use build instead of pip wheel?

[dhellmann]

Revisit the decision to use pip wheel to build wheels. The build command supports a --no-isolation flag, which should prevent installing anything and give the same protection that flag does when running pip.

What was it that led us to switch from build to pip?

[dhellmann]

Switching back to build might also let us change the way we build sdists by default.

[tiran]

+1 build is the recommended tool to create sdists and wheels.

One remark about --no-isolation. build does not install any build dependencies when the flag is passed. All build dependencies from pyproject.toml must be installed manually.

[tiran]

We have to switch to build so we can build matplotlib with system packages. A bug in pip prevents us from passing multiple arguments to pip wheel

https://matplotlib.org/stable/install/dependencies.html#use-system-libraries

python -m pip install \
  --config-settings=setup-args="-Dsystem-freetype=true" \
  --config-settings=setup-args="-Dsystem-qhull=true" \
  .

https://meson-python.readthedocs.io/en/stable/how-to-guides/config-settings.html

Please note that, while pypa/build concatenates arguments for the same key passed to the -C option, pip up to version 23.0.1 does not offer any way to set a build config setting to a list of strings: later values for the same key passed to --config-settings override earlier ones.

This effectively limits the number of options that can be passed to each command invoked in the build process to one. This limitation is tracked in pip issue #11681. This limitation should be removed in the next version of pip.

[dhellmann]

We have to switch to build so we can build matplotlib with system packages. A bug in pip prevents us from passing multiple arguments to pip wheel

Good to know. matplotlib isn't likely to be a priority for a while, but this definitely motivates a move.

[tiran]

We had an internal discussion how Fromager is going to bootstrap the build command into the build environment. @dhellmann and @shubhbapna had objections against my initial solution. My plan was to bundle build wheel with Fromager and use a virtualenv seeder plugin to inject it into the build environments, #435.

After more investigation (code digging), I found an even better, simpler, and faster way. Instead of installing the build package into our build envs, we can install it with Fromager and use its Python API. We no longer need to execute $VIRTUAL_ENV/bin/python -m build in a subprocess. The build API lets us run the hooks with a custom interpreter and runner instead: build.BuildEnv(python_executable="$VIRTUAL_ENV/bin/python"). https://build.pypa.io/en/stable/api.html#build.ProjectBuilder

[shubhbapna]

The build API lets us run the hooks with a custom interpreter and runner instead: build.BuildEnv(python_executable="$VIRTUAL_ENV/bin/python"). https://build.pypa.io/en/stable/api.html#build.ProjectBuilder

I like this idea!