From 1ff672025aadea0731a54ebb428f735eae99b064 Mon Sep 17 00:00:00 2001
From: Yancey <135342560+Yancey2023@users.noreply.github.com>
Date: Wed, 4 Mar 2026 07:08:39 +0800
Subject: [PATCH] add static assertion to prevent lossy type conversion

---
 include/fmt/base.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index 2c186d47..795dacf6 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -1808,6 +1808,7 @@ template <typename T> class buffer {
   /// Appends data to the end of the buffer.
   template <typename U>
   FMT_CONSTEXPR20 void append(const U* begin, const U* end) {
+    static_assert(std::is_same<T, U>::value || std::is_same<U, char>::value);
     while (begin != end) {
       auto size = size_;
       auto free_cap = capacity_ - size;