[Bug bootstrap/49072] Error building the compiler

["franck.z.bugzilla at orange dot fr" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49072

Franck Z <franck.z.bugzilla at orange dot fr> changed:

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--- Comment #5 from Franck Z <franck.z.bugzilla at orange dot fr> 2011-06-21 10:31:45 UTC ---
(In reply to comment #4)

During my first attempts to compile gcc, I also encountered problem with
in-tree compilation of GMP/MPFR/MPC, up to the point that I used the compiled
(but not up-to-date) version provided with the Cygwin distribution.

It took then place with the trunk.

Amont the weird things I observed stood out:
- a file "gmpxx.h" could be found and stopped compilation (with or without
--enable-xx flag in gcc's configure script)
- the architecture recognized by gmp's configure script was different when this
script was launched by me ("pentium4-"-something from what I recall...) or by
gcc's makefile. When with gcc's makefile, gmp opted for a cross-compilation for
i686-pc-cygwin to none-pc-cygwin - although my gcc build was native.

About the architecture point, I can't tell much. But about the gmpxx.h file, I
suspect that it is a mostly silent bug and that a file
/usr/local/include/gmpxx.h provided by Cygwin is used if present.
Apparently, gmp's scripts create a gmp.h file when configure is run, but the
gmpxx.h wrapper is copied only when a command "make install" is issued, so that
gcc multi-stage compilation process may not have it, and this as soon as mpfr
(or mpc, I can't remember) needs to link to gmp. The failure telling that
gmpxx.h was missing occured during a configure script in mpfr (or mpc, again).

When the unavailability of gmpxx.h was by-passed by a local installation of gmp
from Cygwin, I also got a division by zero error or such later in the build
process.

I'm trying to confirm it with 4.6.0 release. I've added a "choke me" line at
the beginning of /usr/local/include/gmpxx.h. Right now, the gcc "make" command
is running (it's entered "configuring stage 1 in ./gmp"). It may take time
before I can get an answer.

Hope this piece of information is useful. :-)
I can't propose a patch for this if it confirms, for want of skills in
makefiles as big as gcc's.