Re: [PING][PATCH][WIP] have configure probe prefix for gmp/mpfr/mpc [PR44425]

[Alexandre Oliva <oliva@gnu.org>]

Hello, Eric,

On Jun  9, 2022, Eric Gallager <egall@gwmail.gwu.edu> wrote:

> (cc-ing the build machinery maintainers listed in MAINTAINERS this time)

Thanks, I'd missed it the first time.

> On Thu, Jun 2, 2022 at 11:53 AM Eric Gallager <egall@gwmail.gwu.edu> wrote:

>> So, I'm working on fixing PR bootstrap/44425, and have this patch to
>> have the top-level configure script check in the value passed to
>> `--prefix=` when looking for gmp/mpfr/mpc. It "works" (in that
>> configuring with just `--prefix=` and none of
>> `--with-gmp=`/`--with-mpfr=`/`--with-mpc=` now works where it failed
>> before), but unfortunately it results in a bunch of duplicated
>> `-I`/`-L` flags stuck in ${gmplibs} and ${gmpinc}... is that
>> acceptable or should I try another approach?

I wonder if it would make sense to add -L${libdir} and -I${includedir}
to host flags.  It would obviate the explicit flag-setting for each of
the libs, and it would address the apparent double-setting when prefix
is set, or confusingly partial overrides when --with-*-include and
--with-*-lib are used.

It would be IMHO preferrable to use libdir and includedir, rather than
prefix, especially for cases in which exec_prefix != prefix, but takes
some work for libdir and includedir to be expanded correctly during
configure.  E.g., libdir is normally set to ${exec_prefix}/lib, and
exec_prefix defaults to ${prefix}, but a shell won't expand multiple
layers of macros like make does, so configure needs some help with that.

-- 
Alexandre Oliva, happy hacker                https://FSFLA.org/blogs/lxo/
   Free Software Activist                       GNU Toolchain Engineer
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