ada4c4cb1f
If a typevar is declared as having a default, we shouldn't require a type to be specified for that typevar when explicitly specializing a generic class: ```py class WithDefault[T, U = int]: ... reveal_type(WithDefault[str]()) # revealed: WithDefault[str, int] ``` --------- Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>