cmd/go: strip trailing slash from versioned arguments

'go get' accepts arguments of the form path@version, and it passes
them through search.CleanPatterns before querying proxies. With this
change, CleanPatterns preserves text after '@' and will strip trailing
slashes from the patn.

Previously, we did not strip trailing slashes when a version was
present, which caused proxy base URL validation to fail. Module paths
that end with ".go" (for example, github.com/nats-io/nats.go) use
trailing slashes to prevent 'go build' and other commands from
interpreting packages as source file names, so this caused unnecessary
problems for them.

Updates #32483

Change-Id: Id3730c52089e52f1cac446617c20132a3021a808
Reviewed-on: https://go-review.googlesource.com/c/go/+/194600
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/src/cmd/go/internal/search/search.go b/src/cmd/go/internal/search/search.go
index 0e420c99bd..33ab4ae36e 100644
--- a/src/cmd/go/internal/search/search.go
+++ b/src/cmd/go/internal/search/search.go
@@ -363,30 +363,40 @@ func ImportPathsQuiet(patterns []string) []*Match {
 
 // CleanPatterns returns the patterns to use for the given
 // command line. It canonicalizes the patterns but does not
-// evaluate any matches.
+// evaluate any matches. It preserves text after '@' for commands
+// that accept versions.
 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 {
+			p = a
+		} else {
+			p = a[:i]
+			v = a[i:]
+		}
+
 		// Arguments are supposed to be import paths, but
 		// as a courtesy to Windows developers, rewrite \ to /
 		// in command-line arguments. Handles .\... and so on.
 		if filepath.Separator == '\\' {
-			a = strings.ReplaceAll(a, `\`, `/`)
+			p = strings.ReplaceAll(p, `\`, `/`)
 		}
 
 		// Put argument in canonical form, but preserve leading ./.
-		if strings.HasPrefix(a, "./") {
-			a = "./" + path.Clean(a)
-			if a == "./." {
-				a = "."
+		if strings.HasPrefix(p, "./") {
+			p = "./" + path.Clean(p)
+			if p == "./." {
+				p = "."
 			}
 		} else {
-			a = path.Clean(a)
+			p = path.Clean(p)
 		}
-		out = append(out, a)
+
+		out = append(out, p+v)
 	}
 	return out
 }