[RFC PATCH]: enable building GMP/MPFR in local tree

[Joseph S. Myers]

On Mon, 9 Oct 2006, Mike Stump wrote:

> On Oct 8, 2006, at 1:42 PM, Kaveh R. GHAZI wrote:
> > It turned out to be much easier than I thought to decipher the top level
> > machinery and get GMP/MPFR building inside the GCC tree. :-)
> 
> Some thoughts, if this configures and builds most (all?) of the time, then we
> are changing the portability profile of gcc to be min(gcc,mpfr,gmp) which
> could be < gcc.  If the user has installed a newer gmp/mpfr on the system, do
> we want to use the build tree version anyway?  Can we rm -rf gmp/mpfr from the
> source tree to disable the building of these?  I suspect all the GMPLIBS and
> GMPINC stuff in the configure script is dead after this (with this version of
> the patch), though, it is probably better to leave it in there for now.  What

Clearly --with-system-gmp --with-system-mpfr (like --with-system-zlib) 
would be the natural way to enable using the system copies of these 
libraries rather than building GCC's local copies.  I expect Linux 
distributors would use these options to link with the system shared 
libraries.  We do want to keep something like the existing --with-gmp 
--with-mpfr options as well to say where the system copies are, if they 
aren't in the default compiler / linker search paths.

> is the change in build time?  Do we want to always build it, or only when some
> languages (fortran?) are configured?  And lastly, do we want to do this in
> stage 3?

The patch is clearly something being proposed now for discussion and 
potential commit in stage 1 or 2.  While a proposal as a GCC 4.3 project 
would have been a good idea (in fact, it might still make sense to create 
a project page linked from 
<http://gcc.gnu.org/wiki/GCC_4.3_Release_Planning>), it's not such a big 
project as to require such a proposal.

-- 
Joseph S. Myers
joseph@codesourcery.com