From 96f4d6655761d8717885e259c3ca93015f2226a9 Mon Sep 17 00:00:00 2001
From: Aaron Son <aaron@dolthub.com>
Date: Sat, 19 Aug 2023 09:24:35 -0700
Subject: [PATCH] fix: go_repository: never shadow a module with a
 compatibility mapping for major versions. (#1608)

Fixes #1595.

Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>
---
 repo/remote.go      | 23 ++++++++++++++++++-----
 repo/remote_test.go | 12 ++++++++++++
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/repo/remote.go b/repo/remote.go
index 361a3242d..1422d4560 100644
--- a/repo/remote.go
+++ b/repo/remote.go
@@ -180,15 +180,28 @@ func NewRemoteCache(knownRepos []Repo) (r *RemoteCache, cleanup func() error) {
 	// allowed to use them. However, we'll return the same result nearly all
 	// the time, and simpler is better.
 	for _, repo := range knownRepos {
-		path := pathWithoutSemver(repo.GoPrefix)
-		if path == "" || r.root.cache[path] != nil {
+		newPath := pathWithoutSemver(repo.GoPrefix)
+		if newPath == "" {
 			continue
 		}
-		r.root.cache[path] = r.root.cache[repo.GoPrefix]
+		// Avoid adding the semver-less path for this module if there
+		// is another known module which already covers this path.
+		// See https://github.com/bazelbuild/bazel-gazelle/issues/1595.
+		found := false
+		for prefix := newPath; prefix != "." && prefix != "/"; prefix = path.Dir(prefix) {
+			if _, ok := r.root.cache[prefix]; ok {
+				found = true
+				break
+			}
+		}
+		if found {
+			continue
+		}
+		r.root.cache[newPath] = r.root.cache[repo.GoPrefix]
 		if e := r.remote.cache[repo.GoPrefix]; e != nil {
-			r.remote.cache[path] = e
+			r.remote.cache[newPath] = e
 		}
-		r.mod.cache[path] = r.mod.cache[repo.GoPrefix]
+		r.mod.cache[newPath] = r.mod.cache[repo.GoPrefix]
 	}
 
 	return r, r.cleanup
diff --git a/repo/remote_test.go b/repo/remote_test.go
index c7ddcaec6..b4149dff6 100644
--- a/repo/remote_test.go
+++ b/repo/remote_test.go
@@ -288,6 +288,18 @@ func TestMod(t *testing.T) {
 			}},
 			wantModPath: "example.com/known",
 			wantName:    "known",
+		}, {
+			desc:       "semver_less_path_is_safe",
+			importPath: "example.com/known/internal/endpoints",
+			repos: []Repo{{
+				Name:     "known",
+				GoPrefix: "example.com/known",
+			}, {
+				Name:     "known_internal_endpoints_v2",
+				GoPrefix: "example.com/known/internal/endpoints/v2",
+			}},
+			wantModPath: "example.com/known",
+			wantName:    "known",
 		}, {
 			desc:        "lookup",
 			importPath:  "example.com/stub/v2/foo",