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.

6 files changed, 160 insertions, 144 deletions

diff --git a/lib/B/Op_private.pm b/lib/B/Op_private.pm
index 4c0018a35e..265a9e334f 100644
--- a/lib/B/Op_private.pm
+++ b/lib/B/Op_private.pm
@@ -158,6 +158,7 @@ $bits{$_}{2} = 'OPpTRANS_IDENTICAL' for qw(trans transr);
 $bits{$_}{3} = 'OPpTRANS_SQUASH' for qw(trans transr);
 $bits{$_}{1} = 'OPpTRANS_USE_SVOP' for qw(trans transr);
 $bits{$_}{5} = 'OPpTRUEBOOL' for qw(grepwhile index length padav padhv pos ref rindex rv2av rv2hv subst);
+$bits{$_}{2} = 'OPpUSEINT' for qw(bit_and bit_or bit_xor complement left_shift nbit_and nbit_or nbit_xor ncomplement right_shift sbit_and sbit_or sbit_xor);
 
 my @bf = (
     {
@@ -270,9 +271,6 @@ $bits{avalues}{0} = $bf[0];
 $bits{backtick}{0} = $bf[0];
 @{$bits{bind}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 @{$bits{binmode}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
-@{$bits{bit_and}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{bit_or}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{bit_xor}}{1,0} = ($bf[1], $bf[1]);
 @{$bits{bless}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 @{$bits{caller}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 $bits{catch}{0} = $bf[0];
@@ -287,7 +285,6 @@ $bits{chroot}{0} = $bf[0];
 $bits{closedir}{0} = $bf[0];
 $bits{cmpchain_and}{0} = $bf[0];
 $bits{cmpchain_dup}{0} = $bf[0];
-$bits{complement}{0} = $bf[0];
 @{$bits{concat}}{6,1,0} = ('OPpCONCAT_NESTED', $bf[1], $bf[1]);
 $bits{cond_expr}{0} = $bf[0];
 @{$bits{connect}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
@@ -418,7 +415,6 @@ $bits{leavesub}{0} = $bf[0];
 $bits{leavesublv}{0} = $bf[0];
 $bits{leavewhen}{0} = $bf[0];
 $bits{leavewrite}{0} = $bf[0];
-@{$bits{left_shift}}{1,0} = ($bf[1], $bf[1]);
 $bits{length}{0} = $bf[0];
 @{$bits{link}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 $bits{list}{6} = 'OPpLIST_GUESSED';
@@ -447,11 +443,7 @@ $bits{method_super}{0} = $bf[0];
 @{$bits{multiconcat}}{6,5,3,0} = ('OPpMULTICONCAT_APPEND', 'OPpMULTICONCAT_FAKE', 'OPpMULTICONCAT_STRINGIFY', $bf[0]);
 @{$bits{multideref}}{5,4,0} = ('OPpMULTIDEREF_DELETE', 'OPpMULTIDEREF_EXISTS', $bf[0]);
 @{$bits{multiply}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{nbit_and}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{nbit_or}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{nbit_xor}}{1,0} = ($bf[1], $bf[1]);
 @{$bits{ncmp}}{1,0} = ($bf[1], $bf[1]);
-$bits{ncomplement}{0} = $bf[0];
 @{$bits{ne}}{1,0} = ($bf[1], $bf[1]);
 $bits{negate}{0} = $bf[0];
 $bits{next}{0} = $bf[0];
@@ -499,7 +491,6 @@ $bits{require}{0} = $bf[0];
 @{$bits{reset}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 @{$bits{reverse}}{3,0} = ('OPpREVERSE_INPLACE', $bf[0]);
 $bits{rewinddir}{0} = $bf[0];
-@{$bits{right_shift}}{1,0} = ($bf[1], $bf[1]);
 @{$bits{rindex}}{3,2,1,0} = ($bf[4], $bf[4], $bf[4], $bf[4]);
 $bits{rmdir}{0} = $bf[0];
 $bits{rv2av}{0} = $bf[0];
@@ -508,9 +499,6 @@ $bits{rv2av}{0} = $bf[0];
 $bits{rv2hv}{0} = 'OPpRV2HV_ISKEYS';
 @{$bits{rv2sv}}{5,4,0} = ($bf[8], $bf[8], $bf[0]);
 @{$bits{sassign}}{7,6,1,0} = ('OPpASSIGN_CV_TO_GV', 'OPpASSIGN_BACKWARDS', $bf[1], $bf[1]);
-@{$bits{sbit_and}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{sbit_or}}{1,0} = ($bf[1], $bf[1]);
-@{$bits{sbit_xor}}{1,0} = ($bf[1], $bf[1]);
 $bits{scalar}{0} = $bf[0];
 $bits{schomp}{0} = $bf[0];
 $bits{schop}{0} = $bf[0];
@@ -698,6 +686,7 @@ our %defines = (
     OPpTRANS_SQUASH          =>   8,
     OPpTRANS_USE_SVOP        =>   2,
     OPpTRUEBOOL              =>  32,
+    OPpUSEINT                =>   4,
 );
 
 our %labels = (
@@ -799,6 +788,7 @@ our %labels = (
     OPpTRANS_SQUASH          => 'SQUASH',
     OPpTRANS_USE_SVOP        => 'USE_SVOP',
     OPpTRUEBOOL              => 'BOOL',
+    OPpUSEINT                => 'USEINT',
 );
 
 
@@ -850,6 +840,7 @@ our %ops_using = (
     OPpTARGET_MY             => [qw(abs add atan2 chdir chmod chomp chown chr chroot concat cos crypt divide exec exp flock getpgrp getppid getpriority hex i_add i_divide i_modulo i_multiply i_subtract index int kill left_shift length link log mkdir modulo multiconcat multiply nbit_and nbit_or nbit_xor ncomplement oct ord pow push rand rename right_shift rindex rmdir schomp scomplement setpgrp setpriority sin sleep sqrt srand stringify subtract symlink system time unlink unshift utime wait waitpid)],
     OPpTRANS_CAN_FORCE_UTF8  => [qw(trans transr)],
     OPpTRUEBOOL              => [qw(grepwhile index length padav padhv pos ref rindex rv2av rv2hv subst)],
+    OPpUSEINT                => [qw(bit_and bit_or bit_xor complement left_shift nbit_and nbit_or nbit_xor ncomplement right_shift sbit_and sbit_or sbit_xor)],
 );
 
 $ops_using{OPpASSIGN_COMMON_RC1} = $ops_using{OPpASSIGN_COMMON_AGG};
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))
diff --git a/opcode.h b/opcode.h
index 2fadc692ff..16f0bcadfe 100644
--- a/opcode.h
+++ b/opcode.h
@@ -2246,6 +2246,7 @@ END_EXTERN_C
 #define OPpSORT_REVERSE         0x04
 #define OPpSPLIT_IMPLIM         0x04
 #define OPpTRANS_IDENTICAL      0x04
+#define OPpUSEINT               0x04
 #define OPpARGELEM_MASK         0x06
 #define OPpARG3_MASK            0x07
 #define OPpPADRANGE_COUNTSHIFT  0x07
@@ -2432,6 +2433,7 @@ EXTCONST char PL_op_private_labels[] = {
     'T','A','R','G','\0',
     'T','A','R','G','M','Y','\0',
     'U','N','I','\0',
+    'U','S','E','I','N','T','\0',
     'U','S','E','_','S','V','O','P','\0',
     'U','T','F','\0',
     'k','e','y','\0',
@@ -2455,11 +2457,11 @@ EXTCONST char PL_op_private_labels[] = {
 EXTCONST I16 PL_op_private_bitfields[] = {
     0, 8, -1,
     0, 8, -1,
-    0, 581, -1,
+    0, 588, -1,
     0, 8, -1,
     0, 8, -1,
-    0, 588, -1,
-    0, 577, -1,
+    0, 595, -1,
+    0, 584, -1,
     1, -1, 0, 545, 1, 30, 2, 295, -1,
     4, -1, 1, 176, 2, 183, 3, 190, -1,
     4, -1, 0, 545, 1, 30, 2, 295, 3, 122, -1,
@@ -2540,8 +2542,8 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
       84, /* concat */
       87, /* multiconcat */
       93, /* stringify */
-      80, /* left_shift */
-      80, /* right_shift */
+      95, /* left_shift */
+      95, /* right_shift */
       12, /* lt */
       12, /* i_lt */
       12, /* gt */
@@ -2563,20 +2565,20 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
       12, /* seq */
       12, /* sne */
       12, /* scmp */
-      12, /* bit_and */
-      12, /* bit_xor */
-      12, /* bit_or */
-      80, /* nbit_and */
-      80, /* nbit_xor */
-      80, /* nbit_or */
-      12, /* sbit_and */
-      12, /* sbit_xor */
-      12, /* sbit_or */
+      97, /* bit_and */
+      97, /* bit_xor */
+      97, /* bit_or */
+      95, /* nbit_and */
+      95, /* nbit_xor */
+      95, /* nbit_or */
+      97, /* sbit_and */
+      97, /* sbit_xor */
+      97, /* sbit_or */
        0, /* negate */
        0, /* i_negate */
        0, /* not */
-       0, /* complement */
-      75, /* ncomplement */
+      97, /* complement */
+      95, /* ncomplement */
       75, /* scomplement */
       12, /* smartmatch */
       93, /* atan2 */
@@ -2591,11 +2593,11 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
       75, /* hex */
       75, /* oct */
       75, /* abs */
-      95, /* length */
-      98, /* substr */
-     101, /* vec */
-     103, /* index */
-     103, /* rindex */
+      98, /* length */
+     101, /* substr */
+     104, /* vec */
+     106, /* index */
+     106, /* rindex */
       52, /* sprintf */
       52, /* formline */
       75, /* ord */
@@ -2606,30 +2608,30 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* uc */
        0, /* lc */
        0, /* quotemeta */
-     107, /* rv2av */
-     114, /* aelemfast */
-     114, /* aelemfast_lex */
-     115, /* aelem */
-     120, /* aslice */
-     123, /* kvaslice */
+     110, /* rv2av */
+     117, /* aelemfast */
+     117, /* aelemfast_lex */
+     118, /* aelem */
+     123, /* aslice */
+     126, /* kvaslice */
        0, /* aeach */
        0, /* avalues */
       40, /* akeys */
        0, /* each */
       40, /* values */
       40, /* keys */
-     124, /* delete */
-     128, /* exists */
-     130, /* rv2hv */
-     115, /* helem */
-     120, /* hslice */
-     123, /* kvhslice */
-     138, /* multideref */
+     127, /* delete */
+     131, /* exists */
+     133, /* rv2hv */
+     118, /* helem */
+     123, /* hslice */
+     126, /* kvhslice */
+     141, /* multideref */
       52, /* unpack */
       52, /* pack */
-     145, /* split */
+     148, /* split */
       52, /* join */
-     150, /* list */
+     153, /* list */
       12, /* lslice */
       52, /* anonlist */
       52, /* anonhash */
@@ -2638,50 +2640,50 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* pop */
        0, /* shift */
       93, /* unshift */
-     152, /* sort */
-     157, /* reverse */
+     155, /* sort */
+     160, /* reverse */
        0, /* grepstart */
-     159, /* grepwhile */
+     162, /* grepwhile */
        0, /* mapstart */
        0, /* mapwhile */
        0, /* range */
-     161, /* flip */
-     161, /* flop */
+     164, /* flip */
+     164, /* flop */
        0, /* and */
        0, /* or */
       12, /* xor */
        0, /* dor */
-     163, /* cond_expr */
+     166, /* cond_expr */
        0, /* andassign */
        0, /* orassign */
        0, /* dorassign */
-     165, /* entersub */
-     172, /* leavesub */
-     172, /* leavesublv */
+     168, /* entersub */
+     175, /* leavesub */
+     175, /* leavesublv */
        0, /* argcheck */
-     174, /* argelem */
+     177, /* argelem */
        0, /* argdefelem */
-     176, /* caller */
+     179, /* caller */
       52, /* warn */
       52, /* die */
       52, /* reset */
       -1, /* lineseq */
-     178, /* nextstate */
-     178, /* dbstate */
+     181, /* nextstate */
+     181, /* dbstate */
       -1, /* unstack */
       -1, /* enter */
-     179, /* leave */
+     182, /* leave */
       -1, /* scope */
-     181, /* enteriter */
-     185, /* iter */
+     184, /* enteriter */
+     188, /* iter */
       -1, /* enterloop */
-     186, /* leaveloop */
+     189, /* leaveloop */
       -1, /* return */
-     188, /* last */
-     188, /* next */
-     188, /* redo */
-     188, /* dump */
-     188, /* goto */
+     191, /* last */
+     191, /* next */
+     191, /* redo */
+     191, /* dump */
+     191, /* goto */
       52, /* exit */
        0, /* method */
        0, /* method_named */
@@ -2694,7 +2696,7 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* leavewhen */
       -1, /* break */
       -1, /* continue */
-     190, /* open */
+     193, /* open */
       52, /* close */
       52, /* pipe_op */
       52, /* fileno */
@@ -2710,7 +2712,7 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
       52, /* getc */
       52, /* read */
       52, /* enterwrite */
-     172, /* leavewrite */
+     175, /* leavewrite */
       -1, /* prtf */
       -1, /* print */
       -1, /* say */
@@ -2740,33 +2742,33 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* getpeername */
        0, /* lstat */
        0, /* stat */
-     195, /* ftrread */
-     195, /* ftrwrite */
-     195, /* ftrexec */
-     195, /* fteread */
-     195, /* ftewrite */
-     195, /* fteexec */
-     200, /* ftis */
-     200, /* ftsize */
-     200, /* ftmtime */
-     200, /* ftatime */
-     200, /* ftctime */
-     200, /* ftrowned */
-     200, /* fteowned */
-     200, /* ftzero */
-     200, /* ftsock */
-     200, /* ftchr */
-     200, /* ftblk */
-     200, /* ftfile */
-     200, /* ftdir */
-     200, /* ftpipe */
-     200, /* ftsuid */
-     200, /* ftsgid */
-     200, /* ftsvtx */
-     200, /* ftlink */
-     200, /* fttty */
-     200, /* fttext */
-     200, /* ftbinary */
+     198, /* ftrread */
+     198, /* ftrwrite */
+     198, /* ftrexec */
+     198, /* fteread */
+     198, /* ftewrite */
+     198, /* fteexec */
+     203, /* ftis */
+     203, /* ftsize */
+     203, /* ftmtime */
+     203, /* ftatime */
+     203, /* ftctime */
+     203, /* ftrowned */
+     203, /* fteowned */
+     203, /* ftzero */
+     203, /* ftsock */
+     203, /* ftchr */
+     203, /* ftblk */
+     203, /* ftfile */
+     203, /* ftdir */
+     203, /* ftpipe */
+     203, /* ftsuid */
+     203, /* ftsgid */
+     203, /* ftsvtx */
+     203, /* ftlink */
+     203, /* fttty */
+     203, /* fttext */
+     203, /* ftbinary */
       93, /* chdir */
       93, /* chown */
       75, /* chroot */
@@ -2786,17 +2788,17 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* rewinddir */
        0, /* closedir */
       -1, /* fork */
-     204, /* wait */
+     207, /* wait */
       93, /* waitpid */
       93, /* system */
       93, /* exec */
       93, /* kill */
-     204, /* getppid */
+     207, /* getppid */
       93, /* getpgrp */
       93, /* setpgrp */
       93, /* getpriority */
       93, /* setpriority */
-     204, /* time */
+     207, /* time */
       -1, /* tms */
        0, /* localtime */
       52, /* gmtime */
@@ -2816,8 +2818,8 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* require */
        0, /* dofile */
       -1, /* hintseval */
-     205, /* entereval */
-     172, /* leaveeval */
+     208, /* entereval */
+     175, /* leaveeval */
        0, /* entertry */
       -1, /* leavetry */
        0, /* ghbyname */
@@ -2855,18 +2857,18 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* lock */
        0, /* once */
       -1, /* custom */
-     211, /* coreargs */
-     215, /* avhvswitch */
+     214, /* coreargs */
+     218, /* avhvswitch */
        3, /* runcv */
        0, /* fc */
       -1, /* padcv */
       -1, /* introcv */
       -1, /* clonecv */
-     217, /* padrange */
-     219, /* refassign */
-     225, /* lvref */
-     231, /* lvrefslice */
-     232, /* lvavref */
+     220, /* padrange */
+     222, /* refassign */
+     228, /* lvref */
+     234, /* lvrefslice */
+     235, /* lvavref */
        0, /* anonconst */
       12, /* isa */
        0, /* cmpchain_and */
@@ -2894,13 +2896,13 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
  */
 
 EXTCONST U16  PL_op_private_bitdefs[] = {
-    0x0003, /* scalar, prototype, refgen, srefgen, readline, regcmaybe, regcreset, regcomp, substcont, chop, schop, defined, undef, study, preinc, i_preinc, predec, i_predec, postinc, i_postinc, postdec, i_postdec, negate, i_negate, not, complement, ucfirst, lcfirst, uc, lc, quotemeta, aeach, avalues, each, pop, shift, grepstart, mapstart, mapwhile, range, and, or, dor, andassign, orassign, dorassign, argcheck, argdefelem, method, method_named, method_super, method_redir, method_redir_super, entergiven, leavegiven, enterwhen, leavewhen, untie, tied, dbmclose, getsockname, getpeername, lstat, stat, readlink, readdir, telldir, rewinddir, closedir, localtime, alarm, require, dofile, entertry, ghbyname, gnbyname, gpbyname, shostent, snetent, sprotoent, sservent, gpwnam, gpwuid, ggrnam, ggrgid, lock, once, fc, anonconst, cmpchain_and, cmpchain_dup, entertrycatch, catch, pushdefer */
+    0x0003, /* scalar, prototype, refgen, srefgen, readline, regcmaybe, regcreset, regcomp, substcont, chop, schop, defined, undef, study, preinc, i_preinc, predec, i_predec, postinc, i_postinc, postdec, i_postdec, negate, i_negate, not, ucfirst, lcfirst, uc, lc, quotemeta, aeach, avalues, each, pop, shift, grepstart, mapstart, mapwhile, range, and, or, dor, andassign, orassign, dorassign, argcheck, argdefelem, method, method_named, method_super, method_redir, method_redir_super, entergiven, leavegiven, enterwhen, leavewhen, untie, tied, dbmclose, getsockname, getpeername, lstat, stat, readlink, readdir, telldir, rewinddir, closedir, localtime, alarm, require, dofile, entertry, ghbyname, gnbyname, gpbyname, shostent, snetent, sprotoent, sservent, gpwnam, gpwuid, ggrnam, ggrgid, lock, once, fc, anonconst, cmpchain_and, cmpchain_dup, entertrycatch, catch, pushdefer */
     0x2fdc, 0x40d9, /* pushmark */
     0x00bd, /* wantarray, runcv */
     0x0438, 0x1a50, 0x418c, 0x3d28, 0x3505, /* const */
     0x2fdc, 0x3659, /* gvsv */
     0x18b5, /* gv */
-    0x0067, /* gelem, lt, i_lt, gt, i_gt, le, i_le, ge, i_ge, eq, i_eq, ne, i_ne, ncmp, i_ncmp, slt, sgt, sle, sge, seq, sne, scmp, bit_and, bit_xor, bit_or, sbit_and, sbit_xor, sbit_or, smartmatch, lslice, xor, isa */
+    0x0067, /* gelem, lt, i_lt, gt, i_gt, le, i_le, ge, i_ge, eq, i_eq, ne, i_ne, ncmp, i_ncmp, slt, sgt, sle, sge, seq, sne, scmp, smartmatch, lslice, xor, isa */
     0x2fdc, 0x40d8, 0x03d7, /* padsv */
     0x2fdc, 0x40d8, 0x05b4, 0x30cc, 0x3ea9, /* padav */
     0x2fdc, 0x40d8, 0x05b4, 0x0650, 0x30cc, 0x3ea8, 0x2b41, /* padhv */
@@ -2912,16 +2914,18 @@ EXTCONST U16  PL_op_private_bitdefs[] = {
     0x018f, /* bless, glob, sprintf, formline, unpack, pack, join, anonlist, anonhash, splice, warn, die, reset, exit, close, pipe_op, fileno, umask, binmode, tie, dbmopen, sselect, select, getc, read, enterwrite, sysopen, sysseek, sysread, syswrite, eof, tell, seek, truncate, fcntl, ioctl, send, recv, socket, sockpair, bind, connect, listen, accept, shutdown, gsockopt, ssockopt, open_dir, seekdir, gmtime, shmget, shmctl, shmread, shmwrite, msgget, msgctl, msgsnd, msgrcv, semop, semget, semctl, ghbyaddr, gnbyaddr, gpbynumber, gsbyname, gsbyport, syscall */
     0x383c, 0x3758, 0x2894, 0x27d0, 0x0003, /* backtick */
     0x05b5, /* subst */
-    0x117c, 0x21b8, 0x09b4, 0x3fec, 0x2548, 0x4684, 0x07c1, /* trans, transr */
+    0x117c, 0x21b8, 0x09b4, 0x3fec, 0x2548, 0x4764, 0x07c1, /* trans, transr */
     0x0fbc, 0x04d8, 0x0067, /* sassign */
     0x0c78, 0x0b74, 0x0a70, 0x30cc, 0x05a8, 0x0067, /* aassign */
-    0x4530, 0x0003, /* chomp, schomp, ncomplement, scomplement, sin, cos, exp, log, sqrt, int, hex, oct, abs, ord, chr, chroot, rmdir */
+    0x4530, 0x0003, /* chomp, schomp, scomplement, sin, cos, exp, log, sqrt, int, hex, oct, abs, ord, chr, chroot, rmdir */
     0x05b4, 0x30cc, 0x0003, /* pos */
-    0x4530, 0x0067, /* pow, multiply, i_multiply, divide, i_divide, modulo, i_modulo, add, i_add, subtract, i_subtract, left_shift, right_shift, nbit_and, nbit_xor, nbit_or */
+    0x4530, 0x0067, /* pow, multiply, i_multiply, divide, i_divide, modulo, i_modulo, add, i_add, subtract, i_subtract */
     0x1538, 0x0067, /* repeat */
     0x32b8, 0x4530, 0x0067, /* concat */
     0x2fdc, 0x0218, 0x1c34, 0x4530, 0x426c, 0x0003, /* multiconcat */
     0x4530, 0x018f, /* stringify, atan2, rand, srand, crypt, push, unshift, flock, chdir, chown, unlink, chmod, utime, rename, link, symlink, mkdir, waitpid, system, exec, kill, getpgrp, setpgrp, getpriority, setpriority, sleep */
+    0x4530, 0x4689, /* left_shift, right_shift, nbit_and, nbit_xor, nbit_or, ncomplement */
+    0x4689, /* bit_and, bit_xor, bit_or, sbit_and, sbit_xor, sbit_or, complement */
     0x05b4, 0x4530, 0x0003, /* length */
     0x3a90, 0x30cc, 0x012b, /* substr */
     0x30cc, 0x0067, /* vec */
@@ -2951,7 +2955,7 @@ EXTCONST U16  PL_op_private_bitdefs[] = {
     0x2fdc, 0x3658, 0x10ec, 0x3c05, /* enteriter */
     0x3c05, /* iter */
     0x2e7c, 0x0067, /* leaveloop */
-    0x47bc, 0x0003, /* last, next, redo, dump, goto */
+    0x489c, 0x0003, /* last, next, redo, dump, goto */
     0x383c, 0x3758, 0x2894, 0x27d0, 0x018f, /* open */
     0x1df0, 0x204c, 0x1f08, 0x1cc4, 0x0003, /* ftrread, ftrwrite, ftrexec, fteread, ftewrite, fteexec */
     0x1df0, 0x204c, 0x1f08, 0x0003, /* ftis, ftsize, ftmtime, ftatime, ftctime, ftrowned, fteowned, ftzero, ftsock, ftchr, ftblk, ftfile, ftdir, ftpipe, ftsuid, ftsgid, ftsvtx, ftlink, fttty, fttext, ftbinary */
@@ -3041,8 +3045,8 @@ EXTCONST U8 PL_op_private_valid[] = {
     /* CONCAT     */ (OPpARG2_MASK|OPpTARGET_MY|OPpCONCAT_NESTED),
     /* MULTICONCAT */ (OPpARG1_MASK|OPpMULTICONCAT_STRINGIFY|OPpTARGET_MY|OPpMULTICONCAT_FAKE|OPpMULTICONCAT_APPEND|OPpLVAL_INTRO),
     /* STRINGIFY  */ (OPpARG4_MASK|OPpTARGET_MY),
-    /* LEFT_SHIFT */ (OPpARG2_MASK|OPpTARGET_MY),
-    /* RIGHT_SHIFT */ (OPpARG2_MASK|OPpTARGET_MY),
+    /* LEFT_SHIFT */ (OPpUSEINT|OPpTARGET_MY),
+    /* RIGHT_SHIFT */ (OPpUSEINT|OPpTARGET_MY),
     /* LT         */ (OPpARG2_MASK),
     /* I_LT       */ (OPpARG2_MASK),
     /* GT         */ (OPpARG2_MASK),
@@ -3064,20 +3068,20 @@ EXTCONST U8 PL_op_private_valid[] = {
     /* SEQ        */ (OPpARG2_MASK),
     /* SNE        */ (OPpARG2_MASK),
     /* SCMP       */ (OPpARG2_MASK),
-    /* BIT_AND    */ (OPpARG2_MASK),
-    /* BIT_XOR    */ (OPpARG2_MASK),
-    /* BIT_OR     */ (OPpARG2_MASK),
-    /* NBIT_AND   */ (OPpARG2_MASK|OPpTARGET_MY),
-    /* NBIT_XOR   */ (OPpARG2_MASK|OPpTARGET_MY),
-    /* NBIT_OR    */ (OPpARG2_MASK|OPpTARGET_MY),
-    /* SBIT_AND   */ (OPpARG2_MASK),
-    /* SBIT_XOR   */ (OPpARG2_MASK),
-    /* SBIT_OR    */ (OPpARG2_MASK),
+    /* BIT_AND    */ (OPpUSEINT),
+    /* BIT_XOR    */ (OPpUSEINT),
+    /* BIT_OR     */ (OPpUSEINT),
+    /* NBIT_AND   */ (OPpUSEINT|OPpTARGET_MY),
+    /* NBIT_XOR   */ (OPpUSEINT|OPpTARGET_MY),
+    /* NBIT_OR    */ (OPpUSEINT|OPpTARGET_MY),
+    /* SBIT_AND   */ (OPpUSEINT),
+    /* SBIT_XOR   */ (OPpUSEINT),
+    /* SBIT_OR    */ (OPpUSEINT),
     /* NEGATE     */ (OPpARG1_MASK),
     /* I_NEGATE   */ (OPpARG1_MASK),
     /* NOT        */ (OPpARG1_MASK),
-    /* COMPLEMENT */ (OPpARG1_MASK),
-    /* NCOMPLEMENT */ (OPpARG1_MASK|OPpTARGET_MY),
+    /* COMPLEMENT */ (OPpUSEINT),
+    /* NCOMPLEMENT */ (OPpUSEINT|OPpTARGET_MY),
     /* SCOMPLEMENT */ (OPpARG1_MASK|OPpTARGET_MY),
     /* SMARTMATCH */ (OPpARG2_MASK),
     /* ATAN2      */ (OPpARG4_MASK|OPpTARGET_MY),
diff --git a/perl.h b/perl.h
index 7dc9e0e5bd..9f89d1b16a 100644
--- a/perl.h
+++ b/perl.h
@@ -5482,8 +5482,7 @@ typedef enum {
 #define KEY_sigvar 0xFFFF /* fake keyword representing a signature var */
 
 /* Hints are now stored in a dedicated U32, so the bottom 8 bits are no longer
-   special and there is no need for HINT_PRIVATE_MASK for COPs
-   However, bitops store HINT_INTEGER in their op_private.
+   special and there is no need for HINT_PRIVATE_MASK for COPs.
 
     NOTE: The typical module using these has the bit value hard-coded, so don't
     blindly change the values of these.
diff --git a/pp.c b/pp.c
index 8054e7da11..e37e3dd6d9 100644
--- a/pp.c
+++ b/pp.c
@@ -2038,7 +2038,7 @@ PP(pp_left_shift)
     svl = TOPs;
     {
       const int shift = S_shift_amount(aTHX_ svr);
-      if (PL_op->op_private & HINT_INTEGER) {
+      if (PL_op->op_private & OPpUSEINT) {
           SETi(IV_LEFT_SHIFT(SvIV_nomg(svl), shift));
       }
       else {
@@ -2056,7 +2056,7 @@ PP(pp_right_shift)
     svl = TOPs;
     {
       const int shift = S_shift_amount(aTHX_ svr);
-      if (PL_op->op_private & HINT_INTEGER) {
+      if (PL_op->op_private & OPpUSEINT) {
           SETi(IV_RIGHT_SHIFT(SvIV_nomg(svl), shift));
       }
       else {
@@ -2361,7 +2361,7 @@ PP(pp_bit_and)
       if (SvNIOKp(left) || SvNIOKp(right)) {
         const bool left_ro_nonnum  = !SvNIOKp(left) && SvREADONLY(left);
         const bool right_ro_nonnum = !SvNIOKp(right) && SvREADONLY(right);
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV i = SvIV_nomg(left) & SvIV_nomg(right);
           SETi(i);
         }
@@ -2386,7 +2386,7 @@ PP(pp_nbit_and)
     tryAMAGICbin_MG(band_amg, AMGf_assign|AMGf_numarg);
     {
         dATARGET; dPOPTOPssrl;
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV i = SvIV_nomg(left) & SvIV_nomg(right);
           SETi(i);
         }
@@ -2422,7 +2422,7 @@ PP(pp_bit_or)
       if (SvNIOKp(left) || SvNIOKp(right)) {
         const bool left_ro_nonnum  = !SvNIOKp(left) && SvREADONLY(left);
         const bool right_ro_nonnum = !SvNIOKp(right) && SvREADONLY(right);
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV l = (USE_LEFT(left) ? SvIV_nomg(left) : 0);
           const IV r = SvIV_nomg(right);
           const IV result = op_type == OP_BIT_OR ? (l | r) : (l ^ r);
@@ -2456,7 +2456,7 @@ PP(pp_nbit_or)
                     AMGf_assign|AMGf_numarg);
     {
         dATARGET; dPOPTOPssrl;
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV l = (USE_LEFT(left) ? SvIV_nomg(left) : 0);
           const IV r = SvIV_nomg(right);
           const IV result = op_type == OP_NBIT_OR ? (l | r) : (l ^ r);
@@ -2608,7 +2608,7 @@ PP(pp_complement)
     {
       dTOPss;
       if (SvNIOKp(sv)) {
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV i = ~SvIV_nomg(sv);
           SETi(i);
         }
@@ -2631,7 +2631,7 @@ PP(pp_ncomplement)
     tryAMAGICun_MG(compl_amg, AMGf_numeric|AMGf_numarg);
     {
         dTARGET; dTOPss;
-        if (PL_op->op_private & HINT_INTEGER) {
+        if (PL_op->op_private & OPpUSEINT) {
           const IV i = ~SvIV_nomg(sv);
           SETi(i);
         }
diff --git a/regen/op_private b/regen/op_private
index ea24474308..357b4a1a32 100644
--- a/regen/op_private
+++ b/regen/op_private
@@ -201,6 +201,13 @@ use strict;
     $args0{$_} = 1 for qw(entersub avhvswitch
                        rv2hv);                  # UNOPs that usurp bit 0
 
+    # Historically, bit ops used bit 0 to indicate 'use integer' in scope;
+    # For now, ban use of bits 0..1 as an arg count, in order to detect
+    # any residual code which conflates use of the HINT_INTEGER and
+    # OPpUSEINT flags
+
+    $args0{$_} = 1 for ops_with_check('ck_bitop');
+
     $args1{$_} = 1 for (
                         qw(reverse), # ck_fun(), but most bits stolen
                         qw(mapstart grepstart), # set in ck_fun, but
@@ -281,6 +288,16 @@ use strict;
 }
 
 
+# Are these bit ops in the scope of 'use integer'?
+#
+# Note that historically they used to use bit 0, which corresponded to
+# HINT_INTEGER (a bit flags within PL_hints). We deliberately choose
+# a value (2) different than that flag, and different to the two bits used
+# to store the argument count, to flush out any residual code which
+# conflates the two.
+
+addbits($_, 2 => qw(OPpUSEINT USEINT))
+    for ops_with_check('ck_bitop');
 
 # if NATIVE_HINTS is defined, op_private on cops holds the top 8 bits
 # of PL_hints, although only bits 6 & 7 are officially used for that