package PkgB;
sub errmsg {
   local $Carp::CarpLevel = $Carp::CarpLevel + 1;
   PkgA::errmsg(@_);
}

##</code><code>##

package PkgB;
our @ISA = 'PkgA';

##</code><code>##

package PkgB;
our @CARP_NOT = 'PkgA';