cmd/go: ignore '@' when cleaning local and absolute file path args

Since CL 194600, search.CleanPaths preserves characters after '@' in
each argument. This was done so that paths could be cleaned while
version queries were preserved. However, local and absolute file paths
may contain '@' characters.

With this change, '@' is treated as a normal character by
search.CleanPaths in local and absolute paths.

Fixes #35115

Change-Id: Ia7d37e0a2737442d4f1796cc2fc3a59237a8ddfe
Reviewed-on: https://go-review.googlesource.com/c/go/+/202761
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/cmd/go/internal/search/search.go

@@ -361,18 +361,20 @@ func ImportPathsQuiet(patterns []string) []*Match {
 	return out
 }
 
-// CleanPatterns returns the patterns to use for the given
-// command line. It canonicalizes the patterns but does not
-// evaluate any matches. It preserves text after '@' for commands
-// that accept versions.
+// CleanPatterns returns the patterns to use for the given command line. It
+// canonicalizes the patterns but does not evaluate any matches. For patterns
+// that are not local or absolute paths, it preserves text after '@' to avoid
+// modifying version queries.
 func CleanPatterns(patterns []string) []string {
 	if len(patterns) == 0 {
 		return []string{"."}
 	}
 	var out []string
 	for _, a := range patterns {
 		var p, v string
-		if i := strings.IndexByte(a, '@'); i < 0 {
+		if build.IsLocalImport(a) || filepath.IsAbs(a) {
+			p = a
+		} else if i := strings.IndexByte(a, '@'); i < 0 {
 			p = a
 		} else {
 			p = a[:i]

src/cmd/go/script_test.go

@@ -117,6 +117,7 @@ func (ts *testScript) setup() {
 		"GOSUMDB=" + testSumDBVerifierKey,
 		"GONOPROXY=",
 		"GONOSUMDB=",
+		"PWD=" + ts.cd,
 		tempEnvName() + "=" + filepath.Join(ts.workdir, "tmp"),
 		"devnull=" + os.DevNull,
 		"goversion=" + goVersion(ts),
@@ -414,6 +415,7 @@ func (ts *testScript) cmdCd(neg bool, args []string) {
 		ts.fatalf("%s is not a directory", dir)
 	}
 	ts.cd = dir
+	ts.envMap["PWD"] = dir
 	fmt.Fprintf(&ts.log, "%s\n", ts.cd)
 }
 

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

@@ -1,7 +1,6 @@
-# File system pattern searches should skip sub-modules and vendor directories.
-
 env GO111MODULE=on
 
+# File system pattern searches should skip sub-modules and vendor directories.
 cd x
 
 # all packages
@@ -40,6 +39,24 @@ stderr '^can.t load package: package ./nonexist: cannot find package "." in:\n\t
 ! stderr 'import lookup disabled'
 stderr 'can.t load package: package ./go.mod: cannot find package'
 
+
+# File system paths and patterns should allow the '@' character.
+cd ../@at
+go list $PWD
+stdout '^at$'
+go list $PWD/...
+stdout '^at$'
+
+# The '@' character is not allowed in directory paths that are part of
+# a package path.
+cd ../badat/bad@
+! go list .
+stderr 'directory . outside available modules'
+! go list $PWD
+stderr 'directory . outside available modules'
+! go list $PWD/...
+stderr 'directory . outside available modules'
+
 -- x/go.mod --
 module m
 
@@ -64,3 +81,17 @@ package z
 
 -- x/y/z/w/w.go --
 package w
+
+-- @at/go.mod --
+module at
+
+go 1.14
+-- @at/at.go --
+package at
+
+-- badat/go.mod --
+module badat
+
+go 1.14
+-- badat/bad@/bad.go --
+package bad