Make @ISA changes update overloadedness

If a non-overloaded class begins inheriting overloading due to @ISA
changes, we need to set the overloaded (AMAGIC) flag on the stash to
indicate that.  Updating caches shouldn’t require a dummy blessing.

1 files changed, 3 insertions, 0 deletions

diff --git a/mro.c b/mro.c
index a8ff42ec8d..41e34cd6d5 100644
--- a/mro.c
+++ b/mro.c
@@ -542,6 +542,9 @@ Perl_mro_isa_changed_in(pTHX_ HV* stash)
     /* wipe next::method cache too */
     if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
 
+    /* Changes to @ISA might turn overloading on */
+    HvAMAGIC_on(stash);
+
     /* Iterate the isarev (classes that are our children),
        wiping out their linearization, method and isa caches
        and upating PL_isarev. */