pythonPackages.sip: make sip-module name overridable

[orivej]

Motivation for this change

This is an alternative to #52897 that trades patching pyqt5 for building another copy of sip.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• 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 nox --run "nox-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)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

[orivej]

This change is based on the contents of the package at https://pypi.org/project/PyQt5-sip/ : it has only PyQt5/sip.so (and metadata files).

[veprbl]

@GrahamcOfBorg build python2Packages.sip python2Packages.pyqt5 python3Packages.sip python3Packages.pyqt5

[veprbl]

Suggested change

	name = "${sip-module}-${version}";
	pname = sip-module;

[FRidh]

What happens when I get two versions with different names in the same closure? I'm pretty sure we get a conflict then.

[veprbl]

@FRidh I don't see any potential for conflict here. The different versions export modules with different names. In fact, there are cases where we do use both sip and pyqt5 in the same closure.

[orivej]

Yet the sip tool and the pyqt5 sip module may be separated further: #52968.
This would prevent a file conflict in the user environment if the user somehow installs multiple sips.

[FRidh]

If you include both in the same Python env they each provide the "same" dist-info folder.

[orivej]

No, one is sip-4.19.13.dist-info, another is PyQt5_sip-4.19.13.dist-info.
The files in common are sipconfig.py, sipdistutils.py, bin/sip and include/sip.h. (They are gone with --no-tools option proposed in #52968.)

[veprbl]

This seems to show no collisions:

# nix-env -f . -iA pythonPackages.sip pythonPackages.pyqt5
installing 'python2.7-sip-4.19.13'
installing 'python2.7-PyQt-5.11.3'
building '/nix/store/95dxdxa67353zgwsvgm3i3bpqmifxhhi-user-environment.drv'...
created 2230 symlinks in user environment

"PyQt5_sip" doesn't have a public attribute so there is no trivial way to cause collisions with it.