Update references

28 files changed, 43 insertions, 506 deletions

diff --git a/tests/ui/borrow_box.stderr b/tests/ui/borrow_box.stderr
index a40789cd426..3eac32815be 100644
--- a/tests/ui/borrow_box.stderr
+++ b/tests/ui/borrow_box.stderr
@@ -22,15 +22,6 @@ error: you seem to be trying to use `&Box<T>`. Consider using just `&T`
 LL |     fn test4(a: &Box<bool>);
    |                 ^^^^^^^^^^ help: try: `&bool`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/borrow_box.rs:63:5
-   |
-LL |     let _ = foo;
-   |     ^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: you seem to be trying to use `&Box<T>`. Consider using just `&T`
   --> $DIR/borrow_box.rs:95:25
    |
@@ -73,5 +64,5 @@ error: you seem to be trying to use `&Box<T>`. Consider using just `&T`
 LL | pub fn test20(_display: &Box<(dyn Display + Send)>) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&(dyn Display + Send)`
 
-error: aborting due to 11 previous errors
+error: aborting due to 10 previous errors
 
diff --git a/tests/ui/borrow_interior_mutable_const/others.stderr b/tests/ui/borrow_interior_mutable_const/others.stderr
index 976c412c7a8..9a908cf30e9 100644
--- a/tests/ui/borrow_interior_mutable_const/others.stderr
+++ b/tests/ui/borrow_interior_mutable_const/others.stderr
@@ -47,15 +47,6 @@ LL |     let _once_mut = &mut ONCE_INIT; //~ ERROR interior mutability
    |
    = help: assign this const to a local or static variable, and use the variable here
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/others.rs:72:5
-   |
-LL |     let _ = &ATOMIC_TUPLE; //~ ERROR interior mutability
-   |     ^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: a `const` item with interior mutability should not be borrowed
   --> $DIR/others.rs:72:14
    |
@@ -104,22 +95,6 @@ LL |     let _ = ATOMIC_TUPLE.0[0]; //~ ERROR interior mutability
    |
    = help: assign this const to a local or static variable, and use the variable here
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/others.rs:83:5
-   |
-LL |     let _ = ATOMIC_TUPLE.1.into_iter();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/others.rs:85:5
-   |
-LL |     let _ = &{ ATOMIC_TUPLE };
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: a `const` item with interior mutability should not be borrowed
   --> $DIR/others.rs:87:5
    |
@@ -136,5 +111,5 @@ LL |     assert_eq!(CELL.get(), 6); //~ ERROR interior mutability
    |
    = help: assign this const to a local or static variable, and use the variable here
 
-error: aborting due to 17 previous errors
+error: aborting due to 14 previous errors
 
diff --git a/tests/ui/box_vec.stderr b/tests/ui/box_vec.stderr
index a4983df1d30..fca12eddd57 100644
--- a/tests/ui/box_vec.stderr
+++ b/tests/ui/box_vec.stderr
@@ -1,16 +1,3 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/box_vec.rs:7:9
-   |
-LL |         let _: Box<$x> = Box::new($init);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-...
-LL |     boxit!(Vec::new(), Vec<u8>);
-   |     ---------------------------- in this macro invocation
-   |
-   = note: `-D clippy::let-underscore-drop` implied by `-D warnings`
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
-
 error: you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`
   --> $DIR/box_vec.rs:14:18
    |
@@ -20,5 +7,5 @@ LL | pub fn test(foo: Box<Vec<bool>>) {
    = note: `-D clippy::box-vec` implied by `-D warnings`
    = help: `Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation.
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
diff --git a/tests/ui/crashes/ice-4968.stderr b/tests/ui/crashes/ice-4968.stderr
deleted file mode 100644
index 9ce39027451..00000000000
--- a/tests/ui/crashes/ice-4968.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/ice-4968.rs:16:9
-   |
-LL |         let _: Vec<ManuallyDrop<T::Assoc>> = mem::transmute(slice);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to previous error
-
diff --git a/tests/ui/crashes/ice-5223.stderr b/tests/ui/crashes/ice-5223.stderr
deleted file mode 100644
index 3ae2dd5f770..00000000000
--- a/tests/ui/crashes/ice-5223.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/ice-5223.rs:14:9
-   |
-LL |         let _ = self.arr.iter().cloned().collect::<Vec<_>>();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to previous error
-
diff --git a/tests/ui/escape_analysis.stderr b/tests/ui/escape_analysis.stderr
index 6e1c1c07b6e..c86a769a3da 100644
--- a/tests/ui/escape_analysis.stderr
+++ b/tests/ui/escape_analysis.stderr
@@ -12,26 +12,5 @@ error: local variable doesn't need to be boxed here
 LL | pub fn new(_needs_name: Box<PeekableSeekable<&()>>) -> () {}
    |            ^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/escape_analysis.rs:166:9
-   |
-LL | /         let _ = move || {
-LL | |             consume(x);
-LL | |         };
-   | |__________^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/escape_analysis.rs:172:9
-   |
-LL | /         let _ = || {
-LL | |             borrow(&x);
-LL | |         };
-   | |__________^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/eta.stderr b/tests/ui/eta.stderr
index bc79caee887..c4713ca8083 100644
--- a/tests/ui/eta.stderr
+++ b/tests/ui/eta.stderr
@@ -64,15 +64,6 @@ error: redundant closure found
 LL |     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
    |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove closure as shown: `char::to_ascii_uppercase`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/eta.rs:107:5
-   |
-LL |     let _: Vec<_> = arr.iter().map(|x| x.map_err(|e| some.take().unwrap()(e))).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: redundant closure found
   --> $DIR/eta.rs:172:27
    |
@@ -85,13 +76,5 @@ error: redundant closure found
 LL |     let a = Some(1u8).map(|a| closure(a));
    |                           ^^^^^^^^^^^^^^ help: remove closure as shown: `closure`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/eta.rs:203:5
-   |
-LL |     let _ = [Bar].iter().map(|s| s.to_string()).collect::<Vec<_>>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 14 previous errors
+error: aborting due to 12 previous errors
 
diff --git a/tests/ui/filter_methods.stderr b/tests/ui/filter_methods.stderr
index 08b781d7363..b5ac90282dc 100644
--- a/tests/ui/filter_methods.stderr
+++ b/tests/ui/filter_methods.stderr
@@ -1,4 +1,4 @@
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/filter_methods.rs:5:5
    |
 LL |     let _: Vec<_> = vec![5; 6].into_iter().filter(|&x| x == 0).map(|x| x * 2).collect();
@@ -16,7 +16,7 @@ LL |     let _: Vec<_> = vec![5; 6].into_iter().filter(|&x| x == 0).map(|x| x *
    = note: `-D clippy::filter-map` implied by `-D warnings`
    = help: this is more succinctly expressed by calling `.filter_map(..)` instead
 
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/filter_methods.rs:7:5
    |
 LL | /     let _: Vec<_> = vec![5_i8; 6]
@@ -40,7 +40,7 @@ LL | |         .flat_map(|x| x.checked_mul(2))
    |
    = help: this is more succinctly expressed by calling `.flat_map(..)` and filtering by returning `iter::empty()`
 
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/filter_methods.rs:13:5
    |
 LL | /     let _: Vec<_> = vec![5_i8; 6]
@@ -64,7 +64,7 @@ LL | |         .flat_map(|x| x.checked_mul(2))
    |
    = help: this is more succinctly expressed by calling `.flat_map(..)` and filtering by returning `iter::empty()`
 
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/filter_methods.rs:19:5
    |
 LL | /     let _: Vec<_> = vec![5_i8; 6]
diff --git a/tests/ui/get_unwrap.stderr b/tests/ui/get_unwrap.stderr
index 6aa5452bac1..76a098df82a 100644
--- a/tests/ui/get_unwrap.stderr
+++ b/tests/ui/get_unwrap.stderr
@@ -70,34 +70,17 @@ error: called `.get_mut().unwrap()` on a VecDeque. Using `[]` is more clear and
 LL |         *some_vecdeque.get_mut(0).unwrap() = 1;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vecdeque[0]`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/get_unwrap.rs:59:9
-   |
-LL |         let _ = some_vec.get(0..1).unwrap().to_vec();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `.get().unwrap()` on a Vec. Using `[]` is more clear and more concise
   --> $DIR/get_unwrap.rs:59:17
    |
 LL |         let _ = some_vec.get(0..1).unwrap().to_vec();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vec[0..1]`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/get_unwrap.rs:60:9
-   |
-LL |         let _ = some_vec.get_mut(0..1).unwrap().to_vec();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
   --> $DIR/get_unwrap.rs:60:17
    |
 LL |         let _ = some_vec.get_mut(0..1).unwrap().to_vec();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vec[0..1]`
 
-error: aborting due to 15 previous errors
+error: aborting due to 13 previous errors
 
diff --git a/tests/ui/into_iter_on_ref.stderr b/tests/ui/into_iter_on_ref.stderr
index efe9d20920b..28003b365bb 100644
--- a/tests/ui/into_iter_on_ref.stderr
+++ b/tests/ui/into_iter_on_ref.stderr
@@ -1,12 +1,3 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/into_iter_on_ref.rs:13:5
-   |
-LL |     let _ = vec![1, 2, 3].into_iter();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: this `.into_iter()` call is equivalent to `.iter()` and will not consume the `Vec`
   --> $DIR/into_iter_on_ref.rs:14:30
    |
@@ -171,5 +162,5 @@ error: this `.into_iter()` call is equivalent to `.iter()` and will not consume
 LL |     let _ = (&[1, 2, 3]).into_iter().next(); //~ WARN equivalent to .iter()
    |                          ^^^^^^^^^ help: call directly: `iter`
 
-error: aborting due to 28 previous errors
+error: aborting due to 27 previous errors
 
diff --git a/tests/ui/iter_cloned_collect.stderr b/tests/ui/iter_cloned_collect.stderr
index f5cd43b3da5..b90a1e6c919 100644
--- a/tests/ui/iter_cloned_collect.stderr
+++ b/tests/ui/iter_cloned_collect.stderr
@@ -6,33 +6,12 @@ LL |     let v2: Vec<isize> = v.iter().cloned().collect();
    |
    = note: `-D clippy::iter-cloned-collect` implied by `-D warnings`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/iter_cloned_collect.rs:15:5
-   |
-LL |     let _: Vec<isize> = vec![1, 2, 3].iter().cloned().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
   --> $DIR/iter_cloned_collect.rs:15:38
    |
 LL |     let _: Vec<isize> = vec![1, 2, 3].iter().cloned().collect();
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `.to_vec()`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/iter_cloned_collect.rs:19:9
-   |
-LL | /         let _: Vec<u8> = std::ffi::CStr::from_ptr(std::ptr::null())
-LL | |             .to_bytes()
-LL | |             .iter()
-LL | |             .cloned()
-LL | |             .collect();
-   | |_______________________^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
   --> $DIR/iter_cloned_collect.rs:20:24
    |
@@ -43,5 +22,5 @@ LL | |             .cloned()
 LL | |             .collect();
    | |______________________^ help: try: `.to_vec()`
 
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/tests/ui/let_underscore_drop.stderr b/tests/ui/let_underscore_drop.stderr
index 6dc8904c4fe..66069e0c5e1 100644
--- a/tests/ui/let_underscore_drop.stderr
+++ b/tests/ui/let_underscore_drop.stderr
@@ -1,4 +1,4 @@
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/let_underscore_drop.rs:16:5
    |
 LL |     let _ = Box::new(());
@@ -7,7 +7,7 @@ LL |     let _ = Box::new(());
    = note: `-D clippy::let-underscore-drop` implied by `-D warnings`
    = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
 
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/let_underscore_drop.rs:17:5
    |
 LL |     let _ = Droppable;
@@ -15,7 +15,7 @@ LL |     let _ = Droppable;
    |
    = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
 
-error: non-binding let on a type that implements `Drop`
+error: non-binding `let` on a type that implements `Drop`
   --> $DIR/let_underscore_drop.rs:18:5
    |
 LL |     let _ = Some(Droppable);
diff --git a/tests/ui/map_clone.fixed b/tests/ui/map_clone.fixed
index 6e3a8e67e81..ce92b3c0c30 100644
--- a/tests/ui/map_clone.fixed
+++ b/tests/ui/map_clone.fixed
@@ -2,6 +2,7 @@
 #![warn(clippy::all, clippy::pedantic)]
 #![allow(clippy::iter_cloned_collect)]
 #![allow(clippy::clone_on_copy, clippy::redundant_clone)]
+#![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::redundant_closure_for_method_calls)]
 #![allow(clippy::many_single_char_names)]
diff --git a/tests/ui/map_clone.rs b/tests/ui/map_clone.rs
index 6fd395710d4..324c776c3c9 100644
--- a/tests/ui/map_clone.rs
+++ b/tests/ui/map_clone.rs
@@ -2,6 +2,7 @@
 #![warn(clippy::all, clippy::pedantic)]
 #![allow(clippy::iter_cloned_collect)]
 #![allow(clippy::clone_on_copy, clippy::redundant_clone)]
+#![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::redundant_closure_for_method_calls)]
 #![allow(clippy::many_single_char_names)]
diff --git a/tests/ui/map_clone.stderr b/tests/ui/map_clone.stderr
index 122a678f118..d84a5bf8d4d 100644
--- a/tests/ui/map_clone.stderr
+++ b/tests/ui/map_clone.stderr
@@ -1,97 +1,40 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:10:5
-   |
-LL |     let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::let-underscore-drop` implied by `-D warnings`
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: you are using an explicit closure for copying elements
-  --> $DIR/map_clone.rs:10:22
+  --> $DIR/map_clone.rs:11:22
    |
 LL |     let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `vec![5_i8; 6].iter().copied()`
    |
    = note: `-D clippy::map-clone` implied by `-D warnings`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:11:5
-   |
-LL |     let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: you are using an explicit closure for cloning elements
-  --> $DIR/map_clone.rs:11:26
+  --> $DIR/map_clone.rs:12:26
    |
 LL |     let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `vec![String::new()].iter().cloned()`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:12:5
-   |
-LL |     let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: you are using an explicit closure for copying elements
-  --> $DIR/map_clone.rs:12:23
+  --> $DIR/map_clone.rs:13:23
    |
 LL |     let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `vec![42, 43].iter().copied()`
 
 error: you are using an explicit closure for copying elements
-  --> $DIR/map_clone.rs:14:26
+  --> $DIR/map_clone.rs:15:26
    |
 LL |     let _: Option<u64> = Some(&16).map(|b| *b);
    |                          ^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `Some(&16).copied()`
 
 error: you are using an explicit closure for copying elements
-  --> $DIR/map_clone.rs:15:25
+  --> $DIR/map_clone.rs:16:25
    |
 LL |     let _: Option<u8> = Some(&1).map(|x| x.clone());
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `Some(&1).copied()`
 
 error: you are needlessly cloning iterator elements
-  --> $DIR/map_clone.rs:26:29
+  --> $DIR/map_clone.rs:27:29
    |
 LL |     let _ = std::env::args().map(|v| v.clone());
    |                             ^^^^^^^^^^^^^^^^^^^ help: remove the `map` call
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:35:9
-   |
-LL |         let _: Vec<u32> = v.into_iter().map(|x| *x).collect();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:42:9
-   |
-LL |         let _: Vec<u32> = v.into_iter().map(|x| *x).collect();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:45:9
-   |
-LL |         let _: Vec<u32> = v.into_iter().map(|&mut x| x).collect();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_clone.rs:53:9
-   |
-LL |         let _: Vec<_> = items.into_iter().map(|x| x.clone()).collect();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 13 previous errors
+error: aborting due to 6 previous errors
 
diff --git a/tests/ui/map_collect_result_unit.stderr b/tests/ui/map_collect_result_unit.stderr
index 26e876b1808..8b06e13baa6 100644
--- a/tests/ui/map_collect_result_unit.stderr
+++ b/tests/ui/map_collect_result_unit.stderr
@@ -12,22 +12,5 @@ error: `.map().collect()` can be replaced with `.try_for_each()`
 LL |         let _: Result<(), _> = (0..3).map(|t| Err(t + 1)).collect();
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `(0..3).try_for_each(|t| Err(t + 1))`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_collect_result_unit.rs:14:5
-   |
-LL |     let _ = (0..3).map(|t| Err(t + 1)).collect::<Result<Vec<i32>, _>>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_collect_result_unit.rs:15:5
-   |
-LL |     let _ = (0..3).map(|t| Err(t + 1)).collect::<Vec<Result<(), _>>>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/map_flatten.fixed b/tests/ui/map_flatten.fixed
index a5fdf7df613..a7ab5a12cb7 100644
--- a/tests/ui/map_flatten.fixed
+++ b/tests/ui/map_flatten.fixed
@@ -1,6 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::all, clippy::pedantic)]
+#![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
 
diff --git a/tests/ui/map_flatten.rs b/tests/ui/map_flatten.rs
index abbc4e16e56..e364a05f376 100644
--- a/tests/ui/map_flatten.rs
+++ b/tests/ui/map_flatten.rs
@@ -1,6 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::all, clippy::pedantic)]
+#![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
 
diff --git a/tests/ui/map_flatten.stderr b/tests/ui/map_flatten.stderr
index 6159b5256ee..d4e27f9aa07 100644
--- a/tests/ui/map_flatten.stderr
+++ b/tests/ui/map_flatten.stderr
@@ -1,81 +1,40 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_flatten.rs:14:5
-   |
-LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::let-underscore-drop` implied by `-D warnings`
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:14:46
+  --> $DIR/map_flatten.rs:15:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id)`
    |
    = note: `-D clippy::map-flatten` implied by `-D warnings`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_flatten.rs:15:5
-   |
-LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:15:46
+  --> $DIR/map_flatten.rs:16:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_ref)`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_flatten.rs:16:5
-   |
-LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:16:46
+  --> $DIR/map_flatten.rs:17:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_closure)`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_flatten.rs:17:5
-   |
-LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:17:46
+  --> $DIR/map_flatten.rs:18:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(|x| x.checked_add(1))`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_flatten.rs:20:5
-   |
-LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:20:46
+  --> $DIR/map_flatten.rs:21:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `flat_map` instead: `.flat_map(|x| 0..x)`
 
 error: called `map(..).flatten()` on an `Option`
-  --> $DIR/map_flatten.rs:23:39
+  --> $DIR/map_flatten.rs:24:39
    |
 LL |     let _: Option<_> = (Some(Some(1))).map(|x| x).flatten();
    |                                       ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)`
 
-error: aborting due to 11 previous errors
+error: aborting due to 6 previous errors
 
diff --git a/tests/ui/map_identity.stderr b/tests/ui/map_identity.stderr
index 6bfeb186bad..e4a0320cbda 100644
--- a/tests/ui/map_identity.stderr
+++ b/tests/ui/map_identity.stderr
@@ -1,12 +1,3 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_identity.rs:8:5
-   |
-LL |     let _: Vec<_> = x.iter().map(not_identity).map(|x| return x).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: unnecessary map of the identity function
   --> $DIR/map_identity.rs:8:47
    |
@@ -15,14 +6,6 @@ LL |     let _: Vec<_> = x.iter().map(not_identity).map(|x| return x).collect();
    |
    = note: `-D clippy::map-identity` implied by `-D warnings`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_identity.rs:9:5
-   |
-LL |     let _: Vec<_> = x.iter().map(std::convert::identity).map(|y| y).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: unnecessary map of the identity function
   --> $DIR/map_identity.rs:9:57
    |
@@ -50,21 +33,5 @@ LL | |         return x;
 LL | |     });
    | |______^ help: remove the call to `map`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_identity.rs:15:5
-   |
-LL |     let _: Vec<_> = x.iter().map(|x| 2 * x).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/map_identity.rs:16:5
-   |
-LL |     let _: Vec<_> = x.iter().map(not_identity).map(|x| return x - 4).collect();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 9 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/tests/ui/match_single_binding.stderr b/tests/ui/match_single_binding.stderr
index 8b07599817b..795c8c3e24d 100644
--- a/tests/ui/match_single_binding.stderr
+++ b/tests/ui/match_single_binding.stderr
@@ -150,20 +150,6 @@ LL |     let Point { x, y } = coords();
 LL |     let product = x * y;
    |
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/match_single_binding.rs:96:5
-   |
-LL | /     let _ = v
-LL | |         .iter()
-LL | |         .map(|i| match i.unwrap() {
-LL | |             unwrapped => unwrapped,
-LL | |         })
-LL | |         .collect::<Vec<u8>>();
-   | |______________________________^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: this match could be written as a `let` statement
   --> $DIR/match_single_binding.rs:98:18
    |
@@ -181,5 +167,5 @@ LL |             unwrapped
 LL |         })
    |
 
-error: aborting due to 12 previous errors
+error: aborting due to 11 previous errors
 
diff --git a/tests/ui/needless_pass_by_value.stderr b/tests/ui/needless_pass_by_value.stderr
index cf04ee4b257..9aa783bf904 100644
--- a/tests/ui/needless_pass_by_value.stderr
+++ b/tests/ui/needless_pass_by_value.stderr
@@ -90,15 +90,6 @@ help: change `v.clone()` to
 LL |     let _ = v.to_owned();
    |             ^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/needless_pass_by_value.rs:85:5
-   |
-LL |     let _ = v.clone();
-   |     ^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: this argument is passed by value, but not consumed in the function body
   --> $DIR/needless_pass_by_value.rs:94:12
    |
@@ -183,5 +174,5 @@ error: this argument is passed by value, but not consumed in the function body
 LL | fn more_fun(_item: impl Club<'static, i32>) {}
    |                    ^^^^^^^^^^^^^^^^^^^^^^^ help: consider taking a reference instead: `&impl Club<'static, i32>`
 
-error: aborting due to 23 previous errors
+error: aborting due to 22 previous errors
 
diff --git a/tests/ui/redundant_clone.stderr b/tests/ui/redundant_clone.stderr
index 270c3fac990..89b39254299 100644
--- a/tests/ui/redundant_clone.stderr
+++ b/tests/ui/redundant_clone.stderr
@@ -167,14 +167,5 @@ note: cloned value is neither consumed nor mutated
 LL |     let y = x.clone().join("matthias");
    |             ^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/redundant_clone.rs:180:5
-   |
-LL |     let _ = a.clone(); // OK
-   |     ^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
-error: aborting due to 15 previous errors
+error: aborting due to 14 previous errors
 
diff --git a/tests/ui/reversed_empty_ranges_fixable.stderr b/tests/ui/reversed_empty_ranges_fixable.stderr
index 707a5d5032e..de83c4f3d63 100644
--- a/tests/ui/reversed_empty_ranges_fixable.stderr
+++ b/tests/ui/reversed_empty_ranges_fixable.stderr
@@ -10,15 +10,6 @@ help: consider using the following if you are attempting to iterate over this ra
 LL |     (21..=42).rev().for_each(|x| println!("{}", x));
    |     ^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/reversed_empty_ranges_fixable.rs:10:5
-   |
-LL |     let _ = (ANSWER..21).filter(|x| x % 2 == 0).take(10).collect::<Vec<_>>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: this range is empty so it will yield no values
   --> $DIR/reversed_empty_ranges_fixable.rs:10:13
    |
@@ -52,5 +43,5 @@ help: consider using the following if you are attempting to iterate over this ra
 LL |     for _ in (21u32..42u32).rev() {}
    |              ^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
diff --git a/tests/ui/transmute.stderr b/tests/ui/transmute.stderr
index d6767dc9f15..ad9953d12bc 100644
--- a/tests/ui/transmute.stderr
+++ b/tests/ui/transmute.stderr
@@ -24,71 +24,30 @@ error: transmute from a reference to a pointer
 LL |     let _: *const U = core::intrinsics::transmute(t);
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *const U`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute.rs:34:9
-   |
-LL |         let _: Vec<i32> = core::intrinsics::transmute(my_vec());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
   --> $DIR/transmute.rs:34:27
    |
 LL |         let _: Vec<i32> = core::intrinsics::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute.rs:36:9
-   |
-LL |         let _: Vec<i32> = core::mem::transmute(my_vec());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
   --> $DIR/transmute.rs:36:27
    |
 LL |         let _: Vec<i32> = core::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute.rs:38:9
-   |
-LL |         let _: Vec<i32> = std::intrinsics::transmute(my_vec());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
   --> $DIR/transmute.rs:38:27
    |
 LL |         let _: Vec<i32> = std::intrinsics::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute.rs:40:9
-   |
-LL |         let _: Vec<i32> = std::mem::transmute(my_vec());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
   --> $DIR/transmute.rs:40:27
    |
 LL |         let _: Vec<i32> = std::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute.rs:42:9
-   |
-LL |         let _: Vec<i32> = my_transmute(my_vec());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
   --> $DIR/transmute.rs:42:27
    |
@@ -195,5 +154,5 @@ error: transmute from a `&mut [u8]` to a `&mut str`
 LL |     let _: &mut str = unsafe { std::mem::transmute(mb) };
    |                                ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`
 
-error: aborting due to 29 previous errors
+error: aborting due to 24 previous errors
 
diff --git a/tests/ui/transmute_collection.stderr b/tests/ui/transmute_collection.stderr
index e89f6d8539f..ebc05c402ab 100644
--- a/tests/ui/transmute_collection.stderr
+++ b/tests/ui/transmute_collection.stderr
@@ -1,12 +1,3 @@
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:9:9
-   |
-LL |         let _ = transmute::<_, Vec<u32>>(vec![0u8]);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::vec::Vec<u8>` to `std::vec::Vec<u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:9:17
    |
@@ -15,42 +6,18 @@ LL |         let _ = transmute::<_, Vec<u32>>(vec![0u8]);
    |
    = note: `-D clippy::unsound-collection-transmute` implied by `-D warnings`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:11:9
-   |
-LL |         let _ = transmute::<_, Vec<[u8; 4]>>(vec![1234u32]);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::vec::Vec<u32>` to `std::vec::Vec<[u8; 4]>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:11:17
    |
 LL |         let _ = transmute::<_, Vec<[u8; 4]>>(vec![1234u32]);
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:14:9
-   |
-LL |         let _ = transmute::<_, VecDeque<u32>>(VecDeque::<u8>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::VecDeque<u8>` to `std::collections::VecDeque<u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:14:17
    |
 LL |         let _ = transmute::<_, VecDeque<u32>>(VecDeque::<u8>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:16:9
-   |
-LL |         let _ = transmute::<_, VecDeque<u32>>(VecDeque::<[u8; 4]>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::VecDeque<[u8; 4]>` to `std::collections::VecDeque<u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:16:17
    |
@@ -93,56 +60,24 @@ error: transmute from `std::collections::HashSet<[u8; 4]>` to `std::collections:
 LL |         let _ = transmute::<_, HashSet<u32>>(HashSet::<[u8; 4]>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:34:9
-   |
-LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, u8>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::BTreeMap<u8, u8>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:34:17
    |
 LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, u8>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:35:9
-   |
-LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u32, u32>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::BTreeMap<u32, u32>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:35:17
    |
 LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u32, u32>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:37:9
-   |
-LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, [u8; 4]>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::BTreeMap<u8, [u8; 4]>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:37:17
    |
 LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, [u8; 4]>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/transmute_collection.rs:38:9
-   |
-LL |         let _ = transmute::<_, BTreeMap<u32, u32>>(BTreeMap::<[u8; 4], u32>::new());
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: transmute from `std::collections::BTreeMap<[u8; 4], u32>` to `std::collections::BTreeMap<u32, u32>` with mismatched layout is unsound
   --> $DIR/transmute_collection.rs:38:17
    |
@@ -173,5 +108,5 @@ error: transmute from `std::collections::HashMap<[u8; 4], u32>` to `std::collect
 LL |         let _ = transmute::<_, HashMap<u32, u32>>(HashMap::<[u8; 4], u32>::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 26 previous errors
+error: aborting due to 18 previous errors
 
diff --git a/tests/ui/unnecessary_clone.stderr b/tests/ui/unnecessary_clone.stderr
index 1f89cb0cdef..5ffa6c4fd06 100644
--- a/tests/ui/unnecessary_clone.stderr
+++ b/tests/ui/unnecessary_clone.stderr
@@ -24,15 +24,6 @@ error: using `.clone()` on a ref-counted pointer
 LL |     arc_weak.clone();
    |     ^^^^^^^^^^^^^^^^ help: try this: `Weak::<bool>::clone(&arc_weak)`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/unnecessary_clone.rs:36:5
-   |
-LL |     let _: Arc<dyn SomeTrait> = x.clone();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: using `.clone()` on a ref-counted pointer
   --> $DIR/unnecessary_clone.rs:36:33
    |
@@ -111,5 +102,5 @@ error: using `.clone()` on a ref-counted pointer
 LL |         Some(try_opt!(Some(rc)).clone())
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `Rc::<u8>::clone(&try_opt!(Some(rc)))`
 
-error: aborting due to 13 previous errors
+error: aborting due to 12 previous errors
 
diff --git a/tests/ui/useless_conversion.stderr b/tests/ui/useless_conversion.stderr
index ea3e96111cb..11c6efb25cc 100644
--- a/tests/ui/useless_conversion.stderr
+++ b/tests/ui/useless_conversion.stderr
@@ -52,15 +52,6 @@ error: useless conversion to the same type: `std::str::Lines`
 LL |     let _ = "".lines().into_iter();
    |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `"".lines()`
 
-error: non-binding let on a type that implements `Drop`
-  --> $DIR/useless_conversion.rs:65:5
-   |
-LL |     let _ = vec![1, 2, 3].into_iter().into_iter();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[deny(clippy::let_underscore_drop)]` on by default
-   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
-
 error: useless conversion to the same type: `std::vec::IntoIter<i32>`
   --> $DIR/useless_conversion.rs:65:13
    |
@@ -79,5 +70,5 @@ error: useless conversion to the same type: `i32`
 LL |     let _ = i32::from(a + b) * 3;
    |             ^^^^^^^^^^^^^^^^ help: consider removing `i32::from()`: `(a + b)`
 
-error: aborting due to 12 previous errors
+error: aborting due to 11 previous errors