fix handling of const and size type generics when generating Index impls

crates/fayalite/tests/hdl_types.rs

@@ -1,16 +1,22 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
-use fayalite::{
-    array::ArrayType,
-    hdl,
-    int::{IntType, Size, UInt},
-};
+use fayalite::prelude::*;
 
 #[hdl(outline_generated)]
-pub struct S<T: IntType, Len: Size> {
+pub struct S<T, Len: Size, T2> {
     pub a: T,
     b: UInt<3>,
     pub(crate) c: ArrayType<UInt<1>, Len>,
+    pub d: T2,
+}
+
+//#[cfg(todo)]
+#[hdl(outline_generated)]
+pub struct S3<const LEN: usize, T> {
+    pub a: T,
+    b: UInt<3>,
+    pub(crate) c: Array<UInt<1>, LEN>,
+    pub d: S<T, ConstUsize<LEN>, ()>,
 }
 
 #[hdl(outline_generated)]