//   [p, q, ...] ➞ [x, y, ...]    mapping from type parameters to types
	traceInference = false
)

// A unifier maintains a list of type parameters and
// corresponding types inferred for each type parameter.
// A unifier is created by calling newUnifier.
type unifier struct {
	// handles maps each type parameter to its inferred type through
	// an indirection *Type called (inferred type) "handle".

	//   [p, q, ...] ➞ [x, y, ...]    mapping from type parameters to types
	traceInference = false
)

// A unifier maintains a list of type parameters and
// corresponding types inferred for each type parameter.
// A unifier is created by calling newUnifier.
type unifier struct {
	// handles maps each type parameter to its inferred type through
	// an indirection *Type called (inferred type) "handle".

	ignoreInvalids bool // if set, identical treats an invalid type as identical to any type
}

// For changes to this code the corresponding changes should be made to unifier.nify.
func (c *comparer) identical(x, y Type, p *ifacePair) bool {
	x = Unalias(x)
	y = Unalias(y)

	if x == y {
		return true
	}

	if c.ignoreInvalids && (!isValid(x) || !isValid(y)) {

	ignoreInvalids bool // if set, identical treats an invalid type as identical to any type
}

// For changes to this code the corresponding changes should be made to unifier.nify.
func (c *comparer) identical(x, y Type, p *ifacePair) bool {
	x = Unalias(x)
	y = Unalias(y)

	if x == y {
		return true
	}

	if c.ignoreInvalids && (!isValid(x) || !isValid(y)) {