conf-openblas failing to install on Manjaro 23 about opam-repository HOT 4 OPEN

Thanks for the pointer, @mseri!

Here are notes on what I've done to get the install working for future searchers:

By looking at https://github.com/owlbarn/owl/blob/48434ea744d8e5f488a56bb06ecd15659c58f186/Dockerfile#L31 I was able to infer that the "right paths" for the CFLAGS variable should at least include the openblas header files.

On my system, after installing openblas via pacman, these were located at /usr/include/openblas.

The working invocation for opam, therefore, was

CFLAGS="-I/usr/include/openblas" opam install owl

CFLAGS was not set at all on my system. Is it expected to be? Or are users meant to know that they need to set this variable to install the package?

perhaps we should just use pkg-config if manjaro ships the pc files

The openblas package does indeed ship with a blas.pc file, and this works on my system:

$ pkg-config --cflags blas
-I/usr/include/openblas

from opam-repository.

If you run it with CFLAGS set to the right paths it should work

from opam-repository.

Otherwise we may need to check where openblas is installed in manjaro and fix it (perhaps we should just use pkg-config if manjaro ships the pc files)

from opam-repository.

I would suggest to submit a new version of the conf-blas package doing

build: ["pkg-config" "--exists" "--print-errors" "blas"]

for all the distributions that ship the pc file for blas.
owl uses pkg-config internally afaik, so this should solve the issue

from opam-repository.