$ perl -Mstrict -Mwarnings -le " my $hr; $hr->{stuff}"
Useless use of hash element in void context at -e line 1.

$ perl -Mstrict -Mwarnings -le " my $hr; map { $hr->{stuff} } 1"

$ perl -Mstrict -Mwarnings -le " my $hr;  $hr->{stuff} for 1"
Useless use of hash element in void context at -e line 1.