perl -wE "$a=undef; say length($a); printf qq~Version: %vd\n~, $^V; "
Use of uninitialized value in say at -e line 1.

Version: 5.14.2

# alternativ
perl -wle "$a=undef; print length($a); printf qq~Version: %vd\n~, $^V; "
Use of uninitialized value in print at -e line 1.

Version: 5.14.2