Macro try_pattern

try_pattern!() { /* proc-macro */ }

Similar to unwrap_pattern but returns Result<_, &str>.

Example:

let a = try_pattern!(some_enum, A(x)=>x)?;

Equivalent:

let result = if let A(x) = some_enum {
    Ok(x)
} else {
    Err("failed")
};
let a = result?;