It should, yes. But don't expect it to in any 5.8.x release. The maint pumpking is very cautious about adding new warnings, and for a while there were a number of people advocating

sub foo {
   my $x if 0;
   ...
}
[download]

to create a "static" variable, rather than using a closure

{
   my $x;
   sub foo {
      ...
   }
}
[download]