On Thu, 20 Jun 2019 at 12:28, Chris Hall wrote: > > > I find that gcc 4.9.0 onwards defines __STDC_NO_THREADS__ to be '1', > denying support for <threads.h>. Nevertheless, it does support > _Thread_local. > > As of glibc 2.28, <threads.h> appears in the library. I guess that > means some version of gcc will no longer set __STDC_NO_THREADS__ ? > > On gcc.godbolt.org, I find that __STDC_NO_THREADS__ is defined for all > versions up to and including the "trunk". > > But on my machine, __STDC_NO_THREADS__ is no longer set by gcc v9.1.1, > and no longer set by gcc v7.2.0 (which I just built on my machine). > > I note that gcc.godbolt.org has glibc 2.27, while my machine has glibc > 2.28. I'm guessing that something, somewhere is taking that into account. > > 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.
