From 2f2e0fe0fc09715080aa321de444c4f21f6aff30 Mon Sep 17 00:00:00 2001
From: Casey Carter <cacarter@microsoft.com>
Date: Wed, 2 Oct 2024 10:50:18 -0700
Subject: [PATCH] Derp: iterator concepts require a non-`void`difference type

---
 include/fmt/format.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index f63aefc91823..46522b6a8708 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -122,7 +122,7 @@ namespace std {
 template <class T> struct iterator_traits<fmt::basic_appender<T>> {
   using iterator_category = output_iterator_tag;
   using value_type = T;
-  using difference_type = void;
+  using difference_type = decltype(static_cast<int*>(nullptr) - static_cast<int*>(nullptr));
   using pointer = void;
   using reference = void;
 };