$Data::Dumper::Indent is fully qualified , you don't need resp. can't declare it.

Workarounds:

• you can disable the specific warning
• eval the use and your settings

D:\tmp>perl
use strict;
use warnings;
eval <<'__CODE__';
    use Data::Dumper;
    $Data::Dumper::Indent = 0;
__CODE__
__END__

D:\tmp>
[download]

update

Full demo:

NB: in order to use Dumper w/o parens or leading '&'-sigil you will need to declare it at compile time with subs

D:\tmp>perl
use strict;
use warnings;
#use subs qw/Dumper/;

eval <<'__CODE__';
    use Data::Dumper;
    $Data::Dumper::Indent = 0;
__CODE__

print Dumper( [map {{$_=>$a++}} "a".."d"] );

__END__
$VAR1 = [{'a' => 0},{'b' => 1},{'c' => 2},{'d' => 3}];
D:\tmp>
[download]