Object unions of same type do not collapse
type a = 1 | 1 // 1, collapsed
// ^?
type b = { a:1 } | { a:1 } // { a:1 } | { a:1 }, do not collapse
// ^?
type c = { a:1 } | { a:1 } | { a:1 } // { a:1 } | { a:1 } | { a:1 }, do not collapse
// ^?
this should be fine most of the time but it can be problematic if we use identical check on it
union is equal to union, but not equal to non union
type o = 1 | 1 // 1
// ^?
type p = { c:1 } | { c:1 } // { c:1 } | { c:1 }, what?
// ^?
type IsSame<T, U> = (<G>() => G extends T ? 1 : 2) extends <
G
>() => G extends U ? 1 : 2
? true
: false
type q = IsSame<p, {c:1 }> // false, huh?
// ^?
type r = IsSame<p, {c:1 } | {c:1}> // true, ok
// ^?
type s = IsSame<p, {c:1 } | {c:1} | {c:1}> // true, huh?
// ^?
type k = IsSame<p, {c:1 } | {c:1} | {c:1} | {c:1}> // true, huh?
// ^?
