`x = x or y` with x undeclared gives no error

[jhance]

I think it should, because python considers such recursive definitions to be an error.

[JukkaL]

This should definitely be an error.

[jhance]

I had a bit of trouble replicating. Easiest way was a type annotation:

x = x or 0 # type: int

Another way is to just do it in function scope (no type annotation needed).

Seems like we treat this as x already being defined (since we know its type). A bit of introspection reveals that lvalue.is_def = False so the fault is probably within the semantic analyzer. However, this only happens in global scope, I'm finding that in function scope that is_def = True (and in this scenario, I have no idea how its not encountering an error).