cmd/release: don't include godoc in releases in Go 1.13+

Tested that it's still present in Go 1.12:

$ release -version=go1.12.999 -target=linux-amd64 -watch -skip_tests -rev=release-branch.go1.12 -tools=release-branch.go1.12 -net=release-branch.go1.12
...
$ ls -lh go1.12.999.linux-amd64.tar.gz
-rw-r--r-- 1 bradfitz bradfitz 122M Apr 29 19:28 go1.12.999.linux-amd64.tar.gz
$ tar -ztf go1.12.999.linux-amd64.tar.gz | grep godoc
go/bin/godoc
go/src/cmd/vendor/github.com/google/pprof/profile/testdata/go.godoc.thread
go/src/cmd/vendor/github.com/google/pprof/profile/testdata/go.godoc.thread.string

But not with Go 1.13:

$ release -version=go1.13beta0 -target=linux-amd64 -watch -skip_tests -rev=8c1f78524e421ac01e35e8805dd7a45bf98c2a79
...
$ ls -lh go1.13beta0.linux-amd64.tar.gz
-rw-r--r-- 1 bradfitz bradfitz 115M Apr 29 19:00 go1.13beta0.linux-amd64.tar.gz
$ tar -ztf go1.13beta0.linux-amd64.tar.gz | grep godoc
$

Fixes golang/go#30029
Updates golang/go#27151

Change-Id: I9ac5c1b2bc76f184bf05fdcac86bb2e37b57c77c
Reviewed-on: https://go-review.googlesource.com/c/build/+/174322
Reviewed-by: Dmitri Shuralyov <[email protected]>

cmd/release/release.go

@@ -72,13 +72,13 @@ func main() {
 	}
 
 	if (*rev == "" && *tarball == "") || (*rev != "" && *tarball != "") {
-		log.Fatal("must specify one of -rev and -tarball")
-	}
-	if *toolsRev == "" {
-		log.Fatal("must specify -tools flag")
+		log.Fatal("must specify one of -rev or -tarball")
 	}
 	if *version == "" {
-		log.Fatal("must specify -version flag")
+		log.Fatal(`must specify -version flag (such as "go1.12" or "go1.13beta1")`)
+	}
+	if *toolsRev == "" && (versionIncludesGodoc(*version) || versionIncludesTour(*version)) {
+		log.Fatal("must specify -tools flag")
 	}
 
 	coordClient = coordinatorClient()
@@ -317,6 +317,9 @@ func (b *Build) make() error {
 		if r.repo == "tour" && !versionIncludesTour(*version) {
 			continue
 		}
+		if (r.repo == "net" || r.repo == "tools") && !versionIncludesGodoc(*version) {
+			continue
+		}
 		dir := goPath + "/src/golang.org/x/" + r.repo
 		tar := "https://go.googlesource.com/" + r.repo + "/+archive/" + r.rev + ".tar.gz"
 		if err := client.PutTarFromURL(tar, dir); err != nil {
@@ -442,15 +445,18 @@ func (b *Build) make() error {
 		}
 	}
 
-	toolPaths := []string{
-		"golang.org/x/tools/cmd/godoc",
+	var toolPaths []string
+	if versionIncludesGodoc(*version) {
+		toolPaths = append(toolPaths, "golang.org/x/tools/cmd/godoc")
 	}
 	if versionIncludesTour(*version) {
 		toolPaths = append(toolPaths, "golang.org/x/tour")
 	}
-	b.logf("Building %v.", strings.Join(toolPaths, ", "))
-	if err := runGo(append([]string{"install"}, toolPaths...)...); err != nil {
-		return err
+	if len(toolPaths) > 0 {
+		b.logf("Building %v.", strings.Join(toolPaths, ", "))
+		if err := runGo(append([]string{"install"}, toolPaths...)...); err != nil {
+			return err
+		}
 	}
 
 	// postBuildCleanFiles are the list of files to remove in the go/ directory
@@ -839,3 +845,13 @@ func versionIncludesTour(goVer string) bool {
 	return strings.HasPrefix(goVer, "go1.10.") ||
 		strings.HasPrefix(goVer, "go1.11.")
 }
+
+// versionIncludesGodoc reports whether the provided Go version (of the
+// form "go1.N" or "go1.N.M" includes the godoc binary.
+func versionIncludesGodoc(goVer string) bool {
+	// We don't do releases of Go 1.10 and earlier, so this only
+	// needs to recognize the two current past releases. From Go
+	// 1.13 and on, we won't ship the godoc binary (see Issue 30029).
+	return strings.HasPrefix(goVer, "go1.11.") ||
+		strings.HasPrefix(goVer, "go1.12.")
+}

cmd/release/releaselet.go

@@ -77,7 +77,17 @@ func archDir() string {
 	return ""
 }
 
+// godoc copies the godoc binary into place for Go 1.12 and earlier.
+//
+// TODO: remove this function once Go 1.14 is released (when Go 1.12
+// is no longer supported).
 func godoc() error {
+	_, version, _ := environ()
+	verMajor, verMinor, _ := splitVersion(version)
+	if verMajor > 1 || verMinor >= 13 {
+		return nil // Only include the godoc binary in go1.12.x and earlier releases; Issue 30029
+	}
+
 	// Pre Go 1.7, the godoc binary is placed here by cmd/go.
 	// After Go 1.7, we need to copy the binary from GOPATH/bin to GOROOT/bin.
 	// TODO(cbro): Remove after Go 1.6 is no longer supported.