[PPL-devel] Re: ac_check_gmp.m4 in ppl

[Roberto Bagnara]

Bruno Haible wrote:
> While compiling ppl-0.5 I had problems telling the configure script where
> my libgmp is installed. Just
> 
>    --with-gmp-includes=/packages/gnu/include --with-gmp-lib=/packages/gnu/lib
> 
> wasn't enough, because
>    1. the test program is linked without any -L option,
>    2. the test program is linked without any -rpath option and then immediately
>       run - which doesn't work when a program depends on shared libraries
>       in nonstandard locations.
> As a workaround, I had to use
> 
>    LDFLAGS="-L/packages/gnu/lib -Wl,-rpath,/packages/gnu/lib" \
>    ./configure --prefix=/packages/gnu \
>      --with-gmp-includes=/packages/gnu/include --with-gmp-lib=/packages/gnu/lib
> 
> You could make this easier by using
>    AC_LIB_LINKFLAGS(gmpxx, gmp)
> in your configure.ac file. The AC_LIB_LINKFLAGS macro is defined in
> gettext-0.12.1/autoconf-lib-link/m4/*.m4 from the GNU gettext-0.12.1
> distribution.

Dear Bruno,

thank you very much for your suggestion.  I have just downloaded gettext-0.12.1
and looking at AC_LIB_LINKFLAGS(gmpxx, gmp).  I must say I was aware of the
problem but could not find a portable solution (I know too little about shared
libraries and libtool and so on and never find the time to fill this gap).

I agree the problem is very annoying: for example, if you happen to have one libgmp
installed into a standard location, but you want to experiment with another version
of libgmp, our --with-gmp-* options are of little help.

Would you be so kind to tell us more about the solution you suggest?
Is adding AC_LIB_LINKFLAGS(gmpxx, gmp) to configure.ac really all what
needs to be done?  Shouldn't ac_check_gmp.m4 also be modified so that
the directory specified with the option --with-gmp-dir can be taken
into account?  I also guess the position into configure.ac must be chosen
carefully.
Thanks again,

     Roberto

-- 
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it