Re: [RFC] Update gmp/mpfr/mpc minimum versions

[Marc Glisse <marc dot glisse at inria dot fr>]

On Tue, 26 Apr 2016, Bernd Edlinger wrote:

> For instance PR libstdc++/69881: gmp.h did this:
>
> #define __need_size_t  /* tell gcc stddef.h we only want size_t */
> #include <cstddef>     /* for size_t */
>
> I've persuaded Jonathan to work around that in libstdc++.
>
> Of course the in-tree build does work with less versions than
> otherwise.

IIUC, the bug only shows up if you compile in C++11 or later, so basically 
g++-6 or later, and there is a workaround in libstdc++ starting from 
version 6 that means that it doesn't cause any problem. So there might be 
a problem if someone tries to build gcc using CXX='g++-5 -std=c++11' or 
CXX='clang++ -stdlib=libc++' on a glibc system (I don't think others use 
__need_size_t?), but those are rather odd cases.

> > > To support gmp-6.1.0 in-tree we have to set AM_CFLAGS=-DNO_ASM
> > > as already done with mpfr.  This was already discussed recently on
> > > this list.
> >
> > Note that gmp-6.1.1 is supposed to be out any day now and will not
> > require -DNO_ASM anymore.
>
> Yes, I know.  I mean, I have tested the patch already with the gmp
> snapshots, but was not aware that it will be available so soon.
> However I think it would not really hurt to allow a little
> more interoperability, even for in-tree builds.
>
> It is just a matter what versions we want to test, I have not really
> any idea where the limits will be, just that it can no longer be 4.3.2.

Even if in-tree builds work with several versions, we may still want to 
document only one as supported.

--
Marc Glisse