Generics not typechecked

[msullivan]

The following code passes typechecking:

# pyre-strict
from typing import TypeVar

T = TypeVar('T')
def coerce(x: T) -> int:
    1 + 'foo'
    return x

In general it seems that functions with types involving generics are not typechecked.

For comparison, mypy produces the following errors:

poly.py:6: error: Unsupported operand types for + ("int" and "str")
poly.py:7: error: Incompatible return value type (got "T", expected "int")

[dark]

Yeah, that seems correct. --debug produces: Undefined type [11]: Type T is not defined.

@dkgi, any comment?

[dkgi]

@sinancepel was looking into this recently.

[dkgi]

Basically what happens here is that we try to figure out whether T <= int on the return statement and then give up because we do not store variables in the type order. We haven't yet really put much thought into surfacing these issues :|

[oscarvarto]

Any further progress to support generics?

[mrkmndz]

Over the course of the past few months we have done a lot of work on correctly supporting type variables. The given example as well as many many others now work correctly.

Please file new issues for any other type variable issues.