On Tue, 16 Jun 2020, Jonathan Wakely via Gcc-patches wrote:
> Currently the __atomic_{load,store,exchange,compare_exchange} built-ins
> will happily store values through pointers to const, or use pointers to
> volatile as the input and output arguments. This patch ensures that any
> pointer that will be written through does not point to a const object,
> and only the pointer to the atomic variable can be volatile.
>
> This differs slightly from Clang, which allows the third argument to
> __atomic_exchange (the one that is used to return the old value) to be
> volatile if and only if the first argument is volatile. That doesn't
> seem useful.
>
> For C++ emit errors, but for C use pedwarns that are controlled by
> -Wincompatible-pointer-types.
>
> gcc/c-family/ChangeLog:
>
> * c-common.c (get_atomic_generic_size): Check cv-qualifiers in
> pointer arguments.
>
> gcc/testsuite/ChangeLog:
>
> * c-c++-common/pr95378.c: New test.
>
>
> Tested powerpc64le-linux.
>
> OK for master?
OK.
--
Joseph S. Myers
jos...@codesourcery.com
