Because this specific UB is static (not usually the case) both gcc and clang will flag it if Wsequence-point is enabled (and it is part of Wall) (technically th

Because this specific UB is static (not usually the case) both gcc and clang will flag it if Wsequence-point is enabled (and it is part of Wall) (technically the clang warning is Wunsequenced but aliased to the GCC version). edit: apparently Wunsequenced is enabled by default so clang should warn you out of the box.