Auto merge of #13117 - GuillaumeGomez:fix-single_element_loop-suggestion, r=Alexendoo

Fix wrong suggestion for `single_element_loop` where parens were missing

Fixes https://github.com/rust-lang/rust-clippy/issues/12782.

changelog: Fix missing parens in `single_element_loop` suggestion

tests/ui/single_element_loop.fixed

@@ -57,4 +57,12 @@ fn main() {
             }
         };
     }
+
+    // Should lint with correct suggestion (issue #12782)
+    let res_void: Result<bool, bool> = Ok(true);
+
+    {
+        let (Ok(mut _x) | Err(mut _x)) = res_void;
+        let ptr: *const bool = std::ptr::null();
+    }
 }

tests/ui/single_element_loop.rs

@@ -54,4 +54,11 @@ fn main() {
             }
         };
     }
+
+    // Should lint with correct suggestion (issue #12782)
+    let res_void: Result<bool, bool> = Ok(true);
+
+    for (Ok(mut _x) | Err(mut _x)) in [res_void] {
+        let ptr: *const bool = std::ptr::null();
+    }
 }

tests/ui/single_element_loop.stderr

@@ -83,5 +83,21 @@ LL +         };
 LL +     }
    |
 
-error: aborting due to 7 previous errors
+error: for loop over a single element
+  --> tests/ui/single_element_loop.rs:61:5
+   |
+LL | /     for (Ok(mut _x) | Err(mut _x)) in [res_void] {
+LL | |         let ptr: *const bool = std::ptr::null();
+LL | |     }
+   | |_____^
+   |
+help: try
+   |
+LL ~     {
+LL +         let (Ok(mut _x) | Err(mut _x)) = res_void;
+LL +         let ptr: *const bool = std::ptr::null();
+LL +     }
+   |
+
+error: aborting due to 8 previous errors