drop-in type check for rb_define_singleton_method

We can check the function pointer passed to
rb_define_singleton_method like how we do so in rb_define_method.
Doing so revealed many arity mismatches.

1 files changed, 3 insertions, 0 deletions

diff --git a/class.c b/class.c
index 0714f54e16..2e8710194d 100644
--- a/class.c
+++ b/class.c
@@ -1746,6 +1746,9 @@ rb_singleton_class(VALUE obj)
  * \{
  */
 
+#ifdef rb_define_singleton_method
+#undef rb_define_singleton_method
+#endif
 /*!
  * Defines a singleton method for \a obj.
  * \param obj    an arbitrary object