cmd/go: make file:line for cgo files look like non-cgo files

Passing the absolute path to cgo puts the absolute path in the
generated file's //line directives, which then shows that path
in the compiler output, which the go command can then
make relative to the current directory, same as it does for
other compiler output.

Change-Id: Ia2064fea40078c46fd97e3a3b8c9fa1488f913e3
Reviewed-on: https://go-review.googlesource.com/77154
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/cgo/out.go

@@ -15,6 +15,7 @@ import (
 	"go/token"
 	"io"
 	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 )
@@ -526,7 +527,7 @@ func (p *Package) writeOutput(f *File, srcfile string) {
 	if strings.HasSuffix(base, ".go") {
 		base = base[0 : len(base)-3]
 	}
-	base = strings.Map(slashToUnderscore, base)
+	base = filepath.Base(base)
 	fgo1 := creat(*objDir + base + ".cgo1.go")
 	fgcc := creat(*objDir + base + ".cgo2.c")
 

src/cmd/go/go_test.go

@@ -2439,16 +2439,16 @@ func TestCoverageErrorLine(t *testing.T) {
 	tg.setenv("GOTMPDIR", tg.tempdir)
 
 	tg.runFail("test", "coverbad")
-	tg.grepStderr(`coverbad[\\/]p.go:4`, "did not find correct line number for error")
+	tg.grepStderr(`coverbad[\\/]p\.go:4`, "did not find coverbad/p.go:4")
+	tg.grepStderr(`coverbad[\\/]p1\.go:6`, "did not find coverbad/p1.go:6")
 	tg.grepStderrNot(regexp.QuoteMeta(tg.tempdir), "found temporary directory in error")
 	stderr := tg.getStderr()
 
 	tg.runFail("test", "-cover", "coverbad")
-	tg.grepStderr(`coverbad[\\/]p.go:4`, "did not find correct line number for error")
 	stderr2 := tg.getStderr()
 
 	// It's OK that stderr2 drops the character position in the error,
-	// because of the //line directive.
+	// because of the //line directive (see golang.org/issue/22662).
 	stderr = strings.Replace(stderr, "p.go:4:2:", "p.go:4:", -1)
 	if stderr != stderr2 {
 		t.Logf("test -cover changed error messages:\nbefore:\n%s\n\nafter:\n%s", stderr, stderr2)
@@ -4707,10 +4707,11 @@ func TestExecBuildX(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	out, err = exec.Command("/bin/sh", sh).CombinedOutput()
+	out, err = exec.Command("/usr/bin/env", "bash", "-x", sh).CombinedOutput()
 	if err != nil {
 		t.Fatalf("/bin/sh %s: %v\n%s", sh, err, out)
 	}
+	t.Logf("shell output:\n%s", out)
 
 	out, err = exec.Command(obj).CombinedOutput()
 	if err != nil {

src/cmd/go/internal/work/exec.go

@@ -426,7 +426,7 @@ func (b *Builder) build(a *Action) (err error) {
 			sfiles = nil
 		}
 
-		outGo, outObj, err := b.cgo(a, base.Tool("cgo"), objdir, pcCFLAGS, pcLDFLAGS, cgofiles, objdirCgofiles, gccfiles, cxxfiles, a.Package.MFiles, a.Package.FFiles)
+		outGo, outObj, err := b.cgo(a, base.Tool("cgo"), objdir, pcCFLAGS, pcLDFLAGS, mkAbsFiles(a.Package.Dir, cgofiles), objdirCgofiles, gccfiles, cxxfiles, a.Package.MFiles, a.Package.FFiles)
 		if err != nil {
 			return err
 		}
@@ -481,17 +481,10 @@ func (b *Builder) build(a *Action) (err error) {
 		// so that vet's error messages will use absolute paths,
 		// so that we can reformat them relative to the directory
 		// in which the go command is invoked.
-		absfiles := make([]string, len(gofiles))
-		for i, f := range gofiles {
-			if !filepath.IsAbs(f) {
-				f = filepath.Join(a.Package.Dir, f)
-			}
-			absfiles[i] = f
-		}
 		vcfg = &vetConfig{
 			Compiler:    cfg.BuildToolchainName,
 			Dir:         a.Package.Dir,
-			GoFiles:     absfiles,
+			GoFiles:     mkAbsFiles(a.Package.Dir, gofiles),
 			ImportMap:   make(map[string]string),
 			PackageFile: make(map[string]string),
 		}
@@ -1351,8 +1344,8 @@ func (b *Builder) showOutput(a *Action, dir, desc, out string) {
 // print this error.
 var errPrintedOutput = errors.New("already printed output - no need to show error")
 
-var cgoLine = regexp.MustCompile(`\[[^\[\]]+\.cgo1\.go:[0-9]+(:[0-9]+)?\]`)
-var cgoTypeSigRe = regexp.MustCompile(`\b_Ctype_\B`)
+var cgoLine = regexp.MustCompile(`\[[^\[\]]+\.(cgo1|cover)\.go:[0-9]+(:[0-9]+)?\]`)
+var cgoTypeSigRe = regexp.MustCompile(`\b_C2?(type|func|var|macro)_\B`)
 
 // run runs the command given by cmdline in the directory dir.
 // If the command fails, run prints information about the failure
@@ -1895,9 +1888,9 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 	gofiles := []string{objdir + "_cgo_gotypes.go"}
 	cfiles := []string{"_cgo_export.c"}
 	for _, fn := range cgofiles {
-		f := cgoRe.ReplaceAllString(fn[:len(fn)-2], "_")
-		gofiles = append(gofiles, objdir+f+"cgo1.go")
-		cfiles = append(cfiles, f+"cgo2.c")
+		f := strings.TrimSuffix(filepath.Base(fn), ".go")
+		gofiles = append(gofiles, objdir+f+".cgo1.go")
+		cfiles = append(cfiles, f+".cgo2.c")
 	}
 
 	// TODO: make cgo not depend on $GOARCH?
@@ -2286,3 +2279,17 @@ func (b *Builder) disableBuildID(ldflags []string) []string {
 	}
 	return ldflags
 }
+
+// mkAbsFiles converts files into a list of absolute files,
+// assuming they were originally relative to dir,
+// and returns that new list.
+func mkAbsFiles(dir string, files []string) []string {
+	abs := make([]string, len(files))
+	for i, f := range files {
+		if !filepath.IsAbs(f) {
+			f = filepath.Join(dir, f)
+		}
+		abs[i] = f
+	}
+	return abs
+}

src/cmd/go/testdata/src/coverbad/p1.go

@@ -0,0 +1,7 @@
+package p
+
+import "C"
+
+func h() {
+	j()
+}