Method getIntersectionType

internal/checker/checker.go:25946–25948

We normalize combinations of intersection and union types based on the distributive property of the '&' operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection types with union type constituents into equivalent union types with intersection type cons

(types []*Type)

// Also, unlike union types, the order of the constituent types is preserved in order that overload resolution
// for intersections of types with signatures can be deterministic.
func (c *Checker) getIntersectionType(types []*Type) *Type {
	return c.getIntersectionTypeEx(types, IntersectionFlagsNone, nil /*alias*/)
}

func (c *Checker) getIntersectionTypeEx(types []*Type, flags IntersectionFlags, alias *TypeAlias) *Type {
	var orderedTypes orderedSet[*Type]