Prevent the hook from erroring out on missing specifiers, as reported for
`highspy`, which currently ships with a pre-release version, triggering
the following error message:
- highspy not satisfied by version 1.7.1.dev1
When building a python environment's bin directory, we now detect
wrapped python scripts from installed packages, and generate unwrapped
copies with the environment's python executable as the interpreter.
The way we build python environments is subtly broken. A python
environment should be semantically identical to a vanilla Python
installation in, say, /usr/local. The current implementation, however,
differs in two important ways. The first is that it's impossible to use
python packages from the environment in python virtual environments. The
second is that the nix-generated environment appears to be a venv, but
it's not.
This commit changes the way python environments are built:
* When generating wrappers for python executables, we inherit argv[0]
from the wrapper. This causes python to initialize its configuration
in the environment with all the correct paths.
* We remove the sitecustomize.py file from the base python package.
This file was used tweak the python configuration after it was
incorrectly initialized. That's no longer necessary.
The end result is that python environments no longer appear to be venvs,
and behave more like a vanilla python installation. In addition it's
possible to create a venv using an environment and use packages from
both the environment and the venv.
The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
Albeit counter-intutive, the `propagatedBuildInputs`
mechanism and the corresponding package files in
`nix-support/propagated-build-inputs`
can form a dependency cycle.
This can happen if a package adds itself to this file,
or if multiple outputs of one derivation reference each other.
An example for this is the `patchPpdFilesHook`:
In its mission to collect dependency packages with binaries
that might be required by the dependent package to be created,
it sometimes picks up the dependent package itself.
This indicates that if a file of the dependent package
is used, the package itself should also be installed.
In the case of a multiple output package,
it is also possible that two outputs depend on each other,
creating a dependency cycle.
Since commit 2651ddc7b0,
the `find_packages` function in `catch_conflicts.py`
recursively collects all `propagated-build-inputs` files.
If it encounters a dependency cycle, it must not follow the
cycle to avoid infinite recursion (and a stack overflow).
The commit at hand adds a check so that the function skips over
a package that it already encountered and processed earlier.
This does not loosen the script's checks as the script
still recursively collects all propagated build inputs.
Much like the previous commit that adds dependencies &
optional-dependencies this aligns PEP-517 build systems with how they
are defined in PEP-518/PEP-621.
The naming `build-system` (singular) is aligned with upstream Python standards.
Since https://github.com/NixOS/nixpkgs/pull/161835 we've had the
concept of `passthru.optional-dependencies` for Python optional deps.
Having to explicitly put optional-dependencies in the passthru attrset
is a bit strange API-wise, even though it semantically makes sense.
This change unifies the handling of non-optional & optional Python
dependencies using the names established from PEP-621 (standardized pyproject.toml project metadata).
This changes the non-legacy version of pythonCatchConflictsHook
to recursively scan the output of the target derivation as well
as its propagatedBuildInputs for duplicate dependencies.
Previously, we did scan sys.path but did prove problematic as it
produced false positives i.e. when build-time dependencies of
hooks - such as setuptools in pythonCatchConflictsHook itself -
where mistakenly flagged as duplicates; even though the are
not included in the outputs of the target dervation.
As all python runtime-dependencies are currently passed via
propagatedBuildInputs in nixpkgs, scanning that plus
site-packages seems sufficient to catch all conflicts that
matter at runtime and less likely to produce false positives.
The legacyHook in catch_conflicts_py2.py needs to be migrated
as well, if it's still needed.
