Make the new warning report undef constants as undef

p4raw-id: //depot/perl@33309

diff --git a/op.c b/op.c
index ab5041f..3ec1979 100644 (file)
--- a/op.c
+++ b/op.c
@@ -1075,8 +1075,13 @@ Perl_scalarvoid(pTHX_ OP *o)
            no_bareword_allowed(o);
        else {
            if (ckWARN(WARN_VOID)) {
-               SV* msv = sv_2mortal(Perl_newSVpvf(aTHX_ "a constant (%"SVf")", sv));
-               useless = SvPV_nolen(msv);
+               if (SvOK(sv)) {
+                   SV* msv = sv_2mortal(Perl_newSVpvf(aTHX_
+                               "a constant (%"SVf")", sv));
+                   useless = SvPV_nolen(msv);
+               }
+               else
+                   useless = "a constant (undef)";
                if (o->op_private & OPpCONST_ARYBASE)
                    useless = NULL;
                /* don't warn on optimised away booleans, eg 

diff --git a/t/lib/warnings/op b/t/lib/warnings/op
index edd2741..9740e39 100644 (file)
--- a/t/lib/warnings/op
+++ b/t/lib/warnings/op
@@ -531,8 +531,9 @@ use warnings 'void' ;
 7 ; # OP_CONST
 "x" . "y"; # optimized to OP_CONST
 2 + 2; # optimized to OP_CONST
-5 || print "bad\n";    # test OPpCONST_SHORTCIRCUIT
 use constant U => undef;
+U;
+5 || print "bad\n";    # test OPpCONST_SHORTCIRCUIT
 print "boo\n" if U;    # test OPpCONST_SHORTCIRCUIT
 $[ = 2; # should not warn
 no warnings 'void' ;
@@ -545,6 +546,7 @@ Useless use of a constant (abc) in void context at - line 3.
 Useless use of a constant (7) in void context at - line 4.
 Useless use of a constant (xy) in void context at - line 5.
 Useless use of a constant (4) in void context at - line 6.
+Useless use of a constant (undef) in void context at - line 8.
 ########
 # op.c
 #