[clang-tools-extra] [clang-tidy] Add readability-use-builtin-literals check (PR #76065)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,161 @@
+//===--- UseBuiltinLiteralsCheck.cpp - clang-tidy -------------------------===//
+//
+// 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 "UseBuiltinLiteralsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include <optional>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+namespace {
+
+using RuleOnStd = bool (*)(const LangStandard &LS);
+
+struct Replacement {
+  Replacement(StringRef Seq, const RuleOnStd Std = nullptr)
+      : Seq(Seq), Std(Std) {}
+  bool operator()(const LangOptions &LO) const {
+    return Std ? Std(LangStandard::getLangStandardForKind(LO.LangStd)) : true;
+  }
+  StringRef Seq;
+  RuleOnStd Std;
+};
+
+} // namespace
+
+static const llvm::Regex CharRegex("^(u8|u|U|L)?");
+static const llvm::StringMap<Replacement> CharPrefix({
+    {"char", {""}},
+    {"char8_t", {"u8"}},
+    {"char16_t", {"u"}},
+    {"char32_t", {"U"}},
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PiotrZSL wrote:

Missing check for C++17.

https://github.com/llvm/llvm-project/pull/76065