[clang-tools-extra] [clang-tidy] Add check 'bugprone-cast-to-struct' (PR #153428)

[Balázs Kéri via cfe-commits]

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@@ -0,0 +1,39 @@
+//===--- CastToStructCheck.h - clang-tidy -----------------------*- C++ -*-===//
+//
+// 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_BUGPRONE_CASTTOSTRUCTCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_CASTTOSTRUCTCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::bugprone {
+
+/// Finds casts from pointers to struct or scalar type to pointers to struct
+/// type.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/cast-to-struct.html
+class CastToStructCheck : public ClangTidyCheck {
+public:
+  CastToStructCheck(StringRef Name, ClangTidyContext *Context);
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.C99;
----------------
balazske wrote:

I think in C++ the problem can be handled in different way. C-style cast is discouraged in C++, so all C style casts should be converted to other kind of cast (this is job of another checker, probably it exists already). The `reinterpret_cast` indicates already by syntax that it is a potentially dangerous operation and many uses of `reinterpret_cast` would be likely found by the checker (if it checks for it in similar way), so a checker is not much more than find all uses of `reinterpret_cast`. It is possible to check exact data layout but probably still many false positives would appear. Additionally in C++ the casting rules are more complicated at least because inheritance.

https://github.com/llvm/llvm-project/pull/153428