[CI] Compile Uno with MUMPS

[amontoison]

I cross-compiled MUMPS 5.8.0 (static mode) with METIS + reference BLAS / LAPACK.
-> https://github.com/amontoison/MUMPS_static_jll.jl

[cvanaret]

Thanks Alexis!
So there seem to be two issues:

• BQPD is somehow not found by the macOS build.
• my logic in QPSolverFactory is flawed, it won't compile when no QP solver is available 😅
  I'll check the CI script.

[cvanaret]

Somehow some arguments of CMake are ignored. Investigating

[cvanaret]

@amontoison
METIS cannot be found for macOS. Can you set the METIS_LIBRARY path?

[amontoison]

Yes, I can do that :)
I am working in parallel with Iain Duff in Glasgow, do that asap.

[cvanaret]

@amontoison
Perfect! The only issue remaining is in unit-tests-ubuntu.yml: BLAS and LAPACK don't seem to be installed. Perhaps we can load an action there.

[amontoison]

libblas.a and liblapack.a are in the archive with libmetis.a and libdmumps.a so the issue is how you link it. ;)

[amontoison]

@cvanaret

[cvanaret]

Indeed!
Here's the CMake configuration:

-- Found BLAS: ./deps/lib/libblas.a
-- Found LAPACK: ./deps/lib/liblapack.a

then linking:

/usr/bin/ld: cannot find -l./deps/lib/libblas.a: No such file or directory
/usr/bin/ld: cannot find -l./deps/lib/liblapack.a: No such file or directory

[amontoison]

I think that the linking is done from a different folder that the "root" of Uno and the relative path is not valid anymore.
The question is why does it work for MUMPS and BQPD and not for BLAS / LAPACK?

[amontoison]

@cvanaret I added absolute paths everywhere and it fixed the issue. You should probably add a comment about it somewhere.
The current error is that you don't correctly link with BLAS / LAPACK in Uno.
If we have two libraries (one for BLAS and one for LAPACK), it seems that you only link to liblapack.a and not libblas.a, which is required by LAPACK.

[amontoison]

@cvanaret All tests passed, I fixed a bug in the CMakeLists.txt, we must link BLAS after LAPACK if they are static libraries.

[cvanaret]

Wonderful, thank you for looking into this!