if sig == origSig {
		// No substitution occurred, but we still need to create a new signature to
		// hold the instantiated receiver.
		copy := *origSig
		sig = &copy
	}

	var rtyp Type
	if origm.hasPtrRecv() {
		rtyp = NewPointer(t)
	} else {
		rtyp = t
	}

	sig.recv = substVar(origSig.recv, rtyp)
	return substFunc(origm, sig)
}

// SetUnderlying sets the underlying type and marks t as complete.

	if sig == origSig {
		// No substitution occurred, but we still need to create a new signature to
		// hold the instantiated receiver.
		copy := *origSig
		sig = &copy
	}

	var rtyp Type
	if origm.hasPtrRecv() {
		rtyp = NewPointer(t)
	} else {
		rtyp = t
	}

	sig.recv = substVar(origSig.recv, rtyp)
	return substFunc(origm, sig)
}

// SetUnderlying sets the underlying type and marks t as complete.