Log Backtrace / Stacktrace with a custom ErrorHandler

[vincent-herlemont]

Is possible to return the line number/backtrace or event custom backtrace when we log errors with CustomErrorHandler?

NOTE: Some libraries allow to customize stack trace and offer divers report improvements like miette, stable_eyre etc. There is some method to retrieve manually the line number when the program panic here: Getting line numbers with ? as I would with unwrap().

More context

Below is an example to log a panic produces by unreachable!().

#[derive(Clone, Copy)]
pub struct CustomErrorHandler(pub handler::ReportDartErrorHandler);

impl handler::ErrorHandler for CustomErrorHandler {
    fn handle_error(&self, port: i64, error: handler::Error) {
        logs::info(&error.message());
        self.0.handle_error(port, error)
    }
...

pub fn failed_function() {
    unreachable!("throw error")
}

We can see it that only the message of throw error is displayed.

I/flutter ( 6694): log from rust: internal error: entered unreachable code: throw error 

In this case, it should be greater to retrieve the file name and line number. Here is the goal of this discussion.

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Related to:

• Support for Result<MyType, MyError> with exception throwing on Dart by lattice0 · Pull Request #582
• `Result<(),MyCustomError>` instead of `anyhow`? · Issue #533

[fzyzcjy]

I personally use sentry and it knows the stack trace IIRC.

[vincent-herlemont]

@fzyzcjy Thanks for your answer. I will try it. However, in a full offline configuration, it should be greater to have readable error logs with the most details as possible.

Is it possible to provide a custom handler::Error in the same way that we can purpose a custom implementation of handler::ErrorHandler?

[fzyzcjy]

Just look at sentry's source code, its client is OSS