dmypy: Line number disappears when invoking multiple times

[intgr]

Bug Report

% dmypy restart
Daemon stopped
Daemon started
% dmypy run lib/testlib.py
lib/testlib.py:46: error: Unexpected attribute "xxxx" for model "Xxxx"
lib/testlib.py:142: error: The return type of a generator function should be "Generator" or one of its supertypes
Found 2 errors in 1 file (checked 945 source files)
% dmypy run lib/testlib.py
lib/testlib.py: error: The return type of a generator function should be "Generator" or one of its supertypes
lib/testlib.py:46: error: Unexpected attribute "xxxx" for model "Xxxx"
Found 2 errors in 1 file (checked 1 source file)

Note in the 2nd invocation lib/testlib.py: error: The return type of a generator function no longer has a line number.

To Reproduce

I tried reducing this to a smaller example, but failed to reproduce it that way. :(

Your Environment

• Mypy version used: 0.942
• Mypy command-line flags: (none)
• Mypy configuration options from mypy.ini (and other config files): I can reproduce this when I delete mypy config of my project
• Python version used: 3.10.2
• Operating system and version: macOS

[dubreuia]

I have the same issue

[emmatyping]

Can one of you provide a project/example that reproduces this?

[bzoracler]

This issue seems to only occur with generator functions which are typed wrongly in the return type. Minimum reproducible example:

# generator_test.py

def gen() -> None:  # Deliberately wrong return type
    yield ""

With no daemon started, invoke dmypy run twice:

$ dmypy run .
Daemon started
generator_test.py:1: error: The return type of a generator function should be "Generator" or one of its supertypes  [misc]
$ dmypy run .
generator_test.py: error: The return type of a generator function should be "Generator" or one of its supertypes  [misc]

This doesn't happen when dmypy recheck is the second run, but as soon as dmypy run is run another time, the line number disappears:

$ dmypy run .
Daemon started
generator_test.py:1: error: The return type of a generator function should be "Generator" or one of its supertypes  [misc]
$ dmypy recheck
generator_test.py:1: error: The return type of a generator function should be "Generator" or one of its supertypes  [misc]
$ dmypy run .
generator_test.py: error: The return type of a generator function should be "Generator" or one of its supertypes  [misc]

If the return type is Generator or Iterator, this issue doesn't occur, even if the type argument isn't right:

# generator_test_2.py

from collections.abc import Iterator

def gen() -> Iterator[None]:  # Deliberately wrong return type
    yield ""

$ dmypy run .
Daemon started
generator_test_2.py:4: error: Incompatible types in "yield" (actual type "int", expected type "None")  [misc]
$ dmypy run .
generator_test_2.py:4: error: Incompatible types in "yield" (actual type "int", expected type "None")  [misc]