ROBJECT_IV_INDEX_TBL: convert into an inline function

Former ROBJECT_IV_INDEX_TBL macro included RCLASS_IV_INDEX_TBL, which is
not disclosed to extension libraies.  The macro was kind of broken.  Why
not just deprecate it, and convert the internal use into an inline
function.

include/ruby/internal/core/robject.h

@@ -27,6 +27,7 @@
 #endif
 
 #include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/deprecated.h"
 #include "ruby/internal/attr/pure.h"
 #include "ruby/internal/cast.h"
 #include "ruby/internal/fl_type.h"
@@ -39,24 +40,31 @@
 /** @cond INTERNAL_MACRO */
 #define ROBJECT_NUMIV         ROBJECT_NUMIV
 #define ROBJECT_IVPTR         ROBJECT_IVPTR
+#define ROBJECT_IV_INDEX_TBL  ROBJECT_IV_INDEX_TBL
 /** @endcond */
 
 enum ruby_robject_flags { ROBJECT_EMBED = RUBY_FL_USER1 };
 
 enum ruby_robject_consts { ROBJECT_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(VALUE) };
 
+struct st_table;
+
 struct RObject {
     struct RBasic basic;
     union {
         struct {
             uint32_t numiv;
             VALUE *ivptr;
-            void *iv_index_tbl; /* shortcut for RCLASS_IV_INDEX_TBL(rb_obj_class(obj)) */
+            struct st_table *iv_index_tbl; /* shortcut for RCLASS_IV_INDEX_TBL(rb_obj_class(obj)) */
         } heap;
         VALUE ary[ROBJECT_EMBED_LEN_MAX];
     } as;
 };
 
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+struct st_table *rb_obj_iv_index_tbl(const struct RObject *obj);
+RBIMPL_SYMBOL_EXPORT_END()
+
 RBIMPL_ATTR_PURE_UNLESS_DEBUG()
 RBIMPL_ATTR_ARTIFICIAL()
 static inline uint32_t
@@ -89,9 +97,17 @@ ROBJECT_IVPTR(VALUE obj)
     }
 }
 
-#define ROBJECT_IV_INDEX_TBL(o) \
+RBIMPL_ATTR_DEPRECATED(("Whoever have used it before?  Just tell us so.  We can stop deleting it."))
-    ((RBASIC(o)->flags & ROBJECT_EMBED) ? \
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
-     RCLASS_IV_INDEX_TBL(rb_obj_class(o)) : \
+RBIMPL_ATTR_ARTIFICIAL()
-     ROBJECT(o)->as.heap.iv_index_tbl)
+static inline struct st_table *
+ROBJECT_IV_INDEX_TBL(VALUE obj)
+{
+    RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
+
+    struct RObject *const ptr = ROBJECT(obj);
+
+    return rb_obj_iv_index_tbl(ptr);
+}
 
 #endif /* RBIMPL_ROBJECT_H */

internal.h

@@ -47,6 +47,9 @@
 #undef RHASH_IFNONE
 #undef RHASH_SIZE
 
+/* internal/object.h */
+#undef ROBJECT_IV_INDEX_TBL
+
 /* internal/struct.h */
 #undef RSTRUCT_LEN
 #undef RSTRUCT_PTR

internal/object.h

@@ -10,6 +10,11 @@
  * @brief      Internal header for Object.
  */
 #include "ruby/ruby.h"          /* for VALUE */
+#include "internal/class.h"     /* for RCLASS_IV_INDEX_TBL */
+
+#ifdef ROBJECT_IV_INDEX_TBL
+# undef ROBJECT_IV_INDEX_TBL
+#endif
 
 /* object.c */
 VALUE rb_class_search_ancestor(VALUE klass, VALUE super);
@@ -22,6 +27,7 @@ int rb_bool_expected(VALUE, const char *);
 static inline void RBASIC_CLEAR_CLASS(VALUE obj);
 static inline void RBASIC_SET_CLASS_RAW(VALUE obj, VALUE klass);
 static inline void RBASIC_SET_CLASS(VALUE obj, VALUE klass);
+static inline struct st_table *ROBJECT_IV_INDEX_TBL_inline(VALUE obj);
 
 RUBY_SYMBOL_EXPORT_BEGIN
 /* object.c (export) */
@@ -58,4 +64,20 @@ RBASIC_SET_CLASS(VALUE obj, VALUE klass)
     RBASIC_SET_CLASS_RAW(obj, klass);
     RB_OBJ_WRITTEN(obj, oldv, klass);
 }
+
+RBIMPL_ATTR_PURE()
+static inline struct st_table *
+ROBJECT_IV_INDEX_TBL_inline(VALUE obj)
+{
+    if (RB_FL_ANY_RAW(obj, ROBJECT_EMBED)) {
+        VALUE klass = rb_obj_class(obj);
+        return RCLASS_IV_INDEX_TBL(klass);
+    }
+    else {
+        const struct RObject *const ptr = ROBJECT(obj);
+        return ptr->as.heap.iv_index_tbl;
+    }
+}
+#define ROBJECT_IV_INDEX_TBL ROBJECT_IV_INDEX_TBL_inline
+
 #endif /* INTERNAL_OBJECT_H */

object.c

@@ -320,6 +320,14 @@ rb_obj_singleton_class(VALUE obj)
     return rb_singleton_class(obj);
 }
 
+struct st_table *
+rb_obj_iv_index_tbl(const struct RObject *obj)
+{
+    /* This is a function that practically never gets used.  Just to keep
+     * backwards compatibility to ruby 2.x. */
+    return ROBJECT_IV_INDEX_TBL((VALUE)obj);
+}
+
 /*! \private */
 MJIT_FUNC_EXPORTED void
 rb_obj_copy_ivar(VALUE dest, VALUE obj)

variable.c

@@ -25,6 +25,7 @@
 #include "internal/error.h"
 #include "internal/eval.h"
 #include "internal/hash.h"
+#include "internal/object.h"
 #include "internal/re.h"
 #include "internal/symbol.h"
 #include "internal/thread.h"