optional cuda system dependency

[geoHeil]

my pyproject.toml looks like

[project]
name = "chemxtract"
version = "1.0.0"
description = "foo"
authors = [{ name = "bar", email = "baz" }]
requires-python = "==3.13"

[tool.pixi.project]
platforms = ["linux-64", "osx-arm64", "osx-64", "win-64", "linux-aarch64"]
channels = ["pytorch", "conda-forge", "bioconda", "anaconda"]

[build-system]
build-backend = "hatchling.build"
requires = ["hatchling"]

[tool.pixi.environments]

img2txt = { features = [
  "img2txt",
  "img2txt_base",
], solve-group = "img2txt",  no-default-feature = true }
img2txt-cuda = { features = [
  "img2txt_base",
  "img2txt-cuda",
], solve-group = "img2txt",  no-default-feature = true }

[tool.pixi.feature.img2txt_base.dependencies]
python = "~=3.12.0"

[tool.pixi.feature.img2txt_base.pypi-dependencies]
layoutparser = { version = "==0.3.4", extras = ["layoutmodels", "ocr"] }
easyocr = "~=1.7.2"

[tool.pixi.feature.img2txt.dependencies]
[tool.pixi.feature.img2txt.pypi-dependencies]
paddlepaddle = "~=2.6.2"

[tool.pixi.feature.img2txt-cuda]
platforms = ["win-64", "linux-64"]
system-requirements = { cuda = "12" }

[tool.pixi.feature.img2txt-cuda.target.linux-64.dependencies]
cuda-version = { version = ">=12.0,<=12.6" }

[tool.pixi.feature.img2txt-cuda.target.linux-64.pypi-dependencies]
paddlepaddle-gpu = "~=2.6.2"

A pixi install works and is properly resolved. A pixi shell -e img2txt fails with × The platform you are running on should at least have the virtual package __cuda on version 12, build_string: 0 even tough the feature was instantiated without cuda.

what is wrong?

[ruben-arts]

With the current implementation, we make the solve group environments behave as one. For now the fix would be to skip the solve-group.

[geoHeil]

will 0.39.4 bring any refinement there?

Thx for adding https://pixi.sh/latest/features/pytorch/#installing-from-conda-forge

[lucascolley]

this works now! On osx-arm64 with no CUDA:

~/sandbox/pixi2746 is 📦 v1.0.0 via 🐍 via 🧚 v0.50.2
❯ pixi shell --environment img2txt

~/sandbox/pixi2746 is 📦 v1.0.0 via 🐍 v3.12.11 via 🧚 v0.50.2 (img2txt) 
❯ pixi ls -x
Environment: img2txt
Package       Version  Build               Size      Kind   Source
easyocr       1.7.2                        15 MiB    pypi   easyocr-1.7.2-py3-none-any.whl
layoutparser  0.3.4                        22.7 MiB  pypi   layoutparser-0.3.4-py3-none-any.whl
paddlepaddle  2.6.2                        270 MiB   pypi   paddlepaddle-2.6.2-cp312-cp312-macosx_11_0_arm64.whl
python        3.12.11  hc22306f_0_cpython  12.4 MiB  conda  https://conda.anaconda.org/conda-forge/