This is stupid, but I made it anyway

void.pm

package void;
use strict;
use Exporter 'import';
use Carp;

our @EXPORT = 'void';

sub void {
    return unless defined wantarray;
    my $caller = (caller 1)[3];
    Carp::croak("$caller() is designed for void context");
}

return 1 if defined wantarray;

# perl ./void.pm
require Test::More;
my $manipulate = sub {
  $_[0]->{foo} = 123;
  return void;
};

eval { $manipulate->({}) };
Test::More::ok(!$@, 'void context') or Test::More::diag($@);

my $x = eval { $manipulate->({}) };
Test::More::like($@, qr{void::__ANON__\(\) is designed for void}, 'not void context');

Test::More::done_testing();