Re: compiling gcc 5.x from the scratch: issues

[Martin Sebor <msebor@gmail.com>]

On 09/10/2015 12:49 AM, Markus Trippelsdorf wrote:
> On 2015.09.10 at 08:40 +0200, Markus Trippelsdorf wrote:
>> On 2015.09.10 at 05:36 +0000, Michael Mishourovsky wrote:
>>> Dear Sirs, following your suggestions I checked again  https://gcc.gnu.org/wiki/InstallingGCC.
>>>
>>> Key point was here: https://gcc.gnu.org/install/download.html (last
>>> passage) "Likewise the GMP, MPFR and MPC libraries can be
>>> automatically built together with GCC. Unpack the GMP, MPFR and/or MPC
>>> source distributions in the directory containing the GCC sources and
>>> rename their directories to gmp, mpfr and mpc, respectively (or use
>>> symbolic links with the same name)."
>>>
>>> Actually my assumption was that if I run download_prerequisites from
>>> /contrib, it will download everything and put it at right places; but
>>> actually it does not follow statement above (it does not create gmp,
>>> mpfr and mpc folder in main gcc package directory) So I did it
>>> manually and copied files there.
>>
>> Well, https://gcc.gnu.org/wiki/InstallingGCC says:
>>
>> »Alternatively, after extracting the GCC source archive, simply run the
>> ./contrib/download_prerequisites script in the GCC source directory.«
>>
>> The »in the GCC source directory« part is important. If you run it from
>> anywhere else it will not work.
>
> So perhaps a patch like this one would help:

FWIW, I think the more common source of problems for those new
to building GCC is not having all the right prerequisites. The
GCC configure script tries to detect whether the right versions
are available but does only a superficial job (checks their
version macros) which can lead to cryptic build failures down
the line when not all the right architectures are installed
(e.g., the i686 in addition to x86_64). It also proceeds when
MPC is not installed at all which then causes the build to fail.

Martin