cmd/go: propagate origin information for inexact module queries

Module queries for "@latest" and inexact constraints (like "@v1.3")
may consult information about tags and/or branches before finally
returning either a result or an error.

To correctly invalidate the origin information for the -reuse flag,
the reported Origin needs to reflect all of those inputs.

Fixes #61415.

Change-Id: I054acbef7d218a92a3bbb44517326385e458d907
Reviewed-on: https://go-review.googlesource.com/c/go/+/542717
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Bryan Mills <[email protected]>
Reviewed-by: Michael Matloob <[email protected]>

Author: Bryan C. Mills

src/cmd/go/internal/modfetch/coderepo.go

@@ -322,6 +322,9 @@ func (r *codeRepo) Stat(ctx context.Context, rev string) (*RevInfo, error) {
 func (r *codeRepo) Latest(ctx context.Context) (*RevInfo, error) {
 	info, err := r.code.Latest(ctx)
 	if err != nil {
+		if info != nil {
+			return &RevInfo{Origin: info.Origin}, err
+		}
 		return nil, err
 	}
 	return r.convert(ctx, info, "")
@@ -332,7 +335,44 @@ func (r *codeRepo) Latest(ctx context.Context) (*RevInfo, error) {
 //
 // If statVers is a valid module version, it is used for the Version field.
 // Otherwise, the Version is derived from the passed-in info and recent tags.
-func (r *codeRepo) convert(ctx context.Context, info *codehost.RevInfo, statVers string) (*RevInfo, error) {
+func (r *codeRepo) convert(ctx context.Context, info *codehost.RevInfo, statVers string) (revInfo *RevInfo, err error) {
+	defer func() {
+		if info.Origin == nil {
+			return
+		}
+		if revInfo == nil {
+			revInfo = new(RevInfo)
+		} else if revInfo.Origin != nil {
+			panic("internal error: RevInfo Origin unexpectedly already populated")
+		}
+
+		origin := *info.Origin
+		revInfo.Origin = &origin
+		origin.Subdir = r.codeDir
+
+		v := revInfo.Version
+		if module.IsPseudoVersion(v) && (v != statVers || !strings.HasPrefix(v, "v0.0.0-")) {
+			// Add tags that are relevant to pseudo-version calculation to origin.
+			prefix := r.codeDir
+			if prefix != "" {
+				prefix += "/"
+			}
+			if r.pathMajor != "" { // "/v2" or "/.v2"
+				prefix += r.pathMajor[1:] + "." // += "v2."
+			}
+			tags, tagsErr := r.code.Tags(ctx, prefix)
+			if tagsErr != nil {
+				origin.ClearCheckable()
+				if err == nil {
+					err = tagsErr
+				}
+			} else {
+				origin.TagPrefix = tags.Origin.TagPrefix
+				origin.TagSum = tags.Origin.TagSum
+			}
+		}
+	}()
+
 	// If this is a plain tag (no dir/ prefix)
 	// and the module path is unversioned,
 	// and if the underlying file tree has no go.mod,
@@ -463,31 +503,7 @@ func (r *codeRepo) convert(ctx context.Context, info *codehost.RevInfo, statVers
 			return nil, errIncompatible
 		}
 
-		origin := info.Origin
-		if origin != nil {
-			o := *origin
-			origin = &o
-			origin.Subdir = r.codeDir
-			if module.IsPseudoVersion(v) && (v != statVers || !strings.HasPrefix(v, "v0.0.0-")) {
-				// Add tags that are relevant to pseudo-version calculation to origin.
-				prefix := r.codeDir
-				if prefix != "" {
-					prefix += "/"
-				}
-				if r.pathMajor != "" { // "/v2" or "/.v2"
-					prefix += r.pathMajor[1:] + "." // += "v2."
-				}
-				tags, err := r.code.Tags(ctx, prefix)
-				if err != nil {
-					return nil, err
-				}
-				origin.TagPrefix = tags.Origin.TagPrefix
-				origin.TagSum = tags.Origin.TagSum
-			}
-		}
-
 		return &RevInfo{
-			Origin:  origin,
 			Name:    info.Name,
 			Short:   info.Short,
 			Time:    info.Time,

src/cmd/go/internal/modload/build.go

@@ -162,7 +162,7 @@ func addUpdate(ctx context.Context, m *modinfo.ModulePublic) {
 }
 
 // mergeOrigin merges two origins,
-// returning and possibly modifying one of its arguments.
+// returning either a new origin or one of its unmodified arguments.
 // If the two origins conflict, mergeOrigin returns a non-specific one
 // that will not pass CheckReuse.
 // If m1 or m2 is nil, the other is returned unmodified.
@@ -194,11 +194,17 @@ func mergeOrigin(m1, m2 *codehost.Origin) *codehost.Origin {
 		merged.TagPrefix = m2.TagPrefix
 	}
 	if m2.Hash != "" {
-		if m1.Hash != "" && (m1.Hash != m2.Hash || m1.Ref != m2.Ref) {
+		if m1.Hash != "" && m1.Hash != m2.Hash {
 			merged.ClearCheckable()
 			return merged
 		}
 		merged.Hash = m2.Hash
+	}
+	if m2.Ref != "" {
+		if m1.Ref != "" && m1.Ref != m2.Ref {
+			merged.ClearCheckable()
+			return merged
+		}
 		merged.Ref = m2.Ref
 	}
 	return merged

src/cmd/go/internal/modload/query.go

@@ -216,34 +216,35 @@ func queryProxy(ctx context.Context, proxy, path, query, current string, allowed
 	if err != nil {
 		return nil, err
 	}
-	revErr := &modfetch.RevInfo{Origin: versions.Origin} // RevInfo to return with error
+	origin := versions.Origin
 
-	releases, prereleases, err := qm.filterVersions(ctx, versions.List)
-	if err != nil {
-		return revErr, err
+	revWithOrigin := func(rev *modfetch.RevInfo) *modfetch.RevInfo {
+		if rev == nil {
+			if origin == nil {
+				return nil
+			}
+			return &modfetch.RevInfo{Origin: origin}
+		}
+
+		clone := *rev
+		clone.Origin = origin
+		return &clone
 	}
 
-	mergeRevOrigin := func(rev *modfetch.RevInfo, origin *codehost.Origin) *modfetch.RevInfo {
-		merged := mergeOrigin(rev.Origin, origin)
-		if merged == rev.Origin {
-			return rev
-		}
-		clone := new(modfetch.RevInfo)
-		*clone = *rev
-		clone.Origin = merged
-		return clone
+	releases, prereleases, err := qm.filterVersions(ctx, versions.List)
+	if err != nil {
+		return revWithOrigin(nil), err
 	}
 
 	lookup := func(v string) (*modfetch.RevInfo, error) {
 		rev, err := repo.Stat(ctx, v)
-		// Stat can return a non-nil rev and a non-nil err,
-		// in order to provide origin information to make the error cacheable.
-		if rev == nil && err != nil {
-			return revErr, err
+		if rev != nil {
+			// Note that Stat can return a non-nil rev and a non-nil err,
+			// in order to provide origin information to make the error cacheable.
+			origin = mergeOrigin(origin, rev.Origin)
 		}
-		rev = mergeRevOrigin(rev, versions.Origin)
 		if err != nil {
-			return rev, err
+			return revWithOrigin(nil), err
 		}
 
 		if (query == "upgrade" || query == "patch") && module.IsPseudoVersion(current) && !rev.Time.IsZero() {
@@ -268,18 +269,20 @@ func queryProxy(ctx context.Context, proxy, path, query, current string, allowed
 			currentTime, err := module.PseudoVersionTime(current)
 			if err == nil && rev.Time.Before(currentTime) {
 				if err := allowed(ctx, module.Version{Path: path, Version: current}); errors.Is(err, ErrDisallowed) {
-					return revErr, err
+					return revWithOrigin(nil), err
 				}
 				rev, err = repo.Stat(ctx, current)
-				if rev == nil && err != nil {
-					return revErr, err
+				if rev != nil {
+					origin = mergeOrigin(origin, rev.Origin)
+				}
+				if err != nil {
+					return revWithOrigin(nil), err
 				}
-				rev = mergeRevOrigin(rev, versions.Origin)
-				return rev, err
+				return revWithOrigin(rev), nil
 			}
 		}
 
-		return rev, nil
+		return revWithOrigin(rev), nil
 	}
 
 	if qm.preferLower {
@@ -300,24 +303,27 @@ func queryProxy(ctx context.Context, proxy, path, query, current string, allowed
 
 	if qm.mayUseLatest {
 		latest, err := repo.Latest(ctx)
+		if latest != nil {
+			origin = mergeOrigin(origin, latest.Origin)
+		}
 		if err == nil {
 			if qm.allowsVersion(ctx, latest.Version) {
 				return lookup(latest.Version)
 			}
 		} else if !errors.Is(err, fs.ErrNotExist) {
-			return revErr, err
+			return revWithOrigin(nil), err
 		}
 	}
 
 	if (query == "upgrade" || query == "patch") && current != "" && current != "none" {
 		// "upgrade" and "patch" may stay on the current version if allowed.
 		if err := allowed(ctx, module.Version{Path: path, Version: current}); errors.Is(err, ErrDisallowed) {
-			return nil, err
+			return revWithOrigin(nil), err
 		}
 		return lookup(current)
 	}
 
-	return revErr, &NoMatchingVersionError{query: query, current: current}
+	return revWithOrigin(nil), &NoMatchingVersionError{query: query, current: current}
 }
 
 // IsRevisionQuery returns true if vers is a version query that may refer to

src/cmd/go/testdata/script/mod_list_issue61415.txt

@@ -0,0 +1,76 @@
+[short] skip 'generates a vcstest git repo'
+[!git] skip
+
+env GOPROXY=direct
+
+# Control case: fetching a nested module at a tag that exists should
+# emit Origin metadata for that tag and commit, and the origin should
+# be reusable for that tag.
+
+go list -json -m --versions -e vcs-test.golang.org/git/issue61415.git/nested@has-nested
+cp stdout has-nested.json
+stdout '"Origin":'
+stdout '"VCS": "git"'
+stdout '"URL":'  # randomly-chosen vcweb localhost URL
+stdout '"Subdir": "nested"'
+stdout '"TagPrefix": "nested/"'
+stdout '"TagSum": "t1:47DEQpj8HBSa\+/TImW\+5JCeuQeRkm5NMpJWZG3hSuFU="'
+stdout '"Ref": "refs/tags/has-nested"'
+stdout '"Hash": "08a4fa6bb9c04ffba03b26ae427b0d6335d90a2a"'
+
+go list -reuse=has-nested.json -json -m --versions -e vcs-test.golang.org/git/issue61415.git/nested@has-nested
+stdout '"Origin":'
+stdout '"VCS": "git"'
+stdout '"URL":'  # randomly-chosen vcweb localhost URL
+stdout '"Subdir": "nested"'
+stdout '"TagPrefix": "nested/"'
+stdout '"TagSum": "t1:47DEQpj8HBSa\+/TImW\+5JCeuQeRkm5NMpJWZG3hSuFU="'
+stdout '"Ref": "refs/tags/has-nested"'
+stdout '"Hash": "08a4fa6bb9c04ffba03b26ae427b0d6335d90a2a"'
+stdout '"Reuse": true'
+
+
+# Experiment case: if the nested module doesn't exist at "latest",
+# the Origin metadata should include the ref that we tried to resolve
+# (HEAD for a repo without version tags) and the hash to which it refers,
+# so that changing the HEAD ref will invalidate the result.
+
+go list -json -m --versions -e vcs-test.golang.org/git/issue61415.git/nested@latest
+cp stdout no-nested.json
+stdout '"Err": "module vcs-test.golang.org/git/issue61415.git/nested: no matching versions for query \\"latest\\""'
+stdout '"URL":'  # randomly-chosen vcweb localhost URL
+stdout '"Subdir": "nested"'
+stdout '"TagPrefix": "nested/"'
+stdout '"TagSum": "t1:47DEQpj8HBSa\+/TImW\+5JCeuQeRkm5NMpJWZG3hSuFU="'
+
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "f213069baa68ec26412fb373c7cf6669db1f8e69"'
+
+# The error result should be reusable.
+
+go list -reuse=no-nested.json -json -m --versions -e vcs-test.golang.org/git/issue61415.git/nested@latest
+
+stdout '"Err": "module vcs-test.golang.org/git/issue61415.git/nested: no matching versions for query \\"latest\\""'
+stdout '"URL":'  # randomly-chosen vcweb localhost URL
+stdout '"Subdir": "nested"'
+stdout '"TagPrefix": "nested/"'
+stdout '"TagSum": "t1:47DEQpj8HBSa\+/TImW\+5JCeuQeRkm5NMpJWZG3hSuFU="'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "f213069baa68ec26412fb373c7cf6669db1f8e69"'
+stdout '"Reuse": true'
+
+
+# If the hash refers to some other commit instead, the
+# result should not be reused.
+
+replace f213069baa68ec26412fb373c7cf6669db1f8e69 08a4fa6bb9c04ffba03b26ae427b0d6335d90a2a no-nested.json
+
+go list -reuse=no-nested.json -json -m --versions -e vcs-test.golang.org/git/issue61415.git/nested@latest
+stdout '"Err": "module vcs-test.golang.org/git/issue61415.git/nested: no matching versions for query \\"latest\\""'
+stdout '"URL":'  # randomly-chosen vcweb localhost URL
+stdout '"Subdir": "nested"'
+stdout '"TagPrefix": "nested/"'
+stdout '"TagSum": "t1:47DEQpj8HBSa\+/TImW\+5JCeuQeRkm5NMpJWZG3hSuFU="'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "f213069baa68ec26412fb373c7cf6669db1f8e69"'
+! stdout '"Reuse"'

src/cmd/go/testdata/script/reuse_git.txt

@@ -55,7 +55,9 @@ stdout '"Version": "latest"'
 stdout '"Error":.*no matching versions'
 ! stdout '"TagPrefix"'
 stdout '"TagSum": "t1:47DEQpj8HBSa[+]/TImW[+]5JCeuQeRkm5NMpJWZG3hSuFU="'
-! stdout '"(Ref|Hash|RepoSum)":'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "fc3a09f3dc5cfe0d7a743ea18f1f5226e68b3777"'
+! stdout 'RepoSum'
 
 # go mod download vcstest/hello/sub/v9 should also fail, print origin info with TagPrefix
 ! go mod download -x -json vcs-test.golang.org/git/hello.git/sub/v9@latest
@@ -64,7 +66,9 @@ stdout '"Version": "latest"'
 stdout '"Error":.*no matching versions'
 stdout '"TagPrefix": "sub/"'
 stdout '"TagSum": "t1:47DEQpj8HBSa[+]/TImW[+]5JCeuQeRkm5NMpJWZG3hSuFU="'
-! stdout '"(Ref|Hash|RepoSum)":'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "fc3a09f3dc5cfe0d7a743ea18f1f5226e68b3777"'
+! stdout 'RepoSum'
 
 # go mod download vcstest/hello@nonexist should fail, still print origin info
 ! go mod download -x -json vcs-test.golang.org/git/hello.git@nonexist
@@ -200,7 +204,8 @@ stdout '"Reuse": true'
 stdout '"Error":.*no matching versions'
 ! stdout '"TagPrefix"'
 stdout '"TagSum": "t1:47DEQpj8HBSa[+]/TImW[+]5JCeuQeRkm5NMpJWZG3hSuFU="'
-! stdout '"(Ref|Hash)":'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "fc3a09f3dc5cfe0d7a743ea18f1f5226e68b3777"'
 ! stdout '"(Dir|Info|GoMod|Zip)"'
 
 # reuse go mod download vcstest/hello/sub/v9 error result
@@ -210,7 +215,8 @@ stdout '"Reuse": true'
 stdout '"Error":.*no matching versions'
 stdout '"TagPrefix": "sub/"'
 stdout '"TagSum": "t1:47DEQpj8HBSa[+]/TImW[+]5JCeuQeRkm5NMpJWZG3hSuFU="'
-! stdout '"(Ref|Hash)":'
+stdout '"Ref": "HEAD"'
+stdout '"Hash": "fc3a09f3dc5cfe0d7a743ea18f1f5226e68b3777"'
 ! stdout '"(Dir|Info|GoMod|Zip)"'
 
 # reuse go mod download vcstest/hello@nonexist

src/cmd/go/testdata/vcstest/git/issue61415.txt

@@ -0,0 +1,42 @@
+handle git
+
+env GIT_AUTHOR_NAME='Bryan C. Mills'
+env GIT_AUTHOR_EMAIL='[email protected]'
+env GIT_COMMITTER_NAME=$GIT_AUTHOR_NAME
+env GIT_COMMITTER_EMAIL=$GIT_AUTHOR_EMAIL
+
+at 2023-11-14T13:00:00-05:00
+
+git init
+
+git add go.mod nested
+git commit -m 'nested: add go.mod'
+git branch -m main
+
+git tag has-nested
+
+at 2023-11-14T13:00:01-05:00
+
+git rm -r nested
+git commit -m 'nested: delete subdirectory'
+
+git show-ref --tags --heads
+cmp stdout .git-refs
+
+git log --pretty=oneline
+cmp stdout .git-log
+
+-- .git-refs --
+f213069baa68ec26412fb373c7cf6669db1f8e69 refs/heads/main
+08a4fa6bb9c04ffba03b26ae427b0d6335d90a2a refs/tags/has-nested
+-- .git-log --
+f213069baa68ec26412fb373c7cf6669db1f8e69 nested: delete subdirectory
+08a4fa6bb9c04ffba03b26ae427b0d6335d90a2a nested: add go.mod
+-- go.mod --
+module vcs-test.golang.org/git/issue61415.git
+
+go 1.20
+-- nested/go.mod --
+module vcs-test.golang.org/git/issue61415.git/nested
+
+go 1.20