Also implement the negated versions of the flagged operators; ne:u and !=:u

Author: leonerd

lib/B/Op_private.pm

@@ -16200,8 +16200,10 @@ Perl_apply_opflags(pTHX_ U32 opcode, char *flagstr)
 
     for(char flag; (flag = *flagstr); flagstr++) {
         switch(opcode_base) {
-            case OP_SEQ:
-            case OP_EQ:
+            case OP_SEQ: /* eq */
+            case OP_SNE: /* ne */
+            case OP_EQ:  /* == */
+            case OP_NE:  /* != */
                 switch(flag) {
                     case 'u':
                         priv |= OPpEQ_UNDEF;

op.c

@@ -2290,6 +2290,15 @@ PP(pp_ne)
     SV *right = PL_stack_sp[0];
     SV *left  = PL_stack_sp[-1];
 
+    if(UNLIKELY(PL_op->op_private & OPpEQ_UNDEF)) {
+        bool lundef = !SvOK(left), rundef = !SvOK(right);
+
+        if(lundef || rundef) {
+            rpp_replace_2_IMM_NN(boolSV(!(lundef && rundef)));
+            return NORMAL;
+        }
+    }
+
     U32 flags_and = SvFLAGS(left) & SvFLAGS(right);
     U32 flags_or  = SvFLAGS(left) | SvFLAGS(right);
 
@@ -2473,6 +2482,15 @@ PP(pp_sne)
     SV *right = PL_stack_sp[0];
     SV *left  = PL_stack_sp[-1];
 
+    if(PL_op->op_private & OPpEQ_UNDEF) {
+        bool lundef = !SvOK(left), rundef = !SvOK(right);
+
+        if(lundef || rundef) {
+            rpp_replace_2_IMM_NN(boolSV(!(lundef && rundef)));
+            return NORMAL;
+        }
+    }
+
     rpp_replace_2_IMM_NN(boolSV(!sv_eq_flags(left, right, 0)));
     return NORMAL;
 }

opcode.h

@@ -922,7 +922,7 @@ addbits('emptyavhv',
 
 addbits($_,
     7 => qw(OPpEQ_UNDEF UNDEF),
-) for qw( eq seq );
+) for qw( eq ne seq sne );
 
 addbits('argdefelem',
     7 => qw(OPpARG_IF_UNDEF  IF_UNDEF),

pp.c

@@ -60,6 +60,11 @@ ok(not(123 ==:u 456), '==:u on different values');
     is($warnings, 0, 'no warnings were produced by use of undef');
 }
 
+foreach (["abc", "abc"], ["abc", "def"], ["", undef], [undef, undef]) {
+    my ($left, $right) = @$_;
+    is(not($left ne:u $right), ($left eq:u $right), 'ne:u is a synonym for not(eq:u)');
+}
+
 # ==:u treats undef as distinct, equal to itself, with no warnings
 {
     my $warnings = 0;
@@ -71,6 +76,11 @@ ok(not(123 ==:u 456), '==:u on different values');
     is($warnings, 0, 'no warnings were produced by use of undef');
 }
 
+foreach ([123, 123], [123, 456], [0, undef], [undef, undef]) {
+    my ($left, $right) = @$_;
+    is(not($left !=:u $right), ($left ==:u $right), '!=:u is a synonym for not(==:u)');
+}
+
 # performs GETMAGIC
 {
     "abc" =~ m/(\d+)/;