bail macro in try block

[kgv]

What do you think about changing the bail macro for use it or ensure in the try-blocks?

current:

#[macro_export]
macro_rules! bail {
    ($e:expr) => {
        return Err($crate::err_msg($e));
    };
    ($fmt:expr, $($arg:tt)+) => {
        return Err($crate::err_msg(format!($fmt, $($arg)+)));
    };
}

changed:

#[macro_export]
macro_rules! bail {
    ($e:expr) => {
        Err($crate::err_msg($e))?;
    };
    ($fmt:expr, $($arg:tt)+) => {
        Err($crate::err_msg(format!($fmt, $($arg)+)))?;
    };
}

[yoshuawuyts]

@kgv I didn't realize try {} blocks were available already! Do you have any links to (nightly) docs / feature tracking issues? It would probably help provide some context for anyone that hasn't caught up on the latest around try {} (e.g. people like me, haha). Thanks!

[kgv]

@yoshuawuyts try-blocks

[mitsuhiko]

I think I'm in favour of this change. Would accept a PR if it comes with tests.

[bossmc]

Would also fix https://github.com/rust-lang-nursery/failure/issues/110 which just tripped me up as unobvious (bail! is strictly less versatile than ?)