================
@@ -0,0 +1,49 @@
+//===--- VirtualArithmeticCheck.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 "VirtualArithmeticCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+void VirtualArithmeticCheck::registerMatchers(MatchFinder *Finder) {
+ const auto PointerExprWithVirtualMethod =
+ expr(hasType(pointerType(pointee(hasDeclaration(
+ cxxRecordDecl(hasMethod(isVirtualAsWritten())))))))
+ .bind("pointer");
+
+ const auto ArraySubscript =
+ arraySubscriptExpr(hasBase(PointerExprWithVirtualMethod));
+
+ const auto BinaryOperators =
+ binaryOperator(hasAnyOperatorName("+", "-", "+=", "-="),
+ hasEitherOperand(PointerExprWithVirtualMethod));
+
+ const auto UnaryOperators =
+ unaryOperator(hasAnyOperatorName("++", "--"),
+ hasUnaryOperand(PointerExprWithVirtualMethod));
+
+ Finder->addMatcher(
+ expr(anyOf(ArraySubscript, BinaryOperators, UnaryOperators)), this);
+}
+
+void VirtualArithmeticCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *PointerExpr = Result.Nodes.getNodeAs<Expr>("pointer");
+ const CXXRecordDecl *PointeeType =
+ PointerExpr->getType()->getPointeeType()->getAsCXXRecordDecl();
+
+ diag(PointerExpr->getBeginLoc(),
+ "pointer arithmetic on class '%0' that declares a virtual function, "
+ "undefined behavior if the pointee is a different class")
+ << PointeeType->getName();
----------------
5chmidti wrote:
The `diag` member function only accepts a `SourceLocation` as the first
parameter, that is correct.
When you stream a `SourceRange` into the diagnostic, that range will be
underlined by the diagnostic engine (and in clangd). The same goes for attached
fix-it hints, which highlight the ranges they change.
E.g.
```
125 | base += 1;
| ^
```
vs
```
125 | base += 1;
| ^~~~
```
when using
```c++
diag(PointerExpr->getBeginLoc(),
"pointer arithmetic on polymorphic class '%0', which can result in "
"undefined behavior if the pointee is a different class")
<< PointeeType->getName()
<< PointerExpr->getSourceRange(); // adding this
```
https://github.com/llvm/llvm-project/pull/91951
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