Adds a missing clippy allow (#663)

It also add a simple function on the roundtrip wit that triggers the clippy failure as a way to test that clippy is fixed

Signed-off-by: James Sturtevant <[email protected]>

Author: jsturtevant

src/hyperlight_component_util/src/host.rs

@@ -61,6 +61,7 @@ fn emit_export_extern_decl<'a, 'b, 'c>(
                                 (#(#marshal,)*)
                             );
                             let ::std::result::Result::Ok(#ret) = #ret else { panic!("bad return from guest {:?}", #ret) };
+                            #[allow(clippy::unused_unit)]
                             #unmarshal
                         }
                     }

src/hyperlight_host/tests/wit_test.rs

@@ -155,6 +155,8 @@ impl test::wit::Roundtrip for Host {
     ) -> test::wit::roundtrip::Testenum {
         x
     }
+
+    fn roundtrip_no_result(&mut self, _x: u32) {}
 }
 
 struct TestResource {
@@ -330,6 +332,11 @@ mod wit_test {
     make_test! { roundtrip_variant,     in arb_testvariant() }
     make_test! { roundtrip_enum,        in arb_testenum() }
 
+    #[test]
+    fn test_simple_func() {
+        sb().roundtrip().roundtrip_no_result(42);
+    }
+
     #[test]
     fn test_host_resource() {
         {

src/tests/rust_guests/witguest/guest.wit

@@ -25,6 +25,7 @@ interface roundtrip {
   roundtrip-tuple: func(x: tuple<string, u8>) -> tuple<string, u8>;
   roundtrip-option: func(x: option<string>) -> option<string>;
   roundtrip-result: func(x: result<char, string>) -> result<char, string>;
+  roundtrip-no-result: func(x: u32);
 
   record testrecord {
     contents: string,

src/tests/rust_guests/witguest/src/main.rs

@@ -113,6 +113,9 @@ impl test::wit::Roundtrip for Guest {
     ) -> test::wit::roundtrip::Testenum {
         (Host {}).roundtrip_enum(x)
     }
+    fn roundtrip_no_result(&mut self, x: u32) {
+        (Host {}).roundtrip_no_result(x)
+    }
 }
 
 impl test::wit::TestHostResource for Guest {