Ryan Cavanaugh

What we've discovered trying (multiple times!) to implement non-workarounded completion lists for open-ended unions is that the instant something doesn't have type system effects, it tends to disappear nearly immediately,...

> To that end, when two function types (or two promise types) “combine” to produce a new type It's notable that there is no existing "combine" mechanism where two types...

I think there's a possible parsing ambiguity in the referenced comment > Note that this does not apply to functions with union return types that include undefined `Foo | (()...

This is not supported. `Array` must be an interface. You're the only person trying to do this, please stop 😅

Good catch; I think we changed how eagerly type aliases are resolved in some cases and broke that check.

Gonna hijack this one

It looks like we created an unintentional dependency on this codepath not flagging type aliases when we added `PromiseConstructorLike`, which is defined as ```ts declare type PromiseConstructorLike = new (executor:...

@denis-migdal I'm just going to ask that you *please* not learn TypeScript's various ins and outs via filing bugs on the issue tracker. If you have some behavior that also...

It's not like we're not aware of the downsides of this. If it were easy and simple to fix, we would have done it already.

This sounds identical to #12400?