[clang-tools-extra] [clang-tidy] Add readability-redundant-lambda-parentheses check (PR #190438)

[Victor Chernyakin via cfe-commits]

================
@@ -0,0 +1,82 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "RedundantLambdaParenthesesCheck.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+namespace {
+
+AST_MATCHER(LambdaExpr, hasNoParameters) {
+  return Node.getCallOperator()->getNumParams() == 0;
+}
+
+AST_MATCHER(LambdaExpr, hasExplicitOrGenericParameters) {
+  return Node.hasExplicitParameters() || Node.isGenericLambda();
+}
+
+AST_MATCHER(LambdaExpr, isGenericLambdaInCxx20OrLater) {
+  return !Node.isGenericLambda() ||
+         Finder->getASTContext().getLangOpts().CPlusPlus20;
+}
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localspook wrote:

Since all these matchers are only ever used together, I think it may be simpler to merge them into one `hasRedundantParens` matcher.

https://github.com/llvm/llvm-project/pull/190438