# tentative: Currently, the hidden instance variable belongs to Foo, not Anonymous Struct. # Thus, it outputs "untyped" class Foo < Struct.new(:a) end Foo.new.a = 1 __END__ # Classes class AnonymousStruct_generated_1 < Struct[untyped] attr_accessor a(): untyped end class Foo < AnonymousStruct_generated_1 end