cmd/release: remove the tour from the releases

This removes the tour from the release binary for go1.12.x and later
releases, lowering the size of each release. It will now redirect to
tour.golang.org, unless the user runs "go get -u golang.org/x/tour" to
cache it locally, in which case the local copy will be preferred.

The release size was 170.0 MiB for go1.11rc1, this change reduces the
size by 6.3 MiB, a 3.7% reduction. After this change, and others which
reduced the release size, the release candidate is now 115.2 MiB.

Updates golang/go#27151

Change-Id: I6687c34f3d4ae161c5e6df1f7af8cf3adc016fc4
Reviewed-on: https://go-review.googlesource.com/131156
Reviewed-by: Brad Fitzpatrick <[email protected]>

cmd/release/releaselet.go

@@ -109,7 +109,14 @@ var tourPackages = []string{
 	"wc",
 }
 
+// TODO: Remove after Go 1.13 is released, and Go 1.11 is no longer supported.
 func tour() error {
+	_, version, _ := environ()
+	verMajor, verMinor, _ := splitVersion(version)
+	if verMajor > 1 || verMinor >= 12 {
+		return nil // Only include the tour in go1.11.x and earlier releases.
+	}
+
 	tourSrc := filepath.Join("gopath/src", tourPath)
 	contentDir := filepath.FromSlash("go/misc/tour")
 
@@ -262,7 +269,7 @@ func windowsMSI() error {
 	}
 
 	// Build package.
-	verMajor, verMinor, verPatch := wixVersion(version)
+	verMajor, verMinor, verPatch := splitVersion(version)
 
 	if err := runDir(win, filepath.Join(wix, "candle"),
 		"-nologo",
@@ -436,10 +443,10 @@ func ext() string {
 
 var versionRe = regexp.MustCompile(`^go(\d+(\.\d+)*)`)
 
-// wixVersion splits a Go version string such as "go1.9" or "go1.10.2" (as matched by versionRe)
+// splitVersion splits a Go version string such as "go1.9" or "go1.10.2" (as matched by versionRe)
 // into its three parts: major, minor, and patch
 // It's based on the Git tag.
-func wixVersion(v string) (major, minor, patch int) {
+func splitVersion(v string) (major, minor, patch int) {
 	m := versionRe.FindStringSubmatch(v)
 	if m == nil {
 		return
@@ -463,7 +470,7 @@ func wixVersion(v string) (major, minor, patch int) {
 // support is expected from the specified version.
 // (WinXP is no longer supported starting Go v1.11)
 func wixIsWinXPSupported(v string) bool {
-	major, minor, _ := wixVersion(v)
+	major, minor, _ := splitVersion(v)
 	if major > 1 {
 		return false
 	}
@@ -837,7 +844,7 @@ var windowsData = map[string]string{
 // +build ignore. This is called by releaselet_test.go with an
 // environment variable set, which func main above recognizes.
 func runSelfTests() {
-	// Test wixVersion.
+	// Test splitVersion.
 	for _, tt := range []struct {
 		v                   string
 		major, minor, patch int
@@ -846,9 +853,9 @@ func runSelfTests() {
 		{"go1.34", 1, 34, 0},
 		{"go1.34.7", 1, 34, 7},
 	} {
-		major, minor, patch := wixVersion(tt.v)
+		major, minor, patch := splitVersion(tt.v)
 		if major != tt.major || minor != tt.minor || patch != tt.patch {
-			log.Fatalf("wixVersion(%q) = %v, %v, %v; want %v, %v, %v",
+			log.Fatalf("splitVersion(%q) = %v, %v, %v; want %v, %v, %v",
 				tt.v, major, minor, patch, tt.major, tt.minor, tt.patch)
 		}
 	}