Make *{undef} self-consistent

Commit afd1915d made filehandle vivification work on hash and array
elements, but in doing so it accidentally changed

    *{;undef} = 3;

to do the same thing as

    *{""} = 3;

while leaving

    *{$some_undefined_variable}

an error.

This commit adjusts the if() conditions in S_rv2gv (formerly in
pp_rv2gv) in pp.c to make PL_sv_undef follow the same path as before.

It also removes the uninit tests from lib/warnings/pp, since they
are now errors.  The uninit warning in rv2gv is only triggered now
when it is implicit, as in close().  That is already tested in
lib/warnings/9uninit.

1 files changed, 2 insertions, 2 deletions

diff --git a/pp.c b/pp.c
index ea6eb00504..e2427f8e8b 100644
--- a/pp.c
+++ b/pp.c
@@ -176,11 +176,11 @@ S_rv2gv(pTHX_ SV *sv, const bool vivify_sv, const bool strict,
     }
     else {
 	if (!isGV_with_GP(sv)) {
-	    if (!SvOK(sv) && sv != &PL_sv_undef) {
+	    if (!SvOK(sv)) {
 		/* If this is a 'my' scalar and flag is set then vivify
 		 * NI-S 1999/05/07
 		 */
-		if (vivify_sv) {
+		if (vivify_sv && sv != &PL_sv_undef) {
 		    GV *gv;
 		    if (SvREADONLY(sv))
 			Perl_croak_no_modify(aTHX);