[Bug c/88576] -fno-math-errno causes GCC to consider that malloc does not set errno

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88576

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Aurelien Jarno from comment #2)
> (In reply to Andrew Pinski from comment #1)
> > IIRC malloc setting errno also non standard.
> 
> According to POSIX:
> 
>     The malloc() function shall fail if:
> 
>     [ENOMEM]
>         [CX] [Option Start] Insufficient storage space is available. [Option
> End]
> 
> In that case malloc returns a NULL pointer. However even after adding a
> check for the return value, GCC still optimizes-out saving and restoring
> errno.

POSIX says one thing but C99 says another thing.