No solve on osx-64 platfrom when a dependency does not support Python 3.13

[hoxbro]

Checklist

• [x] I added a descriptive title
• [x] I searched open reports and couldn't find a duplicate

What happened?

Starting to see failing to solve for the osx-64 platform (6 hours and cancel). I think this is because of Python 3.13 + numba (which currently does not support Python 3.13). This is a (reduced) pixi.toml file and using this command: rm -rf pixi.lock .pixi && pixi install

[project]
name = "datashader"
channels = ["conda-forge"]
platforms = ["osx-64"]

[dependencies]
colorcet = "*"
numba = "*"
numpy = "*"
pip = "*"
# This takes 14 seconds to solve on osx-64
# Adding more deps now increase the time significant for osx-64
# requests = "*"  # 21 seconds
# setuptools = "*"  # 33 seconds
# pandas = "*"  # ctrl + c after 2.5 minutes

Moving numba to the top or adding a python <3.13 pin will make it solve instant for osx-64. So, likely, the solver gets in a weird state where it never solves.

Additional Context

No response

[hoxbro]

Another example is this, the same solution as above. However, numba is about to be released with Python 3.13 support. So will likely not be reproducible before Python 3.14.

[project]
name = "spatialpandas"
channels = ["conda-forge"]
platforms = ["osx-64"]

[dependencies]
dask-core = "*"
fsspec = "*"
numba = "*"
packaging = "*"
pandas = "*"
pip = "*"
pyarrow = ">=10"

[baszalmstra]

I can no longer reproduce this, probably due to some optimizations in the solver (there were many)

I ran the following command to verify this:

rattler create --dry-run -c https://prefix.dev/conda-forge \
  --platform osx-64 \
  --exclude-newer 2024-10-30 \
  colorcet numba numpy pip

--exclude-newer requires this PR: https://github.com/conda/rattler/pull/1815

[hoxbro]

This also solved for me in 14 seconds. Adding the other dependencies was what tipped the scales.