Use fallback version when no Git tags are found?

[pawamoy]

Currently, it looks like the fallback version is only used when pdm-backend completely fails reading anything from the SCM, i.e. the project is not a Git repository. When the project is a Git repository, but doesn't have any tags, pdm-backend will infer a version like 0.1.devN+gHASH.dDATE.

I'm in a situation where uv refuses to solve my dependencies, because my current project dev-depends on a library that depends on back the current project, and since the current project version is computed as 0.1.etc (because it doesn't have Git tags¹) , it's not compatible with what the library requires, and uv fails. See astral-sh/uv#8148. I think uv should not fail, or have a config flag to ignore the current project version.

In the meantime, I'm trying to use the fallback version, but since my project is a Git repo, the fallback version doesn't seem to be used. That's also what I gather from reading the code:

            scm_version = get_version_from_scm(
                context.root, tag_regex=tag_regex, tag_filter=tag_filter
            )
            if scm_version is None:  # <-- probably false, and branch is not entered
                if fallback_version is not None:
                    version = fallback_version

Do you think it would be feasible to use the fallback version if no tags were found, even though the project is a proper Git repository?

Footnotes

1. It doesn't have Git tags for various reasons. For example it could be a contributor fork, and GitHub doesn't copy tags when creating a fork. ↩

[pawamoy]

OK I found a uv-based solution (see astral-sh/uv#8148 (comment)), this issue can be closed 🙂

[pawamoy]

Actually that led to other issues. So I used my brain and found a pdm-backend solution:

[tool.pdm.version]
source = "call"
getter = "scripts.get_version:get_version"

# scripts/get_version.py
import re
from contextlib import suppress
from pathlib import Path

from pdm.backend.hooks.version import SCMVersion, Version, default_version_formatter, get_version_from_scm

_root = Path(__file__).parent.parent
_changelog = _root / "CHANGELOG.md"
_changelog_version_re = re.compile(r"^## \[(\d+\.\d+\.\d+)\].*$")
_default_scm_version = SCMVersion(Version("0.0.0"), None, False, None, None)


def get_version():
    scm_version = get_version_from_scm(_root) or _default_scm_version
    if scm_version.version <= Version("0.1"):  # Missing Git tags?
        with suppress(OSError, StopIteration):
            with _changelog.open("r", encoding="utf8") as file:
                match = next(filter(None, map(_changelog_version_re.match, file)))
                scm_version = scm_version._replace(version=Version(match.group(1)))
    return default_version_formatter(scm_version)