GeezerVison

The top-level scope is never popped, so warnUnusedVariables never ran
for it, and unused top-level variables were never reported. Report them
from finalizeDynamicScope instead, using the lexer's file because a
reused TOPLEVEL_BINDING scope has no file of its own.

pushBlockScope and pushLocalScope set warnOnUnusedVariables from
isVerbose() alone. That dropped the eval and -e exception that
initTopLocalVariables had just set up, and popCurrentScope never
restored the old value. As in MRI's dyna_push, a block now keeps the
setting of its enclosing scope, and a local scope saves the old setting
and restores it when popped.

With -w, now matching CRuby:

  ruby -w script.rb (top-level a = 1)     now warns (was silent),
                                          also for required files
  echo 'a = 1' | ruby -w -                now warns (was silent)
  ruby -we "1.times do\n  a = 1\nend"     now silent (was warning)
  eval("1.times do\n  a = 1\nend")        now silent (was warning)

Unexcludes TestRubyOptions#test_unused_variable.