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Cannot use parens for grouping in patterns #554

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@rust-highfive

Issue by cmr
Friday Dec 05, 2014 at 23:28 GMT

For earlier discussion, see rust-lang/rust#19580

This issue was labelled with: A-grammar, B-clarifying, I-papercut in the Rust repository


The fact that

fn main() {
    let x = &4i;

    match x {
        // wanted to type `e @ &1 ... &4`
        e @ &1 ... 4 => println!("Got a small value: {}", e),
        &val => println!("Got a value: {}", val),
    }
}

works but

fn main() {
    let x = &4i;

    match x {
        // wanted to type `e @ &1 ... &4`
        e @ &(1 ... 4) => println!("Got a small value: {}", e),
        &val => println!("Got a value: {}", val),
    }
}

is quite surprising. Presumably the &( is expecting a tuple pattern, should consider investigating and seeing if patterns can be parenthesized in general.

cc #11144

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