`lib.extends hooks pythonPackagesFun` includes python which we want to
splice
what this fixes:
```
nix-repl> lib.elemAt pkgsCross.aarch64-multiplatform.python3Packages.xpybutil.nativeBuildInputs 0
«derivation /nix/store/39dkb51rciw6zwg0c2c44gpmpjapddxc-python3-aarch64-unknown-linux-gnu-3.10.12.drv»
```
to
```
nix-repl> lib.elemAt pkgsCross.aarch64-multiplatform.python3Packages.xpybutil.nativeBuildInputs 0
«derivation /nix/store/21ldw2dp26xvv9iyxn9x77a8yh4waqz5-python3-3.10.12.drv»
```
Before https://github.com/NixOS/nixpkgs/pull/194205 The keep python used to work by accident because self was passed from
__splicedPackages https://github.com/NixOS/nixpkgs/pull/196052/files#diff-44ce3495c4f983ce64dd47c86a9d3e77bad210b2709c098a3806998dcd9b000bR213
But now it does not work because overrideAttrs is used on python in
python-packages-base.nix
Preferably we would [ splice the hooks too ](https://github.com/NixOS/nixpkgs/pull/228139) but we cannot do that until [Package sets within derivations (i.e. python3.pkgs) are not spliced](https://github.com/NixOS/nixpkgs/issues/211340) is fixed, because people often use `python3.pkgs.wrapPython` in `nativeBuildInputs` (it's correct but python3.pkgs should be python3Packages to get splicing.
Since python documentation requires Sphinx to build, documentation is built in
separate derivation to avoid hard recursion/bootstrapping questions and plugged
into main derivation. Care is taken that "python3.doc" derivation feels and
looks as close as possible to as if it were main derivation were multi-output
one.
This change does not cause rebuild of python3 itself.
Add a marker file to the python outputs that tells pip and other tooling
following PEP 668 that they should not be installing things system-wide.
This provides better feedback to the user and also potentially avoids issues in
single-user installs where the /nix/store is owned by the user.
For more details, see <https://peps.python.org/pep-0668/>
Here is how it currently looks like:
$ pip install requests
error: externally-managed-environment
× This environment is externally managed
╰─> This command has been disabled as it tries to modify the immutable
`/nix/store` filesystem.
To use Python with Nix and nixpkgs, have a look at the online documentation:
<https://nixos.org/manual/nixpkgs/stable/#python>.
mkPythonDerivation: apply checks to buildInputs as well
fixup: add a suggestion about nativeBuildInputs
Clean up the wording, add reasons for the suggestions
switch to throw
Adjust error to clarify build-time vs. run-time
- Prune unused imports
- Collect imports at the top
- Removed unused exception assignments
- Fill bare except clause with
- Expand overly long check_output lines
Retrieve the current package hash and use it for a more precise match,
which allows us to update a derivation in situation where multiple
hashes are present.
