"$unused_local = UndefinedConstant;" was being optimized away, so
we didnt get a warning for the constant. return it instead.
$unused_local = new Object;
return;
became
new Object;
return;
This affected the (unspecified) order of destruction of $this
vs $unused_local. Since we're specifically trying to test that
we dont crash when a local generates a backtrace after $this
has been destroyed, force the variable to be used.
mwilliams