Print diagnostics with non-owned source code

[MattX]

Hello! I'm writing a small interpreter for a DSL, and would like to use miette for error reporting,

I've tried defining an error type like this:

#[derive(Debug, Error, Diagnostic)]
#[error("Runtime error")]
pub enum RuntimeError<'source> {
    #[error("Empty input")]
    EmptyInput {
        #[source_code]
        source_code: &'source str,

        #[label = "Empty input"]
        range: SourceSpan,
    },
    // ...
}

But calling .into_diagnostic() on something that returns Result<T, RuntimeError<'source>> creates a 'source = 'static requirement, whereas I would like my source code to be temporary (in fact I want to drop it immediately after printing the diagnostic).

I know I could wrap the source in an Rc or use another trick to extend its lifetime, but is there a way to reduce the lifetime requirement to "alive while the diagnostic is being printed"?

[zkat]

You can "delay" passing the source code in (and thus make it temporary) by using Report::with_source_code

[MattX]

But that still requires the source code to be 'static, doesn't it? That trait bound exists in Report::with_source_code. It feels like it should be possible to create a Report with a non-'static source code, as long as the Report doesn't outlive the source code?

[scriptandcompile]

I would also like some assistance with this. I'm running into basically the same issue. I can just clone it, but since I was counting on my error type to extremely light weight. I'm using it as the error side of a parser combinator and so returning the error side is common. I've noticed a massive slow down when I tried to integrate source code reporting to my error reporting.

[MattX]

In the end I've used a wrapper type that implements Diagnostic and delegates every method to a wrapped Diagnostic, except source_code(), which it gets from another field. Near the top-level of my code, I wrap the error with this type and bubble that up instead.

It's just a lot of boilerplate: https://gist.github.com/MattX/e6e01b453aad4778947e54a58c6f5be5