Pixi requires cuda in system-requirements even if CUDA is installed by Pixi via dependencies

[garymm]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

[project]
name = "jax-env"
channels = ["conda-forge", "nvidia"]
platforms = ["linux-64"]

[dependencies]
jax = ">=0.4.23,<0.5.0"

[host-dependencies]
python = ">=3.10,<3.11"

[target.linux-64.dependencies]
jaxlib = { version = ">=0.4.23,<0.5.0", build = "*cuda12*" }
cuda-nvcc = ">=12.0,<13"
cuda-cupti = "*"

With this file, pixi install fails with:

 × failed to solve the conda requirements of 'default' 'linux-64'
  ╰─▶ Cannot solve the request because of: jaxlib >=0.4.23,<0.5.0 *cuda12* cannot be installed because there are no viable options:
      └─ jaxlib 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 | 0.4.23 would require
         └─ __cuda *, for which no candidates were found.

Issue description

But if I add:

[system-requirements]
cuda = "12"

Then things work.
This is ugly because:

1. It's not a system requirement: it's managed by pixi.
2. I only want it to apply to a specific target, not all targets.

Expected behavior

No system-requirements required.

[dennis-wey]

We are having the same issue.
I think it's related to #480

[2themaxx]

Editing to add that this behavior is also on Windows. I've been trying to run pytorch stuff on Windows and was pulling my hair out as to why cuda wasn't available. The "system-requirements" bug is above is the reason.

Adding:

[tool.pixi.system-requirements]
cuda = "12"

to the pyproject.toml is required to get pytorch with cuda to work.

executing
pixi run python -c "import torch;print(torch.cuda.is_available())"

returns "False" without the "tool.pixi.system-requirements" and the cuda requirement to the file.