$ perl -e' sub say(&@) { "..." } say { "..." };' $ perl -e'use 5.010; sub say(&@) { "..." } say { "..." };' syntax error at -e line 1, near "};" Execution of -e aborted due to compilation errors. #### $ perl -e' print $x;' $ perl -e'use 5.012; print $x;' Global symbol "$x" requires explicit package name at -e line 1. Execution of -e aborted due to compilation errors. #### $ perl -e' die "Validation error" if uc(chr(0xE9))=~/\xC9/;' $ perl -e'use 5.012; die "Validation error" if uc(chr(0xE9))=~/\xC9/;' Validation error at -e line 1.