[clang-tools-extra] [clang-tidy] Add performance-expensive-value-or check (PR #200166)

[Yanzuo Liu via cfe-commits]

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Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/200166 at github.com>


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@@ -0,0 +1,174 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "ExpensiveValueOrCheck.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "../utils/TypeTraits.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+static bool hasOperatorStar(const CXXRecordDecl *RD) {
+  return llvm::any_of(RD->methods(), [](const CXXMethodDecl *M) {
+    return M->getOverloadedOperator() == OO_Star;
+  });
+}
+
+static StringRef findValueMethod(const CXXRecordDecl *RD) {
+  for (const auto *M : RD->methods()) {
+    if (!M->getDeclName().isIdentifier())
+      continue;
+    StringRef Name = M->getName();
+    if (Name == "value" || Name == "Value")
+      return Name;
+  }
+  return {};
+}
----------------
zwuis wrote:

Does it work for libc++ implementation?

```cpp
struct base {
  T operator*();
  T value();
};
struct optional : base {
  using base::operator*;
  using base::value;
};
```

If I remember correctly, you can use `DeclContext::lookup`.

https://github.com/llvm/llvm-project/pull/200166