Use `RBasic` padding for embedded string on 64-bit CPU

On 64-bit CPU, there is padding in `RBasic`, so reorder the fields and use
it as buffer of embedded string. This change allows 4 more bytes to be
embedded on 64-bit CPU.

However, an incompatibility will occur if `RString::as::ary` is accessed
directly because `RString` structure has changed.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gc.c b/src/gc.c
index 211980b19..a2a904477 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -521,7 +521,7 @@ MRB_API struct RBasic*
 mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
 {
   struct RBasic *p;
-  static const RVALUE RVALUE_zero = { { { MRB_TT_FALSE } } };
+  static const RVALUE RVALUE_zero = { { { NULL, NULL, MRB_TT_FALSE } } };
   mrb_gc *gc = &mrb->gc;
 
   if (cls) {