$^P= 0x100;

    # x100
    # Provide informative "file" names for evals based on the place they were compiled.

perl -wlE "BEGIN{$^P= 0x100}eval '1+1; 1'; eval qq(\n;1+1;2)"

Useless use of a constant (2) in void context at (eval 1)[-e:1] line 1.
Useless use of a constant (2) in void context at (eval 2)[-e:1] line 2.