Inconsistent results with --no-strict-optional

[vfazio]

Bug Report

When using --no-strict-optional the determined type within a one-line boolean expression does not always get calculated correctly

To Reproduce

from contextlib import nullcontext
import pytest

def test(raises: bool) -> None:
    ctx = pytest.raises(ValueError) if raises else nullcontext()
    #ctx = nullcontext() if not raises else pytest.raises(ValueError)
    import typing
    if typing.TYPE_CHECKING:
        reveal_type(ctx)
    with ctx:
        pass

Expected Behavior

The context manager types would be resolved correctly

Actual Behavior

(.venv) vfazio@VFAZIO1:~/development/xtf$ mypy --no-strict-optional contextlib_check.py 
contextlib_check.py:9:21: note: Revealed type is "builtins.object"
contextlib_check.py:10:10: error: "object" has no attribute "__enter__"  [attr-defined]
contextlib_check.py:10:10: error: "object" has no attribute "__exit__"  [attr-defined]
Found 2 errors in 1 file (checked 1 source file)
(.venv) vfazio@VFAZIO1:~/development/xtf$ mypy -V
mypy 1.11.0 (compiled: yes)

If you use the line that's commented out, it "works" and it only changes the order of object evaluation:

(xtf-py3.11) (.venv) vfazio@VFAZIO1:~/development/xtf$ mypy --no-strict-optional contextlib_check.py 
contextlib_check.py:9:21: note: Revealed type is "contextlib.AbstractContextManager[_pytest._code.code.ExceptionInfo[builtins.ValueError], builtins.bool]"
Success: no issues found in 1 source file

If --no-strict-optional is not passed, it also checks fine:

(.venv) vfazio@VFAZIO1:~/development/xtf$ mypy contextlib_check.py 
contextlib_check.py:9:21: note: Revealed type is "contextlib.AbstractContextManager[Union[_pytest._code.code.ExceptionInfo[builtins.ValueError], None], Union[builtins.bool, None]]"

In all cases, rightly (probably) or wrongly, the revealed type is also different than it was in 1.10.x.

(.venv) vfazio@VFAZIO1:~/development/xtf$ mypy --no-strict-optional contextlib_check.py 
contextlib_check.py:9:21: note: Revealed type is "contextlib.AbstractContextManager[_pytest._code.code.ExceptionInfo[builtins.ValueError]]"
Success: no issues found in 1 source file
(.venv) vfazio@VFAZIO1:~/development/xtf$ mypy -V
mypy 1.10.1 (compiled: yes)

 (.venv) vfazio@VFAZIO1:~/development/xtf$ mypy contextlib_check.py 
contextlib_check.py:9:21: note: Revealed type is "contextlib.AbstractContextManager[Union[_pytest._code.code.ExceptionInfo[builtins.ValueError], None]]"

I think I'd expect some cooked down version of _pytest.python_api.RaisesContext[builtins.ValueError] | contextlib.nullcontext[None]. it's not clear to me where the builtins.bool value is coming from in 1.11.x.

In the meantime, i can restructure the code, but this wasn't necessary in previous versions.

    ctx: AbstractContextManager
    if raises:
        ctx = pytest.raises(ValueError)
    else:
        ctx = nullcontext()

Your Environment

• Mypy version used: 1.11.0
• Mypy command-line flags: --no-strict-optional
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.11

[asottile-sentry]

seems similar to #16264 #10109 #5512

[vfazio]

This may be a duplicate. it does seem related to other issues in topic-join-v-union Using join vs. using unions it just seemed a bit odd that behavior changed across versions and with this knob turned on.

[vfazio]

Seems resolved as of 55a0812