diff --git a/clippy_lints/src/no_effect.rs b/clippy_lints/src/no_effect.rs
index 8dffe04fd656..82f5d644e742 100644
--- a/clippy_lints/src/no_effect.rs
+++ b/clippy_lints/src/no_effect.rs
@@ -1,4 +1,5 @@
 use clippy_utils::diagnostics::{span_lint_hir, span_lint_hir_and_then};
+use clippy_utils::is_lint_allowed;
 use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::has_drop;
 use rustc_errors::Applicability;
@@ -79,12 +80,13 @@ impl<'tcx> LateLintPass<'tcx> for NoEffect {
 
 fn check_no_effect(cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) -> bool {
     if let StmtKind::Semi(expr) = stmt.kind {
-        if has_no_effect(cx, expr) {
+        if has_no_effect(cx, expr) && !is_lint_allowed(cx, NO_EFFECT, expr.hir_id) {
             span_lint_hir(cx, NO_EFFECT, expr.hir_id, stmt.span, "statement with no effect");
             return true;
         }
     } else if let StmtKind::Local(local) = stmt.kind {
         if_chain! {
+            if !is_lint_allowed(cx, NO_EFFECT_UNDERSCORE_BINDING, local.hir_id);
             if let Some(init) = local.init;
             if !local.pat.span.from_expansion();
             if has_no_effect(cx, init);
diff --git a/tests/ui-internal/if_chain_style.stderr b/tests/ui-internal/if_chain_style.stderr
index d0f100f00692..de6a0b599a2c 100644
--- a/tests/ui-internal/if_chain_style.stderr
+++ b/tests/ui-internal/if_chain_style.stderr
@@ -32,6 +32,14 @@ error: `let` expression should be inside `then { .. }`
 LL |         let x = "";
    |         ^^^^^^^^^^^
 
+error: unnecessary operation
+  --> $DIR/if_chain_style.rs:26:13
+   |
+LL |             ();
+   |             ^^^ help: statement can be reduced to
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: this `if` can be part of the outer `if_chain!`
   --> $DIR/if_chain_style.rs:35:13
    |
@@ -81,5 +89,23 @@ LL | /             let x = "";
 LL | |             let x = "";
    | |_______________________^
 
-error: aborting due to 7 previous errors
+error: unnecessary operation
+  --> $DIR/if_chain_style.rs:57:9
+   |
+LL |         ();
+   |         ^^^ help: statement can be reduced to
+
+error: unnecessary operation
+  --> $DIR/if_chain_style.rs:61:20
+   |
+LL |             then { (); }
+   |                    ^^^ help: statement can be reduced to
+
+error: unnecessary operation
+  --> $DIR/if_chain_style.rs:68:16
+   |
+LL |         then { (); }
+   |                ^^^ help: statement can be reduced to
+
+error: aborting due to 11 previous errors
 
diff --git a/tests/ui/author/blocks.rs b/tests/ui/author/blocks.rs
index c8465cd59aae..ec26e866727e 100644
--- a/tests/ui/author/blocks.rs
+++ b/tests/ui/author/blocks.rs
@@ -1,4 +1,4 @@
-#![allow(redundant_semicolons, clippy::no_effect)]
+#![allow(redundant_semicolons, clippy::no_effect, clippy::unnecessary_operation)]
 
 #[rustfmt::skip]
 fn main() {
diff --git a/tests/ui/cfg_attr_rustfmt.fixed b/tests/ui/cfg_attr_rustfmt.fixed
index 4e583a25b94c..061a4ab9b2ef 100644
--- a/tests/ui/cfg_attr_rustfmt.fixed
+++ b/tests/ui/cfg_attr_rustfmt.fixed
@@ -1,7 +1,7 @@
 // run-rustfix
 #![feature(stmt_expr_attributes)]
 
-#![allow(unused, clippy::no_effect)]
+#![allow(unused, clippy::no_effect, clippy::unnecessary_operation)]
 #![warn(clippy::deprecated_cfg_attr)]
 
 // This doesn't get linted, see known problems
diff --git a/tests/ui/cfg_attr_rustfmt.rs b/tests/ui/cfg_attr_rustfmt.rs
index 9c0fcf6fb454..035169fab85b 100644
--- a/tests/ui/cfg_attr_rustfmt.rs
+++ b/tests/ui/cfg_attr_rustfmt.rs
@@ -1,7 +1,7 @@
 // run-rustfix
 #![feature(stmt_expr_attributes)]
 
-#![allow(unused, clippy::no_effect)]
+#![allow(unused, clippy::no_effect, clippy::unnecessary_operation)]
 #![warn(clippy::deprecated_cfg_attr)]
 
 // This doesn't get linted, see known problems
diff --git a/tests/ui/crashes/ice-7340.rs b/tests/ui/crashes/ice-7340.rs
index 7d2351d606f1..62c78bcbbc56 100644
--- a/tests/ui/crashes/ice-7340.rs
+++ b/tests/ui/crashes/ice-7340.rs
@@ -1,4 +1,4 @@
-#![allow(clippy::no_effect)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation)]
 
 fn main() {
     const CONSTANT: usize = 8;
diff --git a/tests/ui/erasing_op.stderr b/tests/ui/erasing_op.stderr
index e54ce85f98ec..c07595120a64 100644
--- a/tests/ui/erasing_op.stderr
+++ b/tests/ui/erasing_op.stderr
@@ -1,3 +1,11 @@
+error: unnecessary operation
+  --> $DIR/erasing_op.rs:6:5
+   |
+LL |     x * 0;
+   |     ^^^^^^ help: statement can be reduced to: `x;0;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: this operation will always return zero. This is likely not the intended outcome
   --> $DIR/erasing_op.rs:6:5
    |
@@ -6,17 +14,29 @@ LL |     x * 0;
    |
    = note: `-D clippy::erasing-op` implied by `-D warnings`
 
+error: unnecessary operation
+  --> $DIR/erasing_op.rs:7:5
+   |
+LL |     0 & x;
+   |     ^^^^^^ help: statement can be reduced to: `0;x;`
+
 error: this operation will always return zero. This is likely not the intended outcome
   --> $DIR/erasing_op.rs:7:5
    |
 LL |     0 & x;
    |     ^^^^^
 
+error: unnecessary operation
+  --> $DIR/erasing_op.rs:8:5
+   |
+LL |     0 / x;
+   |     ^^^^^^ help: statement can be reduced to: `0;x;`
+
 error: this operation will always return zero. This is likely not the intended outcome
   --> $DIR/erasing_op.rs:8:5
    |
 LL |     0 / x;
    |     ^^^^^
 
-error: aborting due to 3 previous errors
+error: aborting due to 6 previous errors
 
diff --git a/tests/ui/eta.fixed b/tests/ui/eta.fixed
index 1de79667f55f..3f018adc0230 100644
--- a/tests/ui/eta.fixed
+++ b/tests/ui/eta.fixed
@@ -29,7 +29,7 @@ macro_rules! closure_mac {
 
 fn main() {
     let a = Some(1u8).map(foo);
-    let c = Some(1u8).map(|a| {1+2; foo}(a));
+    let c = Some(1u8).map(|a| {1;2; foo}(a));
     true.then(|| mac!()); // don't lint function in macro expansion
     Some(1).map(closure_mac!()); // don't lint closure in macro expansion
     let _: Option<Vec<u8>> = true.then(std::vec::Vec::new); // special case vec!
diff --git a/tests/ui/eta.stderr b/tests/ui/eta.stderr
index 8092f04c3fc3..b3916ac878ee 100644
--- a/tests/ui/eta.stderr
+++ b/tests/ui/eta.stderr
@@ -6,6 +6,14 @@ LL |     let a = Some(1u8).map(|a| foo(a));
    |
    = note: `-D clippy::redundant-closure` implied by `-D warnings`
 
+error: unnecessary operation
+  --> $DIR/eta.rs:32:32
+   |
+LL |     let c = Some(1u8).map(|a| {1+2; foo}(a));
+   |                                ^^^^ help: statement can be reduced to: `1;2;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: redundant closure
   --> $DIR/eta.rs:35:40
    |
@@ -130,5 +138,5 @@ error: redundant closure
 LL |     map_str_to_path(|s| s.as_ref());
    |                     ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::convert::AsRef::as_ref`
 
-error: aborting due to 21 previous errors
+error: aborting due to 22 previous errors
 
diff --git a/tests/ui/if_same_then_else.stderr b/tests/ui/if_same_then_else.stderr
index 2f38052fc209..5b999980b989 100644
--- a/tests/ui/if_same_then_else.stderr
+++ b/tests/ui/if_same_then_else.stderr
@@ -25,6 +25,92 @@ LL | |         foo();
 LL | |     }
    | |_____^
 
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:22:9
+   |
+LL |         Foo { bar: 42 };
+   |         ^^^^^^^^^^^^^^^^ help: statement can be reduced to: `42;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:23:9
+   |
+LL |         0..10;
+   |         ^^^^^^ help: statement can be reduced to: `0;10;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:24:9
+   |
+LL |         ..;
+   |         ^^^ help: statement can be reduced to
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:25:9
+   |
+LL |         0..;
+   |         ^^^^ help: statement can be reduced to: `0;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:26:9
+   |
+LL |         ..10;
+   |         ^^^^^ help: statement can be reduced to: `10;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:31:9
+   |
+LL |         Foo { bar: 42 };
+   |         ^^^^^^^^^^^^^^^^ help: statement can be reduced to: `42;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:32:9
+   |
+LL |         0..10;
+   |         ^^^^^^ help: statement can be reduced to: `0;10;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:33:9
+   |
+LL |         ..;
+   |         ^^^ help: statement can be reduced to
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:34:9
+   |
+LL |         0..;
+   |         ^^^^ help: statement can be reduced to: `0;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:35:9
+   |
+LL |         ..10;
+   |         ^^^^^ help: statement can be reduced to: `10;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:41:9
+   |
+LL |         Foo { bar: 42 };
+   |         ^^^^^^^^^^^^^^^^ help: statement can be reduced to: `42;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:43:9
+   |
+LL |         Foo { bar: 43 };
+   |         ^^^^^^^^^^^^^^^^ help: statement can be reduced to: `43;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:47:9
+   |
+LL |         ();
+   |         ^^^ help: statement can be reduced to
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:53:9
+   |
+LL |         0..10;
+   |         ^^^^^^ help: statement can be reduced to: `0;10;`
+
 error: this `if` has identical blocks
   --> $DIR/if_same_then_else.rs:65:21
    |
@@ -108,5 +194,17 @@ LL | |         bar + 1;
 LL | |     }
    | |_____^
 
-error: aborting due to 5 previous errors
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:101:9
+   |
+LL |         bar + 1;
+   |         ^^^^^^^^ help: statement can be reduced to: `bar;1;`
+
+error: unnecessary operation
+  --> $DIR/if_same_then_else.rs:109:9
+   |
+LL |         bar + 1;
+   |         ^^^^^^^^ help: statement can be reduced to: `bar;1;`
+
+error: aborting due to 21 previous errors
 
diff --git a/tests/ui/let_unit.fixed b/tests/ui/let_unit.fixed
index f398edc23cb5..250d7539f7a2 100644
--- a/tests/ui/let_unit.fixed
+++ b/tests/ui/let_unit.fixed
@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::let_unit_value)]
-#![allow(clippy::no_effect)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation)]
 #![allow(unused_variables)]
 
 macro_rules! let_and_return {
diff --git a/tests/ui/let_unit.rs b/tests/ui/let_unit.rs
index af5b1fb2ac7e..5166984b7876 100644
--- a/tests/ui/let_unit.rs
+++ b/tests/ui/let_unit.rs
@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::let_unit_value)]
-#![allow(clippy::no_effect)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation)]
 #![allow(unused_variables)]
 
 macro_rules! let_and_return {
diff --git a/tests/ui/needless_bool/fixable.fixed b/tests/ui/needless_bool/fixable.fixed
index a2e3988daff1..7f46fce56d35 100644
--- a/tests/ui/needless_bool/fixable.fixed
+++ b/tests/ui/needless_bool/fixable.fixed
@@ -5,6 +5,7 @@
     unused,
     dead_code,
     clippy::no_effect,
+    clippy::unnecessary_operation,
     clippy::if_same_then_else,
     clippy::equatable_if_let,
     clippy::needless_return,
diff --git a/tests/ui/needless_bool/fixable.rs b/tests/ui/needless_bool/fixable.rs
index 75805e857891..18b1a5948c13 100644
--- a/tests/ui/needless_bool/fixable.rs
+++ b/tests/ui/needless_bool/fixable.rs
@@ -5,6 +5,7 @@
     unused,
     dead_code,
     clippy::no_effect,
+    clippy::unnecessary_operation,
     clippy::if_same_then_else,
     clippy::equatable_if_let,
     clippy::needless_return,
diff --git a/tests/ui/needless_bool/fixable.stderr b/tests/ui/needless_bool/fixable.stderr
index 1fa12add1673..781a387fcb8a 100644
--- a/tests/ui/needless_bool/fixable.stderr
+++ b/tests/ui/needless_bool/fixable.stderr
@@ -1,5 +1,5 @@
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:41:5
+  --> $DIR/fixable.rs:42:5
    |
 LL | /     if x {
 LL | |         true
@@ -11,7 +11,7 @@ LL | |     };
    = note: `-D clippy::needless-bool` implied by `-D warnings`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:46:5
+  --> $DIR/fixable.rs:47:5
    |
 LL | /     if x {
 LL | |         false
@@ -21,7 +21,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `!x`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:51:5
+  --> $DIR/fixable.rs:52:5
    |
 LL | /     if x && y {
 LL | |         false
@@ -31,7 +31,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `!(x && y)`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:71:5
+  --> $DIR/fixable.rs:72:5
    |
 LL | /     if x {
 LL | |         return true;
@@ -41,7 +41,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `return x`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:79:5
+  --> $DIR/fixable.rs:80:5
    |
 LL | /     if x {
 LL | |         return false;
@@ -51,7 +51,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `return !x`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:87:5
+  --> $DIR/fixable.rs:88:5
    |
 LL | /     if x && y {
 LL | |         return true;
@@ -61,7 +61,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `return x && y`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:95:5
+  --> $DIR/fixable.rs:96:5
    |
 LL | /     if x && y {
 LL | |         return false;
@@ -71,7 +71,7 @@ LL | |     };
    | |_____^ help: you can reduce it to: `return !(x && y)`
 
 error: equality checks against true are unnecessary
-  --> $DIR/fixable.rs:103:8
+  --> $DIR/fixable.rs:104:8
    |
 LL |     if x == true {};
    |        ^^^^^^^^^ help: try simplifying it as shown: `x`
@@ -79,25 +79,25 @@ LL |     if x == true {};
    = note: `-D clippy::bool-comparison` implied by `-D warnings`
 
 error: equality checks against false can be replaced by a negation
-  --> $DIR/fixable.rs:107:8
+  --> $DIR/fixable.rs:108:8
    |
 LL |     if x == false {};
    |        ^^^^^^^^^^ help: try simplifying it as shown: `!x`
 
 error: equality checks against true are unnecessary
-  --> $DIR/fixable.rs:117:8
+  --> $DIR/fixable.rs:118:8
    |
 LL |     if x == true {};
    |        ^^^^^^^^^ help: try simplifying it as shown: `x`
 
 error: equality checks against false can be replaced by a negation
-  --> $DIR/fixable.rs:118:8
+  --> $DIR/fixable.rs:119:8
    |
 LL |     if x == false {};
    |        ^^^^^^^^^^ help: try simplifying it as shown: `!x`
 
 error: this if-then-else expression returns a bool literal
-  --> $DIR/fixable.rs:127:12
+  --> $DIR/fixable.rs:128:12
    |
 LL |       } else if returns_bool() {
    |  ____________^
diff --git a/tests/ui/needless_update.stderr b/tests/ui/needless_update.stderr
index b154b3b306dd..b37a2a8c0e15 100644
--- a/tests/ui/needless_update.stderr
+++ b/tests/ui/needless_update.stderr
@@ -1,3 +1,23 @@
+error: unnecessary operation
+  --> $DIR/needless_update.rs:17:5
+   |
+LL |     S { ..base }; // no error
+   |     ^^^^^^^^^^^^^ help: statement can be reduced to: `base;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
+error: unnecessary operation
+  --> $DIR/needless_update.rs:18:5
+   |
+LL |     S { a: 1, ..base }; // no error
+   |     ^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `1;base;`
+
+error: unnecessary operation
+  --> $DIR/needless_update.rs:19:5
+   |
+LL |     S { a: 1, b: 1, ..base };
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `1;1;base;`
+
 error: struct update has no effect, all the fields in the struct have already been specified
   --> $DIR/needless_update.rs:19:23
    |
@@ -6,5 +26,23 @@ LL |     S { a: 1, b: 1, ..base };
    |
    = note: `-D clippy::needless-update` implied by `-D warnings`
 
-error: aborting due to previous error
+error: unnecessary operation
+  --> $DIR/needless_update.rs:22:5
+   |
+LL |     T { ..base }; // no error
+   |     ^^^^^^^^^^^^^ help: statement can be reduced to: `base;`
+
+error: unnecessary operation
+  --> $DIR/needless_update.rs:23:5
+   |
+LL |     T { x: 1, ..base }; // no error
+   |     ^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `1;base;`
+
+error: unnecessary operation
+  --> $DIR/needless_update.rs:24:5
+   |
+LL |     T { x: 1, y: 1, ..base }; // no error
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `1;1;base;`
+
+error: aborting due to 7 previous errors
 
diff --git a/tests/ui/out_of_bounds_indexing/issue-3102.stderr b/tests/ui/out_of_bounds_indexing/issue-3102.stderr
index 516c1df40be0..181a4f8349f5 100644
--- a/tests/ui/out_of_bounds_indexing/issue-3102.stderr
+++ b/tests/ui/out_of_bounds_indexing/issue-3102.stderr
@@ -1,3 +1,11 @@
+error: unnecessary operation
+  --> $DIR/issue-3102.rs:9:5
+   |
+LL |     &x[num..10]; // should trigger out of bounds error
+   |     ^^^^^^^^^^^^ help: statement can be reduced to: `x;num..10;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: range is out of bounds
   --> $DIR/issue-3102.rs:9:13
    |
@@ -6,11 +14,17 @@ LL |     &x[num..10]; // should trigger out of bounds error
    |
    = note: `-D clippy::out-of-bounds-indexing` implied by `-D warnings`
 
+error: unnecessary operation
+  --> $DIR/issue-3102.rs:10:5
+   |
+LL |     &x[10..num]; // should trigger out of bounds error
+   |     ^^^^^^^^^^^^ help: statement can be reduced to: `x;10..num;`
+
 error: range is out of bounds
   --> $DIR/issue-3102.rs:10:8
    |
 LL |     &x[10..num]; // should trigger out of bounds error
    |        ^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 4 previous errors
 
diff --git a/tests/ui/redundant_field_names.fixed b/tests/ui/redundant_field_names.fixed
index 5b4b8eeedd46..264b55e5c413 100644
--- a/tests/ui/redundant_field_names.fixed
+++ b/tests/ui/redundant_field_names.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 #![warn(clippy::redundant_field_names)]
-#![allow(clippy::no_effect, dead_code, unused_variables)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code, unused_variables)]
 
 #[macro_use]
 extern crate derive_new;
diff --git a/tests/ui/redundant_field_names.rs b/tests/ui/redundant_field_names.rs
index 3f97b80c5682..6778af5c4afd 100644
--- a/tests/ui/redundant_field_names.rs
+++ b/tests/ui/redundant_field_names.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 #![warn(clippy::redundant_field_names)]
-#![allow(clippy::no_effect, dead_code, unused_variables)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code, unused_variables)]
 
 #[macro_use]
 extern crate derive_new;
diff --git a/tests/ui/unnecessary_cast.stderr b/tests/ui/unnecessary_cast.stderr
index 70aa448af68e..4b0cdceda562 100644
--- a/tests/ui/unnecessary_cast.stderr
+++ b/tests/ui/unnecessary_cast.stderr
@@ -1,3 +1,11 @@
+error: unnecessary operation
+  --> $DIR/unnecessary_cast.rs:6:5
+   |
+LL |     1i32 as i32;
+   |     ^^^^^^^^^^^^ help: statement can be reduced to: `1i32;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: casting integer literal to `i32` is unnecessary
   --> $DIR/unnecessary_cast.rs:6:5
    |
@@ -6,17 +14,41 @@ LL |     1i32 as i32;
    |
    = note: `-D clippy::unnecessary-cast` implied by `-D warnings`
 
+error: unnecessary operation
+  --> $DIR/unnecessary_cast.rs:7:5
+   |
+LL |     1f32 as f32;
+   |     ^^^^^^^^^^^^ help: statement can be reduced to: `1f32;`
+
 error: casting float literal to `f32` is unnecessary
   --> $DIR/unnecessary_cast.rs:7:5
    |
 LL |     1f32 as f32;
    |     ^^^^^^^^^^^ help: try: `1_f32`
 
+error: unnecessary operation
+  --> $DIR/unnecessary_cast.rs:8:5
+   |
+LL |     false as bool;
+   |     ^^^^^^^^^^^^^^ help: statement can be reduced to: `false;`
+
 error: casting to the same type is unnecessary (`bool` -> `bool`)
   --> $DIR/unnecessary_cast.rs:8:5
    |
 LL |     false as bool;
    |     ^^^^^^^^^^^^^ help: try: `false`
 
-error: aborting due to 3 previous errors
+error: unnecessary operation
+  --> $DIR/unnecessary_cast.rs:9:5
+   |
+LL |     &1i32 as &i32;
+   |     ^^^^^^^^^^^^^^ help: statement can be reduced to: `1i32;`
+
+error: unnecessary operation
+  --> $DIR/unnecessary_cast.rs:25:5
+   |
+LL |     1 as std::os::raw::c_char;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `1;`
+
+error: aborting due to 8 previous errors
 
diff --git a/tests/ui/unnecessary_wraps.stderr b/tests/ui/unnecessary_wraps.stderr
index 8e31db395024..6f3e86c63a46 100644
--- a/tests/ui/unnecessary_wraps.stderr
+++ b/tests/ui/unnecessary_wraps.stderr
@@ -25,6 +25,14 @@ LL ~         2
 LL |     } else {
  ...
 
+error: unnecessary operation
+  --> $DIR/unnecessary_wraps.rs:13:9
+   |
+LL |         Some(-1);
+   |         ^^^^^^^^^ help: statement can be reduced to: `-1;`
+   |
+   = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
+
 error: this function's return value is unnecessarily wrapped by `Option`
   --> $DIR/unnecessary_wraps.rs:21:1
    |
@@ -124,6 +132,12 @@ LL ~
 LL |     } else {
  ...
 
+error: unnecessary operation
+  --> $DIR/unnecessary_wraps.rs:109:9
+   |
+LL |         Some(());
+   |         ^^^^^^^^^ help: statement can be reduced to: `();`
+
 error: this function's return value is unnecessary
   --> $DIR/unnecessary_wraps.rs:117:1
    |
@@ -150,5 +164,5 @@ LL |     } else {
 LL ~         return ;
    |
 
-error: aborting due to 7 previous errors
+error: aborting due to 9 previous errors
 
diff --git a/tests/ui/unused_unit.fixed b/tests/ui/unused_unit.fixed
index 7bb43cf7ae82..e5901e4f4e32 100644
--- a/tests/ui/unused_unit.fixed
+++ b/tests/ui/unused_unit.fixed
@@ -11,7 +11,7 @@
 
 #![deny(clippy::unused_unit)]
 #![allow(dead_code)]
-#![allow(clippy::from_over_into)]
+#![allow(clippy::from_over_into, clippy::unnecessary_operation)]
 
 struct Unitter;
 impl Unitter {
diff --git a/tests/ui/unused_unit.rs b/tests/ui/unused_unit.rs
index 21073fb802ad..f9c126c5e3cc 100644
--- a/tests/ui/unused_unit.rs
+++ b/tests/ui/unused_unit.rs
@@ -11,7 +11,7 @@
 
 #![deny(clippy::unused_unit)]
 #![allow(dead_code)]
-#![allow(clippy::from_over_into)]
+#![allow(clippy::from_over_into, clippy::unnecessary_operation)]
 
 struct Unitter;
 impl Unitter {
diff --git a/tests/ui/use_self.fixed b/tests/ui/use_self.fixed
index dcf818f80763..5cc3850689e0 100644
--- a/tests/ui/use_self.fixed
+++ b/tests/ui/use_self.fixed
@@ -5,6 +5,7 @@
 #![warn(clippy::use_self)]
 #![allow(dead_code)]
 #![allow(
+    clippy::unnecessary_operation,
     clippy::should_implement_trait,
     clippy::upper_case_acronyms,
     clippy::from_over_into,
diff --git a/tests/ui/use_self.rs b/tests/ui/use_self.rs
index 9da6fef7a380..7a6b6778d5cc 100644
--- a/tests/ui/use_self.rs
+++ b/tests/ui/use_self.rs
@@ -5,6 +5,7 @@
 #![warn(clippy::use_self)]
 #![allow(dead_code)]
 #![allow(
+    clippy::unnecessary_operation,
     clippy::should_implement_trait,
     clippy::upper_case_acronyms,
     clippy::from_over_into,
diff --git a/tests/ui/use_self.stderr b/tests/ui/use_self.stderr
index e14368a11aa7..c01db6b1b620 100644
--- a/tests/ui/use_self.stderr
+++ b/tests/ui/use_self.stderr
@@ -1,5 +1,5 @@
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:23:21
+  --> $DIR/use_self.rs:24:21
    |
 LL |         fn new() -> Foo {
    |                     ^^^ help: use the applicable keyword: `Self`
@@ -7,163 +7,163 @@ LL |         fn new() -> Foo {
    = note: `-D clippy::use-self` implied by `-D warnings`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:24:13
+  --> $DIR/use_self.rs:25:13
    |
 LL |             Foo {}
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:26:22
+  --> $DIR/use_self.rs:27:22
    |
 LL |         fn test() -> Foo {
    |                      ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:27:13
+  --> $DIR/use_self.rs:28:13
    |
 LL |             Foo::new()
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:32:25
+  --> $DIR/use_self.rs:33:25
    |
 LL |         fn default() -> Foo {
    |                         ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:33:13
+  --> $DIR/use_self.rs:34:13
    |
 LL |             Foo::new()
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:98:24
+  --> $DIR/use_self.rs:99:24
    |
 LL |         fn bad(foos: &[Foo]) -> impl Iterator<Item = &Foo> {
    |                        ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:98:55
+  --> $DIR/use_self.rs:99:55
    |
 LL |         fn bad(foos: &[Foo]) -> impl Iterator<Item = &Foo> {
    |                                                       ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:113:13
+  --> $DIR/use_self.rs:114:13
    |
 LL |             TS(0)
    |             ^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:148:29
+  --> $DIR/use_self.rs:149:29
    |
 LL |                 fn bar() -> Bar {
    |                             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:149:21
+  --> $DIR/use_self.rs:150:21
    |
 LL |                     Bar { foo: Foo {} }
    |                     ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:160:21
+  --> $DIR/use_self.rs:161:21
    |
 LL |         fn baz() -> Foo {
    |                     ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:161:13
+  --> $DIR/use_self.rs:162:13
    |
 LL |             Foo {}
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:178:21
+  --> $DIR/use_self.rs:179:21
    |
 LL |             let _ = Enum::B(42);
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:179:21
+  --> $DIR/use_self.rs:180:21
    |
 LL |             let _ = Enum::C { field: true };
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:180:21
+  --> $DIR/use_self.rs:181:21
    |
 LL |             let _ = Enum::A;
    |                     ^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:222:13
+  --> $DIR/use_self.rs:223:13
    |
 LL |             nested::A::fun_1();
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:223:13
+  --> $DIR/use_self.rs:224:13
    |
 LL |             nested::A::A;
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:225:13
+  --> $DIR/use_self.rs:226:13
    |
 LL |             nested::A {};
    |             ^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:244:13
+  --> $DIR/use_self.rs:245:13
    |
 LL |             TestStruct::from_something()
    |             ^^^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:258:25
+  --> $DIR/use_self.rs:259:25
    |
 LL |         async fn g() -> S {
    |                         ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:259:13
+  --> $DIR/use_self.rs:260:13
    |
 LL |             S {}
    |             ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:263:16
+  --> $DIR/use_self.rs:264:16
    |
 LL |             &p[S::A..S::B]
    |                ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:263:22
+  --> $DIR/use_self.rs:264:22
    |
 LL |             &p[S::A..S::B]
    |                      ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:286:29
+  --> $DIR/use_self.rs:287:29
    |
 LL |         fn foo(value: T) -> Foo<T> {
    |                             ^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:287:13
+  --> $DIR/use_self.rs:288:13
    |
 LL |             Foo::<T> { value }
    |             ^^^^^^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:459:13
+  --> $DIR/use_self.rs:460:13
    |
 LL |             A::new::<submod::B>(submod::B {})
    |             ^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:496:13
+  --> $DIR/use_self.rs:497:13
    |
 LL |             S2::new()
    |             ^^ help: use the applicable keyword: `Self`