Auto merge of rust-lang#10768 - c410-f3r:arith-3, r=Jarcho

[arithmetic_side_effects] Consider referenced allowed or hard-coded types

Fix rust-lang#10767

```
changelog: [`arithmetic_side_effects`]: Do not fire when dealing with allowed or hard-coded types that are referenced.
```

Author: bors

clippy_lints/src/operators/arithmetic_side_effects.rs

@@ -21,7 +21,7 @@ const HARD_CODED_ALLOWED_BINARY: &[[&str; 2]] = &[
     ["f64", "f64"],
     ["std::num::Saturating", "std::num::Saturating"],
     ["std::num::Wrapping", "std::num::Wrapping"],
-    ["std::string::String", "&str"],
+    ["std::string::String", "str"],
 ];
 const HARD_CODED_ALLOWED_UNARY: &[&str] = &["f32", "f64", "std::num::Saturating", "std::num::Wrapping"];
 const INTEGER_METHODS: &[&str] = &["saturating_div", "wrapping_div", "wrapping_rem", "wrapping_rem_euclid"];
@@ -144,8 +144,10 @@ impl ArithmeticSideEffects {
         ) {
             return;
         };
-        let lhs_ty = cx.typeck_results().expr_ty(lhs);
-        let rhs_ty = cx.typeck_results().expr_ty(rhs);
+        let (actual_lhs, lhs_ref_counter) = peel_hir_expr_refs(lhs);
+        let (actual_rhs, rhs_ref_counter) = peel_hir_expr_refs(rhs);
+        let lhs_ty = cx.typeck_results().expr_ty(actual_lhs).peel_refs();
+        let rhs_ty = cx.typeck_results().expr_ty(actual_rhs).peel_refs();
         if self.has_allowed_binary(lhs_ty, rhs_ty) {
             return;
         }
@@ -154,8 +156,6 @@ impl ArithmeticSideEffects {
                 // At least for integers, shifts are already handled by the CTFE
                 return;
             }
-            let (actual_lhs, lhs_ref_counter) = peel_hir_expr_refs(lhs);
-            let (actual_rhs, rhs_ref_counter) = peel_hir_expr_refs(rhs);
             match (
                 Self::literal_integer(cx, actual_lhs),
                 Self::literal_integer(cx, actual_rhs),

tests/ui/arithmetic_side_effects.rs

@@ -458,4 +458,12 @@ pub fn issue_10583(a: u16) -> u16 {
     10 / a
 }
 
+pub fn issue_10767() {
+    let n = &1.0;
+    n + n;
+    3.1_f32 + &1.2_f32;
+    &3.4_f32 + 1.5_f32;
+    &3.5_f32 + &1.3_f32;
+}
+
 fn main() {}