uv fails to parse pyproject.toml when using Hatchling's {root:uri} for dependencies

[object-Object]

Hatchling includes a feature that allows specifying local dependencies relative to a project's root directory using the following syntax:

dependencies = [
    "<NAME> @ {root:uri}/pkg_inside_project"
]

uv fails to install projects that are using this feature, even if only used in an optional dependency that is not selected.

Reproduction steps

To reproduce, create this file structure:

/pyproject.toml

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

[project]
name = "project"
version = "0.1.0"
# NOTE: error also occurs if using this instead of optional-dependencies
# dependencies = [
#     "subproject @ {root:uri}/subproject",
# ]

[project.optional-dependencies]
local = [
    "subproject @ {root:uri}/subproject",
]

[tool.hatch.metadata]
allow-direct-references = true

[tool.hatch.build]
include = ["*"]

/subproject/pyproject.toml

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

[project]
name = "subproject"
version = "0.1.0"

[tool.hatch.build]
include = ["*"]

Then run these commands:

uv pip install -e . OR uv pip install -e .[local]

error: Failed to build editables                                                                                                                    
  Caused by: Failed to build editable: file:///C:/Users/object/test/uv-hatch-bug
  Caused by: Invalid pyproject.toml
  Caused by: TOML parse error at line 8, column 16
  |
8 | dependencies = [
  |                ^^^^^^^^^^^^^^^^^
relative path without a working directory: {root:uri}/subproject
subproject @ {root:uri}/subproject
             ^^^^^^^^^^^^^^^^^^^^^

pip install -e .

Obtaining file:///C:/Users/object/test/uv-hatch-bug
  Installing build dependencies ... done
  Checking if build backend supports build_editable ... done
  Getting requirements to build editable ... done
  Preparing editable metadata (pyproject.toml) ... done
Building wheels for collected packages: project
  Building editable for project (pyproject.toml) ... done
  Created wheel for project: filename=project-0.1.0-py2.py3-none-any.whl size=992 sha256=11807b7ff67c86dc454cef307552ec3d8ac732c790feca196b64012ab91f81b1
  Stored in directory: C:\Users\object\AppData\Local\Temp\pip-ephem-wheel-cache-v6xjjlqo\wheels\06\2b\f9\aa218f95f265aa64e3013e3ab97f138c95307be54f63b231e6
Successfully built project
Installing collected packages: project
Successfully installed project-0.1.0

pip install -e .[local]

Obtaining file:///C:/Users/object/test/uv-hatch-bug
  Installing build dependencies ... done
  Checking if build backend supports build_editable ... done
  Getting requirements to build editable ... done
  Preparing editable metadata (pyproject.toml) ... done
Processing c:\users\object\test\uv-hatch-bug\subproject (from project==0.1.0)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... done
Checking if build backend supports build_editable ... done
Building wheels for collected packages: project, subproject
  Building editable for project (pyproject.toml) ... done
  Created wheel for project: filename=project-0.1.0-py2.py3-none-any.whl size=992 sha256=11807b7ff67c86dc454cef307552ec3d8ac732c790feca196b64012ab91f81b1
  Stored in directory: C:\Users\object\AppData\Local\Temp\pip-ephem-wheel-cache-_aeumxhm\wheels\06\2b\f9\aa218f95f265aa64e3013e3ab97f138c95307be54f63b231e6
  Building wheel for subproject (pyproject.toml) ... done
  Created wheel for subproject: filename=subproject-0.1.0-py2.py3-none-any.whl size=1017 sha256=0fa7cad32cdb573d95efda0c6e5153e0eec075cfeb7b7e208e893bfd8780da0a
  Stored in directory: C:\Users\object\AppData\Local\Temp\pip-ephem-wheel-cache-_aeumxhm\wheels\96\35\a1\4cbdc9a17151719b42abce24fbf536ab374c79142e12ee2f74
Successfully built project subproject
Installing collected packages: subproject, project
  Attempting uninstall: project
    Found existing installation: project 0.1.0
    Uninstalling project-0.1.0:
      Successfully uninstalled project-0.1.0
Successfully installed project-0.1.0 subproject-0.1.0

Versions

OS: Windows 11
Python: 3.11.0 (main, Oct 24 2022, 18:26:48) [MSC v.1933 64 bit (AMD64)] on win32
uv: 0.1.17 (bb2d06cbb 2024-03-10)

[zanieb]

Thanks for the well written report! I think this might be solved by making a PEP 517 request per #1624 — or we could add support for this context formatting directly but I'm hesitant to do that since it's not a Python standard.

[charliermarsh]

Hmm, I'm not quite sure how projects other than hatch are supposed to be able to build that.

[charliermarsh]

@ofek - are other frontends expected to be able to build these projects? Any advice? I know Rye doesn't support this either: astral-sh/rye#826.

[ofek]

PDM added support for that but generally no, other projects can't use it without doing the PEP 517 process.

[charliermarsh]

We do go through the PEP 517 process so assuming all the build hooks work, it should "just work". I think we're failing because we're trying to parse the requirements even though we don't "need" them here. I'll take a look and see if it's easy.

[charliermarsh]

Okay yeah, we can support this.