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Re: C++ PATCH to change default dialect to C++14
- From: Jim Wilson <jim dot wilson at linaro dot org>
- To: Jason Merrill <jason at redhat dot com>, gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 01 Jul 2015 21:10:05 -0700
- Subject: Re: C++ PATCH to change default dialect to C++14
- Authentication-results: sourceware.org; auth=none
- References: <559430F3 dot 2040109 at redhat dot com>
On 07/01/2015 11:26 AM, Jason Merrill wrote:
> I've been threatening to do this for a couple of months, and now that
> the regressions are under control I think it's time. This patch changes
> the default C++ dialect to C++14.
>
> Tested x86_64-pc-linux-gnu, applying to trunk.
This causes a build failure on Ubuntu 14.04 LTS (Trusty) for x86_64 and
armhf and probably others. All of the graphite*.c files fail with
/home/wilson/FOSS/GCC/X-palantir/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include/cstddef:51:11:
error: â::max_align_tâ has not been declared
using ::max_align_t;
This is a known gmp problem, documented in PR56019 and in
https://gcc.gnu.org/gcc-4.9/porting_to.html
near the bottom where it discusses cstddef.h changes. Except the
cstddef.h changes didn't matter until C++11 or later became the default.
This is apparently fixed in gmp 6.0.0. I haven't had a chance to try
that yet. The prereqs section on doc/install.texi says we need gmp
4.3.2 or later, so it appears that this needs to change too.
This is maybe only a problem if you have the isl libraries installed.
Jim