Add check for unary-operator

Fix typo and add test for unary-opeator

3 files changed, 44 insertions, 36 deletions

diff --git a/clippy_lints/src/no_effect.rs b/clippy_lints/src/no_effect.rs
index 1d92b928880..a0e7dbf9ec6 100644
--- a/clippy_lints/src/no_effect.rs
+++ b/clippy_lints/src/no_effect.rs
@@ -93,7 +93,7 @@ fn check_no_effect(cx: &LateContext<'_>, stmt: &Stmt<'_>) -> bool {
         }
         let expr = peel_blocks(expr);
         // assume nontrivial oprand of `Binary` Expr can skip `check_unnecessary_operation`
-        if is_operator_overrided(cx, expr) {
+        if is_operator_overriden(cx, expr) {
             return true;
         }
         if has_no_effect(cx, expr) {
@@ -162,18 +162,18 @@ fn check_no_effect(cx: &LateContext<'_>, stmt: &Stmt<'_>) -> bool {
     false
 }
 
-fn is_operator_overrided(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+fn is_operator_overriden(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     // It's very hard or impossable to check whether overrided operator have side-effect this lint.
-    // So, this function assume user-defined binary operator is overrided with an side-effect.
+    // So, this function assume user-defined operator is overrided with an side-effect.
     // The definition of user-defined structure here is ADT-type,
     // Althrough this will weaken the ability of this lint, less error lint-fix happen.
     match expr.kind {
-        ExprKind::Binary(..) => {
+        ExprKind::Binary(..) | ExprKind::Unary(..) => {
             // No need to check type of `lhs` and `rhs`
             // because if the operator is overrided, at least one operand is ADT type
 
             // reference: rust/compiler/rustc_middle/src/ty/typeck_results.rs: `is_method_call`.
-            // use this function to check whether operator is overrided in `ExprKind::Binary`.
+            // use this function to check whether operator is overrided in `ExprKind::{Binary, Unary}`.
             cx.typeck_results().is_method_call(expr)
         },
         _ => false,
diff --git a/tests/ui/no_effect.rs b/tests/ui/no_effect.rs
index 7ffdeef6582..777b1e52c2d 100644
--- a/tests/ui/no_effect.rs
+++ b/tests/ui/no_effect.rs
@@ -10,7 +10,7 @@
 )]
 
 use std::fmt::Display;
-use std::ops::Shl;
+use std::ops::{Neg, Shl};
 
 struct Cout;
 
@@ -25,6 +25,14 @@ where
     }
 }
 
+impl Neg for Cout {
+    type Output = Self;
+    fn neg(self) -> Self::Output {
+        println!("hello world");
+        self
+    }
+}
+
 struct Unit;
 struct Tuple(i32);
 struct Struct {
@@ -196,5 +204,5 @@ fn main() {
     }
 
     Cout << 142;
-    Cout << n();
+    -Cout;
 }
diff --git a/tests/ui/no_effect.stderr b/tests/ui/no_effect.stderr
index 437e556a7a8..f5ba234b4cb 100644
--- a/tests/ui/no_effect.stderr
+++ b/tests/ui/no_effect.stderr
@@ -1,5 +1,5 @@
 error: statement with no effect
-  --> $DIR/no_effect.rs:114:5
+  --> $DIR/no_effect.rs:122:5
    |
 LL |     0;
    |     ^^
@@ -8,151 +8,151 @@ LL |     0;
    = help: to override `-D warnings` add `#[allow(clippy::no_effect)]`
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:117:5
+  --> $DIR/no_effect.rs:125:5
    |
 LL |     s2;
    |     ^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:119:5
+  --> $DIR/no_effect.rs:127:5
    |
 LL |     Unit;
    |     ^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:121:5
+  --> $DIR/no_effect.rs:129:5
    |
 LL |     Tuple(0);
    |     ^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:123:5
+  --> $DIR/no_effect.rs:131:5
    |
 LL |     Struct { field: 0 };
    |     ^^^^^^^^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:125:5
+  --> $DIR/no_effect.rs:133:5
    |
 LL |     Struct { ..s };
    |     ^^^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:127:5
+  --> $DIR/no_effect.rs:135:5
    |
 LL |     Union { a: 0 };
    |     ^^^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:129:5
+  --> $DIR/no_effect.rs:137:5
    |
 LL |     Enum::Tuple(0);
    |     ^^^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:131:5
+  --> $DIR/no_effect.rs:139:5
    |
 LL |     Enum::Struct { field: 0 };
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:133:5
+  --> $DIR/no_effect.rs:141:5
    |
 LL |     5 + 6;
    |     ^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:135:5
+  --> $DIR/no_effect.rs:143:5
    |
 LL |     *&42;
    |     ^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:137:5
+  --> $DIR/no_effect.rs:145:5
    |
 LL |     &6;
    |     ^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:139:5
+  --> $DIR/no_effect.rs:147:5
    |
 LL |     (5, 6, 7);
    |     ^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:141:5
+  --> $DIR/no_effect.rs:149:5
    |
 LL |     ..;
    |     ^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:143:5
+  --> $DIR/no_effect.rs:151:5
    |
 LL |     5..;
    |     ^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:145:5
+  --> $DIR/no_effect.rs:153:5
    |
 LL |     ..5;
    |     ^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:147:5
+  --> $DIR/no_effect.rs:155:5
    |
 LL |     5..6;
    |     ^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:149:5
+  --> $DIR/no_effect.rs:157:5
    |
 LL |     5..=6;
    |     ^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:151:5
+  --> $DIR/no_effect.rs:159:5
    |
 LL |     [42, 55];
    |     ^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:153:5
+  --> $DIR/no_effect.rs:161:5
    |
 LL |     [42, 55][1];
    |     ^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:155:5
+  --> $DIR/no_effect.rs:163:5
    |
 LL |     (42, 55).1;
    |     ^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:157:5
+  --> $DIR/no_effect.rs:165:5
    |
 LL |     [42; 55];
    |     ^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:159:5
+  --> $DIR/no_effect.rs:167:5
    |
 LL |     [42; 55][13];
    |     ^^^^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:162:5
+  --> $DIR/no_effect.rs:170:5
    |
 LL |     || x += 5;
    |     ^^^^^^^^^^
 
 error: statement with no effect
-  --> $DIR/no_effect.rs:165:5
+  --> $DIR/no_effect.rs:173:5
    |
 LL |     FooString { s: s };
    |     ^^^^^^^^^^^^^^^^^^^
 
 error: binding to `_` prefixed variable with no side-effect
-  --> $DIR/no_effect.rs:167:5
+  --> $DIR/no_effect.rs:175:5
    |
 LL |     let _unused = 1;
    |     ^^^^^^^^^^^^^^^^
@@ -161,19 +161,19 @@ LL |     let _unused = 1;
    = help: to override `-D warnings` add `#[allow(clippy::no_effect_underscore_binding)]`
 
 error: binding to `_` prefixed variable with no side-effect
-  --> $DIR/no_effect.rs:170:5
+  --> $DIR/no_effect.rs:178:5
    |
 LL |     let _penguin = || println!("Some helpful closure");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: binding to `_` prefixed variable with no side-effect
-  --> $DIR/no_effect.rs:172:5
+  --> $DIR/no_effect.rs:180:5
    |
 LL |     let _duck = Struct { field: 0 };
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: binding to `_` prefixed variable with no side-effect
-  --> $DIR/no_effect.rs:174:5
+  --> $DIR/no_effect.rs:182:5
    |
 LL |     let _cat = [2, 4, 6, 8][2];
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^