Method getSingleCommonSupertype

internal/checker/inference.go:1523–1532

(types []*Type)

}

func (c *Checker) getSingleCommonSupertype(types []*Type) *Type {
	// First, find the leftmost type for which no type to the right is a strict supertype, and if that
	// type is a strict supertype of all other candidates, return it. Otherwise, return the leftmost type
	// for which no type to the right is a (regular) supertype.
	candidate := c.findLeftmostType(types, (*Checker).isTypeStrictSubtypeOf)
	if core.Every(types, func(t *Type) bool { return t == candidate || c.isTypeStrictSubtypeOf(t, candidate) }) {
		return candidate
	}
	return c.findLeftmostType(types, (*Checker).isTypeSubtypeOf)
}

func (c *Checker) findLeftmostType(types []*Type, f func(c *Checker, s *Type, t *Type) bool) *Type {
	var candidate *Type