Re: Minimum GCC version for building glibc

["Carlos O'Donell" <carlos at redhat dot com>]

On 10/31/2014 10:03 AM, Joseph S. Myers wrote:
> Currently the minimum GCC version for building glibc is 4.4.  I propose 
> that we increase this to either 4.6 or 4.7.  (Release branches before 4.8 
> are no longer maintained, but I don't propose 4.8 as a minimum.)
> 
> If we require at least 4.7 that means various C11 features are available, 
> and __atomic_* (as discussed, we may not want to use __atomic_* on all 
> architectures, but with 4.7 __atomic_* will be available for use when 
> desired).  Whatever version we choose, __GNUC_PREREQ conditionals in 
> non-installed files not shared with gnulib or other projects would be 
> removed if no longer relevant with the new minimum requirement.
> 
> Questions:
> 
> * Should 4.6 or 4.7 be the minimum?

GCC 4.7 please.

In deciding this I looked at both the features we want from C11, and what
Red Hat supports in RHEL6 and RHEL6.

In RHEL6 we have DTS with GCC 4.7 support which makes it possible to still
build and test newer glibc variants on those systems, which is useful for
certain kinds of testing we do.

Requiring 4.8 makes things a little more difficult, but possible, in that
F20 has gcc 4.8, DTS 2.0 provides GCC 4.8 to all versions of RHEL, so we
should be covered there.
 
> * Should we give a recommendation for a specific version or "X or newer", 
> or just specify the minimum without a separate recommendation?  
> Experience says the recommendation gets out of date (I don't think 4.6 is 
> really likely that widely used for building glibc now), and none of the 
> other components come with such a recommendation in install.texi.

I think "GCC 4.6 or newer" is good enough.

Cheers,
Carlos.