Support build system requirements

[abn]

This change adds support of build requirements. This is implemented such that build requirements are always installed on poetry install and poetry install --no-dev since the package installation will require build-system.requires packages. When poetry build is executed, existing behaviour is retained for cases where additional build requirements are not required. If additional, dependencies are required (eg: cython) these and only these are installed before build and environment executable is configured for use when build script is executed.

Resolves: #2789

Requires: #2732 python-poetry/poetry-core#58

• Added tests for changed code.
• Updated documentation for changed code.

[mdgoldberg]

Any updates here @abn ? Is this still being developed?

[schneiderfelipe]

Any updates on this?

[abn]

@mdgoldberg @schneiderfelipe I am guessing there is still interest in this? I have had some push backs from core about this. But happy to push it forward.

[schneiderfelipe]

@mdgoldberg @schneiderfelipe I am guessing there is still interest in this? I have had some push backs from core about this. But happy to push it forward.

Very much interested. Out of curiosity, what's holding this back?

[espdev]

@abn,
Support of build dependencies is very much needed. Please see my last comment:
#2789 (comment)

[GuillaumeDesforges]

@abn are you still on this? Would be very helpful 🙂

[abn]

@GuillaumeDesforges guess now I am :D unfortunately python-poetry/poetry-core#58 got a bit stuck. Let me have a rethink with the new groups changes. The appraoch I took there will no longer really work. Since "dev" is not necesarily a group that is always going to be present.

That said, in the interim I would recommend you redefine the dependency like so.

poetry add --group build 'cpython@*'

Or use the TOML.

[tool.poetry.group.build.dependencies]
cpython = "*"

Personally, I do not like that I'd have to re-specify the dependency, but that is where it is at present.

[abn]

Closing this in favour of #5401 for now as the core issue was stuck without concensus.

[github-actions]

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