Re: [Patch] Bump minimum required MPFR version

[Richard Guenther <richard dot guenther at gmail dot com>]

On Sun, May 6, 2012 at 7:24 PM, Janne Blomqvist
<blomqvist.janne@gmail.com> wrote:
> On Sun, May 6, 2012 at 2:39 PM, Richard Guenther
> <richard.guenther@gmail.com> wrote:
>> On Sun, May 6, 2012 at 10:33 AM, Janne Blomqvist
>> <blomqvist.janne@gmail.com> wrote:
>>> Hi,
>>>
>>> in http://gcc.gnu.org/install/prerequisites.html we say that GCC
>>> requires at least MPFR 2.4.2, but in the toplevel configure.ac we only
>>> require 2.3.1, printing a warning that the result is likely to be
>>> buggy if the version is lower than 2.4.2.
>>>
>>> The attached patch bumps the minimum version to 2.4.0. We started
>>> requiring 2.3.1, which was released on 2008-01-29, on 2009-04-08, that
>>> is, about 1 year and a few months after the release. MPFR 2.4.0 was
>>> released on 2009-01-26, so by now it's 3 years old. And by the time we
>>> release 4.8 it's most likely over 4 years old already.
>>>
>>> For some background, the fortran frontend recently started using
>>> mpfr_fmod to fix some bugs in the constant folding of the MOD and
>>> MODULO intrinsics, effectively requiring at least MPFR 2.4.0 in order
>>> to build.
>>>
>>> Also, if this patch is accepted the middle-end could be modified to
>>> constant fold BUILT_IN_FMOD{F,,L} relatively easily, something which
>>> isn't done today.
>>>
>>> Ok for trunk?
>>
>> Please make the check match documentation, thus 2.4.2, not 2.4.0.
>
> Something like the attached patch? FWIW, this removes the distinction
> we have between "buggy, but builds" and "ok".
>
> Ok for trunk?

The change that bumped the documented requirement was logged with

+2010-01-31  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+       * doc/install.texi: Update recommended GMP/MPFR/MPC versions.

which suggests a recommended version.  So I'd revert my earlier comment
and if 2.4.0 builds ok then we should check for that version instead.

Thus, the earlier patch is ok.

Thanks,
Richard.



> 2012-05-06 ?Janne Blomqvist ?<jb@gcc.gnu.org>
>
> ? ? ? ?* configure.ac: Bump minimum MPFR version to 2.4.2.
> ? ? ? ?* configure: Regenerated.
>
>
>
> --
> Janne Blomqvist