c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my %h;
 @h{ qw(a b c) };
 dd \%h;
"
Useless use of hash slice in void context at -e line 1.
{}

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my %h;
 @h{ qw(a b c) } = undef;
 dd \%h;
"
{ a => undef, b => undef, c => undef }