warning: unnecessary parentheses around assigned value
  --> $DIR/suggestions.rs:17:21
   |
17 |         let mut a = (1); // should suggest no `mut`, no parens
   |                     ^^^ help: remove these parentheses
   |
   = note: #[warn(unused_parens)] on by default

warning: use of deprecated attribute `no_debug`: the `#[no_debug]` attribute was an experimental feature that has been deprecated due to lack of demand. See https://github.com/rust-lang/rust/issues/29721
  --> $DIR/suggestions.rs:14:1
   |
14 | #[no_debug] // should suggest removal of deprecated attribute
   | ^^^^^^^^^^^ help: remove this attribute
   |
   = note: #[warn(deprecated)] on by default

warning: variable does not need to be mutable
  --> $DIR/suggestions.rs:17:13
   |
17 |         let mut a = (1); // should suggest no `mut`, no parens
   |             ---^^
   |             |
   |             help: remove this `mut`
   |
note: lint level defined here
  --> $DIR/suggestions.rs:11:9
   |
11 | #![warn(unused_mut)] // UI tests pass `-A unused`—see Issue #43896
   |         ^^^^^^^^^^

warning: denote infinite loops with `loop { ... }`
  --> $DIR/suggestions.rs:16:5
   |
16 |       while true { // should suggest `loop`
   |       ^---------
   |       |
   |  _____help: use `loop`
   | |
17 | |         let mut a = (1); // should suggest no `mut`, no parens
18 | |         println!("{}", a);
19 | |     }
   | |_____^
   |
   = note: #[warn(while_true)] on by default