Re: compiler standards (and/or min gcc version) supported with installed headers ?

[Mike Frysinger <vapier at gentoo dot org>]

On Friday 28 December 2012 23:57:51 Mike Frysinger wrote:
> seems like something we should have spelled out in the manual and/or faq.
> what standards do we want to support with installed headers ?  and
> similarly, what min gcc version ?
> 
> going by features.h, it seems like we support very old standards, which
> means it should be easy to support old gcc versions too.  a quick grep on
> my system shows we have __GNUC_PREREQ(2,0).

as a data point, nptl hasn't worked with at least <=gcc-2.95.3 on x86 targets 
due to an anonymous union in bits/pthreadtypes.h (pthread_mutex_t).

bits/libc-lock.h defines __libc_cleanup_region_start which uses PTFAVAIL & 
__libc_ptf_call_always which isn't defined anywhere.  the header also uses 
LLL_LOCK_INITIALIZER which isn't setup.  nptl's internal libc-lockP.h appears 
to have most of that stuff.

bits/resource.h also has a number of anonymous unions in struct rusage.

there are also attributes unconditionally used such as:
	stdlib.h: malloc (new to gcc-3.0)
	mathcalls.h: nonnull (new to gcc-3.3)
	stdlib.h: alloc_size (new to gcc-4.3)
-mike

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