public SignatureVisitor visitReturnType() {
if (type != METHOD_SIGNATURE || (state & (EMPTY | FORMAL | BOUND | PARAM)) == 0) {
throw new IllegalArgumentException();
}
state = RETURN;
SignatureVisitor v = sv == null ? null : sv.visitReturnType();
CheckSignatureAdapter cv = new CheckSignatureAdapter(TYPE_SIGNATURE, v);
cv.canBeVoid = true;
return cv;
}