I see your point and completely agree with it.

You mean something similar to following log:

D:\Work\PerlCompile\perl@16925mgnu\lib\B>perl -MO=Terse -we "for(;;){}
+"
LISTOP (0x1be3c00) leave [1]
    OP (0x1a88ca4) enter
    COP (0x1be3c28) nextstate
    BINOP (0x1be3c64) leaveloop
        LOOP (0x1be3c8c) enterloop
        LISTOP (0x1be3cc0) lineseq
            OP (0x1be3d64) stub
            OP (0x1be3d44) unstack
            COP (0x1be3d08) nextstate
-e syntax OK

D:\Work\PerlCompile\perl@16925mgnu\lib\B>perl -MO=Terse -we "for(@$a){
+}"
Name "main::a" used only once: possible typo at -e line 1.
LISTOP (0x1a812d0) leave [1]
    OP (0x1a812b0) enter
    COP (0x1a81318) nextstate
    BINOP (0x1be3ad8) leaveloop
        LOOP (0x1be3bd4) enteriter
            OP (0x1be3c08) null [3]
            UNOP (0x1a88c78) null [141]
                OP (0x1a88c58) pushmark
                UNOP (0x1be3c70) rv2av [2]
                    UNOP (0x1be3c94) rv2sv
                        PADOP (0x1be3d74) gv  1
            PADOP (0x1a88ca0) gv  3
        UNOP (0x1be3b04) null
            LOGOP (0x1be3b28) and
                OP (0x1be3c28) iter
                LISTOP (0x1be3b50) lineseq
                    OP (0x1be3c50) stub
                    OP (0x1be3bb4) unstack
                    COP (0x1be3b78) nextstate
-e syntax OK
[download]

Id that's it, it succeeds even without -DDEBUGGING for me.