add test for block comment and add note to description

clippy_lints/src/matches/mod.rs

@@ -38,6 +38,11 @@ declare_clippy_lint! {
     /// Checks for matches with a single arm where an `if let`
     /// will usually suffice.
     ///
+    /// This intentionally does not lint if there are comments
+    /// inside of the other arm, so as to allow the user to document
+    /// why having another explicit pattern with an empty body is necessary,
+    /// or because the comments need to be preserved for other reasons.
+    ///
     /// ### Why is this bad?
     /// Just readability – `if let` nests less than a `match`.
     ///

tests/ui/single_match.fixed

@@ -237,4 +237,18 @@ mod issue8634 {
             },
         }
     }
+
+    fn block_comment(x: Result<i32, SomeError>) {
+        match x {
+            Ok(y) => {
+                println!("Yay! {y}");
+            },
+            Err(_) => {
+                /*
+                let's make sure that this also
+                does not lint block comments.
+                */
+            },
+        }
+    }
 }

tests/ui/single_match.rs

@@ -295,4 +295,18 @@ mod issue8634 {
             },
         }
     }
+
+    fn block_comment(x: Result<i32, SomeError>) {
+        match x {
+            Ok(y) => {
+                println!("Yay! {y}");
+            },
+            Err(_) => {
+                /*
+                let's make sure that this also
+                does not lint block comments.
+                */
+            },
+        }
+    }
 }