Config file at ~/.mypy.ini is not used #18977

Bug Report

I have my mypy configuration file at ~/.mypy.ini.

In that config file I have the following option:

[mypy]
cache_dir=/tmp/mypy_cache

However when I run mypy from some working directory, .mypy_cache directory gets created in that directory, which means my config file is not used.

However, if I specify path to that config file directly, it's used correctly:

$ mypy -v --config-file ~/.mypy.ini SomeFile.py

LOG:  Mypy Version:           1.15.0
LOG:  Config File:            /home/user/.mypy.ini
LOG:  Configured Executable:  /usr/bin/python3
LOG:  Current Executable:     /usr/bin/python3
LOG:  Cache Dir:              /tmp/mypy_cache
...

Unfortunately, mypy doesn't print the location of the config file it uses, or the locations where it tries to find a config file, so no more details on the problem is available.

Expected Behavior

As stated in the documentation: https://mypy.readthedocs.io/en/stable/config_file.html
~/.mypy.ini should be used if --config-file is not specified and other preferred config file locations do not exist, which it true in my case.

So I would expect the exact same behavior if --config-file ~/.mypy.ini is specified and if --config-file is not specified at all.

Actual Behavior

$ mypy -v SomeFile.py

LOG:  Mypy Version:           1.15.0
LOG:  Config File:            Default
LOG:  Configured Executable:  /usr/bin/python3
LOG:  Current Executable:     /usr/bin/python3
LOG:  Cache Dir:              .mypy_cache
...

Note Config File: Default and Cache Dir: .mypy_cache.

And indeed, ./.mypy_cache folder is created.

Your Environment

$ mypy --version
mypy 1.15.0 (compiled: yes)

$ python --version
Python 3.12.3