use 5.032;
sub foo {
    local $!;
    my $err = shift;
    say "foo found: '$err'";
}
sub bar {
    my $err = shift;
    local $!;
    say "bar found: '$err'";
}
open (my $foo, '<', 'doesnotexist.dat') or foo($!);
open (my $bar, '<', 'doesnotexist.dat') or bar($!);

##</code><code>##

foo found: ''
bar found: 'No such file or directory'