Add a feature to compile platform-agnostic requirements.in (or pyproject.toml) for a specific platform (darwin, windows, linux)

[barseghyanartur]

What's the problem this feature will solve?

Something similar to poetry currently does, although it doesn't work as I wish it would. There you need to specify the platform inside your requirements in pyproject.toml.

Describe the solution you'd like

I prefer to have an platform agnostic requirements that can be compiled for the given platform (pip-compile --platform=darwin ...)

Alternative Solutions

There are many paths to go. For instance, one could compile things on GitHub Actions and then generate a PR from it. But doing it differently would be really good.

Additional context

[webknjaz]

Duplicate of #826

[webknjaz]

You may also find the following notes interesting:

• multiple pip-compile runs with multiple python versions -> single requirements.txt #1326 (comment)
• Merge constraint contents for different envs #826 (comment)