Don't all the functions that use convertType in this file need to be parameterized? What happens if there's a wildcard in a constraint in a type application, for example?

Don't all the functions that use convertType in this file need to be parameterized? What happens if there's a wildcard in a constraint in a type application, for example?

Could you give an example of what you mean? Meaning, what would this look like in syntax?

What happens if there's a wildcard in a constraint in a type application, for example?

This is a highly contrived example, but I imagine something like this:

class Foo a b c | a -> b c where
  fooMember :: a -> b

f :: forall @a. Array a -> Array (Array a)
f as = [as]

x :: forall c. Array (Foo Int Boolean c => Int -> Boolean)
x = [fooMember]

y :: forall c. Array (Array (Foo Int Boolean c => Int -> Boolean))
y = f @(Foo Int Boolean _ => _) x -- neither wildcard should warn IMO

Don't all the functions that use convertType in this file need to be parameterized? What happens if there's a wildcard in a constraint in a type application, for example?

Using your contrived example, no wildcard is emitted.
But to answer your question, no I don't think they need to parameterized. If there's a wildcard anywhere in the type expression passed to the VTA, it'll be parsed as an IgnoreWildcard rather than an UnnamedWildcard.

Tests that no warnings are issued need to be in tests/purs/warning. If after making that change the test works then I have no further objections, but I believe it won't—in which case, I think parameterizing convertConstraint is sufficient, as it looks like the only function that convertType' uses to call back into itself (though if you could double-check me on this, I'd appreciate it).

Ah.... No, you're right. I see the issue now.

it looks like [convertConstraint is] the only function that convertType' uses to call back into itself (though if you could double-check me on this, I'd appreciate it).

I can confirm that convertConstraint is the only other convert* function used in convertType whose implementation calls back into convertType.