[release-branch.go1.21] cmd/go/internal/modfetch/codehost: add new git tags before statLocal instead of after

gitRepo.statLocal reports tag and version information.
If we are statting a hash that corresponds to a tag, we need to add that tag
before calling statLocal so that it can be included in that information.

For #53955.
For #56881.
For #64586

Change-Id: I69a71428e6ed9096d4cb8ed1bb79531415ff06c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/547155
Auto-Submit: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
(cherry picked from commit 7b5a3733fce46aa44449c5ba28876f5a1e630650)
Reviewed-on: https://go-review.googlesource.com/c/go/+/585815
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>

2 files changed, 82 insertions, 9 deletions

diff --git a/src/cmd/go/internal/modfetch/codehost/git.go b/src/cmd/go/internal/modfetch/codehost/git.go
index d1a18a8d58..294e50ff12 100644
--- a/src/cmd/go/internal/modfetch/codehost/git.go
+++ b/src/cmd/go/internal/modfetch/codehost/git.go
@@ -18,6 +18,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -154,7 +155,7 @@ type gitRepo struct {
 	refsErr error
 
 	localTagsOnce sync.Once
-	localTags     map[string]bool
+	localTags     sync.Map // map[string]bool
 }
 
 const (
@@ -166,7 +167,6 @@ const (
 
 // loadLocalTags loads tag references from the local git cache
 // into the map r.localTags.
-// Should only be called as r.localTagsOnce.Do(r.loadLocalTags).
 func (r *gitRepo) loadLocalTags(ctx context.Context) {
 	// The git protocol sends all known refs and ls-remote filters them on the client side,
 	// so we might as well record both heads and tags in one shot.
@@ -176,10 +176,9 @@ func (r *gitRepo) loadLocalTags(ctx context.Context) {
 		return
 	}
 
-	r.localTags = make(map[string]bool)
 	for _, line := range strings.Split(string(out), "\n") {
 		if line != "" {
-			r.localTags[line] = true
+			r.localTags.Store(line, true)
 		}
 	}
 }
@@ -430,7 +429,7 @@ func (r *gitRepo) stat(ctx context.Context, rev string) (info *RevInfo, err erro
 	// Maybe rev is a tag we already have locally.
 	// (Note that we're excluding branches, which can be stale.)
 	r.localTagsOnce.Do(func() { r.loadLocalTags(ctx) })
-	if r.localTags[rev] {
+	if _, ok := r.localTags.Load(rev); ok {
 		return r.statLocal(ctx, rev, "refs/tags/"+rev)
 	}
 
@@ -506,11 +505,18 @@ func (r *gitRepo) stat(ctx context.Context, rev string) (info *RevInfo, err erro
 	// Either way, try a local stat before falling back to network I/O.
 	if !didStatLocal {
 		if info, err := r.statLocal(ctx, rev, hash); err == nil {
-			if after, found := strings.CutPrefix(ref, "refs/tags/"); found {
-				// Make sure tag exists, so it will be in localTags next time the go command is run.
-				Run(ctx, r.dir, "git", "tag", after, hash)
+			tag, fromTag := strings.CutPrefix(ref, "refs/tags/")
+			if fromTag && !slices.Contains(info.Tags, tag) {
+				// The local repo includes the commit hash we want, but it is missing
+				// the corresponding tag. Add that tag and try again.
+				_, err := Run(ctx, r.dir, "git", "tag", tag, hash)
+				if err != nil {
+					return nil, err
+				}
+				r.localTags.Store(tag, true)
+				return r.statLocal(ctx, rev, ref)
 			}
-			return info, nil
+			return info, err
 		}
 	}
 
diff --git a/src/cmd/go/testdata/script/get_issue53955.txt b/src/cmd/go/testdata/script/get_issue53955.txt
new file mode 100644
index 0000000000..c6d45d5c50
--- /dev/null
+++ b/src/cmd/go/testdata/script/get_issue53955.txt
@@ -0,0 +1,67 @@
+# Regression test for https://go.dev/issue/53955.
+# New remote tags were erroneously added to the local clone of a repo
+# only *after* extracting version information for a locally-cached commit,
+# causing the version information to have incomplete Tags and Version fields.
+
+[short] skip 'constructs a local git repo'
+[!git] skip
+[!net:github.com] skip 'does not actually use github.com because of insteadOf, but silence network check just in case'
+
+env GIT_CONFIG_GLOBAL=$WORK/.gitconfig
+env GIT_ALLOW_PROTOCOL=file
+env GOPRIVATE=github.com/golang/issue53955
+
+[!GOOS:windows] exec git config --global 'url.file://'$WORK'/repo.insteadOf' 'https://github.com/golang/issue53955'
+[GOOS:windows]  exec git config --global 'url.file:///'$WORK'/repo.insteadOf' 'https://github.com/golang/issue53955'
+
+cd $WORK/repo
+
+env GIT_AUTHOR_NAME='Go Gopher'
+env GIT_AUTHOR_EMAIL='gopher@golang.org'
+env GIT_COMMITTER_NAME=$GIT_AUTHOR_NAME
+env GIT_COMMITTER_EMAIL=$GIT_AUTHOR_EMAIL
+
+exec git init
+
+env GIT_COMMITTER_DATE=2022-07-19T11:07:00-04:00
+env GIT_AUTHOR_DATE=2022-07-19T11:07:00-04:00
+exec git add go.mod issue53955.go
+exec git commit -m 'initial commit'
+exec git branch -m main
+exec git tag v1.0.9
+
+env GIT_COMMITTER_DATE=2022-07-19T11:07:01-04:00
+env GIT_AUTHOR_DATE=2022-07-19T11:07:01-04:00
+exec git add extra.go
+exec git commit -m 'next commit'
+exec git show-ref --tags --heads
+cmp stdout $WORK/.git-refs-1
+
+cd $WORK/m
+go get -x github.com/golang/issue53955@2cb3d49f
+stderr '^go: added github.com/golang/issue53955 v1.0.10-0.20220719150701-2cb3d49f8874$'
+
+cd $WORK/repo
+exec git tag v1.0.10
+
+cd $WORK/m
+go get -x github.com/golang/issue53955@v1.0.10
+! stderr 'v1\.0\.10 is not a tag'
+stderr '^go: upgraded github.com/golang/issue53955 v.* => v1\.0\.10$'
+
+-- $WORK/repo/go.mod --
+module github.com/golang/issue53955
+
+go 1.18
+-- $WORK/repo/issue53955.go --
+package issue53955
+-- $WORK/repo/extra.go --
+package issue53955
+-- $WORK/.git-refs-1 --
+2cb3d49f8874b9362ed0ddd2a6512e4108bbf6b1 refs/heads/main
+050526ebf5883191e990529eb3cc9345abaf838c refs/tags/v1.0.9
+-- $WORK/m/go.mod --
+module m
+
+go 1.18
+-- $WORK/.gitconfig --