fix method cache generation when package contains blessed subs

When generating the method cache, the code was trying to call ->body on
it if it was an object.  The add_method code had previously been fixed
to only call ->body on meta objects rather than anything blessed.  The
XS code was only checking for objects being making that call.  This was
masked by method cache being kept up to date.

If the method cache is out of date though, this can crash.  The cache
can be intentionally reset, or we may not be able to track its status
properly (perl 5.8 without Class::C3::XS).

Fixes RT#113704

Changes

@@ -3,6 +3,11 @@ for, noteworthy changes.
 
 {{$NEXT}}
 
+  [BUG FIXES]
+
+  - Fixed method cache regeneration when a class contains a blessed sub
+    (RT#113704)
+
   [TESTS]
 
   - restore test on perl 5.8.x when Class::C3::XS is not installed (RT#113704)

t/cmop/methods.t

@@ -101,6 +101,12 @@ is( exception {
   $Foo->add_method('bork', $bork_blessed);
 }, undef, 'can add blessed sub as method');
 
+$Foo->reset_package_cache_flag;
+
+is( exception {
+  $Foo->has_method('bork');
+}, undef, 'regeneration of method cache works after adding blessed sub as method');
+
 # now check all our other items ...
 
 ok( $Foo->has_method('FOO_CONSTANT'),

xs/HasMethods.xs

@@ -24,7 +24,7 @@ mop_update_method_map(pTHX_ HV *const stash, HV *const map)
             continue;
         }
 
-        if (sv_isobject(method)) {
+        if (sv_derived_from(method, "Class::MOP::Method")) {
             /* $method_object->body() */
             body = mop_call0(aTHX_ method, KEY_FOR(body));
         }