Re: lib/57312: Missing atomic symbols generated by gcc

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Thu, 30 Mar 2023 21:05:01 +0000 (UTC)
> From: Joerg Sonnenberger <joerg%bec.de@localhost>
> 
> I strongly object to adding implementations that have hidden bugs when
> used with shared memory, signals and other situations. I'd go a step
> further and would ask to de-orbit SPARCv8 SMP just for that alone. HPPA
> etc doesn't matter as RAS is fine for shared memory.

These aren't hidden bugs.  They are spelled out in the C standard:

   When the processing of the abstract machine is interrupted by
   receipt of a signal, the values of objects that are neither
   lock-free atomic objects nor of type volatile sig_atomic_t are
   unspecified....  The value of any object modified by the handler
   that is neither a lock-free atomic nor of type volatile
   sig_atomic_t becomes indeterminate when the handler exits....

> I'd also note that the whole atomic API is majorly broken for the
> non-lockfree case, but I guess no one else cares enough about the hidden
> bugs... For those that doesn't care, they can use -latomic.

Is this part of the contract of using C11 in NetBSD?  If so, we should
really ship libatomic.