fix review comments

Signed-off-by: Marin Veršić <marin.versic101@gmail.com>

ffi/derive/src/arg.rs

@@ -1,3 +1,5 @@
+//! Logic related to FFI function argument. Visitor implementation visits the given type
+//! and collects the FFI conversion information into the [`Arg`] struct
 #![allow(clippy::unimplemented)]
 
 use proc_macro2::Span;
@@ -99,7 +101,6 @@ impl Arg {
     }
 }
 
-/// Struct representing a method/function argument
 struct TypeVisitor<'ast> {
     self_ty: &'ast Path,
     name: &'ast Ident,
@@ -120,6 +121,7 @@ impl<'ast> TypeVisitor<'ast> {
             ffi_to_src: None,
         }
     }
+
     fn visit_item_binding(&mut self, seg: &'ast syn::PathSegment) {
         let bindings = generic_arg_bindings(seg);
 
@@ -352,13 +354,16 @@ impl<'ast> Visit<'ast> for TypeVisitor<'ast> {
                         }
                     };
                 });
-                self.ffi_to_src = Some(parse_quote! { #ok_ffi_to_src });
+                self.ffi_to_src = Some(parse_quote! {
+                    #ok_ffi_to_src
+                    let #arg_name = Ok(#arg_name);
+                });
             }
             _ => {
                 if self.is_input {
                     self.ffi_type = Some(parse_quote! { *const #node });
                     self.src_to_ffi = Some(parse_quote! {
-                        let #arg_name: *const _ = #arg_name;
+                        let #arg_name: *const _ = &#arg_name;
                     });
                     self.ffi_to_src = Some(parse_quote! {
                         let #arg_name = Clone::clone(&*#arg_name);
@@ -459,16 +464,18 @@ impl<'ast> Visit<'ast> for TypeVisitor<'ast> {
 
 pub fn generic_arg_types(seg: &syn::PathSegment) -> Vec<&Type> {
     if let AngleBracketed(arguments) = &seg.arguments {
-        let mut args = vec![];
-
-        for arg in &arguments.args {
-            if let syn::GenericArgument::Type(ty) = &arg {
-                args.push(ty);
-            }
-        }
-
-        return args;
-    };
+        return arguments
+            .args
+            .iter()
+            .filter_map(|arg| {
+                if let syn::GenericArgument::Type(ty) = &arg {
+                    Some(ty)
+                } else {
+                    None
+                }
+            })
+            .collect();
+    }
 
     abort!(seg, "Type not found in the given path segment")
 }