Have the drop code suggestion not include let _ =

compiler/rustc_lint/src/let_underscore.rs

@@ -157,7 +157,7 @@ fn build_and_emit_lint(
         .multipart_suggestion(
             "consider immediately dropping the value",
             vec![
-                (init_span.shrink_to_lo(), "drop(".to_string()),
+                (local.span.until(init_span), "drop(".to_string()),
                 (init_span.shrink_to_hi(), ")".to_string()),
             ],
             Applicability::MachineApplicable,

src/test/ui/lint/let_underscore/let_underscore_drop.stderr

@@ -11,8 +11,8 @@ LL |     let _unused = NontrivialDrop;
    |         ~~~~~~~
 help: consider immediately dropping the value
    |
-LL |     let _ = drop(NontrivialDrop);
+LL |     drop(NontrivialDrop);
-   |             +++++              +
+   |     ~~~~~              +
 
 warning: 1 warning emitted
 

src/test/ui/lint/let_underscore/let_underscore_lock.stderr

@@ -11,8 +11,8 @@ LL |     let _unused = data.lock().unwrap();
    |         ~~~~~~~
 help: consider immediately dropping the value
    |
-LL |     let _ = drop(data.lock().unwrap());
+LL |     drop(data.lock().unwrap());
-   |             +++++                    +
+   |     ~~~~~                    +
 
 error: aborting due to previous error