cmd/go: add support for release tags via git branches

R=rsc, remyoudompheng, gustavo, dsymonds
CC=golang-dev
https://golang.org/cl/5617057

diff --git a/src/cmd/go/vcs.go b/src/cmd/go/vcs.go
index d26c6bc7a1c93cc7bc3fddf5aa75239d82a652d6..56fe25303887ce19e239532b5b47265516a99a13 100644 (file)
--- a/src/cmd/go/vcs.go
+++ b/src/cmd/go/vcs.go
@@ -24,6 +24,7 @@ type vcsCmd struct {
        downloadCmd string // command to download updates into an existing repository
 
        tagCmd         []tagCmd // commands to list tags
+       tagLookupCmd   []tagCmd // commands to lookup tags before running tagSyncCmd
        tagSyncCmd     string   // command to sync to specific tag
        tagSyncDefault string   // command to sync to default tag
 }
@@ -83,7 +84,14 @@ var vcsGit = &vcsCmd{
        createCmd:   "clone {repo} {dir}",
        downloadCmd: "fetch",
 
-       tagCmd:         []tagCmd{{"tag", `^(\S+)$`}},
+       tagCmd: []tagCmd{
+               // tags/xxx matches a git tag named xxx
+               // origin/xxx matches a git branch named xxx on the default remote repository
+               {"show-ref", `(?:tags|origin)/(\S+)$`},
+       },
+       tagLookupCmd: []tagCmd{
+               {"show-ref tags/{tag} origin/{tag}", `((?:tags|origin)/\S+)$`},
+       },
        tagSyncCmd:     "checkout {tag}",
        tagSyncDefault: "checkout origin/master",
 }
@@ -128,17 +136,17 @@ func (v *vcsCmd) String() string {
 // command's combined stdout+stderr to standard error.
 // Otherwise run discards the command's output.
 func (v *vcsCmd) run(dir string, cmd string, keyval ...string) error {
-       _, err := v.run1(dir, false, cmd, keyval)
+       _, err := v.run1(dir, cmd, keyval)
        return err
 }
 
 // runOutput is like run but returns the output of the command.
 func (v *vcsCmd) runOutput(dir string, cmd string, keyval ...string) ([]byte, error) {
-       return v.run1(dir, true, cmd, keyval)
+       return v.run1(dir, cmd, keyval)
 }
 
 // run1 is the generalized implementation of run and runOutput.
-func (v *vcsCmd) run1(dir string, output bool, cmdline string, keyval []string) ([]byte, error) {
+func (v *vcsCmd) run1(dir string, cmdline string, keyval []string) ([]byte, error) {
        m := make(map[string]string)
        for i := 0; i < len(keyval); i += 2 {
                m[keyval[i]] = keyval[i+1]
@@ -187,7 +195,9 @@ func (v *vcsCmd) tags(dir string) ([]string, error) {
                        return nil, err
                }
                re := regexp.MustCompile(`(?m-s)` + tc.pattern)
-               tags = append(tags, re.FindAllString(string(out), -1)...)
+               for _, m := range re.FindAllStringSubmatch(string(out), -1) {
+                       tags = append(tags, m[1])
+               }
        }
        return tags, nil
 }
@@ -198,6 +208,20 @@ func (v *vcsCmd) tagSync(dir, tag string) error {
        if v.tagSyncCmd == "" {
                return nil
        }
+       if tag != "" {
+               for _, tc := range v.tagLookupCmd {
+                       out, err := v.runOutput(dir, tc.cmd, "tag", tag)
+                       if err != nil {
+                               return err
+                       }
+                       re := regexp.MustCompile(`(?m-s)` + tc.pattern)
+                       m := re.FindStringSubmatch(string(out))
+                       if len(m) > 1 {
+                               tag = m[1]
+                               break
+                       }
+               }
+       }
        if tag == "" && v.tagSyncDefault != "" {
                return v.run(dir, v.tagSyncDefault)
        }