The rules for unboxing conversions in assignments (5.2) and various other contexts (invocation, 5.3; casting, 5.5; numeric, 5.6) assert that an unboxing may be followed by a widening primitive conversion, but do not allow a widening reference conversion before the unboxing occurs.

Despite these rules, longstanding behavior of javac is to allow, e.g., type variables to be widened to a boxed primitive type.

<T extends Integer> void test(T arg) {
  int i = arg;
  int i2 = (int) arg;
  double d = arg + 1.0;
  Double d2 = Double.valueOf(arg);
  double d3 = (double) arg;
}

This behavior is especially important for interoperability with capture: various existing programs expect to be able to treat the elements of a 'List<? extends Integer>' as if they were ints.

List<? extends Integer> li = null;
int i = li.get(0);

Propose to change JLS in these sections to allow a widening reference conversion before unboxing.