cmd/go: cache and replay command output during build

It's nice that

	go build -gcflags=-m errors
	go build -gcflags=-m errors

uses the cache for the second command.

Even nicer is to make the second command
print the same output as the first command.

Fixes #22587.

Change-Id: I64350839f01c86c9a095d9d22f6924cd7a0b9105
Reviewed-on: https://go-review.googlesource.com/77110
Reviewed-by: Ian Lance Taylor <iant@golang.org>

7 files changed, 143 insertions, 55 deletions

diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index fb69e5324c..fa3ca530d1 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -4803,6 +4803,32 @@ func TestBuildCache(t *testing.T) {
 	tg.grepStderr(`[\\/]link|gccgo`, "did not run linker")
 }
 
+func TestCacheOutput(t *testing.T) {
+	// Test that command output is cached and replayed too.
+	if strings.Contains(os.Getenv("GODEBUG"), "gocacheverify") {
+		t.Skip("GODEBUG gocacheverify")
+	}
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
+	tg.makeTempdir()
+	tg.setenv("GOCACHE", tg.tempdir)
+
+	tg.run("build", "-gcflags=-m", "errors")
+	stdout1 := tg.getStdout()
+	stderr1 := tg.getStderr()
+
+	tg.run("build", "-gcflags=-m", "errors")
+	stdout2 := tg.getStdout()
+	stderr2 := tg.getStderr()
+
+	if stdout2 != stdout1 || stderr2 != stderr1 {
+		t.Errorf("cache did not reproduce output:\n\nstdout1:\n%s\n\nstdout2:\n%s\n\nstderr1:\n%s\n\nstderr2:\n%s",
+			stdout1, stdout2, stderr1, stderr2)
+	}
+}
+
 func TestIssue22588(t *testing.T) {
 	// Don't get confused by stderr coming from tools.
 	tg := testgo(t)
diff --git a/src/cmd/go/internal/cache/hash.go b/src/cmd/go/internal/cache/hash.go
index 7f1dc4dd70..0e45e7db54 100644
--- a/src/cmd/go/internal/cache/hash.go
+++ b/src/cmd/go/internal/cache/hash.go
@@ -38,6 +38,26 @@ type Hash struct {
 // which are still addressed by unsalted SHA256.
 var hashSalt = []byte(runtime.Version())
 
+// Subkey returns an action ID corresponding to mixing a parent
+// action ID with a string description of the subkey.
+func Subkey(parent ActionID, desc string) ActionID {
+	h := sha256.New()
+	h.Write([]byte("subkey:"))
+	h.Write(parent[:])
+	h.Write([]byte(desc))
+	var out ActionID
+	h.Sum(out[:0])
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH subkey %x %q = %x\n", parent, desc, out)
+	}
+	if verify {
+		hashDebug.Lock()
+		hashDebug.m[out] = fmt.Sprintf("subkey %x %q", parent, desc)
+		hashDebug.Unlock()
+	}
+	return out
+}
+
 // NewHash returns a new Hash.
 // The caller is expected to Write data to it and then call Sum.
 func NewHash(name string) *Hash {
diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go
index 4a12858170..46ba3447c6 100644
--- a/src/cmd/go/internal/work/action.go
+++ b/src/cmd/go/internal/work/action.go
@@ -81,6 +81,7 @@ type Action struct {
 
 	needVet bool       // Mode=="build": need to fill in vet config
 	vetCfg  *vetConfig // vet config
+	output  []byte     // output redirect buffer (nil means use b.Print)
 
 	// Execution state.
 	pending  int  // number of deps yet to complete
diff --git a/src/cmd/go/internal/work/buildid.go b/src/cmd/go/internal/work/buildid.go
index caf6195abb..593eae3f7a 100644
--- a/src/cmd/go/internal/work/buildid.go
+++ b/src/cmd/go/internal/work/buildid.go
@@ -244,6 +244,10 @@ func (b *Builder) fileHash(file string) string {
 // and returns false. When useCache returns false the expectation is that
 // the caller will build the target and then call updateBuildID to finish the
 // build ID computation.
+// When useCache returns false, it may have initiated buffering of output
+// during a's work. The caller should defer b.flushOutput(a), to make sure
+// that flushOutput is eventually called regardless of whether the action
+// succeeds. The flushOutput call must happen after updateBuildID.
 func (b *Builder) useCache(a *Action, p *load.Package, actionHash cache.ActionID, target string) bool {
 	// The second half of the build ID here is a placeholder for the content hash.
 	// It's important that the overall buildID be unlikely verging on impossible
@@ -358,26 +362,47 @@ func (b *Builder) useCache(a *Action, p *load.Package, actionHash cache.ActionID
 	// We treat hits in this cache as being "stale" for the purposes of go list
 	// (in effect, "stale" means whether p.Target is up-to-date),
 	// but we're still happy to use results from the build artifact cache.
-	if !cfg.BuildA {
-		if c := cache.Default(); c != nil {
+	if c := cache.Default(); c != nil {
+		if !cfg.BuildA {
 			outputID, size, err := c.Get(actionHash)
 			if err == nil {
 				file := c.OutputFile(outputID)
 				info, err1 := os.Stat(file)
 				buildID, err2 := buildid.ReadFile(file)
 				if err1 == nil && err2 == nil && info.Size() == size {
-					a.built = file
-					a.Target = "DO NOT USE - using cache"
-					a.buildID = buildID
-					return true
+					stdout, err := c.GetBytes(cache.Subkey(a.actionID, "stdout"))
+					if err == nil {
+						if len(stdout) > 0 {
+							if cfg.BuildX || cfg.BuildN {
+								id, _, _ := c.Get(cache.Subkey(a.actionID, "stdout"))
+								b.Showcmd("", "%s  # internal", joinUnambiguously(str.StringList("cat", c.OutputFile(id))))
+							}
+							if !cfg.BuildN {
+								b.Print(string(stdout))
+							}
+						}
+						a.built = file
+						a.Target = "DO NOT USE - using cache"
+						a.buildID = buildID
+						return true
+					}
 				}
 			}
 		}
+
+		// Begin saving output for later writing to cache.
+		a.output = []byte{}
 	}
 
 	return false
 }
 
+// flushOutput flushes the output being queued in a.
+func (b *Builder) flushOutput(a *Action) {
+	b.Print(string(a.output))
+	a.output = nil
+}
+
 // updateBuildID updates the build ID in the target written by action a.
 // It requires that useCache was called for action a and returned false,
 // and that the build was then carried out and given the temporary
@@ -447,7 +472,11 @@ func (b *Builder) updateBuildID(a *Action, target string, rewrite bool) error {
 	if c := cache.Default(); c != nil && a.Mode == "build" {
 		r, err := os.Open(target)
 		if err == nil {
+			if a.output == nil {
+				panic("internal error: a.output not set")
+			}
 			c.Put(a.actionID, r)
+			c.PutBytes(cache.Subkey(a.actionID, "stdout"), a.output)
 			r.Close()
 		}
 	}
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 1323394a35..44f4a91ca5 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -295,6 +295,7 @@ func (b *Builder) build(a *Action) (err error) {
 			}
 			cached = true
 		}
+		defer b.flushOutput(a)
 	}
 
 	defer func() {
@@ -364,7 +365,7 @@ func (b *Builder) build(a *Action) (err error) {
 	// Each run will generate two files, a .go file and a .c or .cxx file.
 	// The .go file will use import "C" and is to be processed by cgo.
 	if a.Package.UsesSwig() {
-		outGo, outC, outCXX, err := b.swig(a.Package, objdir, pcCFLAGS)
+		outGo, outC, outCXX, err := b.swig(a, a.Package, objdir, pcCFLAGS)
 		if err != nil {
 			return err
 		}
@@ -544,7 +545,7 @@ func (b *Builder) build(a *Action) (err error) {
 	objpkg := objdir + "_pkg_.a"
 	ofile, out, err := BuildToolchain.gc(b, a, objpkg, icfg.Bytes(), len(sfiles) > 0, gofiles)
 	if len(out) > 0 {
-		b.showOutput(a.Package.Dir, a.Package.ImportPath, b.processOutput(out))
+		b.showOutput(a, a.Package.Dir, a.Package.ImportPath, b.processOutput(out))
 		if err != nil {
 			return errPrintedOutput
 		}
@@ -671,7 +672,7 @@ func (b *Builder) vet(a *Action) error {
 	}
 
 	p := a.Package
-	return b.run(p.Dir, p.ImportPath, nil, cfg.BuildToolexec, base.Tool("vet"), VetFlags, a.Objdir+"vet.cfg")
+	return b.run(a, p.Dir, p.ImportPath, nil, cfg.BuildToolexec, base.Tool("vet"), VetFlags, a.Objdir+"vet.cfg")
 }
 
 // linkActionID computes the action ID for a link action.
@@ -759,6 +760,7 @@ func (b *Builder) link(a *Action) (err error) {
 	if b.useCache(a, a.Package, b.linkActionID(a), a.Package.Target) {
 		return nil
 	}
+	defer b.flushOutput(a)
 
 	if err := b.Mkdir(a.Objdir); err != nil {
 		return err
@@ -866,7 +868,7 @@ func (b *Builder) getPkgConfigFlags(p *load.Package) (cflags, ldflags []string,
 		var out []byte
 		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.PkgconfigCmd(), "--cflags", pkgs)
 		if err != nil {
-			b.showOutput(p.Dir, b.PkgconfigCmd()+" --cflags "+strings.Join(pkgs, " "), string(out))
+			b.showOutput(nil, p.Dir, b.PkgconfigCmd()+" --cflags "+strings.Join(pkgs, " "), string(out))
 			b.Print(err.Error() + "\n")
 			err = errPrintedOutput
 			return
@@ -876,7 +878,7 @@ func (b *Builder) getPkgConfigFlags(p *load.Package) (cflags, ldflags []string,
 		}
 		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.PkgconfigCmd(), "--libs", pkgs)
 		if err != nil {
-			b.showOutput(p.Dir, b.PkgconfigCmd()+" --libs "+strings.Join(pkgs, " "), string(out))
+			b.showOutput(nil, p.Dir, b.PkgconfigCmd()+" --libs "+strings.Join(pkgs, " "), string(out))
 			b.Print(err.Error() + "\n")
 			err = errPrintedOutput
 			return
@@ -937,6 +939,7 @@ func (b *Builder) linkShared(a *Action) (err error) {
 	if b.useCache(a, nil, b.linkSharedActionID(a), a.Target) {
 		return nil
 	}
+	defer b.flushOutput(a)
 
 	if err := b.Mkdir(a.Objdir); err != nil {
 		return err
@@ -1197,7 +1200,7 @@ func (b *Builder) installHeader(a *Action) error {
 // cover runs, in effect,
 //	go tool cover -mode=b.coverMode -var="varName" -o dst.go src.go
 func (b *Builder) cover(a *Action, dst, src string, perm os.FileMode, varName string) error {
-	return b.run(a.Objdir, "cover "+a.Package.ImportPath, nil,
+	return b.run(a, a.Objdir, "cover "+a.Package.ImportPath, nil,
 		cfg.BuildToolexec,
 		base.Tool("cover"),
 		"-mode", a.Package.Internal.CoverMode,
@@ -1302,7 +1305,10 @@ func (b *Builder) Showcmd(dir string, format string, args ...interface{}) {
 //
 // showOutput also replaces references to the work directory with $WORK.
 //
-func (b *Builder) showOutput(dir, desc, out string) {
+// If a is not nil and a.output is not nil, showOutput appends to that slice instead of
+// printing to b.Print.
+//
+func (b *Builder) showOutput(a *Action, dir, desc, out string) {
 	prefix := "# " + desc
 	suffix := "\n" + out
 	if reldir := base.ShortPath(dir); reldir != dir {
@@ -1311,6 +1317,12 @@ func (b *Builder) showOutput(dir, desc, out string) {
 	}
 	suffix = strings.Replace(suffix, " "+b.WorkDir, " $WORK", -1)
 
+	if a != nil && a.output != nil {
+		a.output = append(a.output, prefix...)
+		a.output = append(a.output, suffix...)
+		return
+	}
+
 	b.output.Lock()
 	defer b.output.Unlock()
 	b.Print(prefix, suffix)
@@ -1329,13 +1341,13 @@ var cgoTypeSigRe = regexp.MustCompile(`\b_Ctype_\B`)
 // run runs the command given by cmdline in the directory dir.
 // If the command fails, run prints information about the failure
 // and returns a non-nil error.
-func (b *Builder) run(dir string, desc string, env []string, cmdargs ...interface{}) error {
+func (b *Builder) run(a *Action, dir string, desc string, env []string, cmdargs ...interface{}) error {
 	out, err := b.runOut(dir, desc, env, cmdargs...)
 	if len(out) > 0 {
 		if desc == "" {
 			desc = b.fmtcmd(dir, "%s", strings.Join(str.StringList(cmdargs...), " "))
 		}
-		b.showOutput(dir, desc, b.processOutput(out))
+		b.showOutput(a, dir, desc, b.processOutput(out))
 		if err != nil {
 			err = errPrintedOutput
 		}
@@ -1542,22 +1554,22 @@ func (noToolchain) cc(b *Builder, a *Action, ofile, cfile string) error {
 }
 
 // gcc runs the gcc C compiler to create an object from a single C file.
-func (b *Builder) gcc(p *load.Package, workdir, out string, flags []string, cfile string) error {
-	return b.ccompile(p, out, flags, cfile, b.GccCmd(p.Dir, workdir))
+func (b *Builder) gcc(a *Action, p *load.Package, workdir, out string, flags []string, cfile string) error {
+	return b.ccompile(a, p, out, flags, cfile, b.GccCmd(p.Dir, workdir))
 }
 
 // gxx runs the g++ C++ compiler to create an object from a single C++ file.
-func (b *Builder) gxx(p *load.Package, workdir, out string, flags []string, cxxfile string) error {
-	return b.ccompile(p, out, flags, cxxfile, b.GxxCmd(p.Dir, workdir))
+func (b *Builder) gxx(a *Action, p *load.Package, workdir, out string, flags []string, cxxfile string) error {
+	return b.ccompile(a, p, out, flags, cxxfile, b.GxxCmd(p.Dir, workdir))
 }
 
 // gfortran runs the gfortran Fortran compiler to create an object from a single Fortran file.
-func (b *Builder) gfortran(p *load.Package, workdir, out string, flags []string, ffile string) error {
-	return b.ccompile(p, out, flags, ffile, b.gfortranCmd(p.Dir, workdir))
+func (b *Builder) gfortran(a *Action, p *load.Package, workdir, out string, flags []string, ffile string) error {
+	return b.ccompile(a, p, out, flags, ffile, b.gfortranCmd(p.Dir, workdir))
 }
 
 // ccompile runs the given C or C++ compiler and creates an object from a single source file.
-func (b *Builder) ccompile(p *load.Package, outfile string, flags []string, file string, compiler []string) error {
+func (b *Builder) ccompile(a *Action, p *load.Package, outfile string, flags []string, file string, compiler []string) error {
 	file = mkAbs(p.Dir, file)
 	desc := p.ImportPath
 	if !filepath.IsAbs(outfile) {
@@ -1581,11 +1593,11 @@ func (b *Builder) ccompile(p *load.Package, outfile string, flags []string, file
 				}
 			}
 			if len(newFlags) < len(flags) {
-				return b.ccompile(p, outfile, newFlags, file, compiler)
+				return b.ccompile(a, p, outfile, newFlags, file, compiler)
 			}
 		}
 
-		b.showOutput(p.Dir, desc, b.processOutput(output))
+		b.showOutput(a, p.Dir, desc, b.processOutput(output))
 		if err != nil {
 			err = errPrintedOutput
 		} else if os.Getenv("GO_BUILDER_NAME") != "" {
@@ -1603,7 +1615,7 @@ func (b *Builder) gccld(p *load.Package, objdir, out string, flags []string, obj
 	} else {
 		cmd = b.GccCmd(p.Dir, objdir)
 	}
-	return b.run(p.Dir, p.ImportPath, nil, cmd, "-o", out, objs, flags)
+	return b.run(nil, p.Dir, p.ImportPath, nil, cmd, "-o", out, objs, flags)
 }
 
 // Grab these before main helpfully overwrites them.
@@ -1911,7 +1923,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 		cgoflags = append(cgoflags, "-exportheader="+objdir+"_cgo_install.h")
 	}
 
-	if err := b.run(p.Dir, p.ImportPath, cgoenv, cfg.BuildToolexec, cgoExe, srcdirarg, "-objdir", objdir, "-importpath", p.ImportPath, cgoflags, "--", cgoCPPFLAGS, cgoCFLAGS, cgofiles); err != nil {
+	if err := b.run(a, p.Dir, p.ImportPath, cgoenv, cfg.BuildToolexec, cgoExe, srcdirarg, "-objdir", objdir, "-importpath", p.ImportPath, cgoflags, "--", cgoCPPFLAGS, cgoCFLAGS, cgofiles); err != nil {
 		return nil, nil, err
 	}
 	outGo = append(outGo, gofiles...)
@@ -1932,7 +1944,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 	cflags := str.StringList(cgoCPPFLAGS, cgoCFLAGS)
 	for _, cfile := range cfiles {
 		ofile := nextOfile()
-		if err := b.gcc(p, a.Objdir, ofile, cflags, objdir+cfile); err != nil {
+		if err := b.gcc(a, p, a.Objdir, ofile, cflags, objdir+cfile); err != nil {
 			return nil, nil, err
 		}
 		outObj = append(outObj, ofile)
@@ -1940,7 +1952,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 
 	for _, file := range gccfiles {
 		ofile := nextOfile()
-		if err := b.gcc(p, a.Objdir, ofile, cflags, file); err != nil {
+		if err := b.gcc(a, p, a.Objdir, ofile, cflags, file); err != nil {
 			return nil, nil, err
 		}
 		outObj = append(outObj, ofile)
@@ -1949,7 +1961,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 	cxxflags := str.StringList(cgoCPPFLAGS, cgoCXXFLAGS)
 	for _, file := range gxxfiles {
 		ofile := nextOfile()
-		if err := b.gxx(p, a.Objdir, ofile, cxxflags, file); err != nil {
+		if err := b.gxx(a, p, a.Objdir, ofile, cxxflags, file); err != nil {
 			return nil, nil, err
 		}
 		outObj = append(outObj, ofile)
@@ -1957,7 +1969,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 
 	for _, file := range mfiles {
 		ofile := nextOfile()
-		if err := b.gcc(p, a.Objdir, ofile, cflags, file); err != nil {
+		if err := b.gcc(a, p, a.Objdir, ofile, cflags, file); err != nil {
 			return nil, nil, err
 		}
 		outObj = append(outObj, ofile)
@@ -1966,7 +1978,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 	fflags := str.StringList(cgoCPPFLAGS, cgoFFLAGS)
 	for _, file := range ffiles {
 		ofile := nextOfile()
-		if err := b.gfortran(p, a.Objdir, ofile, fflags, file); err != nil {
+		if err := b.gfortran(a, p, a.Objdir, ofile, fflags, file); err != nil {
 			return nil, nil, err
 		}
 		outObj = append(outObj, ofile)
@@ -1975,7 +1987,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 	switch cfg.BuildToolchainName {
 	case "gc":
 		importGo := objdir + "_cgo_import.go"
-		if err := b.dynimport(p, objdir, importGo, cgoExe, cflags, cgoLDFLAGS, outObj); err != nil {
+		if err := b.dynimport(a, p, objdir, importGo, cgoExe, cflags, cgoLDFLAGS, outObj); err != nil {
 			return nil, nil, err
 		}
 		outGo = append(outGo, importGo)
@@ -1998,10 +2010,10 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 // dynimport creates a Go source file named importGo containing
 // //go:cgo_import_dynamic directives for each symbol or library
 // dynamically imported by the object files outObj.
-func (b *Builder) dynimport(p *load.Package, objdir, importGo, cgoExe string, cflags, cgoLDFLAGS, outObj []string) error {
+func (b *Builder) dynimport(a *Action, p *load.Package, objdir, importGo, cgoExe string, cflags, cgoLDFLAGS, outObj []string) error {
 	cfile := objdir + "_cgo_main.c"
 	ofile := objdir + "_cgo_main.o"
-	if err := b.gcc(p, objdir, ofile, cflags, cfile); err != nil {
+	if err := b.gcc(a, p, objdir, ofile, cflags, cfile); err != nil {
 		return err
 	}
 
@@ -2022,13 +2034,13 @@ func (b *Builder) dynimport(p *load.Package, objdir, importGo, cgoExe string, cf
 	if p.Standard && p.ImportPath == "runtime/cgo" {
 		cgoflags = []string{"-dynlinker"} // record path to dynamic linker
 	}
-	return b.run(p.Dir, p.ImportPath, nil, cfg.BuildToolexec, cgoExe, "-dynpackage", p.Name, "-dynimport", dynobj, "-dynout", importGo, cgoflags)
+	return b.run(a, p.Dir, p.ImportPath, nil, cfg.BuildToolexec, cgoExe, "-dynpackage", p.Name, "-dynimport", dynobj, "-dynout", importGo, cgoflags)
 }
 
 // Run SWIG on all SWIG input files.
 // TODO: Don't build a shared library, once SWIG emits the necessary
 // pragmas for external linking.
-func (b *Builder) swig(p *load.Package, objdir string, pcCFLAGS []string) (outGo, outC, outCXX []string, err error) {
+func (b *Builder) swig(a *Action, p *load.Package, objdir string, pcCFLAGS []string) (outGo, outC, outCXX []string, err error) {
 	if err := b.swigVersionCheck(); err != nil {
 		return nil, nil, nil, err
 	}
@@ -2039,7 +2051,7 @@ func (b *Builder) swig(p *load.Package, objdir string, pcCFLAGS []string) (outGo
 	}
 
 	for _, f := range p.SwigFiles {
-		goFile, cFile, err := b.swigOne(p, f, objdir, pcCFLAGS, false, intgosize)
+		goFile, cFile, err := b.swigOne(a, p, f, objdir, pcCFLAGS, false, intgosize)
 		if err != nil {
 			return nil, nil, nil, err
 		}
@@ -2051,7 +2063,7 @@ func (b *Builder) swig(p *load.Package, objdir string, pcCFLAGS []string) (outGo
 		}
 	}
 	for _, f := range p.SwigCXXFiles {
-		goFile, cxxFile, err := b.swigOne(p, f, objdir, pcCFLAGS, true, intgosize)
+		goFile, cxxFile, err := b.swigOne(a, p, f, objdir, pcCFLAGS, true, intgosize)
 		if err != nil {
 			return nil, nil, nil, err
 		}
@@ -2174,7 +2186,7 @@ func (b *Builder) swigIntSize(objdir string) (intsize string, err error) {
 }
 
 // Run SWIG on one SWIG input file.
-func (b *Builder) swigOne(p *load.Package, file, objdir string, pcCFLAGS []string, cxx bool, intgosize string) (outGo, outC string, err error) {
+func (b *Builder) swigOne(a *Action, p *load.Package, file, objdir string, pcCFLAGS []string, cxx bool, intgosize string) (outGo, outC string, err error) {
 	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _, _ := b.CFlags(p)
 	var cflags []string
 	if cxx {
@@ -2229,13 +2241,13 @@ func (b *Builder) swigOne(p *load.Package, file, objdir string, pcCFLAGS []strin
 			if bytes.Contains(out, []byte("-intgosize")) || bytes.Contains(out, []byte("-cgo")) {
 				return "", "", errors.New("must have SWIG version >= 3.0.6")
 			}
-			b.showOutput(p.Dir, p.ImportPath, b.processOutput(out)) // swig error
+			b.showOutput(a, p.Dir, p.ImportPath, b.processOutput(out)) // swig error
 			return "", "", errPrintedOutput
 		}
 		return "", "", err
 	}
 	if len(out) > 0 {
-		b.showOutput(p.Dir, p.ImportPath, b.processOutput(out)) // swig warning
+		b.showOutput(a, p.Dir, p.ImportPath, b.processOutput(out)) // swig warning
 	}
 
 	return goFile, objdir + gccBase + gccExt, nil
diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 8fa6cb3a19..e1dd30026b 100644
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -225,8 +225,8 @@ func (gcToolchain) asm(b *Builder, a *Action, sfiles []string) ([]string, error)
 	for _, sfile := range sfiles {
 		ofile := a.Objdir + sfile[:len(sfile)-len(".s")] + ".o"
 		ofiles = append(ofiles, ofile)
-		a := append(args, "-o", ofile, mkAbs(p.Dir, sfile))
-		if err := b.run(p.Dir, p.ImportPath, nil, a...); err != nil {
+		args1 := append(args, "-o", ofile, mkAbs(p.Dir, sfile))
+		if err := b.run(a, p.Dir, p.ImportPath, nil, args1...); err != nil {
 			return nil, err
 		}
 	}
@@ -236,12 +236,12 @@ func (gcToolchain) asm(b *Builder, a *Action, sfiles []string) ([]string, error)
 // toolVerify checks that the command line args writes the same output file
 // if run using newTool instead.
 // Unused now but kept around for future use.
-func toolVerify(b *Builder, p *load.Package, newTool string, ofile string, args []interface{}) error {
+func toolVerify(a *Action, b *Builder, p *load.Package, newTool string, ofile string, args []interface{}) error {
 	newArgs := make([]interface{}, len(args))
 	copy(newArgs, args)
 	newArgs[1] = base.Tool(newTool)
 	newArgs[3] = ofile + ".new" // x.6 becomes x.6.new
-	if err := b.run(p.Dir, p.ImportPath, nil, newArgs...); err != nil {
+	if err := b.run(a, p.Dir, p.ImportPath, nil, newArgs...); err != nil {
 		return err
 	}
 	data1, err := ioutil.ReadFile(ofile)
@@ -283,7 +283,7 @@ func (gcToolchain) pack(b *Builder, a *Action, afile string, ofiles []string) er
 		return nil
 	}
 	if err := packInternal(b, absAfile, absOfiles); err != nil {
-		b.showOutput(p.Dir, p.ImportPath, err.Error()+"\n")
+		b.showOutput(a, p.Dir, p.ImportPath, err.Error()+"\n")
 		return errPrintedOutput
 	}
 	return nil
@@ -454,7 +454,7 @@ func (gcToolchain) ld(b *Builder, root *Action, out, importcfg, mainpkg string)
 		dir, out = filepath.Split(out)
 	}
 
-	return b.run(dir, root.Package.ImportPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags, mainpkg)
+	return b.run(root, dir, root.Package.ImportPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags, mainpkg)
 }
 
 func (gcToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action, out, importcfg string, allactions []*Action) error {
@@ -485,7 +485,7 @@ func (gcToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action,
 		}
 		ldflags = append(ldflags, d.Package.ImportPath+"="+d.Target)
 	}
-	return b.run(".", out, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags)
+	return b.run(root, ".", out, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags)
 }
 
 func (gcToolchain) cc(b *Builder, a *Action, ofile, cfile string) error {
diff --git a/src/cmd/go/internal/work/gccgo.go b/src/cmd/go/internal/work/gccgo.go
index b5fdb819f8..37a828f592 100644
--- a/src/cmd/go/internal/work/gccgo.go
+++ b/src/cmd/go/internal/work/gccgo.go
@@ -163,7 +163,7 @@ func (tools gccgoToolchain) asm(b *Builder, a *Action, sfiles []string) ([]strin
 		}
 		defs = tools.maybePIC(defs)
 		defs = append(defs, b.gccArchArgs()...)
-		err := b.run(p.Dir, p.ImportPath, nil, tools.compiler(), "-xassembler-with-cpp", "-I", a.Objdir, "-c", "-o", ofile, defs, sfile)
+		err := b.run(a, p.Dir, p.ImportPath, nil, tools.compiler(), "-xassembler-with-cpp", "-I", a.Objdir, "-c", "-o", ofile, defs, sfile)
 		if err != nil {
 			return nil, err
 		}
@@ -185,7 +185,7 @@ func (gccgoToolchain) pack(b *Builder, a *Action, afile string, ofiles []string)
 	for _, f := range ofiles {
 		absOfiles = append(absOfiles, mkAbs(objdir, f))
 	}
-	return b.run(p.Dir, p.ImportPath, nil, "ar", "rc", mkAbs(objdir, afile), absOfiles)
+	return b.run(a, p.Dir, p.ImportPath, nil, "ar", "rc", mkAbs(objdir, afile), absOfiles)
 }
 
 func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string, allactions []*Action, buildmode, desc string) error {
@@ -245,11 +245,11 @@ func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string
 				return "", nil
 			}
 		}
-		err := b.run(root.Objdir, desc, nil, "ar", "x", newArchive, "_cgo_flags")
+		err := b.run(root, root.Objdir, desc, nil, "ar", "x", newArchive, "_cgo_flags")
 		if err != nil {
 			return "", err
 		}
-		err = b.run(".", desc, nil, "ar", "d", newArchive, "_cgo_flags")
+		err = b.run(root, ".", desc, nil, "ar", "d", newArchive, "_cgo_flags")
 		if err != nil {
 			return "", err
 		}
@@ -427,13 +427,13 @@ func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string
 		}
 	}
 
-	if err := b.run(".", desc, nil, tools.linker(), "-o", out, ldflags, forcedGccgoflags, root.Package.Internal.Gccgoflags); err != nil {
+	if err := b.run(root, ".", desc, nil, tools.linker(), "-o", out, ldflags, forcedGccgoflags, root.Package.Internal.Gccgoflags); err != nil {
 		return err
 	}
 
 	switch buildmode {
 	case "c-archive":
-		if err := b.run(".", desc, nil, "ar", "rc", realOut, out); err != nil {
+		if err := b.run(root, ".", desc, nil, "ar", "rc", realOut, out); err != nil {
 			return err
 		}
 	}
@@ -464,7 +464,7 @@ func (tools gccgoToolchain) cc(b *Builder, a *Action, ofile, cfile string) error
 		defs = append(defs, "-fsplit-stack")
 	}
 	defs = tools.maybePIC(defs)
-	return b.run(p.Dir, p.ImportPath, nil, envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch)), "-Wall", "-g",
+	return b.run(a, p.Dir, p.ImportPath, nil, envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch)), "-Wall", "-g",
 		"-I", a.Objdir, "-I", inc, "-o", ofile, defs, "-c", cfile)
 }