Re: [PATCH]: bump minimum MPFR version, (includes some fortran bits)

[Geoff Keating <geoffk at geoffk dot org>]

On 26/10/2008, at 12:25 PM, Kaveh R. Ghazi wrote:

> From: "Geoff Keating" <geoffk@geoffk.org>
>
> > I found that simply building MPFR in a non-default location  
> > (configure
> > --prefix && make) and then pointing GCC at it with --with-mpfr, as in
> > the installation instructions, causes the bootstrap to fail when  
> > first
> > running xgcc, because xgcc can't find the built MPFR dynamic library.
>
> First I'd like to thank you for running your regression tester, and  
> I'm
> sorry this upgrade cause you so much difficulty.
>
> The issue you describe is PR 21547.
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21547
>
> It's important IMHO to point out that this issue is not confined to  
> MPFR.
> While MPFR's more stringent version requirements expose the problem  
> more
> often, you'll find the same issue with GMP as well if you compile and
> install your own copy of that library in a non-default location.
>
> Basically, the problem is that the bootstrap process doesn't encode
> the -rpath during the link process of cc1.  Doing this in a portable  
> fashion
> and resolving the PR requires linking cc1 et al. with libtool.  I  
> don't have
> any experience with libtool myself.  However since we use it  
> elsewhere in
> GCC, it may be easy to incorporate.
>
> (Any libtool experts available to help out, or at least talk us  
> through the process?)
>
> > If this is what users (or even developers) of GCC are supposed to be
> > doing, I'd suggest more documentation on what to do and how to do it.
>
> I think the steps you (or your assistant) went through was  
> unfortunately
> unnecessarily complicated.  The solution I use is to build MPFR and/ 
> or GMP
> using --disable-shared.  Then you can install them anywhere you  
> like, pass
> the location with --with-{mpfr,gmp} to GCC and since only the static  
> library
> is available everything links and runs fine.

I did consider this but wasn't sure it would work, and it didn't  
really seem less complicated, because then I'd have had to change the  
build scripts to figure out where MPFR was in order to pass the flag.

> Do you think putting this recommendation in the docs somewhere would  
> have
> been useful to you in this situation?  If so, I would be happy to  
> prepare a
> patch.

Yes, if that's what people are expected to do, it would be good to  
document it.

I guess my real question was, "what do typical developers actually do,  
or are expected to do, to handle this"?  I'd like the regression  
tester to be doing what everyone else does, so as to be a more  
accurate test of how GCC is really built.

Does everyone really type --with-mpfr=.... on every build?  Looking at  
gcc-testresults, I see:

Kaveh: yes
Joey Ye: no
HJ: no
Guerby: yes
Andreas Jaeger: no
Dave Anglin: no
Janis: yes
Gerald Pfeifer: no
Diego: yes
Andreas Krebbel: no

It seems like mostly, anyone using the compiler farm has to use --with- 
mpfr, and otherwise people avoid it.

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