Fix uninit warnings under old cow

Applying copy-on-write to pad names when generating uninitial-
ised warnings results in modifications to SvPVX(sv) after
sv_setsv(sv,padname) affecting the pad name as well.  sv_setsv_flags
with no flags avoids the COW.

Under PERL_OLD_COPY_ON_WRITE and warnings, this:

my (@ma);
$v = sin $ma[1000];
$v = sin $ma[$$];

was producing this:

$ pbpaste|./miniperl -w
Use of uninitialized value $ma[1000] in sin at - line 2.
Use of uninitialized value within $ma in sin at - line 3.

If you comment out the sceond line:

$ pbpaste|./miniperl -w
Name "main::v" used only once: possible typo at - line 3.
Use of uninitialized value within @ma in sin at - line 3.

Notice the @ma/$ma difference.

The first uninit warning was modifying the pad name.

diff --git a/sv.c b/sv.c
index 01ef3df..375a119 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -13925,7 +13925,7 @@ Perl_varname(pTHX_ const GV *const gv, const char gvtype, PADOFFSET targ,
            return NULL;
        av = *PadlistARRAY(CvPADLIST(cv));
        sv = *av_fetch(av, targ, FALSE);
-       sv_setsv(name, sv);
+       sv_setsv_flags(name, sv, 0);
     }
 
     if (subscript_type == FUV_SUBSCRIPT_HASH) {