GMP, MPFR and VS version compatibility

[brg at gladman.plus.com]

>
> "Michael"'s description of his MSVS build problems
> lend further support to my argument that using Visual
> Studio to build libraries like GMP and MPFR is asking
> for trouble.
>
> Brian will, I hope, forgive me (again) for "dissing"
> (again) this approach, but having to re-tool your
> projects because of changes in MSVS would seem to me
> to be an ominous portent for ongoing maintenance!

Hi Jim,

Please don't worry on my behalf since I am used to people here 'dissing'
pretty well anything to do with Microsoft irrespective of whether the
criticism is deserved.  In this case I don't believe it is.

Michael's problem is not one of having to re-tool as a result of MSVS
changes since MS has always provided good mechanisms for moving projects
from older to newer VC++ versions.  In consequence anyone who builds GMP
with an MSVC tool chain is very unlikely to have any maintenance problems
(I have never had any such problems in 10+ years).

The problem in Michael's case is that he wants to move _backwards_ from a
later to an earlier version. And it's no more an MSVC issue than it is a
GNU/GCC/UNIX/LINUX one that moving in this direction is likely to be
problematic.

In my view the major maintenance issues in providing GMP in both
environments are those of coping with the changes needed to exploit new
processors and new processor features. The specific GCC/MSVC maintenance
issues are the different x64 ABI, the different assembler code tool chains
(M4/GAS vs YASM) and the different assembler syntax (although both gas and
YASM are now bilingual).

 best regards to all,

    Brian Gladman