facebook
String literal generic parameter to `Type[]` not allowed
Describe the Bug
from typing import *
SomeT = Type["Foo"]
class Foo:
pass
Unfortunately from __future__ import annotations doesn't help here.
Sandbox Link
https://pyrefly.org/sandbox/?code=MQAg6gpgNgxg9gWwiALnVALZAFAngJwgDMpcQBlAQwDsATAIzgA8AaTASwGcQuRKQADpQDmEAFCgA7lkIhccAK4gYNEJPzsUENpwyVZNWiCgR91PowUpUuAe2rCe5vCgxxqAOgkSQACQgGBsqKAiYgRKYoCoTccEQc3JyGjEwAXD4AtCAA4hDWhJRQGSjsSDYCyDBYMADW9o4REAyUtZkgAKqcyIQAbqZQAPoothAAFACUqOj2nBUw1vYR+IRGwxWcbRBMFRpI1NaSmhiYyACSACIAouGR0RDcrpQHyJwKAgJw+NajEB7CHnwrHB4AhQnltCBhHBitDaMR7Jp2O42G4+vg2HkYOM2mANFo+HQQPgFM5cK53ME4SBaOxCPNSE45Ip8CB6Pg4JIuvgxGIiOyEOV6jxQZ9rAAqHnkRAQAAqIAAvCAZSMANoAIgAYnA4GqALo8mBQSicbhauDpECWwTGzhAA
(Only applicable for extension issues) IDE Information
No response
Prefixing with the type keyword will work. I think this is because for possible implicit type aliases we initially treat this as a regular expression, which doesn't handle these string literals, and use the resulting type to decide if it's a regular assignment or an implicit type alias.
https://github.com/facebook/pyrefly/blob/main/pyrefly/lib/alt/solve.rs#L1943
One possible solution is to defer the error until after we decide it's an implicit type alias, in which case we can re-check it as an annotation.
The problem with rechecking it as an annotation is that many that require Usage bindings which we only generate for things we have a suspicion are types. This one will be tricky.
We eventually might have to persist scope info so we can figure out Usage later. But that's grim.
Without this, we cannot have recursive types like this: JsonType = None | bool | int | float | str | list["JsonType"] | dict[str, "JsonType"]
