for (qw(strict warnings)) {
    print "using $_\n" if $INC{"$_.pm"};
}
[download]

That should do.

To check if a specific warning is enabled, use warnings::enabled(category). See warnings. Consult perllexwarn for the available categories.

The variable $^H is, according to perlvar, strictly for internal use. I guess it is write-only.

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}