revert part of the changes that just makes the code look worse

Author: yotamofek

src/librustdoc/html/render/print_item.rs

@@ -2365,31 +2365,27 @@ fn render_struct_fields(
             {
                 write_str(w, format_args!("<span class=\"comment\">/* private fields */</span>"));
             } else {
-                write_str(
-                    w,
-                    format_args!(
-                        "{}",
-                        fmt::from_fn(|f| fields
-                            .iter()
-                            .map(|field| {
-                                fmt::from_fn(|f| match field.kind {
-                                    clean::StrippedItem(box clean::StructFieldItem(..)) => {
-                                        write!(f, "_")
-                                    }
-                                    clean::StructFieldItem(ref ty) => {
-                                        write!(
-                                            f,
-                                            "{}{}",
-                                            visibility_print_with_space(field, cx),
-                                            ty.print(cx)
-                                        )
-                                    }
-                                    _ => unreachable!(),
-                                })
-                            })
-                            .joined(", ", f))
-                    ),
-                );
+                for (i, field) in fields.iter().enumerate() {
+                    if i > 0 {
+                        w.push_str(", ");
+                    }
+                    match field.kind {
+                        clean::StrippedItem(box clean::StructFieldItem(..)) => {
+                            write_str(w, format_args!("_"));
+                        }
+                        clean::StructFieldItem(ref ty) => {
+                            write_str(
+                                w,
+                                format_args!(
+                                    "{}{}",
+                                    visibility_print_with_space(field, cx),
+                                    ty.print(cx)
+                                ),
+                            );
+                        }
+                        _ => unreachable!(),
+                    }
+                }
             }
             w.push_str(")");
             if let Some(g) = g {