// With constexpr, it is possible to have the same expression
// in multiple places. Each usage of the expression must be able
// to have a different type.
int i = b?;  // XXX this is a bug. should not be allowed!
int j = i;
byte? b = makeopt 1+1;
int z = b?;

() f() {
    byte? bb = makeopt 1+1;
    int ii = bb?;
}

/*
int? i = b;  // XXX this is a bug. should not be allowed!
int? ii = b; // XXX this is a bug. should not be allowed!
*/