Rename `iv_count` on shapes to `next_iv_index`

`iv_count` is a misleading name because when IVs are unset, the new
shape doesn't decrement this value. `next_iv_count` is an accurate, and
more descriptive name.

1 files changed, 2 insertions, 2 deletions

diff --git a/shape.h b/shape.h
index e978bac121..1470cdd4aa 100644
--- a/shape.h
+++ b/shape.h
@@ -45,7 +45,7 @@ typedef uint16_t shape_id_t;
 struct rb_shape {
     struct rb_id_table * edges; // id_table from ID (ivar) to next shape
     ID edge_name; // ID (ivar) for transition from parent to rb_shape
-    attr_index_t iv_count;
+    attr_index_t next_iv_index;
     uint8_t type;
     shape_id_t parent_id;
 };
@@ -129,7 +129,7 @@ static inline uint32_t
 ROBJECT_IV_COUNT(VALUE obj)
 {
     RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
-    uint32_t ivc = rb_shape_get_shape_by_id(ROBJECT_SHAPE_ID(obj))->iv_count;
+    uint32_t ivc = rb_shape_get_shape_by_id(ROBJECT_SHAPE_ID(obj))->next_iv_index;
     RUBY_ASSERT(ivc <= ROBJECT_NUMIV(obj));
     return ivc;
 }