From 77a7bd621f815b96009ea4f9d6c83446191f3524 Mon Sep 17 00:00:00 2001
From: Casey Carter <cacarter@microsoft.com>
Date: Wed, 2 Oct 2024 07:24:14 -0700
Subject: [PATCH] Conform `std::iterator_traits<fmt::appender>` to
 [iterator.traits]/1
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> In addition, the types
> ```c++
> iterator_traits<I>::pointer
> iterator_traits<I>::reference
> ```
> shall be defined as the iterator’s pointer and reference types; that is, for an iterator object `a` of class type, the same type as `decltype(a.operator->())` and `decltype(*a)`, respectively. The type `iterator_traits<I>::pointer` shall be void for an iterator of class type `I` that does not support `operator->`. Additionally, in the case of an output iterator, the types
> ```c++
> iterator_traits<I>::value_type
> iterator_traits<I>::difference_type
> iterator_traits<I>::reference
> ```
> may be defined as `void`.
---
 include/fmt/format.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 4ad1effd..f63aefc9 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -119,11 +119,12 @@
 #endif
 
 namespace std {
-template <> struct iterator_traits<fmt::appender> {
+template <class T> struct iterator_traits<fmt::basic_appender<T>> {
   using iterator_category = output_iterator_tag;
-  using value_type = char;
-  using reference = char&;
-  using difference_type = fmt::appender::difference_type;
+  using value_type = T;
+  using difference_type = void;
+  using pointer = void;
+  using reference = void;
 };
 }  // namespace std