cmd/go: trim objdir, not just workdir, from object files

Otherwise the new numbered directories like b028/ appear in the objects,
and they can change from run to run.

Fixes #22514.

Change-Id: I8d0cf65f3622e48b2547d5757febe0ee1301e2ed
Reviewed-on: https://go-review.googlesource.com/74791
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/go/internal/work/gc.go

@@ -106,7 +106,7 @@ func (gcToolchain) gc(b *Builder, a *Action, archive string, importcfg []byte, a
 		}
 	}
 
-	args := []interface{}{cfg.BuildToolexec, base.Tool("compile"), "-o", ofile, "-trimpath", b.WorkDir, gcflags, gcargs, "-D", p.Internal.LocalPrefix}
+	args := []interface{}{cfg.BuildToolexec, base.Tool("compile"), "-o", ofile, "-trimpath", trimDir(a.Objdir), gcflags, gcargs, "-D", p.Internal.LocalPrefix}
 	if importcfg != nil {
 		if err := b.writeFile(objdir+"importcfg", importcfg); err != nil {
 			return "", nil, err
@@ -204,11 +204,18 @@ CheckFlags:
 	return c
 }
 
+func trimDir(dir string) string {
+	if len(dir) > 1 && dir[len(dir)-1] == filepath.Separator {
+		dir = dir[:len(dir)-1]
+	}
+	return dir
+}
+
 func (gcToolchain) asm(b *Builder, a *Action, sfiles []string) ([]string, error) {
 	p := a.Package
 	// Add -I pkg/GOOS_GOARCH so #include "textflag.h" works in .s files.
 	inc := filepath.Join(cfg.GOROOT, "pkg", "include")
-	args := []interface{}{cfg.BuildToolexec, base.Tool("asm"), "-trimpath", b.WorkDir, "-I", a.Objdir, "-I", inc, "-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch, buildAsmflags}
+	args := []interface{}{cfg.BuildToolexec, base.Tool("asm"), "-trimpath", trimDir(a.Objdir), "-I", a.Objdir, "-I", inc, "-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch, buildAsmflags}
 	if p.ImportPath == "runtime" && cfg.Goarch == "386" {
 		for _, arg := range buildAsmflags {
 			if arg == "-dynlink" {

src/runtime/race/output_test.go

@@ -263,7 +263,7 @@ Previous write at 0x[0-9,a-f]+ by goroutine [0-9]:
   main\.goCallback\(\)
       .*/main\.go:27 \+0x[0-9,a-f]+
   main._cgoexpwrap_[0-9a-z]+_goCallback\(\)
-      .*/_cgo_gotypes\.go:[0-9]+ \+0x[0-9,a-f]+
+      .*_cgo_gotypes\.go:[0-9]+ \+0x[0-9,a-f]+
 
 Goroutine [0-9] \(running\) created at:
   runtime\.newextram\(\)