try_blocks
The tracking issue for this feature is: #31436
The try_blocks feature adds support for try blocks. A try
block creates a new scope one can use the ? operator in.
// This code needs the 2018 edition
#![feature(try_blocks)]
use std::num::ParseIntError;
let result: Result<i32, ParseIntError> = try {
    "1".parse::<i32>()?
        + "2".parse::<i32>()?
        + "3".parse::<i32>()?
};
assert_eq!(result, Ok(6));
let result: Result<i32, ParseIntError> = try {
    "1".parse::<i32>()?
        + "foo".parse::<i32>()?
        + "3".parse::<i32>()?
};
assert!(result.is_err());