Placeholder types are pinned too early #363

Describe the Bug

Consider the following code snippet:

def f[T](xs: list[T], y: T) -> None: pass

f([True], 42)

This should type check just fine since specialising T to int in the call to f is compatible with both arguments. However, pyrefly does not like this code and complains:

ERROR 3:11-13: Argument `Literal[42]` is not assignable to parameter `y` with type `bool` in function `f` [bad-argument-type]

My educated guess is that you're pinning the placeholder type introduced for the call to f too early.

Sandbox Link

https://pyrefly.org/sandbox/?code=CYUwZgBGDaAqC6AKAHgZwFwQDYEtUBc54AaCAT01gEoIBaAPggDkB7AOxEwAcBDVVAFACwiOACcAriBIQALACYqQA

(Only applicable for extension issues) IDE Information

No response