[clang-tools-extra] [clang-tidy] Add new check: `readability-redundant-typename` (PR #161574)

[Baranov Victor via cfe-commits]

================
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "RedundantTypenameCheck.h"
+#include "clang/AST/TypeLoc.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Sema/DeclSpec.h"
+
+using namespace clang::ast_matchers;
+using namespace clang::ast_matchers::internal;
+
+namespace clang::tidy::readability {
+
+void RedundantTypenameCheck::registerMatchers(MatchFinder *Finder) {
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  const VariadicDynCastAllOfMatcher<TypeLoc, TypedefTypeLoc> typedefTypeLoc;
+  Finder->addMatcher(typedefTypeLoc().bind("typeloc"), this);
+
+  if (!getLangOpts().CPlusPlus20)
+    return;
+
+  // NOLINTBEGIN(readability-identifier-naming)
+  const VariadicDynCastAllOfMatcher<Stmt, CXXNamedCastExpr> cxxNamedCastExpr;
+  const auto inImplicitTypenameContext = [&] {
----------------
vbvictor wrote:

I think that adding [cognitive complexity](https://clang.llvm.org/extra/clang-tidy/checks/readability/function-cognitive-complexity.html) to code (by more nesting) is worse that a pair of `()`.
My eyes automatically skip `(`, `)` in matchers so `inImplicitTypenameContext` and `inImplicitTypenameContext()` looks the same to me.

https://github.com/llvm/llvm-project/pull/161574