Fix bug for c structs assigned to a type (crystal-lang#9743)

* Fix bug for c structs assigned to a type

* Call Type#remove_typedef instead of creating a separate method to handle typedefs

* Reassign type argument

spec/compiler/codegen/c_struct_spec.cr

@@ -379,4 +379,19 @@ describe "Code gen: struct" do
       foo.x.call(1)
       )).to_i.should eq(2)
   end
+
+  it "can access member of uninitialized struct behind type (#8774)" do
+    run(%(
+      lib LibFoo
+        struct Foo
+          x : Int32
+        end
+
+        type FooT = Foo
+      end
+
+      foo = uninitialized LibFoo::FooT
+      foo.x
+    ))
+  end
 end

src/compiler/crystal/codegen/codegen.cr

@@ -1187,6 +1187,7 @@ module Crystal
     end
 
     def read_instance_var(node_type, type, name, value)
+      type = type.remove_typedef
       ivar = type.lookup_instance_var(name)
       ivar_ptr = instance_var_ptr type, name, value
       @last = downcast ivar_ptr, node_type, ivar.type, false