[perl #114864] Make UNIVERSAL::DESTROY changes invalidate caches

Commit 8c34e50d inadvertently caused DESTROY caches not to be
reset when UNIVERSAL::DESTROY changes.  Normally, a change to
a method will cause mro_method_changed_in to be called on all
subclasses, but mro.c cheats for UNIVERSAL and just does
++PL_sub_generation.  So clearing the DESTROY cache explicitly
in mro_method_changed_in is clearly not enough.

1 files changed, 15 insertions, 1 deletions

diff --git a/t/mro/basic.t b/t/mro/basic.t
index ab34fc2567..be49f9ab1f 100644
--- a/t/mro/basic.t
+++ b/t/mro/basic.t
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 
-BEGIN { require q(./test.pl); } plan(tests => 59);
+BEGIN { require q(./test.pl); } plan(tests => 60);
 
 require mro;
 
@@ -370,3 +370,17 @@ is(eval { MRO_N->testfunc() }, 123);
     }
     is "il"->can("tomatoes"), "puree", 'local *ISA=[] unwinding';
 }
+
+# Changes to UNIVERSAL::DESTROY should not leave stale DESTROY caches
+# (part of #114864)
+our $destroy_output;
+sub UNIVERSAL::DESTROY { $destroy_output = "old" }
+my $x = bless[];
+undef $x; # cache the DESTROY method
+undef *UNIVERSAL::DESTROY;
+*UNIVERSAL::DESTROY = sub { $destroy_output = "new" };
+$x = bless[];
+undef $x; # should use the new DESTROY
+is $destroy_output, "new",
+    'Changes to UNIVERSAL::DESTROY invalidate DESTROY caches';
+undef *UNIVERSAL::DESTROY;