"invalid syntax" with type annotation on return statement

[blueyed]

Given t-return.py:

from typing import List


def getfoo():
    return ["foo"]


def foo() -> List[str]:
    return getfoo()  # type: List[str]

mypy --show-column-numbers t-return.py shows:

t-return.py:9:31: error: invalid syntax

Note that the reported column is the "i" in "List", which appears to be off in general.

The workaround is to split the return into an assignment (with the annotation), and then returning the variable. But I think it would be nice if the annotation would work with the return statement already.
If that's not going to be supported, the error should be more descriptive probably.

mypy 0.770+dev.9101707bd0c96624d09cb31fe573d7e25c89a35c.dirty

[Cito]

I get the same error with Python 3.8, but with Python 3.7 I get this:

t-return.py:9:39: error: misplaced type annotation

Both with the same mypy version 0.761.

[adithyabsk]

One can use the cast operation here but due to the differences in using cast versus the type comment it might be preferable to use the type comment. Thought I'd add a +1 from me as well.

[JukkaL]

Mypy doesn't implement it's own parser, so this would need to be added to CPython for it to be supported. I don't think that it's a likely addition, however, since comment-based type annotations are primarily for backwards compatibility with older Python versions, and the variable annotation syntax introduced in Python 3.6 is recommended for new code.