F:\Perl>perl -we "use strict; {qw(key val)}; no strict 'refs';"
Useless use of a constant in void context at -e line 1.
Useless use of a constant in void context at -e line 1.

F:\Perl>perl -we "use strict; ({qw(key val)}); no strict 'refs';"
Useless use of single ref constructor in void context at -e line 1