Auto merge of #9474 - c410-f3r:arith, r=llogiq

[arithmetic-side-effects] More non-overflowing ops

* Adding or Subtracting 0
* Division and Module of anything other than 0
* Multiplying 1 or 0

changelog: [arithmetic-side-effects] More non-overflowing operations

Author: bors

clippy_lints/src/operators/arithmetic_side_effects.rs

@@ -48,9 +48,21 @@ impl ArithmeticSideEffects {
         if !Self::is_literal_integer(rhs, rhs_refs) {
             return false;
         }
-        if let hir::BinOpKind::Div | hir::BinOpKind::Mul = op.node
+        if let hir::BinOpKind::Add | hir::BinOpKind::Sub = op.node
             && let hir::ExprKind::Lit(ref lit) = rhs.kind
-            && let ast::LitKind::Int(1, _) = lit.node
+            && let ast::LitKind::Int(0, _) = lit.node
+        {
+            return true;
+        }
+        if let hir::BinOpKind::Div | hir::BinOpKind::Rem = op.node
+            && let hir::ExprKind::Lit(ref lit) = rhs.kind
+            && !matches!(lit.node, ast::LitKind::Int(0, _))
+        {
+            return true;
+        }
+        if let hir::BinOpKind::Mul = op.node
+            && let hir::ExprKind::Lit(ref lit) = rhs.kind
+            && let ast::LitKind::Int(0 | 1, _) = lit.node
         {
             return true;
         }

tests/ui/arithmetic_side_effects.rs

@@ -1,4 +1,8 @@
-#![allow(clippy::assign_op_pattern, clippy::unnecessary_owned_empty_strings)]
+#![allow(
+    clippy::assign_op_pattern,
+    unconditional_panic,
+    clippy::unnecessary_owned_empty_strings
+)]
 #![feature(inline_const, saturating_int_impl)]
 #![warn(clippy::arithmetic_side_effects)]
 
@@ -41,8 +45,12 @@ pub fn non_overflowing_ops() {
     let _ = const { 1 + 1 };
 
     let mut _a = 1;
+    _a += 0;
+    _a -= 0;
+    _a /= 99;
+    _a %= 99;
+    _a *= 0;
     _a *= 1;
-    _a /= 1;
 }
 
 #[rustfmt::skip]
@@ -52,6 +60,14 @@ pub fn overflowing_ops() {
     let mut _b = 1; _b = _b + 1;
 
     let mut _c = 1; _c = 1 + _c;
+
+    let mut _a = 1;
+    _a += 1;
+    _a -= 1;
+    _a /= 0;
+    _a %= 0;
+    _a *= 2;
+    _a *= 3;
 }
 
 fn main() {}

tests/ui/arithmetic_side_effects.stderr

@@ -1,22 +1,58 @@
 error: arithmetic detected
-  --> $DIR/arithmetic_side_effects.rs:50:21
+  --> $DIR/arithmetic_side_effects.rs:58:21
    |
 LL |     let mut _a = 1; _a += 1;
    |                     ^^^^^^^
    |
    = note: `-D clippy::arithmetic-side-effects` implied by `-D warnings`
 
 error: arithmetic detected
-  --> $DIR/arithmetic_side_effects.rs:52:26
+  --> $DIR/arithmetic_side_effects.rs:60:26
    |
 LL |     let mut _b = 1; _b = _b + 1;
    |                          ^^^^^^
 
 error: arithmetic detected
-  --> $DIR/arithmetic_side_effects.rs:54:26
+  --> $DIR/arithmetic_side_effects.rs:62:26
    |
 LL |     let mut _c = 1; _c = 1 + _c;
    |                          ^^^^^^
 
-error: aborting due to 3 previous errors
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:65:5
+   |
+LL |     _a += 1;
+   |     ^^^^^^^
+
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:66:5
+   |
+LL |     _a -= 1;
+   |     ^^^^^^^
+
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:67:5
+   |
+LL |     _a /= 0;
+   |     ^^^^^^^
+
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:68:5
+   |
+LL |     _a %= 0;
+   |     ^^^^^^^
+
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:69:5
+   |
+LL |     _a *= 2;
+   |     ^^^^^^^
+
+error: arithmetic detected
+  --> $DIR/arithmetic_side_effects.rs:70:5
+   |
+LL |     _a *= 3;
+   |     ^^^^^^^
+
+error: aborting due to 9 previous errors