package MyMod1;
use Exporter::Extensible -exporter_setup => 1;
sub foo :Export( :default ) { 42 }

##</code><code>##

package MyMod2;
use Exporter::Extensible -exporter_setup => 1;
sub bar :Export( :default ) { 43 }

##</code><code>##

package MyMod3;
use parent qw( MyMod1 MyMod2 );

##</code><code>##

perl -I. -MMyMod3 -E 'say foo'

##</code><code>##

package MyMod1;
use Exporter::Extensible -exporter_setup => 1;
sub foo :Export { 42 }

##</code><code>##

package MyMod2;
use Exporter::Extensible -exporter_setup => 1;
sub bar :Export { 43 }

##</code><code>##

package MyMod3;
use parent qw( MyMod1 MyMod2 );

##</code><code>##

perl -I. -MMyMod3=:all -E 'say foo'