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// run-pass
// This test illustrates that under NLL, we can remove our overly
// conservative approach for disallowing mutations of match inputs.
// See further discussion on rust-lang/rust#24535,
// rust-lang/rfcs#1006, and rust-lang/rfcs#107
#![feature(if_let_guard)]
fn main() {
rust_issue_24535();
rfcs_issue_1006_1();
rfcs_issue_1006_2();
}
fn rust_issue_24535() {
fn compare(a: &u8, b: &mut u8) -> bool {
a == b
}
let a = 3u8;
match a {
0 => panic!("nope"),
3 if compare(&a, &mut 3) => (),
_ => panic!("nope"),
}
match a {
0 => panic!("nope"),
3 if let true = compare(&a, &mut 3) => (),
_ => panic!("nope"),
}
}
fn rfcs_issue_1006_1() {
let v = vec!["1".to_string(), "2".to_string(), "3".to_string()];
match Some(&v) {
Some(iv) if iv.iter().any(|x| &x[..]=="2") => true,
_ => panic!("nope"),
};
}
fn rfcs_issue_1006_2() {
#[inline(always)]
fn check<'a, I: Iterator<Item=&'a i32>>(mut i: I) -> bool {
i.any(|&x| x == 2)
}
let slice = [1, 2, 3];
match 42 {
_ if slice.iter().any(|&x| x == 2) => { true },
_ => { panic!("nope"); }
};
// (This match is just illustrating how easy it was to circumvent
// the checking performed for the previous `match`.)
match 42 {
_ if check(slice.iter()) => { true },
_ => { panic!("nope"); }
};
}
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