Clippy fixes (#692)

crates/api/src/trampoline/create_handle.rs

@@ -31,16 +31,14 @@ pub(crate) fn create_handle(
 
     // Compute indices into the shared signature table.
     let signatures = signature_registry
-        .and_then(|mut signature_registry| {
-            Some(
-                module
-                    .signatures
-                    .values()
-                    .map(|sig| signature_registry.register_wasmtime_signature(sig))
-                    .collect::<PrimaryMap<_, _>>(),
-            )
+        .map(|mut signature_registry| {
+            module
+                .signatures
+                .values()
+                .map(|sig| signature_registry.register_wasmtime_signature(sig))
+                .collect::<PrimaryMap<_, _>>()
         })
-        .unwrap_or_else(|| PrimaryMap::new());
+        .unwrap_or_else(PrimaryMap::new);
 
     Ok(InstanceHandle::new(
         Rc::new(module),

crates/api/src/trampoline/func.rs

@@ -89,9 +89,9 @@ unsafe extern "C" fn stub_fn(vmctx: *mut VMContext, call_id: u32, values_vec: *m
 
     match func.call(&args, &mut returns) {
         Ok(()) => {
-            for i in 0..returns_len {
+            for (i, r#return) in returns.iter_mut().enumerate() {
                 // TODO check signature.returns[i].value_type ?
-                returns[i].write_value_to(values_vec.add(i));
+                r#return.write_value_to(values_vec.add(i));
             }
             0
         }
@@ -172,7 +172,7 @@ fn make_trampoline(
 
         let callee_args = vec![vmctx_ptr_val, call_id_val, values_vec_ptr_val];
 
-        let new_sig = builder.import_signature(stub_sig.clone());
+        let new_sig = builder.import_signature(stub_sig);
 
         let callee_value = builder
             .ins()