pythonPackages.osqp: remove mkl dependency

[drewrisinger]

Motivation for this change

Removing mkl allows this to be built in Hydra (mkl is unfree-ish license), and it seems the mkl dependency is somewhat optional given downstream packages build cleanly when removing mkl.
Also add explicit numpy/scipy dependency.
Cleanup commit slightly for formatting.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[drewrisinger]

@GrahamcOfBorg build python37Packages.osqp python37Packages.cvxpy python38Packages.osqp python38Packages.cvxpy

[bhipple]

CC @matthewbauer, who is looking at making this type of thing parameterizable in #83888

[drewrisinger]

Re numpy/scipy: They seem to be used in the code, it's just not listed in requirements which I used when originally packaging.

[matthewbauer]

This case is a little different because osqp doesn't use MKL for BLAS, but MKL PARDISO (https://software.intel.com/en-us/mkl-developer-reference-fortran-intel-mkl-pardiso-parallel-direct-sparse-solver-interface) which is unique to MKL.

Anyway, it looks like this library just needs MKL to test the MKL functionality. Since osqp just uses dlopen, you can always enable MKL support through LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(nix-build '<nixpkgs>' -A mkl)/lib.

[drewrisinger]

This case is a little different because osqp doesn't use MKL for BLAS, but MKL PARDISO (https://software.intel.com/en-us/mkl-developer-reference-fortran-intel-mkl-pardiso-parallel-direct-sparse-solver-interface) which is unique to MKL.

Anyway, it looks like this library just needs MKL to test the MKL functionality. Since osqp just uses dlopen, you can always enable MKL support through LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(nix-build '<nixpkgs>' -A mkl)/lib.

Ack, thanks for the good tips. I wasn't familiar with what MKL PARDISO did. pythonPackages.osqp does just use MKL PARDISO for testing PARDISO functionality AFAICT, it probably also enables some runtime functionality but I view that as a downstream thing. I prefer for build purposes to have no unfree dependencies so as much as possible can be built/cached by Hydra.

[drewrisinger]

@GrahamcOfBorg build python37Packages.qiskit-aer python37Packages.qiskit-ignis
@GrahamcOfBorg build python38Packages.qiskit-aer python38Packages.qiskit-ignis

[drewrisinger]

Result of nixpkgs-review pr 84124

9 package built:
python27Packages.osqp python37Packages.cvxpy python37Packages.osqp python37Packages.qiskit-aer python37Packages.qiskit-ignis python38Packages.cvxpy python38Packages.osqp python38Packages.qiskit-aer python38Packages.qiskit-ignis

[bhipple]

Result of nixpkgs-review pr 84124 1

9 package built:

- python27Packages.osqp - python37Packages.cvxpy - python37Packages.osqp - python37Packages.qiskit-aer - python37Packages.qiskit-ignis - python38Packages.cvxpy - python38Packages.osqp - python38Packages.qiskit-aer - python38Packages.qiskit-ignis

[bhipple]

Can you send a 20.03 backport PR as well?

[drewrisinger]

@bhipple python3Packages.osqp isn't in release-20.03.

[bhipple]

Ah ok, my bad! For some reason I thought we'd had this packaged for longer, but I was thinking of another related pkg.