Move the "types are equal" early return ahead of the COW-removal.

1 files changed, 12 insertions, 3 deletions

diff --git a/sv.c b/sv.c
index a22316c72a..a5a3554337 100644
--- a/sv.c
+++ b/sv.c
@@ -1185,13 +1185,22 @@ Perl_sv_upgrade(pTHX_ register SV *const sv, svtype new_type)
 
     PERL_ARGS_ASSERT_SV_UPGRADE;
 
+    if (old_type == new_type)
+	return;
+
+    /* This clause was purposefully added ahead of the early return above to
+       the shared string hackery for (sort {$a <=> $b} keys %hash), with the
+       inference by Nick I-S that it would fix other troublesome cases. See
+       changes 7162, 7163 (f130fd4589cf5fbb24149cd4db4137c8326f49c1 and parent)
+
+       Given that shared hash key scalars are no longer PVIV, but PV, there is
+       no longer need to unshare so as to free up the IVX slot for its proper
+       purpose. So it's safe to move the early return earlier.  */
+
     if (new_type != SVt_PV && SvIsCOW(sv)) {
 	sv_force_normal_flags(sv, 0);
     }
 
-    if (old_type == new_type)
-	return;
-
     old_body = SvANY(sv);
 
     /* Copying structures onto other structures that have been neatly zeroed