No way to specify --experimental for render function

[h-vetinari]

While trying to switch zlib to rattler, I need a feature that's currently under an experimental flag. Aside from the problem of not being able to specify this through smithy yet, the larger issue is that this is not configurable in the compat layer here.

I've monkey-patched my local install to do:

---src/rattler_build_conda_compat/render.py
+++src/rattler_build_conda_compat/render.py
                    run_args = [
                        "rattler-build",
                        "build",
                        "--render-only",
                        "--recipe",
                        self.path,
                        "--target-platform",
                        platform_and_arch,
                        "--build-platform",
                        platform_and_arch,
+                      "--experimental",
                    ]

which still runs into a rendering error:

  File "E:\miniforge\envs\smithy-dev\Lib\site-packages\rattler_build_conda_compat\render.py", line 317, in render
    m.config.variant = package_variants[0]
                       ~~~~~~~~~~~~~~~~^^^

which I solved as follows:

---src/rattler_build_conda_compat/render.py
+++src/rattler_build_conda_compat/render.py
                        ):
                            package_variants.remove(pkg_variant)

-           m.config.variant = package_variants[0]
+           m.config.variant = package_variants[0] if package_variants else []

            # These are always the full set.  just 'variants' is the one that gets
            #     used mostly, and can be reduced

That way I was able to get a basic rerender to succeed at least (though still running into issues on the build invocation, which'll have to be fixed in smithy).

[h-vetinari]

@wolfv @baszalmstra @nichmor
Any help with how an API for using --experimental should look like, so that smithy can build on top (conda-forge/conda-smithy#2057).

[nichmor]

hey @h-vetinari ! let me take a look at this today! sorry for long reply time

[h-vetinari]

Gentle ping on this @nichmor :)

[nichmor]

hey @h-vetinari - sorry I'm on vacation now - maybe @wolfv or @tdejager will could take a look

[h-vetinari]

Ping @nichmor @wolfv

[h-vetinari]

FWIW, I reapplied the monkeypatch to add --experimental to run_args again on the newest 1.2.2, and I'm still running into #58 despite #59, and thus the second patch also remains necessary.

[h-vetinari]

[h-vetinari]

conda-forge/conda-smithy#2057 is collecting more and more examples where cache: (and thus --experimental) is needed.

[wolfv]

Yes, I think part of the reason why it's "experimental" right now is because we wanted to make sure that the semantics are correct. I think we should fix the issue you discovered on Windows and write up how it works, present that to the conda/conda-forge community and lift it out of experimental late december, early january. How does that sound?