--warn-no-return Warns about functions that have no return statements if used in tandem with --strict-optional

[rowillia]

UPDATED - This problem appears to happen when --warn-no-return is used in tandem with --strict-optional

test.py:

class Foo():
    def __init__(self) -> None:
        self.x = 0
    def increment_x(self) -> None:
        self.x += 1

mypy -s --fast-parser --warn-no-return --strict-optional test.py

test.py: note: In member "__init__" of class "Foo":
test.py:2: note: Missing return statement
test.py: note: In member "increment_x" of class "Foo":
test.py:4: note: Missing return statement

[rwbarton]

This is just a bug caused by the fact that --strict-optional changes the meaning of returning None internally in mypy. It works fine without --strict-optional.

[rowillia]

Got it. Thanks @rwbarton for figuring out what I meant even though I forgot to specify what my flags were. Changed the title to reflect the actual problem.

[ddfisher]

So really this is just a problematic interaction between --warn-no-return and --strict-optional.