From ac7f913ca3af970225c9cc93b92eb5c403894180 Mon Sep 17 00:00:00 2001
From: Jean Boussier <byroot@ruby-lang.org>
Date: Mon, 30 Oct 2023 14:55:13 +0100
Subject: [PATCH] Handle SHAPE_TOO_COMPLEX in `generic_ivar_set`

---
 test/ruby/test_shapes.rb | 20 ++++++++++++++++++++
 variable.c               |  5 +++++
 2 files changed, 25 insertions(+)

diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
index 6d98daf233..b9ac1cafe1 100644
--- a/test/ruby/test_shapes.rb
+++ b/test/ruby/test_shapes.rb
@@ -226,6 +226,26 @@ class TestShapes < Test::Unit::TestCase
     end;
   end
 
+  def test_run_out_of_shape_generic_ivar_set
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      class TooComplex < Hash
+      end
+
+      # Try to run out of shapes
+      o = Object.new
+      i = 0
+      while RubyVM::Shape.shapes_available > 0
+        o.instance_variable_set(:"@i#{i}", 1)
+        i += 1
+      end
+
+      tc = TooComplex.new
+      tc.instance_variable_set(:@a, 1)
+      tc.instance_variable_set(:@b, 2)
+    end;
+  end
+
   def test_run_out_of_shape_rb_obj_copy_ivar
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
diff --git a/variable.c b/variable.c
index b5d730ec9a..34934a7b84 100644
--- a/variable.c
+++ b/variable.c
@@ -1484,6 +1484,11 @@ generic_ivar_set(VALUE obj, ID id, VALUE val)
     attr_index_t index;
     // The returned shape will have `id` in its iv_table
     rb_shape_t *shape = rb_shape_get_shape(obj);
+    if (UNLIKELY(shape->type == SHAPE_OBJ_TOO_COMPLEX)) {
+        rb_complex_ivar_set(obj, id, val);
+        return;
+    }
+
     bool found = rb_shape_get_iv_index(shape, id, &index);
     rb_shape_t *next_shape = shape;
     if (!found) {