Re: adjust installation docs to discourage installing GMP, MPFR and MPC separately

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 22 December 2011 00:36, Joseph S. Myers wrote:
> On Thu, 22 Dec 2011, Jonathan Wakely wrote:
>
>> It is almost always caused by installing libgmp.so etc. in a
>> non-standard location and not using ldconfig, DT_RUNPATH,
>> $LD_LIBRARY_PATH or some other method to tell the dynamic linker how
>> to find them. ?The current installation docs mention --with-gmp right
>
> And for the normal case where $build and $host are the same (i.e. not a
> Canadian cross) it should be possible to build and try running a program
> using those libraries, maybe even one that checks the version is the same
> as in the library headers, at an early point in configure, so giving a
> meaningful error if someone is using previously installed libraries
> without proper dynamic linker configuration.
>
> (That's not an argument against your patch; we should improve the
> documentation as well as adding better detection of this common problem.)

Yes, better detection of the problem and a more meaningful error
message would help significantly, but doing that is beyond my autoconf
skills.