[PATCH]: fix the --with-mpfr-dir=PATH configure flag

Kaveh R. GHAZI ghazi@caip.rutgers.edu
Mon Nov 20 02:30:00 GMT 2006

On Sun, 19 Nov 2006, Mark Mitchell wrote:

> Kaveh R. GHAZI wrote:
> > For this discussion, it's actually neither.  The installation logic
> > remains the same across mpfr releases.  The second problem you mentioned
> > (that the GNU/linux distributors diddle with the locations) also occurs
> > but I solved it with a separate patch also cc:ed to you here:
> > http://gcc.gnu.org/ml/gcc-patches/2006-11/msg01310.html
> I'm sorry.  I freely confess that I have hard a time keeping up with all
> that's going on sometimes.  Thanks for being patient with me!
> > The problem problem for this patch is not the installation logic, it's the
> > mpfr >build directory< structure.  We care about that because the flag I'm
> > fixing is GCC's --with-mpfr-dir=PATH which allows one to specify a path to
> > an mpfr source directory where you just compiled mpfr.  Presumably this is
> > for people who don't want to install mpfr just to build gfortran.
> I didn't fully understand this before.  I'm sorry.
> This switch gives us an dependency on the internals of a package we do
> not maintain.  That sounds like a bad idea.  Part of the justification
> for this may be people who want to build these libraries in-tree, but I
> think we should just stop trying to support that -- until/unless the
> top-level build machinery begins to support staged installations, and,
> then we still wouldn't need special build-directory logic.
> So, I think that this switch should be removed from mainline and 4.2.
> It's just not that hard to type "make install".  Even though the issue
> at hand is 4.1, not mainline, I do think the mainline question is
> relevant, because the existence of the switch means that we might well
> see the same kind of breakage in 4.2, and every future GCC release.
> Given that new libmpfr is causing problems for GCC 4.1 users, I agree
> with you that your patch is appropriate there.  Removing the option from
> 4.1.2 would be a needless incompatibility with 4.1.1.  However, I think
> that we should force ourselves to reach consensus on future releases
> before applying to 4.1, so that we don't get to this same situation with
> 4.2.
> Thanks,
> Mark Mitchell

Uh... okay.  That's definitely one way to fix the bug.  :-)

I'm cc'ing the fortran list since they have the most experience with mpfr
and usage in previous GCC releases.  I'd like their opinion on how often
this configure flag is used so we can achieve the consensus you seek.
(Bear in mind I'm initiating this patch based on a bug report from a user,
so it's not just a gcc developer issue.)

SUMMARY for FORTRAN LIST: The GCC configure flag --with-mpfr-dir=PATH is
broken when used with mpfr-2.2.0.  A patch to fix it was approved and
installed on mainline and 4.2.  Then after trying to persuade Mark we
should further backport it he decided the flag is fatally flawed and
should be removed in 4.2 and mainline, but fixed in 4.1 (and presumably

(The analogous --with-gmp-dir=PATH flag currently works fine everywhere.
I would assume that if we remove the mpfr flag, then the gmp one would go
too for the sake of consistency.)

The gory details start here:


Kaveh R. Ghazi			ghazi@caip.rutgers.edu

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