The setuptools-rust requires some environment variables to really
perform cross build, otherwise it just builds for build platform.
This adds setup hook that introduces these environment variables.
There are three variables.
The PYO3_CROSS_LIB_DIR has to point to the target's Python library
directory. This has to be directory for the target not for the build or
host. We have to choose the correct target Python. I am unsure how to do
that simply in nixpkgs and this this implementations just delays this
and waits for the correct Python when package using this hook is build.
The CARGO_BUILD_TARGET triggers cross compilation in setuptools-rust.
This is simply the Rust target specification.
The CARGO_TARGET_*_LINKER variable should not be essentially required
but setuptools-rust probably mangles the Rust build environment somewhat
and that results to the missing linker. By explicitly specifying it
using the environment variable we force the correct linker.
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.
By settings `passthru.skipBulkUpdate = true` in a python package, it
will be excluded from bulk update runs.
This is useful in case of fragile packages, that require special
attention during updates.
Previously when packages that required the git fetcher were updated, we
would wrongly rely on `nix-prefetch-url`, which would reliable break the
hash.
Instead we need to use `nix-prefetch-git` to determine the proper hash,
when the relevant attributes are present.
When PyPy introduced Python 3.8 support with version 7.3.6, they also
migrated to using CPython's directory layout [0]:
> The 3.8 package now uses the same layout as CPython, and many of the
PyPy-specific changes to `sysconfig`, `distutils.sysconfig`, and
`distutils.commands.install.py` have been removed. The stdlib now is
located in `<base>/lib/pypy3.8` on `posix` systems...
When we upgraded past this version and added Python 3.8 support [1], the
`sitePackages` value was never updated, leading `bootstrapped-pip` to fail
to build, because wheel was trying to be located in `$out/site-packages`,
when it was actually installed to `$out/lib/pypy3.8/site-packages`.
[0]: https://www.pypy.org/posts/2021/10/pypy-v736-release.html
[1]: eec28b8cfd
with structuredAttrs lists will be bash arrays which cannot be exported
which will be a issue with some patches and some wrappers like cc-wrapper
this makes it clearer that NIX_CFLAGS_COMPILE must be a string as lists
in env cause a eval failure
The virtualenv mode is trying to be smart and checks whether it can
write to $out, which for some reason fails on darwin.
> virtualenv: error: argument dest: the destination . is not write-able at /nix/store
But what does work is creating it in the pwd and moving it to $out,
because mv just does what it is told.
