From eea97b200061e06918237f77d26e87b9f2899508 Mon Sep 17 00:00:00 2001
From: Marvel Harisson <im.marvel.harisson@gmail.com>
Date: Mon, 19 Oct 2026 11:43:13 +0900
Subject: [PATCH] Write nullptr as a pointer in detail::write

detail::write<Char>(out, nullptr) picked the const Char* overload, so
fmt::to_string(nullptr) and FMT_COMPILE("{}") threw "string pointer is
null". Add a nullptr_t overload that forwards to the const void* one.
---
 include/fmt/format.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index ebaac1a1..a854cd52 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -3913,6 +3913,11 @@ auto write(OutputIt out, const T* value, const format_specs& specs = {},
   return write_ptr<Char>(out, bit_cast<uintptr_t>(value), &specs);
 }
 
+template <typename Char, typename OutputIt>
+auto write(OutputIt out, nullptr_t) -> OutputIt {
+  return write<Char>(out, static_cast<const void*>(nullptr));
+}
+
 template <typename Char, typename OutputIt, typename T,
           FMT_ENABLE_IF(mapped_type_constant<T, Char>::value ==
                             type::custom_type &&