[clang-tools-extra] [clang-tidy] Added bugprone-exception-rethrow check (PR #86448)

[via cfe-commits]

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@@ -0,0 +1,50 @@
+//===--- ExceptionRethrowCheck.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 "ExceptionRethrowCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+AST_MATCHER(VarDecl, isExceptionVariable) { return Node.isExceptionVariable(); }
+} // namespace
+
+void ExceptionRethrowCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      cxxThrowExpr(unless(isExpansionInSystemHeader()),
+                   anyOf(unless(has(expr())),
+                         has(declRefExpr(to(varDecl(isExceptionVariable()))))),
+                   optionally(hasAncestor(cxxCatchStmt().bind("catch"))))
+          .bind("throw"),
+      this);
+}
+
+void ExceptionRethrowCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedThrow = Result.Nodes.getNodeAs<CXXThrowExpr>("throw");
+
+  if (const Expr *ThrownObject = MatchedThrow->getSubExpr()) {
+    diag(MatchedThrow->getThrowLoc(),
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isuckatcs wrote:

In this particular case even headless application of the fixes won't lead to non-compiling code, right? 

I think our goal should be to let the developers know about the issue, and offer them a convenient way to fix it instead of having them manually update every occurence. A lot of other bugprone checks also offer `FixItHint`s, so it's not like with this check it will introduce something they are not used to.

https://github.com/llvm/llvm-project/pull/86448