Use normal python build workflow instead of in-tree builds

[Xiretza]

The project currently uses a rather unconventional in-tree build workflow (I'd never encountered it before in several years of python distro packaging), and I haven't yet been able to find a convincing reason as to why. Of course it's very possible I'm just missing something, but in case I'm not, here's a PR that converts it to the standard python build workflow.

[umarcor]

Hi @Xiretza! Nice to see you around!

Overall, I do agree. However, note the deprecation warning that is shown if the in-tree is not used:

https://github.com/chipsalliance/f4pga/runs/6543658873?check_suite_focus=true#step:4:11

 Processing /home/runner/work/f4pga/f4pga
  DEPRECATION: A future pip version will change local packages to be built in-place without first copying to a temporary directory. We recommend you use --use-feature=in-tree-build to test your packages with this new behavior before it becomes the default.
   pip 21.3 will remove support for this functionality. You can find discussion regarding this at https://github.com/pypa/pip/issues/7555.

pypa/pip#7555

So, I don't have an strong opinion in favour of one solution or the other. I'd like to understand whether not using in-tree now might produce a regression in the near future.

[Xiretza]

Ah, yes, I had misinterpreted that flag - it's actually unrelated to putting setup.py in the module directory, it's just an opt-in for behaviour that will become the default in the future. I've added it back in.

[Xiretza]

Hm, the eos-s3 family somehow installs an older pip version - not sure how that can happen, but I've removed the --use-feature=in-tree-build option from that test job.

[umarcor]

In the end, this PR is removing package_dir={"f4pga": "."}, from the setup.py, and moving both setup.py and requirements.txt to the root of the repo. I guess that will require changing https://github.com/SymbiFlow/f4pga-arch-defs/blob/main/conda_lock.yml#L106 to remove the "subdirectory" option. I'm not sure we want to do that. Subdir f4pga is "standalone" now (it can be "moved" anywhere). By moving the setup to the root, we make the "whole" repo part of the pip package. Overall, when this package is published in pip, users will be unaware of the actual location of the sources within the repo.

The QuickLogic environment is expected to be brought up to date, on par with the xc7 environment. Furthermore, the conflicts between arch-defs packages are to be solved, so that assets for both architecture families can be installed side-to-side. Hence, we might want to keep this PR open for the original purpose (removing option in-tree) when the environments are updated and pip is bumped.

[umarcor]

I'm closing this since it was implemented in 9308536.

[Xiretza]

That commit does the exact opposite of this PR.

[umarcor]

@Xiretza the commit removes --use-feature=in-tree-build, isn't it?

[Xiretza]

It does, and this PR does not (as far as I can tell, --use-feature=in-tree-build is a desired option for future-proofing). The PR is about building the python package from the repository root (the normal python build workflow) instead of having to go into the f4pga source directory.