Allow git dependencies in pyproject.toml format

[crclark]

What's the problem this feature will solve?

While adding a git dependency is undocumented, it seems to supported according to this issue.

However, when I try to use that format in pyproject.toml, I get an uninformative error message:

$ pip-compile --no-emit-index-url --output-file=requirements.txt --resolver=backtracking pyproject.toml                                            
Backend subprocess exited when trying to invoke get_requires_for_build_wheel
Failed to parse pyproject.toml

Describe the solution you'd like

• Allow git dependencies in the above format.
• Document that this is allowed.

Alternative Solutions

I have not been able to find a workaround.

Additional context

Minimal repro pyproject.toml

[project]
name = "foo"
description = ""
authors = [
    { name = "foo", email = "foo@example.com"}
]
version = "0.1.0"
requires-python = ">=3.8"
dependencies = [
    "numpy",
    # uncomment the following to see the failure
    # "git+https://github.com/jazzband/django-axes@0eecff2e57dd1748ce561b9d1340f079feb278f9",
]

[atugushev]

pip-tools support git dependencies. The issue is that the given pyproject.toml is invalid. Try pip install -e . to see the error. We're working on a better error log, see #1711.

[atugushev]

Closing this as a duplicate of #1711.