Pip ignoring "numpy<2" requirement

[jontwo]

Pip ignoring "numpy<2" requirement

[henryiii]

The environment variable is PIP_CONSTRAINT, not PIP_CONSTRAINTS. Otherwise that would have worked.

[jontwo]

That didn't work, but I've figured it out - the build requirements are coming from the pyproject.toml file. If I change the numpy requirement to <2 then it builds OK.

[build-system]
requires = ["setuptools", "wheel", "Cython", "numpy<2"]
build-backend = "setuptools.build_meta"

[jontwo]

It might be possible to use the --config-settings parameter to pass the no isolation flag to the backend, but I haven't been able to get that to work. Something along these lines, maybe:

pip install . -C="--build-option=bdist_wheel"  -C="--build_option=--no-isolation"

[notatallshaw]

I assume this is the build process failing, build time requirements are defined by the package being built, and pip does not have very many options for directly controlling them. There is, however, one way:

Create a file called constraints.txt that has numpy<2 in it. Then export an environmental variable PIP_CONSTRAINTS PIP_CONSTRAINT that points to that file. Then rerun your command.

Constraints force pip to resolve within the bounds of the constraints specified, but does not have to install them, by setting it as an environmental variable it will apply to both your requirements and build requirements.

[notatallshaw]

Ah yes, I thought you had no control over the build requirements, if you do that should be the first approach.

[henryiii]

The flag is --no-build-isolation for pip. Build isolation is not handled by the backend, it's handled by build or pip. Build's flag is --no-isolation since it is always building.

You don't need wheel in your requirements most likely. Also, be sure to fix this to support numpy 2 as soon as possible, as your output wheel won't support numpy 2 if it's built with numpy 1, while a numpy 2 wheel also supports numpy 1.

[jontwo]

So close!

[WrathOfChris]

Sharing a synthesis snippit for all who arrive here with similar issues on other packages, like myself a few hours ago:

echo "numpy<2" >/tmp/constraint.txt
export PIP_CONSTRAINT=/tmp/constraint.txt
pip install pandas==1.2.3     # <-- change to your package/version

[notatallshaw]

Both ways of restricting build dependencies have been explained (directly updating build dependencies or using PIP_CONSTRAINT), closing issue.