error: placement-in expression syntax is experimental and subject to change. (see issue #27779)

Question

I am following Rust By Example and am getting an error which I am not sure how to address:

fn main() {
    let x: f32 = 10.;

    if (x == 10) {
        println!("if");
    } else if (x > 10) && (x<-5) {
        println!("else if");
    } else {
        println!("else");
    }
}

The compiling error below looks to be as a results of the else if. How do perform two conditional checks in the else if and why is it not working?

error: placement-in expression syntax is experimental and subject to change. (see issue #27779)
 --> src/main.rs:6:28
  |
6 |     } else if (x > 10) && (x<-5) {
  |                            ^^^^

Reminded me of this classic.

ljedrz
– ljedrz

2017-10-31 15:32:01 +00:00
Commented Oct 31, 2017 at 15:32 — ljedrz
– ljedrz, Commented Oct 31, 2017 at 15:32

loganfsmyth · Accepted Answer · 2017-10-31 05:39:03Z

6

Because you are writing x<-5 instead of x < -5 with whitespaces, Rust sees <- as the placement operator. Putting whitespace around your operators would in general be best, since it fixes this and also improved readability a lot.

edited Oct 31, 2017 at 5:39

answered Oct 31, 2017 at 5:33

loganfsmyth

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