On 28/02/2020 15:27, Chris Hall wrote:
On 28/02/2020 01:01, Jim Wilson wrote:
On Thu, Feb 27, 2020 at 7:20 AM Chris Hall <gcc@xxxxxxx> wrote:
Now, the Standard also tells us that _Atomic(uint64_t) and uint64_t may
have different sizes, representations and alignment. So I guess:
bar = atomic_fetch_add(&bar, 1) ;
should be an error ?
__atomic_fetch_add accepts any integer or pointer type. So the fact
that _Atomic(uint64_t) and uint64_t may be different types is not a
problem, as long as they are still integer types. This works like an
overloaded function in C++.
https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/_005f_005fatomic-Builtins.html#g_t_005f_005fatomic-Builtins
Sure. But the Standard atomic_fetch_add() takes an _Atomic(xxx)* (as
the first parameter), and for the reasons given, I understand that
uint64_t* is not compatible with _Atomic(uint64_t)*.
FWIW: clang gets this right, and where the Standard says a parameter
must be an _Atomic(foo_t)* [for a standard atomic_xxx()], clang rejects
foo_t* arguments.
Chris
