todo: move .gitignore loading into walk where it has access to trie

walk/config.go

@@ -112,19 +112,6 @@ func (cr *Configurer) Configure(c *config.Config, rel string, f *rule.File) {
 	}
 
 	c.Exts[walkName] = wcCopy
-
-	// TODO: read the gitignore file even if gitignoring is not enabled in this dir
-	// because it might be enabled in a subdir.
-	if wcCopy.gitignoreEnabled {
-		// Collect gitignore style ignore files in this directory.
-		ignoreFilePath := path.Join(c.RepoRoot, rel, ".gitignore")
-
-		// TODO: reuse the fs entry already created by gazelle to avoid os.Open,
-		// see https://github.com/bazelbuild/bazel-gazelle/pull/1737.
-		if ignoreReader, ignoreErr := os.Open(ignoreFilePath); ignoreErr == nil {
-			wcCopy.gitignore = createGitIgnorer(wcCopy.gitignore, rel, ignoreReader)
-		}
-	}
 }
 
 type isIgnoredFunc = func(string) bool

walk/walk.go

@@ -161,6 +161,15 @@ func visit(c *config.Config, cexts []config.Configurer, knownDirectives map[stri
 	c = configure(cexts, knownDirectives, c, rel, f)
 	wc := getWalkConfig(c)
 
+	// Load any .gitignore file
+	if _, hasIgnore := trie.children[".gitignore"]; hasIgnore {
+		// Collect gitignore style ignore files in this directory.
+		ignoreFilePath := path.Join(c.RepoRoot, rel, ".gitignore")
+		if ignoreReader, ignoreErr := os.Open(ignoreFilePath); ignoreErr == nil {
+			wc.gitignore = createGitIgnorer(wc.gitignore, rel, ignoreReader)
+		}
+	}
+
 	if wc.isExcluded(rel) {
 		return
 	}