Just a semicolon in a method body is a null statement.  It has the full status
of a statement except that it is a noop.

Hence, the following method should not compile:

void f() {
  return;;
}

The second semicolon is a different statement and is unreachable.  There
should be an error reported that the second semicolon is unreachable.

N/A

This is a bug.  The ; is being picked out in the parser, but there
should be a special EmptyStatement node that undergoes reachability
like other statements.

  xxxxx@xxxxx   1997-10-06

This bug exists in the jdk1.3 compiler.

  xxxxx@xxxxx   1999-10-28

Well, I fixed it (the tree is called Skip), and discovered how often 
people write things like

	return 0;/* exit success */;

and

	{
	    return f();
	} catch (Whatever e) {
	    throw new Whatever2();
	};

Note the extra semicolon in both cases. I fixed a number of problems
in JDK sources and reported a number of JCK test cases that are broken.
And I'll bet we get lots of problem reports from users once this bug
fix makes it public. My plan is to dup those bug reports to this one, 
so people see WHY it isn't a compiler bug but rather was a bug in their
sources that the compiler simply wasn't catching before.

  xxxxx@xxxxx   2001-02-05

Here's another example of an unreachable ; that is not caught:

void f() {
  try {
    return;
  } catch (Exception e) { return; }
  /* unreachable -> */ ;
}

This fix is all wrong.  Instead of fixing the compiler you
should fix the specification to make unreachable null
statements legal.

I agree with tupari.
This is going to be a silly and annoying bug to find and 
fix. It is diggicult to see the null statement, even when 
you know what the error is ( which may programmers will 
not) and when the lines are tiny and trivially simple.

If the compiler disagrees with the spec, and the spec is
clear and
unambiguous and what was intended, then it is a compiler bug
and
must be fixed.  If you would like to see the spec changed,
by all
means submit an RFE.  If the spec is changed the compiler
will
then be changed to agree with the spec.