[clang-tools-extra] [clang-tidy] Add redundant qualified alias check (PR #180404)

[Baranov Victor via cfe-commits]

================
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTQUALIFIEDALIASCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTQUALIFIEDALIASCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Finds identity type aliases to qualified names that can be expressed as
+/// using-declarations.
+///
+/// For the user-facing documentation see:
+/// https://clang.llvm.org/extra/clang-tidy/checks/readability/redundant-qualified-alias.html
+class RedundantQualifiedAliasCheck : public ClangTidyCheck {
+public:
+  RedundantQualifiedAliasCheck(StringRef Name, ClangTidyContext *Context);
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus11; // C++11 or later.
----------------
vbvictor wrote:

```suggestion
    return LangOpts.CPlusPlus11;
```
It's known behavior for everyone working in clang-tidy, no need to specify here.

https://github.com/llvm/llvm-project/pull/180404