get_next_shape_internal should always return a shape

If it runs out of shapes, or new variations aren't allowed, it will
return "too complex"

object.c

@@ -292,7 +292,7 @@ rb_obj_copy_ivar(VALUE dest, VALUE obj)
     RUBY_ASSERT(BUILTIN_TYPE(dest) == BUILTIN_TYPE(obj));
     rb_shape_t * src_shape = rb_shape_get_shape(obj);
 
-    if (rb_shape_id(src_shape) == OBJ_TOO_COMPLEX_SHAPE_ID) {
+    if (rb_shape_obj_too_complex(obj)) {
         st_table * table = rb_st_init_numtable_with_size(rb_st_table_size(ROBJECT_IV_HASH(obj)));
 
         rb_ivar_foreach(obj, rb_obj_evacuate_ivs_to_hash_table, (st_data_t)table);

shape.c

@@ -484,6 +484,9 @@ get_next_shape_internal(rb_shape_t * shape, ID id, enum shape_type shape_type, b
                         rb_id_table_insert(shape->edges, id, (VALUE)new_shape);
                         res = new_shape;
                     }
+                    else {
+                        res = rb_shape_get_shape_by_id(OBJ_TOO_COMPLEX_SHAPE_ID);
+                    }
                 }
             }
             else {
@@ -496,6 +499,9 @@ get_next_shape_internal(rb_shape_t * shape, ID id, enum shape_type shape_type, b
         }
         RB_VM_LOCK_LEAVE();
     }
+    else {
+        res = rb_shape_get_shape_by_id(OBJ_TOO_COMPLEX_SHAPE_ID);
+    }
     return res;
 }
 
@@ -611,9 +617,6 @@ rb_shape_transition_shape_frozen(VALUE obj)
     bool dont_care;
     next_shape = get_next_shape_internal(shape, (ID)id_frozen, SHAPE_FROZEN, &dont_care, true);
 
-    if (!next_shape) {
-        next_shape = rb_shape_get_shape_by_id(OBJ_TOO_COMPLEX_SHAPE_ID);
-    }
     RUBY_ASSERT(next_shape);
     return next_shape;
 }
@@ -646,10 +649,6 @@ rb_shape_get_next(rb_shape_t* shape, VALUE obj, ID id)
     bool variation_created = false;
     rb_shape_t * new_shape = get_next_shape_internal(shape, id, SHAPE_IVAR, &variation_created, allow_new_shape);
 
-    if (!new_shape) {
-        new_shape = rb_shape_get_shape_by_id(OBJ_TOO_COMPLEX_SHAPE_ID);
-    }
-
     // Check if we should update max_iv_count on the object's class
     if (BUILTIN_TYPE(obj) == T_OBJECT) {
         VALUE klass = rb_obj_class(obj);
@@ -683,6 +682,7 @@ rb_shape_transition_shape_capa_create(rb_shape_t* shape, size_t new_capacity)
     ID edge_name = rb_make_temporary_id(new_capacity);
     bool dont_care;
     rb_shape_t * new_shape = get_next_shape_internal(shape, edge_name, SHAPE_CAPACITY_CHANGE, &dont_care, true);
+    RUBY_ASSERT(rb_shape_id(new_shape) != OBJ_TOO_COMPLEX_SHAPE_ID);
     new_shape->capacity = (uint32_t)new_capacity;
     return new_shape;
 }

shape.h

@@ -178,7 +178,7 @@ ROBJECT_IV_CAPACITY(VALUE obj)
     RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
     // Asking for capacity doesn't make sense when the object is using
     // a hash table for storing instance variables
-    RUBY_ASSERT(ROBJECT_SHAPE_ID(obj) != OBJ_TOO_COMPLEX_SHAPE_ID);
+    RUBY_ASSERT(!rb_shape_obj_too_complex(obj));
     return rb_shape_get_shape_by_id(ROBJECT_SHAPE_ID(obj))->capacity;
 }
 
@@ -186,7 +186,7 @@ static inline st_table *
 ROBJECT_IV_HASH(VALUE obj)
 {
     RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
-    RUBY_ASSERT(ROBJECT_SHAPE_ID(obj) == OBJ_TOO_COMPLEX_SHAPE_ID);
+    RUBY_ASSERT(rb_shape_obj_too_complex(obj));
     return (st_table *)ROBJECT(obj)->as.heap.ivptr;
 }
 
@@ -194,7 +194,7 @@ static inline void
 ROBJECT_SET_IV_HASH(VALUE obj, const st_table *tbl)
 {
     RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
-    RUBY_ASSERT(ROBJECT_SHAPE_ID(obj) == OBJ_TOO_COMPLEX_SHAPE_ID);
+    RUBY_ASSERT(rb_shape_obj_too_complex(obj));
     ROBJECT(obj)->as.heap.ivptr = (VALUE *)tbl;
 }
 
@@ -203,12 +203,12 @@ size_t rb_id_table_size(const struct rb_id_table *tbl);
 static inline uint32_t
 ROBJECT_IV_COUNT(VALUE obj)
 {
-    if (ROBJECT_SHAPE_ID(obj) == OBJ_TOO_COMPLEX_SHAPE_ID) {
+    if (rb_shape_obj_too_complex(obj)) {
         return (uint32_t)rb_st_table_size(ROBJECT_IV_HASH(obj));
     }
     else {
         RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
-        RUBY_ASSERT(ROBJECT_SHAPE_ID(obj) != OBJ_TOO_COMPLEX_SHAPE_ID);
+        RUBY_ASSERT(!rb_shape_obj_too_complex(obj));
         return rb_shape_get_shape_by_id(ROBJECT_SHAPE_ID(obj))->next_iv_index;
     }
 }

variable.c

@@ -76,7 +76,7 @@ static inline st_table *
 RCLASS_IV_HASH(VALUE obj)
 {
     RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));
-    RUBY_ASSERT(RCLASS_SHAPE_ID(obj) == OBJ_TOO_COMPLEX_SHAPE_ID);
+    RUBY_ASSERT(rb_shape_obj_too_complex(obj));
     return (st_table *)RCLASS_IVPTR(obj);
 }
 
@@ -84,7 +84,7 @@ static inline void
 RCLASS_SET_IV_HASH(VALUE obj, const st_table *tbl)
 {
     RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));
-    RUBY_ASSERT(RCLASS_SHAPE_ID(obj) == OBJ_TOO_COMPLEX_SHAPE_ID);
+    RUBY_ASSERT(rb_shape_obj_too_complex(obj));
     RCLASS_IVPTR(obj) = (VALUE *)tbl;
 }