[perl #96326] *{$io} should not be semi-defined

gv_efullname4 produces undef if the GV points to no stash, instead of
using __ANON__, as it does when the stash has no name.

Instead of going through hoops to try and work around it elsewhere, fix
gv_efullname4.

This means that

   $x = *$io;
   $x .= "whate’er";

no longer produces an uninitialized warning.  (The warning was rather
strange, as defined() returned true.)

This commit also gives the glob the name $__ANONIO__ (yes, with a dol-
lar sign).  It may seem a little strange, but there is precedent in
other autovivified globs, such as those open() produces when it cannot
determine the variable name (e.g, open $t->{fh}).

1 files changed, 7 insertions, 5 deletions

diff --git a/t/op/gv.t b/t/op/gv.t
index 8c0e31106c..31e4ca0fd6 100644
--- a/t/op/gv.t
+++ b/t/op/gv.t
@@ -598,10 +598,11 @@ foreach my $type (qw(integer number string)) {
 # RT #60954 anonymous glob should be defined, and not coredump when
 # stringified. The behaviours are:
 #
-#        defined($glob)    "$glob"
-# 5.8.8     false           "" with uninit warning
-# 5.10.0    true            (coredump)
-# 5.12.0    true            ""
+#        defined($glob)    "$glob"                   $glob .= ...
+# 5.8.8     false           "" with uninit warning   "" with uninit warning
+# 5.10.0    true            (coredump)               (coredump)
+# 5.1[24]   true            ""                       "" with uninit warning
+# 5.16      true            "*__ANON__::..."         "*__ANON__::..."
 
 {
     my $io_ref = *STDOUT{IO};
@@ -613,7 +614,8 @@ foreach my $type (qw(integer number string)) {
     use warnings;
     my $str = "$glob";
     is($warn, '', "RT #60954 anon glob stringification shouldn't warn");
-    is($str,  '', "RT #60954 anon glob stringification should be empty");
+    is($str,  '*__ANON__::$__ANONIO__',
+	"RT #60954/#96326 anon glob stringification");
 }
 
 # [perl #71254] - Assigning a glob to a variable that has a current