python3Packages.bootstrapped-build: to replace pip

[FRidh]

build is a lightweight PEP 517 frontend for building wheels that could
replace pip for this purpose.

installer is a new project for installing wheels.

Why replace pip with build and installer? pip has a large
codebase doing many more things, and it vendors its dependencies.

See also https://github.com/FFY00/python-bootstrap

Might become significantly simpler if pypa/flit#511 is merged.

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.

TODO

• separate python2 bootstrapping by splitting python2 infra from python3
• fix prefix https://github.com/pradyunsg/installer/issues/98 https://github.com/pradyunsg/installer/pull/94#issuecomment-1013876999
• package bootstrapped-build
• write hook for bootstrapped-build-installer
• pass arguments to build backends
• set pipInstallFlags = [ "--ignore-installed" ]; for each bootstrapped-build dep
• docs
• use bootstrapped-build to rebuild all the bootstrapping packages

[FRidh]

haven't implemented yet

[FRidh]

for every runtime dep of build we create a wheel and install it. This requires the build backends to be available already. We probably end up needing to add setuptools and flit here as well.

[SuperSandro2000]

That name is not that nice.

[stale]

I marked this as stale due to inactivity. → More info

[FRidh]

Managed to get bootstrapping going with build and installer!

[SuperSandro2000]

some random style comments mostly for when you are done with the implementation.

[SuperSandro2000]

Suggested change

	export PYTHONPATH="$(pwd)/installer/src:$(pwd)/wheel/src:$(pwd)/build/src:$(pwd)/setuptools/pkg_resources:$PYTHONPATH"
	'';
	export PYTHONPATH="$(pwd)/installer/src:$(pwd)/wheel/src:$(pwd)/build/src:$(pwd)/setuptools/pkg_resources:$PYTHONPATH"
	'';

[SuperSandro2000]

Suggested change

	'';
	'';
	meta = {
	description = "Package for bootstrapping the Python packages set.";
	maintainers = [ lib.maintainers.fridh ];
	};

[SuperSandro2000]

I think it would be nice if we had some version attribute but honestly I have no idea what we should use because this is just a collection of files.

[SuperSandro2000]

Suggested change

	data = map (drv: lib.getAttrs ["pname" "src" ] drv) runtimeDeps;
	data = map (drv: lib.getAttrs [ "pname" "src" ] drv) runtimeDeps;

[SuperSandro2000]

Normally shell inside of nix files is intended with 2 spaces.

[FRidh]

not needed

[FRidh]

Superseded by #245509