rust/tests/ui/destructuring-assignment/warn-unused-duplication.rs
2024-02-16 20:02:50 +00:00

22 lines
578 B
Rust

//@ run-pass
#![warn(unused_assignments)]
fn main() {
let mut a;
// Assignment occurs left-to-right.
// However, we emit warnings when this happens, so it is clear that this is happening.
(a, a) = (0, 1); //~ WARN value assigned to `a` is never read
assert_eq!(a, 1);
// We can't always tell when a variable is being assigned to twice, which is why we don't try
// to emit an error, which would be fallible.
let mut x = 1;
(*foo(&mut x), *foo(&mut x)) = (5, 6);
assert_eq!(x, 6);
}
fn foo<'a>(x: &'a mut u32) -> &'a mut u32 {
x
}