test(versionable): test bounds visibility in the generated code

utils/tfhe-versionable/tests/bounds_private_in_public.rs

@@ -0,0 +1,44 @@
+//! This test checks that the bounds added by the proc macro does not prevent the code to
+//! compile by leaking a private type
+use tfhe_versionable::Versionize;
+
+mod mymod {
+    use tfhe_versionable::{Versionize, VersionsDispatch};
+
+    #[derive(Versionize)]
+    #[versionize(PublicVersions)]
+    pub struct Public<T> {
+        private: Private<T>,
+    }
+
+    impl Public<u64> {
+        pub fn new(val: u64) -> Self {
+            Self {
+                private: Private(val),
+            }
+        }
+    }
+
+    #[derive(VersionsDispatch)]
+    #[allow(unused)]
+    pub enum PublicVersions<T> {
+        V0(Public<T>),
+    }
+
+    #[derive(Versionize)]
+    #[versionize(PrivateVersions)]
+    struct Private<T>(T);
+
+    #[derive(VersionsDispatch)]
+    #[allow(dead_code)]
+    enum PrivateVersions<T> {
+        V0(Private<T>),
+    }
+}
+
+#[test]
+fn bounds_private_in_public() {
+    let public = mymod::Public::new(42);
+
+    let _vers = public.versionize();
+}