error[E0599]: the method `as_dyn_error` exists for struct `String`, but its trait bounds were not satisfied
 --> tests/ui/transparent-struct-not-error.rs:4:9
  |
4 | #[error(transparent)]
  |         ^^^^^^^^^^^ method cannot be called on `String` due to unsatisfied trait bounds
  |
 ::: $RUST/alloc/src/string.rs
  |
  | pub struct String {
  | -----------------
  | |
  | doesn't satisfy `String: AsDynError<'_>`
  | doesn't satisfy `String: std::error::Error`
  |
  = note: the following trait bounds were not satisfied:
          `String: std::error::Error`
          which is required by `String: AsDynError<'_>`
          `str: Sized`
          which is required by `str: AsDynError<'_>`
          `str: std::error::Error`
          which is required by `str: AsDynError<'_>`