On Tue, 06 Aug 2024 at 10:32:49 +0700, Dima Kogan wrote:
> As with most packages, python3-numpy has
> 
>   Depends: ${python3:Depends}
> 
> which today expands to
> 
>   Depends: python3 (<< 3.13), python3 (>= 3.12~), python3:any
> 
> Can somebody comment about why the :any is on the un-versioned
> dependency only? Adding the :any to the other two would fix my problem,
> and I'd like to get that added if there isn't a strong reason not to.

I'm guessing you want this because in a cross-compiling scenario, for
example build=amd64 and host=riscv64, you want to be able to install
python3:amd64 (to be able to run Meson, etc.) together with
python3-numpy:riscv64 (so riscv64 code can find numpy.pc)?

If python3-numpy contained "pure Python" then python3:any would be enough.
python3-six is a good simple example of a package in this situation.

But if python3-numpy contains native-code (compiled C/C++/etc.)
extensions, then that would be incorrect, because a compiled riscv64
extension cannot be loaded into an amd64 interpreter, and will
fail if you try; so it would be wrong to allow python3:amd64 and
python3-numpy:riscv64 to be installed together.

It appears that python3-numpy *does* contain native code, for example
/usr/lib/python3/dist-packages/numpy/core/_simd.cpython-312-x86_64-linux-gnu.so.
So the dependency on python3 of the same architecture is correct. This is
also why the dependency has to be versioned: the current numpy binaries
in unstable would not work correctly with Python 3.11 or 3.13, even if
the source does, because the binary package doesn't have *-311-*.so or
*-313-*.so (when Python 3.13 becomes a supported version, *-313-*.so
will be added by a binNMU).

I think you will need to introduce a python-numpy-dev or
python3-numpy-dev that is Architecture:any,Multi-Arch:same, or possibly
Architecture:all,Multi-Arch:foreign if its contents can easily be
made architecture-independent (this only works if the .pc file is
the same for every architecture because it only refers to headers
in /usr/include and not libraries, in which case it can be moved to
/usr/share). You might find that python3-talloc-dev is useful prior art
for the Architecture:any,Multi-Arch:same case, and python-dbus-dev is
an example of the Architecture:all,Multi-Arch:foreign case.

    smcv

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