use strict;
use warnings;
use 5.010;

{
    package Foo;
    our $bar;
}
{
    if (exists $::{'Foo::'}{bar}) {
        say "There's a Foo::bar with some sigil";
    }
    if (exists $::{'Foo::'}{baz}) {
        say "There's a Foo::baz with some sigil";
    }
}