remove vestigial uses of PRIVSHIFT

This is a hangover from when a magic (e.g. tied) var, after calling
mg_get(), would only set the private (SVp_IOK,SVp_NOK,SVp_POK)
flags on the result, indicating that although it now had a valid integer
value (say), it wasn't a "real" integer. This was achieved by, after
calling mg_get(), shifting all the public flags by PRIVSHIFT to convert
them to private flags.

Since 5.18.0, that's not been the case (i.e. mg_get() on a tied var leaves
Svf_IOK etc set). But there are still a couple of vestigial uses of
PRIVSHIFT in the core, and this commit removes them.

For one of them, I added a test that shows that (in slightly contrived
circumnstances), it was possible for a SVp_IOK NV to be upgraded
to a SVf_IOK int on return from localisation, losing its fractional
component.

The other one, in S_sv_unmagicext_flags(), only seemed to get called
when setting a new value (e.g. from mg_set()), so its unlikely that such a
var would still have private flags set that could be incorrectly upgraded
to public.

1 files changed, 14 insertions, 1 deletions

diff --git a/t/op/taint.t b/t/op/taint.t
index eaee77a5a5..101c6da427 100644
--- a/t/op/taint.t
+++ b/t/op/taint.t
@@ -17,7 +17,7 @@ BEGIN {
 use strict;
 use Config;
 
-plan tests => 807;
+plan tests => 808;
 
 $| = 1;
 
@@ -2378,6 +2378,19 @@ is eval { eval $::x.1 }, 1, 'reset does not taint undef';
     is_tainted $n3, "* SETn";
 }
 
+# check that localizing something with get magic (e.g. taint) doesn't
+# upgrade pIOK to IOK
+
+{
+    local our $x = 1.1 + $TAINT0;  # $x should be NOK
+    my $ix = int($x);          #          now NOK, pIOK
+    {
+        local $x = 0;
+    }
+    my $x1 = $x * 1;
+    isnt($x, 1); # it should be 1.1, not 1
+}
+
 
 # This may bomb out with the alarm signal so keep it last
 SKIP: {