Bug#1063340: dh-fortran-mod is wrongly marked Multi-Arch: foreign

[Helmut Grohne]

Package: dh-fortran-mod
Version: 0.39
Severity: important
User: debian-cross at lists.debian.org
Usertags: ftcbfs
Control: affects -1 + src:odc

Hi,

dh-fortran-mod currently is marked Multi-Arch: foreign. That means that
it provides only architecture-dependent functionality to its
dependencies. src:odc Build-Depends on dh-fortran-mod and expects to get
a working fortran compiler in doing so. A fortran compiler very much is
not an architecture-independent interface unless naming a particular
architecture it should be building for. This is not happening here.

Do you think that src:odc's expectation of dh-fortran-mod to provide a
fortran compiler is reasonable? If yes, dh-fortran-mod must not be
Multi-Arch: foreign and it also cannot be Architecture: all, because
such packages cannot transfer an architecture constraint to their
dependencies and such constraint transfer is important in this case.  If
no, please reassign this bug to src:odc as it uses a fortran compiler
during build without depending on it.

Also consider annotating your compiler dependencies using -for-build and
-for-host. A dependency on gfortran will not work for cross compilation,
because gfortran:$arch means a fortran compiler running on $arch and
producing code for $arch, which very much is not what we want in a cross
build. gfortran-for-host addresses this, but it is a very recent
addition to src:gcc-defaults and not backportable, so you should add a
non-default alternative when using -for-host or -for-build for the time
being.

Helmut