return b.run(dir, root.Package.ImportPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags, mainpkg)
 }
 
-// removeLinkmodeExternal removes any attempt to set linkmode=external
-// from ldflags, modifies ldflags in place, and returns ldflags.
-func removeLinkmodeExternal(ldflags []string) []string {
-	out := ldflags[:0]
-	for i := 0; i < len(ldflags); i++ {
-		flag := ldflags[i]
-		if strings.HasPrefix(flag, "--") {
-			flag = flag[1:]
-		}
-		if flag == "-linkmode" && i+1 < len(ldflags) && ldflags[i+1] == "external" {
-			i++
-			continue
-		}
-		if flag == "-linkmode=external" {
-			continue
-		}
-		out = append(out, flag)
-	}
-	return out
-}
-
 func (gcToolchain) ldShared(b *Builder, toplevelactions []*Action, out, importcfg string, allactions []*Action) error {
 	ldflags := []string{"-installsuffix", cfg.BuildContext.InstallSuffix}
 	ldflags = append(ldflags, "-buildmode=shared")