% git clone https://github.com/nedbat/acidica
% cd acidica
% git checkout 3a142e473e319718edf42f514cbde304061d5b75
% uv venv -p 3.14
% source .venv/bin/activate
% uv sync
Resolved 29 packages in 8ms
warning: Skipping installation of entry points (`project.scripts`) for package `acidica` because this project is not packaged; to install entry points, set `tool.uv.package = true` or define a `build-system`
Prepared 4 packages in 217ms
Installed 27 packages in 77ms
+ ast-serialize==0.6.0
+ click==8.4.2
+ coverage==7.15.0
+ iniconfig==2.3.0
+ libcst==1.9.0
+ librt==0.13.0
+ linkify-it-py==2.1.0
+ markdown-it-py==4.2.0
+ mdit-py-plugins==0.6.1
+ mdurl==0.1.2
+ mutmut==3.6.0
+ mypy==2.3.0
+ mypy-extensions==1.1.0
+ packaging==26.2
+ pathspec==1.1.1
+ platformdirs==4.11.0
+ pluggy==1.6.0
+ pygments==2.20.0
+ pytest==9.1.1
+ pytest-cov==7.1.0
+ pyyaml==6.0.3
+ rich==15.0.0
+ setproctitle==1.3.7
+ textual==8.2.8
+ ty==0.0.58
+ typing-extensions==4.16.0
+ uc-micro-py==2.0.0
% uv pip install -e .
Resolved 1 package in 7ms
Built acidica @ file:///private/tmp/acid2/acidica
Prepared 1 package in 792ms
Installed 1 package in 2ms
+ acidica==0.1.0 (from file:///private/tmp/acid2/acidica)
% pytest
====================================================================== test session starts =======================================================================
platform darwin -- Python 3.14.4, pytest-9.1.1, pluggy-1.6.0
rootdir: /private/tmp/acid2/acidica
configfile: pyproject.toml
plugins: cov-7.1.0
collected 140 items
tests/test_programs.py ................................................................................................................................... [ 93%]
......... [100%]
====================================================================== 140 passed in 0.12s =======================================================================
% mypy --strict src tests
Success: no issues found in 9 source files
% mutmut run
⠹ Generating mutants
done in 6770ms (8 files mutated, 0 ignored, 0 unmodified)
⠙ Filtering mutations with type checker
Traceback (most recent call last):
File "/private/tmp/acid2/acidica/.venv/bin/mutmut", line 10, in <module>
sys.exit(cli())
~~~^^
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/click/core.py", line 1569, in __call__
return self.main(*args, **kwargs)
~~~~~~~~~^^^^^^^^^^^^^^^^^
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/click/core.py", line 1490, in main
rv = self.invoke(ctx)
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/click/core.py", line 1970, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/click/core.py", line 1353, in invoke
return ctx.invoke(self.callback, **ctx.params)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/click/core.py", line 907, in invoke
return callback(*args, **kwargs)
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/mutmut/__main__.py", line 1002, in run
_run(mutant_names, max_children)
~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/mutmut/__main__.py", line 1031, in _run
mutants_caught_by_type_checker = filter_mutants_with_type_checker()
File "/private/tmp/acid2/acidica/.venv/lib/python3.14/site-packages/mutmut/mutation/file_mutation.py", line 494, in filter_mutants_with_type_checker
raise Exception(
...<3 lines>...
)
Exception: Could not find mutant for type error /private/tmp/acid2/acidica/mutants/src/acidica/interpreter.py:892 (Cannot determine type of "subline").
Probably, a code mutation influenced types in unexpected locations.
If your project normally has no type errors and uses mypy/pyrefly, please file an issue with steps to reproduce on github.
To reproduce: