Precedence cannot avoid generating associativity

[A4-Tacks]

peg::parser!(grammar p() for str {
    rule x() = "x"
    pub rule foo() = "-" x() / x()
    pub rule bar() = precedence! {
        "-" @ {}
        --
        x() {}
    }
});

fn main() {
    assert_eq!(p::foo("-x"), Ok(()));
    assert_eq!(p::bar("-x"), Ok(()));
    assert!(p::foo("--x").is_err());
    assert!(p::bar("--x").is_err()); // failed!
}

Sometimes it is necessary to not associative infix, prefix, and postfix operators,
But the precedence! cannot express this situation

[eanderton]

There may be something up with the "@" operator. If you use bar() explicitly, this works.

peg::parser!(grammar p() for str {
    rule x() = "x"
    pub rule foo() = "-" x() / x()
    pub rule bar() = precedence! {
        "-" bar() {}
        --
        x() {}
    }
});

[A4-Tacks]

I expect precedence! to be able to perform non associative work, avoiding the need for multiple precedence!

[kevinmehall]

Yeah, it would be ideal if precedence with @ on both sides without (@) would be non-associative. I looked at doing that once and it was not straightforward to implement, but I don't remember exactly why.