Default type parameters vs constraints

[kLabz]

We can currently define default type parameters that are not compatible with their constraints:

class Foo<T:EnumValue = Void> {
    public var data:T;
    public final function new() {}
}

https://try.haxe.org/#8B325355

When used, type inference will use a monomorph there:

    // This is fine
    var e = new Foo();
    $type(e.data); // Unknown<0> : EnumValue

But when explicitly using the default type parameter, it'll fail as expected:

    // This is not fine
    var e:Foo = new Foo();
    $type(e.data); // Void

[ERROR] Test.hx:7: characters 5-27

 7 |     var e:Foo = new Foo();
   |     ^^^^^^^^^^^^^^^^^^^^^^
   | error: Void should be EnumValue
   | have: Foo<Void>
   | want: Foo<EnumValue>

We should probably catch that early, directly in class Foo<T:EnumValue = Void> declaration

[Simn]

I vaguely remember us saying "this is fine", but looking at it I'd also expect this to fail.

[Simn]

Closed by 060ff56