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I have a String newtype ErrorMessage that I'm using for errors in a prototype crate. (I know that this is a bad practice. I will construct a proper set of distinct error types before publication.)

I need ErrorMessage to implement the Error trait, which is (practically) empty but requires that it also implement the Display and Debug traits, which I have done.

pub struct ErrorMessage(pub String);
impl std::error::Error for ErrorMessage 
impl std::fmt::Display for ErrorMessage 
 fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result 
 self.0.fmt(f)
 

impl std::fmt::Debug for ErrorMessage 
 fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result 
 self.0.fmt(f)
 

This works fine. However, I recently came across Deref and was wondering if it could automatically delegate trait implementations to the implementations for String from self.0.

impl std::ops::Deref for ErrorMessage 
 type Target = str;

 fn deref(&self) -> &str 
 &self.0
 

This allows me to call methods like .to_string() on an ErrorMessage, and deref coercion will let it use my Deref implementation to automatically find the fmt and to_string implementations on self.0/*self.

However, ErrorMessage itself isn't actually Display or Debug. If I try to println! or format! an instance directly I get an error, and it doesn't satisfy the bounds for Error.

fn main() -> Result<(), ErrorMessage> 
 Err(ErrorMessage("hello world".to_string()))

error[E0277]: `ErrorMessage` doesn't implement `std::fmt::Display`
 --> src/main.rs:2:6
 |
2 | impl std::error::Error for ErrorMessage 
 | ^^^^^^^^^^^^^^^^^ `ErrorMessage` cannot be formatted with the default formatter
 |
 = help: the trait `std::fmt::Display` is not implemented for `ErrorMessage`

Is there any way to use Deref, DerefMut, or something similar to allow dereffed values to satisfy trait bounds for the original values. I'm looking for somethinig automatic, as an alternative to manually writing impl blocks to delegate each of them.

I recognize that this is probably also a bad idea in practice. This is just hypothetical.