issue-90528-unsizing-suggestion-2.rs

// Issue #90528: provide helpful suggestions when a trait bound is unsatisfied
// due to a missed unsizing coercion.
//
// This test exercises array variables and a trait implemented on immmutable slices.

trait Read {}

impl Read for &[u8] {}

fn wants_read(_: impl Read) {}

fn main() {
    let x = [0u8];
    wants_read(x);
    //~^ ERROR the trait bound `[u8; 1]: Read` is not satisfied
    //~| HELP the following implementations were found
    //~| HELP convert the array
    //~| SUGGESTION &x[..]
    wants_read(&x);
    //~^ ERROR the trait bound `&[u8; 1]: Read` is not satisfied
    //~| HELP the following implementations were found
    //~| HELP convert the array
    //~| SUGGESTION &x[..]
    wants_read(&x[..]);

    let x = &[0u8];
    wants_read(x);
    //~^ ERROR the trait bound `&[u8; 1]: Read` is not satisfied
    //~| HELP the following implementations were found
    //~| HELP convert the array
    //~| SUGGESTION &x[..]
    wants_read(&x);
    //~^ ERROR the trait bound `&&[u8; 1]: Read` is not satisfied
    //~| HELP the following implementations were found
    wants_read(*x);
    //~^ ERROR the trait bound `[u8; 1]: Read` is not satisfied
    //~| HELP the following implementations were found
    //~| HELP convert the array
    //~| SUGGESTION &*x[..]
    //              ^^^^^^^ bad suggestion
    wants_read(&x[..]);
}