gcc-4.7 tries to build fortran when crossing, but no cross-fortran is available

[Wookey]

cross building gcc4.7 for arm64/aarch64 (build !=host, host=target) fails because fortran is an enabled language but we don't build a cross-fortran to build it with, so the build fails.

When cross-building, fortran should be disabled (unless we also start building cross-fortran).

build/config.log says:
../src/configure -v --with-pkgversion=Ubuntu/Linaro 4.7.2-22ubuntu2 --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,fortran --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libssp --disable-libmudflap --disable-libgomp --disable-libitm --enable-plugin --with-system-zlib --disable-libstdcxx-pch --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --enable-checking=release --build=x86_64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu

simple patch attached which fixes this problem.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "gcc-4.7_4.7.2-22ubuntu2-reverse-cross-no-fortran.patch" of this bug report has been identified as being a patch. The ubuntu-reviewers team has been subscribed to the bug report so that they can review the patch. In the event that this is in fact not a patch you can resolve this situation by removing the tag 'patch' from the bug report and editing the attachment so that it is not flagged as a patch. Additionally, if you are member of the ubuntu-reviewers team please also unsubscribe the team from this bug report.

[This is an automated message performed by a Launchpad user owned by Brian Murray. Please contact him regarding any issues with the action taken in this bug report.]

[Matthias Klose (doko)]

both gfortran-aarch64-linux-gnu and gfortran-4.7-aarch64-linux-gnu are in the archive. Just build it.

[Wookey (wookey)]

+++ Matthias Klose [2013-03-01 06:26 -0000]:
> both gfortran-aarch64-linux-gnu and gfortran-4.7-aarch64-linux-gnu are
> in the archive. Just build it.

OK. My mistake.

This leads us to a different problem, that the crossbuild-essential-*
mechanism is very crude and arbitrarily selects C and C++ but not
fortran. A proper mapping from <build-dep> to <target>-<build-dep> is
needed to fix this in the general case (which we already knew) so that
build daemons can just DTRT. I'd better try and spec that up as quite
a few packages have to be manually built because of this.

Wookey
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