[Pkg-pascal-devel] Bug#845498: Bug#845498: /usr/bin/fpc-3.0.0: Provide cross-compilers

[Ben Longbons]

On Mon, Nov 28, 2016 at 12:19 AM, Abou Al Montacir
<abou.almontacir at sfr.fr> wrote:
> For now you can use multi-arch to install fp-compiler

No, you can't (that was the first thing I thought of):
fp-compiler:i386 depends on binutils:i386 rather than
binutils-i586-linux-gnu, and binutils:i386 isn't multiarch
installable. You'd have to do a full cross chroot, currently.

But once the dependency part is fixed, /etc/fpc.cfg can `#INCLUDE
/etc/fpc/$FPCTARGET.cfg` and put `-e/usr/i586-linux-gnu/bin
-Fl/usr/lib/i386-linux-gnu -Fl/lib/i386-linux-gnu -Fl /usr/lib32
-Fl/lib32` in there (each of those .cfg files will have to be manually
written/installed based on the Debian arch (of the fp-compiler
package), the Debian triple (subdir of /usr/lib), the legacy libdir
(/lib32 - actually not sure if this is necessary or not anymore), the
GNU triple (of binutils), and the FPC target (for choice of the
filename)). Incidentally, managing /etc/fpc.cfg through
update-alternatives is a waste since it could be implemented as just
`#INCLUDE /etc/fpc-$fpcversion.cfg` (though since jessie has 2.6.4, an
appropriate upgrade path would need to be written).

The above is fairly trivial and will get you a multiarch "cross"
compiler, with /etc/ ready for real (non-multiarch fp-compiler (I
*think* the libc6-*-cross packages are only needed because of ld.so
conflicting. but fp-units-* are actually multiarch safe already,
they're just not marked as such - they put all their files in
/usr/lib/fpc/$fpcversion/{units,fpmkinst}/$FPCTARGET/ already)) ones.
Then it's just a SMOC to actually build real cross-compilers binary
packages from the Debian source package.

I should probably write a tool to hack-up what I've described above by
using `apt-get download` and extracting/modifying the .deb files.
Maybe test it on Jessie since it has backports to test multiple
*versions* too.

> then just use a shell script to call call the right FPC using qemu

The shell script is unnecessary if you install qemu-user-binfmt (or
qemu-user-static, which `Provides:` it).

-Ben