Dataclass method operations being incorrectly freshened

[jfeser]

The following test should pass:

def test_operation_instance_identity():
    @dataclasses.dataclass
    class A:
        @Operation.define
        def f(self) -> int:
            raise NotHandled

    a = A()
    assert a.f().op == a.f
    assert a.f().op == a.f().op

[eb8680]

I don't think this is particular to dataclasses and from the implementation of Operation.__get__ I'm pretty sure it's intentional - the invariant a.f is a.f holds, and evaluateing a Term a.f() should be equivalent to calling a.f() in a handler context. There is a test here that exercises the expected behavior.

[jfeser]

The behavior in the test above is particular to dataclasses. The test passes if the dataclass annotation is removed.

The surprising thing is that in the following code, op1 and op2 are distinct:

op1 = a.f().op
op2 = a.f().op

I expect them to both be the instance operation a.f.

[eb8680]

Hmm, OK, if there's a discrepancy between behavior with and without dataclass that's a bug, and the behavior without dataclass is the correct behavior since that's what's tested elsewhere. Not sure what could be causing this.

[jfeser]

I think it's related to the evaluation rule for dataclasses interacting with __get__ in a strange way. My suspicion is that we're getting a fresh instance of A from a call to dataclasses.replace somehow.