only wrap on trailing comments, allow /* */ comments in-line

rustfmt-core/src/items.rs

@@ -1204,7 +1204,7 @@ pub fn format_struct_struct(
     )?;
 
     if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget
-        && !contains_comment(&items_str)
+        && !last_line_contains_single_line_comment(&items_str)
     {
         Some(format!("{} {} }}", result, items_str))
     } else {

rustfmt-core/tests/source/issue-2446.rs

@@ -3,3 +3,9 @@ enum Issue2446 {
         f: u8, // x
     },
 }
+
+enum Issue2446TrailingCommentsOnly {
+    V {
+        f: u8, /* */
+    }
+}

rustfmt-core/tests/target/issue-2446.rs

@@ -3,3 +3,7 @@ enum Issue2446 {
         f: u8, // x
     },
 }
+
+enum Issue2446TrailingCommentsOnly {
+    V { f: u8 /* */ },
+}