__STDC_NO_THREADS__ and late model gcc/glibc

Jonathan Wakely jwakely.gcc@gmail.com
Fri Jun 21 09:51:00 GMT 2019


On Fri, 21 Jun 2019 at 10:39, Chris Hall wrote:
>
> On 20/06/2019 13:17, Jonathan Wakely wrote:
> > On Thu, 20 Jun 2019 at 12:28, Chris Hall wrote:
> ...
> >> I have looked everywhere I can think of to find where
> >> __STDC_NO_THREADS__ is configured... but to no avail :-(
> >>
> >> Does anyone know what I should expect, or where I should look to find
> >> out, please ?
>
> > Glibc provides it in the /usr/include/stdc-predef.h file which is
> > implicitly pre-included by GCC.
>
> Ah ha !  Thank you.
>
> I guess that accounts for the "predefined" _STDC_PREDEF_H.
>
> AFAICS, the decision to "preinclude" <stdc-predef.h> is made when gcc is
> built, depending on the target.

Right, see gcc/config/glibc-c.c

>  Deep Magic of the First Magnitude.

:-)



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