Assist for deriving a trait recursively

[Shnatsel]

I am looking at a rather large codebase with lots and lots of structs that contain each other. (It's a crate implementing serialization/deserialization for the CycloneDX format).

I need to add #[derive(Clone)] to a struct, which contains other structs, which contains other structs and so on. It would be very tedious to do manually. It would be great to have an assist that applies the derives of the top-level struct to all the structs in its fields, and so on recursively.

[saiintbrisson]

This idea is nice but not as straightforward as I had imagined. It's tricky to understand when to stop deriving. I came up with three stop points:

• If the type is not local;
• If the trait is already derived for that type (should it just skip the current type and check the children fields?);
• If the trait is implemented for that type manually;

The last condition is the problematic part. How to check if the derive results in an already manually implemented trait? The only certainty we have with derive macros is the automatically_derived (which is also not required, and only some crates adhere to it), so maybe one could expand it during the assist call and check if the resulting impls conflict with existing ones? Or am I not seeing something?