error: this let-binding has unit value. Consider omitting `let _x =`
  --> let_unit.rs:14:5
   |
14 |     let _x = println!("x");
   |     ^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `-D let-unit-value` implied by `-D warnings`

error: this let-binding has unit value. Consider omitting `let _a =`
  --> let_unit.rs:18:9
   |
18 |         let _a = ();
   |         ^^^^^^^^^^^^
   |
   = note: `-D let-unit-value` implied by `-D warnings`

error: aborting due to 2 previous errors

error: Could not compile `clippy_tests`.

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