cmd/go/internal/modload: make QueryPattern consider current versions

QueryPattern will now look up the current version of a module (if any)
before invoking queryProxy. This changes the interpretation of some
patterns (like "upgrade") and avoids the need to download earlier
versions for earlier versions when the current version is
+incompatible.

Fixes #37574

Change-Id: I4089d6099236493df13a7f88a252b5e5e556d383
Reviewed-on: https://go-review.googlesource.com/c/go/+/231599
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/src/cmd/go/internal/modload/query.go b/src/cmd/go/internal/modload/query.go
index f8ea7e6309..5e9cfdcfe3 100644
--- a/src/cmd/go/internal/modload/query.go
+++ b/src/cmd/go/internal/modload/query.go
@@ -455,8 +455,9 @@ func QueryPattern(pattern, query string, allowed func(module.Version) bool) ([]Q
 
 	err := modfetch.TryProxies(func(proxy string) error {
 		queryModule := func(path string) (r QueryResult, err error) {
+			current := findCurrentVersion(path)
 			r.Mod.Path = path
-			r.Rev, err = queryProxy(proxy, path, query, "", allowed)
+			r.Rev, err = queryProxy(proxy, path, query, current, allowed)
 			if err != nil {
 				return r, err
 			}
@@ -508,6 +509,15 @@ func modulePrefixesExcludingTarget(path string) []string {
 	return prefixes
 }
 
+func findCurrentVersion(path string) string {
+	for _, m := range buildList {
+		if m.Path == path {
+			return m.Version
+		}
+	}
+	return ""
+}
+
 type prefixResult struct {
 	QueryResult
 	err error