Multiple conflicting extras installed when using explicit index assignments

[anaoum]

When conflicting extra groups share a dependant, both extra groups seem to be installed.

Consider the following example adapted from the docs:

[project]
name = "project"
version = "0.1.0"
requires-python = ">=3.11,<3.12"
dependencies = []

[project.optional-dependencies]
cpu = [
  "torch>=2.5.1",
  "torchvision>=0.20.1",
]
cu124 = [
  "torch>=2.5.1",
  "torchvision>=0.20.1",
]
metrics = [
  "torchmetrics>=1.2.0",
]

[tool.uv]
conflicts = [
  [
    { extra = "cpu" },
    { extra = "cu124" },
  ],
]

[tool.uv.sources]
torch = [
  { index = "pytorch-cpu", extra = "cpu", marker = "platform_system != 'Darwin'" },
  { index = "pytorch-cu124", extra = "cu124" },
]
torchvision = [
  { index = "pytorch-cpu", extra = "cpu", marker = "platform_system != 'Darwin'" },
  { index = "pytorch-cu124", extra = "cu124" },
]

[[tool.uv.index]]
name = "pytorch-cpu"
url = "https://download.pytorch.org/whl/cpu"
explicit = true

[[tool.uv.index]]
name = "pytorch-cu124"
url = "https://download.pytorch.org/whl/cu124"
explicit = true

The key difference is the additional extra metrics that includes the torchmetrics package that depends on torch.

When I lock and sync both cpu and metrics extras, I get multiple versions of torch installed:

$ uv sync --extra cpu --extra metrics
Resolved 34 packages in 1ms
Uninstalled 3 packages in 199ms
Installed 3 packages in 1.10s
 ~ torch==2.5.1
 ~ torch==2.5.1+cpu
 ~ torch==2.5.1+cu124

[charliermarsh]

Interesting, thanks. I don't think the extra indexes are relevant, since you can reproduce with:

[project]
name = "project"
version = "0.1.0"
requires-python = ">=3.11,<3.12"
dependencies = []

[project.optional-dependencies]
foo = [
  "idna==3.10",
]
bar = [
  "idna==3.9",
]
baz = [
  "anyio",
]

[tool.uv]
conflicts = [
  [
    { extra = "foo" },
    { extra = "bar" },
  ],
]

From there, uv tree gives you:

project v0.1.0
├── idna v3.9 (extra: bar)
├── anyio v4.6.2.post1 (extra: baz)
│   ├── idna v3.9
│   ├── idna v3.10
│   └── sniffio v1.3.1
└── idna v3.10 (extra: foo)

[anaoum]

Thanks. It also happens if the two conflicting extra groups share the common dependant:

[project]
name = "project"
version = "0.1.0"
requires-python = ">=3.11,<3.12"
dependencies = []

[project.optional-dependencies]
foo = [
  "idna==3.10",
  "anyio",
]
bar = [
  "idna==3.9",
  "anyio",
]

[tool.uv]
conflicts = [
  [
    { extra = "foo" },
    { extra = "bar" },
  ],
]

[BurntSushi]

I think i see a path to fixing this. I think it has two components:

• In ResolverOutput::from_state (and possibly also marker_reachability), generate extra = "..." markers from each Resolution's conflicting groups, if they have them. Then apply those markers via intersection to each of the edges in that Resolution. So in Charlie's example above, that means the idna==3.9 dependency would have a extra == "bar" marker and the idna==3.10 dependency would have a extra == "foo" or extra == "baz" marker. Or something similar.
• Update InstallTarget::to_resolution in uv-resolver/lock to pass in extras when doing marker evaluation.

One hiccup here is that this doesn't take groups into account, so we might not be able to reuse markers for this. We'll instead need an additional field to encode this extra/group inclusion logic.

[BurntSushi]

Working it out by hand, I think the conditional logic for each idna dependency in each of the three forks present in this example is:

 idna==3.9: extra != "foo" and (extra == "bar" or extra == "baz")
idna==3.10: extra != "bar" and (extra == "foo" or extra == "baz")
idna==3.10: (extra != "foo" and extra != "bar") and extra == "baz"

Which combines to:

 idna==3.9: extra != "foo" and (extra == "bar" or extra == "baz")
idna==3.10: (extra != "bar" and (extra == "foo" or extra == "baz"))
            or ((extra != "foo" and extra != "bar") and extra == "baz")

And simplifies to:

 idna==3.9: extra != "foo" and (extra == "bar" or extra == "baz")
idna==3.10: (extra != "bar" and extra == "baz") or (extra != "bar" and extra == "foo")

Note that because of how extras work, the above notation is quite misleading. It's more clearly written like this:

 idna==3.9: "foo" not in extras and ("bar" in extras or "baz" in extras)
idna==3.10: ("bar" not in extras and "baz" in extras) or ("bar" not in extras and "foo" in extras)