[1.19 regression] output format overruled by .mypy_cache #20353
Description
Bug Report
Starting with mypy 1.19.0, the --output argument seems to be ignored when a .mypy_cache directory is present.
To Reproduce
Minimum working reproduction:
Have an incorrectly typed Python file.
# foo.py wrong: str = 5Install the latest mypy version.
$ pip freeze librt==0.6.3 mypy==1.19.0 mypy_extensions==1.1.0 pathspec==0.12.1 typing_extensions==4.15.0 Run mypy, with different formats:
$ rm -r .mypy_cache $ mypy foo.py $ mypy --output json foo.py $ rm -r .mypy_cache $ mypy --output json foo.py $ mypy foo.py Expected Behavior
Calls with --output json produce json output, calls without --output json do not (assuming nothing specified in config files).
Actual Behavior
The output format is taken from the first call
$ rm -r .mypy_cache $ mypy foo.py foo.py:1: error: Incompatible types in assignment (expression has type "int", variable has type "str") [assignment] Found 1 error in 1 file (checked 1 source file) $ mypy --output json foo.py foo.py:1: error: Incompatible types in assignment (expression has type "int", variable has type "str") [assignment] Found 1 error in 1 file (checked 1 source file) $ rm -r .mypy_cache $ mypy --output json foo.py {"file": "foo.py", "line": 1, "column": 13, "message": "Incompatible types in assignment (expression has type \"int\", variable has type \"str\")", "hint": null, "code": "assignment", "severity": "error"} Your Environment
- Mypy version used: 1.19.0
- Mypy command-line flags:
--output - Mypy configuration options from
mypy.ini(and other config files): none - Python version used: 3.14.0
Extra remarks
In a larger project, I have seen even --exclude being ignored on successive calls, but could not reproduce this yet in a minimal examples.