[clang-tools-extra] [clang-tidy] Avoid expensive AST traversal in RedundantTypenameCheck (PR #170540)

[Yanzuo Liu via cfe-commits]

================
@@ -18,9 +18,13 @@ using namespace clang::ast_matchers;
 namespace clang::tidy::readability {
 
 void RedundantTypenameCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(typeLoc(unless(hasAncestor(decl(isInstantiated()))))
-                         .bind("nonDependentTypeLoc"),
-                     this);
+  Finder->addMatcher(
+      typeLoc(loc(TypeMatcher(anyOf(typedefType(), tagType(),
+                                    deducedTemplateSpecializationType(),
+                                    templateSpecializationType()))),
+              unless(hasAncestor(decl(isInstantiated()))))
+          .bind("nonDependentTypeLoc"),
+      this);
----------------
zwuis wrote:

> Can't we skip the `hasAncestor` part

Seems good for me. The traverse mode of this checker is `TK_IgnoreUnlessSpelledInSource`, so `decl(isInstantiated())` doesn't matches anything IIUC.

https://github.com/llvm/llvm-project/pull/170540