$ perl -Mdiagnostics -e " my @f; $f[-1] = 0; "
Modification of non-creatable array value attempted, subscript -1 at -e line 1 (#1)
    (F) You tried to make an array value spring into existence, and the
    subscript was probably negative, even counting from end of the array
    backwards.

Uncaught exception from user code:
        Modification of non-creatable array value attempted, subscript -1 at -e line 1.

$ perl -Mdiagnostics -e " my @f = 0; $f[-1] = 0; "