per-method serial number

Methods and their definitions can be allocated/deallocated on-the-fly.
One pathological situation is when a method is deallocated then another
one is allocated immediately after that.  Address of those old/new method
entries/definitions can be the same then, depending on underlying
malloc/free implementation.

So pointer comparison is insufficient.  We have to check the contents.
To do so we introduce def->method_serial, which is an integer unique to
that specific method definition.

PS: Note that method_serial being uintptr_t rather than rb_serial_t is
intentional.  This is because rb_serial_t can be bigger than a pointer
on a 32bit system (rb_serial_t is at least 64bit).  In order to preserve
old packing of struct rb_call_cache, rb_serial_t is inappropriate.

1 files changed, 1 insertions, 0 deletions

diff --git a/method.h b/method.h
index 14ffecc398..b26caaa92d 100644
--- a/method.h
+++ b/method.h
@@ -177,6 +177,7 @@ struct rb_method_definition_struct {
     } body;
 
     ID original_id;
+    uintptr_t method_serial;
 };
 
 typedef struct rb_method_definition_struct rb_method_definition_t;