The derive macro did not support generics well

[tguichaoua]

The following code did not compile because the compiler says the type T did not implement the valuable trait. It seems the macro did not add the trait bound when implementing the trait.

The workaround is to put the trait bound on the type definition, but it's not really idiomatic, as it should be put on the impl block.

#[derive(Valuable)]
struct Foo<T> {
    x: T,
}

#[derive(Valuable)]
enum Goo<T> {
    Goo(T),
}

The compiler error

error[E0277]: the trait bound `T: Valuable` is not satisfied
 --> src\main.rs:9:8
  |
7 | #[derive(Valuable)]
  |          -------- required by a bound introduced by this call
8 | struct Foo<T> {
9 |     x: T,
  |        ^ the trait `Valuable` is not implemented for `T`
  |
help: consider restricting type parameter `T` with trait `Valuable`
  |
8 | struct Foo<T: valuable::Valuable> {
  |             ++++++++++++++++++++

error[E0277]: the trait bound `T: Valuable` is not satisfied
  --> src\main.rs:14:9
   |
12 | #[derive(Valuable)]
   |          -------- required by a bound introduced by this call
13 | enum Goo<T> {
14 |     Goo(T),
   |         ^ the trait `Valuable` is not implemented for `T`
   |
   = note: required for `&T` to implement `Valuable`
help: consider restricting type parameter `T` with trait `Valuable`
   |
13 | enum Goo<T: valuable::Valuable> {
   |           ++++++++++++++++++++

For more information about this error, try `rustc --explain E0277`.