add OPpUSEINT op_private flag bit

The bitwise ops, such as a '<<', have an op_private flag that is set
when compiled within the scope of 'use integer;'.

Unfortunately, due to historical reasons, the defined flag that
indicates this bit (bit 0) is HINT_INTEGER rather than an OPpfoo define.
But HINT_INTEGER is supposed to represent a bit within PL_hints, not a bit
within op_private. If someone reorganised the flags in PL_hints at some
point, it would mess up bitwise ops.

So this commit:

1) adds a new flag, OPpUSEINT, to indicate the bit within op_private.
2) Changes this flag's value from 0x1 to 0x4 to force it to be different
   than HINT_INTEGER - thus potentially flushing out any misuse of this
   flag anywhere (in core or XS code).
3) tells regen/op_private that the lower two bits of op_private in bitwise
   ops don't contain the argument count. They never did, but not
   specifying that in regen/op_private meant that the debugging code in
   op_free() never spotted the unknown bit 0 sometimes being set.
4) Also tell that debugging code to skip the test if the op is banned.
   This fixes a new fail in dist/Safe/t/safeops.t which was croaking
   about a banned op having an unrecognised op_private flag bit set
   before ck_bitop() had a chance to delete the arg count in op_private.

1 files changed, 8 insertions, 3 deletions

diff --git a/op.c b/op.c
index c7ee2c1a4c..d015c390d9 100644
--- a/op.c
+++ b/op.c
@@ -946,11 +946,15 @@ Perl_op_free(pTHX_ OP *o)
          *     inconsistent state then. Note that an error when
          *     compiling the main program leaves PL_parser NULL, so
          *     we can't spot faults in the main code, only
-         *     evaled/required code */
+         *     evaled/required code;
+         *   * it's a banned op - we may be croaking before the op is
+         *     fully formed. - see CHECKOP. */
 #ifdef DEBUGGING
         if (   o->op_ppaddr == PL_ppaddr[type]
             && PL_parser
-            && !PL_parser->error_count)
+            && !PL_parser->error_count
+            && !(PL_op_mask && PL_op_mask[type])
+        )
         {
             assert(!(o->op_private & ~PL_op_private_valid[type]));
         }
@@ -12569,7 +12573,8 @@ Perl_ck_bitop(pTHX_ OP *o)
 {
     PERL_ARGS_ASSERT_CK_BITOP;
 
-    o->op_private = (U8)(PL_hints & HINT_INTEGER);
+    /* get rid of arg count and indicate if in the scope of 'use integer' */
+    o->op_private = (PL_hints & HINT_INTEGER) ? OPpUSEINT : 0;
 
     if (!(o->op_flags & OPf_STACKED) /* Not an assignment */
             && OP_IS_INFIX_BIT(o->op_type))