Author: Oleksandr T Date: 2024-06-17T19:29:28+02:00 New Revision: 2ebe4794b1bdb3519d5dda7ef39f32d868dfa9b0
URL: https://github.com/llvm/llvm-project/commit/2ebe4794b1bdb3519d5dda7ef39f32d868dfa9b0 DIFF: https://github.com/llvm/llvm-project/commit/2ebe4794b1bdb3519d5dda7ef39f32d868dfa9b0.diff LOG: [Clang] Disallow non-lvalue values in constant expressions to prevent invalid pointer offset computation (#95479) Fixes #95366 Added: clang/test/Sema/integral-to-ptr.c Modified: clang/docs/ReleaseNotes.rst clang/lib/AST/ExprConstant.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 69aea6c21ad39..2bf20bcd71f57 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -859,6 +859,8 @@ Bug Fixes to C++ Support (#GH88081), (#GH89496), (#GH90669) and (#GH91633). - Fixed handling of brace ellison when building deduction guides. (#GH64625), (#GH83368). - Clang now instantiates local constexpr functions eagerly for constant evaluators. (#GH35052), (#GH94849) +- Fixed a failed assertion when attempting to convert an integer representing the diff erence + between the addresses of two labels (a GNU extension) to a pointer within a constant expression. (#GH95366). Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index bf9c9baf25cc6..3a6c8b4f82cca 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -9325,6 +9325,13 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) { Result.IsNullPtr = false; return true; } else { + // In rare instances, the value isn't an lvalue. + // For example, when the value is the diff erence between the addresses of + // two labels. We reject that as a constant expression because we can't + // compute a valid offset to convert into a pointer. + if (!Value.isLValue()) + return false; + // Cast is of an lvalue, no need to change value. Result.setFrom(Info.Ctx, Value); return true; diff --git a/clang/test/Sema/integral-to-ptr.c b/clang/test/Sema/integral-to-ptr.c new file mode 100644 index 0000000000000..b8ab4cb79820d --- /dev/null +++ b/clang/test/Sema/integral-to-ptr.c @@ -0,0 +1,3 @@ +// RUN: %clang_cc1 %s -verify -fsyntax-only -std=c11 + +int x(void) { e: b: ; return &&e - &&b < x; } // expected-warning {{ordered comparison between pointer and integer}} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
