Better handle running out of shapes in remove_shape_recursive

2 files changed, 36 insertions, 2 deletions

diff --git a/shape.c b/shape.c
index e402344615..4510c618d4 100644
--- a/shape.c
+++ b/shape.c
@@ -583,12 +583,16 @@ remove_shape_recursive(VALUE obj, ID id, rb_shape_t * shape, VALUE * removed)
             // We found a new parent.  Create a child of the new parent that
             // has the same attributes as this shape.
             if (new_parent) {
-                bool dont_care;
-                rb_shape_t * new_child = get_next_shape_internal(new_parent, shape->edge_name, shape->type, &dont_care, true);
                 if (UNLIKELY(new_parent->type == SHAPE_OBJ_TOO_COMPLEX)) {
                     return new_parent;
                 }
 
+                bool dont_care;
+                rb_shape_t * new_child = get_next_shape_internal(new_parent, shape->edge_name, shape->type, &dont_care, true);
+                if (UNLIKELY(new_child->type == SHAPE_OBJ_TOO_COMPLEX)) {
+                    return new_child;
+                }
+
                 new_child->capacity = shape->capacity;
                 if (new_child->type == SHAPE_IVAR) {
                     move_iv(obj, id, shape->next_iv_index - 1, new_child->next_iv_index - 1);
diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
index b052a4a647..b627b58281 100644
--- a/test/ruby/test_shapes.rb
+++ b/test/ruby/test_shapes.rb
@@ -577,6 +577,36 @@ class TestShapes < Test::Unit::TestCase
     assert_equal [0, 1, nil, 3, 4], ivars
   end
 
+  def test_remove_instance_variable_when_out_of_shapes
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      ivars_count = 5
+      object = Object.new
+      ivars_count.times do |i|
+        object.instance_variable_set("@ivar_#{i}", i)
+      end
+
+      ivars = ivars_count.times.map do |i|
+        object.instance_variable_get("@ivar_#{i}")
+      end
+      assert_equal [0, 1, 2, 3, 4], ivars
+
+      o = Object.new
+      i = 0
+      while RubyVM::Shape.shapes_available > 0
+        o.instance_variable_set(:"@i#{i}", 1)
+        i += 1
+      end
+
+      object.remove_instance_variable(:@ivar_2)
+
+      ivars = ivars_count.times.map do |i|
+        object.instance_variable_get("@ivar_#{i}")
+      end
+      assert_equal [0, 1, nil, 3, 4], ivars
+    end;
+  end
+
   def test_freeze_after_complex
     ensure_complex