================ @@ -433,6 +433,26 @@ Attribute Changes in Clang - Fix a bug where clang doesn't automatically apply the ``[[gsl::Owner]]`` or ``[[gsl::Pointer]]`` to STL explicit template specialization decls. (#GH109442) +- Introduced ``__attribute__((wraps))`` which can be added to type or variable + declarations. Using an attributed type or variable in an arithmetic + expression will define the overflow behavior for that expression as having + two's complement wrap-around. These expressions will not be instrumented by + overflow sanitizers nor will they cause integer overflow warnings. They also + cannot be optimized away by some eager UB optimizations as the behavior of + the arithmetic is no longer "undefined". + + There is also ``__attribute__((no_wraps))`` which can be added to types or + variable declarations. Types or variables with this attribute may be + instrumented by overflow sanitizers, if enabled. Note that this matches the + default behavior of integer types. So, in most cases, ``no_wraps`` serves + purely as an annotation to readers of code that a type or variable really + shouldn't wrap-around. ``__attribute__((no_wraps))`` has the most function + when paired with `Sanitizer Special Case Lists (SSCL) + <https://clang.llvm.org/docs/SanitizerSpecialCaseList.html>`_. + + These attributes are only valid for C, as there are built-in language ---------------- JustinStitt wrote:
No, it won't break the build. You will get an ignored attribute warning and the attributes won't be applied or have any effect. (I'll document this). These attributes are relatively well supported in C++ but that language has many more ways for the attribute to disappear unexpectedly. This attribute is mostly needed in C (as there aren't any alternatives). https://github.com/llvm/llvm-project/pull/115094 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
