Sphinx 4.0 finds more than one target for cross-reference

[felixhuettner]

Hello everyone,

Describe the bug
After upgrading to 4.0.0 we have discovered that existing code is raising a warning with more than one target found for cross-reference. In 3.5.4 we did not see this warning

To Reproduce
I have set up a minimal reproduction repository here: https://github.com/felixhuettner/sphinx-duplicate-import-repoduction

Steps to reproduce the behavior:

$ git clone https://github.com/felixhuettner/sphinx-duplicate-import-repoduction
$ cd sphinx-duplicate-import-repoduction
$ pip install -e .
$ pip install sphinx
$ cd docs
$ sphinx-build -W . _build

Output of the sphinx-build command:

❯ sphinx-build -W . _build
Running Sphinx v4.0.0+/acf66bc4d
making output directory... done
[autosummary] generating autosummary for: index.rst
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 1 source files that are out of date
updating environment: [new config] 1 added, 0 changed, 0 removed
reading sources... [100%] index
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [100%] index

Warning, treated as error:
..../sphinxtest/test/file2.py:docstring of test.file2.SomeClass.somemethod::more than one target found for cross-reference 'TestError': test.TestError, test.file1.TestError

Expected behavior
no warning appears

Your project
https://github.com/felixhuettner/sphinx-duplicate-import-repoduction

Environment info

• OS: Linux
• Python version: 3.9.4
• Sphinx version: 4.0.0
• Sphinx extensions: sphinx.ext.autosummary

Additional context
I have bisected the issue to be introduced by acf66bc

Thanks verry much

[tk0miya]

Thank you for reporting.

I reproduced the same error with this mark-up:

.. py:class:: TestError
   :module: test
   :canonical: test.file1.TestError

.. py:method:: SomeClass.somemethod()
   :module: test.file2

   :raises .TestError: abc

[felixhuettner]

Thank you for the fast fix