ANNOUNCE: GHC version 6.8.2

[Manuel M T Chakravarty]

Ian Lynagh:
> On Mon, Dec 17, 2007 at 12:53:32PM +1100, Manuel M T Chakravarty  
> wrote:
>>
>> It seems to be a matter of the precise ld call parameters whether the
>> gmp/ in the ghc repo is used or the external one.  In using the  
>> stage1
>> compiler to link the stage2 compiler, the external one wins, but in
>> linking other programs with the stage1 compiler, the internal gmp  
>> wins.
>
> Hmm, that's interesting. The internal GMP should only be built if
> HaveLibGmp != YES and HaveFrameworkGMP != YES, in which case it should
> always use the internal one, and there shouldn't be an external one to
> use anyway.

At least on Mac OS (and also on Windows) and probably any other  
platform, except Linux, this is IMHO the wrong policy.

FWIW, the current build system uses the internal GMP even if another  
one is installed (at least a non-framework one).  However, the  
behaviour is a bit flacky (eg, if package readline is also used, it  
uses the external GMP due to some difference between the Darwin linker  
and other Unix linkers).  It also needs to recompile installPackage  
and ifBuildable with the stage1 compiler (like the stuff below utils/)  
as both go into a binary distribution.  I have fixed this all and am  
currently validating a patch.

>> Actually, I think, we should use the gmp/ in the ghc repo by default
>
> If you want to use it when building a bindist that might be used on
> other computers you shold be able to set
>    HaveLibGmp = NO
>    HaveFrameworkGMP = NO
> in mk/build.mk, although I'm not sure I've ever tried it.
>
> The disadvantages of using it are it might be out of date (we had some
> Windows segfaults a while ago that were fixed by updating the in-tree
> gmp) and wasted space.

Sure we waste some space, but the alternative is worse.  Programs  
compiled with GHC will essentially not run on any computer, but the  
one where they were compiled.  For example, the number of Macs with  
gmp installed is minuscule.  The default should be to build programs  
that run everywhere with minimal hassle (not programs that save some  
space, but are unusable on most computers).

Manuel

PS: Readline is a different matter.  It is used by ghci, so needs to  
be installed with ghc, but this dependency does not propagate into  
compiled programs, unless a program explicitly uses package readline  
(at which point I believe it is on this program's developer to make  
sure their users have readline available).