Regression in relative vs. absolute path of dependencies

[mgeier]

Describe the bug

Since Sphinx 9, a CI failure appeared in my project https://github.com/mgeier/sphinx-last-updated-by-git, see e.g. https://github.com/mgeier/sphinx-last-updated-by-git/actions/runs/20314482086/job/58354292735.

I bisected the problem down to #13681, commit f2bf37d.

I think the problem is here:

sphinx/sphinx/environment/__init__.py

Lines 616 to 617 in 038fc40

	# this will do the right thing when *filename* is absolute too
	filename = self.srcdir / filename

This line has been added and it turns previously relative dependency paths into absolute paths.

How to Reproduce

Look at dependencies that have previously been relative paths, now they are absolute paths.

For a concrete example, see the instructions in #10692, just using a different source file. Namely, add this to conf.py:

def _env_updated(app, env):
    print(env.dependencies['example_module.example_function'])
    exit()

def setup(app):
    app.connect('env-updated', _env_updated)

With f2bf37d and later, this is shown:

{_StrPath('/home/[...]/test-repo-for-sphinx-last-updated-by-git/example_module.py')}

With 711eb2b and anything before that, it displays:

{_StrPath('example_module.py')}

Environment Information

-

Sphinx extensions

Additional context

No response

[AA-Turner]

@mgeier does sphinx-last-updated-by-git require relative paths?

I'd prefer to store absolute paths internally & display relative paths to the user (e.g. in CLI output). This means we can de-duplicate paths etc. Over time, I'm hoping to convert all internal relative paths to absolute.

If this will cause problems, please let me know & I can revert for 9.1 and consider an alternative approach.

A

[AA-Turner]

cc @mgeier (if this is a regression & misses 9.1, will fix for 9.2)