src/test/ui/borrowck/reassignment_immutable_fields_twice.rs

// This should never be allowed -- since `x` is not `mut`, so `x.0`
// cannot be assigned twice.

fn var_then_field() {
    let x: (u32, u32);
    x = (22, 44);
    x.0 = 1; //~ ERROR
}

fn same_field_twice() {
    let x: (u32, u32);
    x.0 = 1; //~ ERROR
    x.0 = 22; //~ ERROR
    x.1 = 44; //~ ERROR
}

fn main() { }