Implement improper ctypes check without infinite loop on cyclic structs
diff --git a/syntax/mod.rs b/syntax/mod.rs
index ac6350a..b742e37 100644
--- a/syntax/mod.rs
+++ b/syntax/mod.rs
@@ -10,6 +10,7 @@
 pub mod file;
 pub mod ident;
 mod impls;
+mod improper;
 pub mod mangle;
 mod names;
 pub mod namespace;