Fix formatting of comments in empty structs

Author: Szymongib

src/items.rs

@@ -1426,12 +1426,22 @@ fn format_empty_struct_or_tuple(
         Some(ref s) if s.is_empty() => (),
         Some(ref s) => {
             if !is_single_line(s) || first_line_contains_single_line_comment(s) {
-                let nested_indent_str = offset
-                    .block_indent(context.config)
-                    .to_string_with_newline(context.config);
-                result.push_str(&nested_indent_str);
+                // Indent every comment line
+                for l in s.lines() {
+                    if l.trim_start().starts_with("//") {
+                        let nested_indent_str = offset
+                            .block_indent(context.config)
+                            .to_string_with_newline(context.config);
+                        result.push_str(&nested_indent_str);
+                    } else {
+                        result.push('\n');
+                    }
+                    result.push_str(l);
+                }
+            } else {
+                result.push_str(s);
             }
-            result.push_str(s);
+
             if last_line_contains_single_line_comment(s) {
                 result.push_str(&offset.to_string_with_newline(context.config));
             }

tests/source/structs.rs

@@ -296,3 +296,20 @@ struct Test {
 // #2818
 struct Paren((i32)) where i32: Trait;
 struct Parens((i32, i32)) where i32: Trait;
+
+// #4854
+struct Comments {
+// Hello, this is my
+    // struct where I haven't added
+// any fields yet.
+        // This is weird
+}
+
+struct CommentsTup(
+    // Ok comment
+    // Very good
+    // Don't format me pls
+
+    // With break
+// Yes
+);

tests/target/structs.rs

@@ -356,3 +356,20 @@ where
 struct Parens((i32, i32))
 where
     i32: Trait;
+
+// #4854
+struct Comments {
+    // Hello, this is my
+    // struct where I haven't added
+    // any fields yet.
+    // This is weird
+}
+
+struct CommentsTup(
+    // Ok comment
+    // Very good
+    // Don't format me pls
+
+    // With break
+    // Yes
+);