The Fall-Through Proposal

language design
3

I believe that if let guards are planned, but they always apply to the entire match arm. This restriction could be removed by requiring parentheses in some cases:

match foo {
    A | B if bar => {}
    // is equivalent to
    (A | B) if bar => {}

    // This could be allowed too:
    (A if bar) | (B if !bar) => {}
    (A if let x = true) | (B if let x = false) => {}
}