error: non-binding let on a type that has a destructor
  --> $DIR/issue-119696-err-on-fn.rs:5:5
   |
LL |     let _ = foo();
   |     ^^^^^^^^^^^^^^
   |
note: the lint level is defined here
  --> $DIR/issue-119696-err-on-fn.rs:3:9
   |
LL | #![deny(let_underscore_drop)]
   |         ^^^^^^^^^^^^^^^^^^^
help: consider binding to an unused variable to avoid immediately dropping the value
   |
LL |     let _unused = foo();
   |          ++++++
help: consider immediately dropping the value
   |
LL -     let _ = foo();
LL +     drop(foo());
   |

error: aborting due to 1 previous error