[patch] Add toplevel configure check for MPFR

[Joseph S. Myers]

On Sun, 25 Jul 2004, Paul Brook wrote:

> Gfortran currently requires GMP (GNU Multiple Precision library) for 
> compile-time arithmetic. In order to accurately match target arithmetic we 
> also require MPFR. MPFR is part of GMP, although it is not always enabled.

Note also that the GMP home page <http://www.swox.com/gmp/> says that "In
the next major GMP release, mpfr will not be included.  Users are
encouraged to download mpfr directly from that project's site.".  This may
only be of relevance to the documentation, not the configure tests, though
it would complicate importing GMP into GCC (i.e. we'd need to import both
GMP and MPFR) if we wish to use it outside the Fortran front end (for more
general constant folding of built-in functions).

> +support, ie. specify --enable-mpfr when configuring GMP.  Some common

That should be "i.e.@: specify @option{--enable-mpfr} when configuring
GMP@.".

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
    jsm@polyomino.org.uk (personal mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)