try_v2 0.3.5

Provides a derive macro for `Try` ([try_trait_v2](https://rust-lang.github.io/rfcs/3058-try-trait-v2.html))
Documentation 
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#![feature(assert_matches)]
#![feature(never_type)]
#![feature(try_trait_v2)]

use std::assert_matches::assert_matches;
use try_v2::{Try, Try_ConvertResult};

mod bound_ok_type {
    use super::*;
    use std::process::Termination;

    #[derive(Debug, Try, Try_ConvertResult)]
    #[must_use]
    enum Exit<T: Termination> {
        Ok(T),
        TestsFailed,
        OtherError(String),
        NumberedError(String, i32),
        FormalError { errno: i32, data: String },
    }

    impl From<Exit<!>> for AnError {
        fn from(exit: Exit<!>) -> Self {
            match exit {
                Exit::TestsFailed => AnError("tests failed".to_string()),
                Exit::OtherError(text) => AnError(text),
                Exit::NumberedError(text, n) => AnError(format!("{n}: {text}")),
                Exit::FormalError { errno, data } => AnError(format!("{errno}: {data}")),
            }
        }
    }
    #[derive(Debug)]
    struct AnError(String);

    #[test]
    fn short_circuit_1() {
        fn fail() -> Exit<()> {
            Exit::TestsFailed?;
            Exit::Ok(())
        }
        assert_matches!(fail(), Exit::TestsFailed)
    }

    #[test]
    fn short_circuit_2() {
        fn fail() -> Exit<()> {
            Exit::OtherError("oops!".to_string())?;
            Exit::TestsFailed?;
            Exit::Ok(())
        }
        assert_matches!(fail(), Exit::OtherError(msg) if msg == "oops!")
    }

    #[test]
    fn short_circuit_3() {
        fn fail() -> Exit<()> {
            Exit::NumberedError("oops!".to_string(), 4)?;
            Exit::TestsFailed?;
            Exit::Ok(())
        }
        assert_matches!(fail(), Exit::NumberedError(msg, n) if msg == "oops!" && n == 4)
    }

    #[test]
    fn short_circuit_4() {
        fn fail() -> Exit<()> {
            Exit::FormalError {
                errno: 2,
                data: "oops!".to_string(),
            }?;
            Exit::TestsFailed?;
            Exit::Ok(())
        }
        assert_matches!(fail(), Exit::FormalError{errno, data} if data == "oops!" && errno == 2)
    }

    #[test]
    fn no_short_circuit() {
        fn pass() -> Exit<()> {
            Exit::Ok(())?;
            Exit::Ok(())
        }
        assert_matches!(pass(), Exit::Ok(()))
    }

    #[test]
    fn convert_to_result_1() {
        fn fail() -> Result<(), AnError> {
            Exit::TestsFailed?;
            Ok(())
        }
        assert_matches!(fail(), Result::Err(e) if e.0 == "tests failed")
    }

    #[test]
    fn convert_to_result_2() {
        fn fail() -> Result<(), AnError> {
            Exit::OtherError("oops!".to_string())?;
            Exit::TestsFailed?;
            Ok(())
        }
        assert_matches!(fail(), Result::Err(e) if e.0 == "oops!")
    }
}

mod multiple_generics {
    use super::*;

    #[derive(Debug, Try, Try_ConvertResult)]
    #[must_use]
    enum MyResult<T, E> {
        Ok(T),
        Err(E),
    }

    #[test]
    fn short_circuit_ok() {
        fn pass() -> MyResult<usize, String> {
            let foo = MyResult::Ok(5)?;
            MyResult::Ok(foo)
        }
        assert_matches!(pass(), MyResult::Ok(val) if val == 5);
    }

    #[test]
    fn short_circuit_fail() {
        fn fail() -> MyResult<String, String> {
            let foo = MyResult::Err("oops!".to_string())?;
            MyResult::Ok(foo)
        }
        assert_matches!(fail(), MyResult::Err(msg) if msg == "oops!");
    }
}

mod lifetimes {
    #[allow(unused)]
    use super::*;

    // #[derive(Debug, Try)]
    // enum MyResult<'r, T, E> {
    //     Ok(&'r T),
    //     Err(&'r E),
    // }

    // #[derive(Debug, Try, Try_ConvertResult)]
    // enum MyResult<'t, 'e, T, E> {
    //     Ok(&'t T),
    //     Err(&'e E),
    // }

    // #[derive(Debug, Try)]
    // enum MyResult<T: 'static, E> {
    //     Ok(&'static T),
    //     Err(E),
    // }

    // #[derive(Debug, Try)]
    // enum MyResult<'t, T, E> {
    //     Ok(&'t T),
    //     Err(E),
    // }
}