Sorting an array removes type inference #34099

function getAllValuesUnsorted(m: ReadonlyArray<ReadonlyArray<string>>): ReadonlyArray<string> {
	// OK
	return Array.from(flatten(m.values()))
}

function getAllValuesSorted(m: ReadonlyArray<ReadonlyArray<string>>): ReadonlyArray<string> {
	// Type 'unknown[]' is not assignable to type 'readonly string[]'.
	return Array.from(flatten(m.values())).sort()
}

function* flatten<T>(a: Iterable<Iterable<T>>): Iterable<T> {
	for (const xs of a)
		for (const x of xs)
			yield x
}