From f3d510c10c53819a60aeb443d709fe021094b787 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sat, 31 Jan 2026 20:25:18 -0800
Subject: [PATCH] Improve compatibility with std::format

---
 include/fmt/base.h   | 11 +++++++++--
 include/fmt/format.h |  8 --------
 include/fmt/xchar.h  | 16 ++++++++--------
 3 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index d322d7ce..d6fae38f 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -231,6 +231,14 @@ FMT_PRAGMA_GCC(optimize("Og"))
 #endif
 FMT_PRAGMA_CLANG(diagnostic push)
 
+#ifdef FMT_DEPRECATED
+// Use the provided definition.
+#elif FMT_HAS_CPP14_ATTRIBUTE(deprecated)
+#  define FMT_DEPRECATED [[deprecated]]
+#else
+#  define FMT_DEPRECATED /* deprecated */
+#endif
+
 #ifdef FMT_ALWAYS_INLINE
 // Use the provided definition.
 #elif FMT_GCC_VERSION || FMT_CLANG_VERSION
@@ -2656,8 +2664,7 @@ template <typename... T> struct fstring {
   }
   fstring(runtime_format_string<> fmt) : str(fmt.str) {}
 
-  // Returning by reference generates better code in debug mode.
-  FMT_ALWAYS_INLINE operator const string_view&() const { return str; }
+  FMT_DEPRECATED operator const string_view&() const { return str; }
   auto get() const -> string_view { return str; }
 };
 
diff --git a/include/fmt/format.h b/include/fmt/format.h
index c8d57ddd..d34314d8 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -121,14 +121,6 @@
 #  define FMT_NOINLINE
 #endif
 
-#ifdef FMT_DEPRECATED
-// Use the provided definition.
-#elif FMT_HAS_CPP14_ATTRIBUTE(deprecated)
-#  define FMT_DEPRECATED [[deprecated]]
-#else
-#  define FMT_DEPRECATED /* deprecated */
-#endif
-
 // Detect constexpr std::string.
 #if !FMT_USE_CONSTEVAL
 #  define FMT_USE_CONSTEXPR_STRING 0
diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
index 9334b87f..f80e915d 100644
--- a/include/fmt/xchar.h
+++ b/include/fmt/xchar.h
@@ -109,7 +109,7 @@ template <typename Char, typename... T> struct basic_fstring {
   }
   basic_fstring(runtime_format_string<Char> fmt) : str_(fmt.str) {}
 
-  operator basic_string_view<Char>() const { return str_; }
+  FMT_DEPRECATED operator basic_string_view<Char>() const { return str_; }
   auto get() const -> basic_string_view<Char> { return str_; }
 };
 
@@ -172,14 +172,13 @@ auto vformat(basic_string_view<Char> fmt,
 
 template <typename... T>
 auto format(wformat_string<T...> fmt, T&&... args) -> std::wstring {
-  return vformat(fmt::wstring_view(fmt), fmt::make_wformat_args(args...));
+  return vformat(fmt.get(), fmt::make_wformat_args(args...));
 }
 
 template <typename OutputIt, typename... T>
 auto format_to(OutputIt out, wformat_string<T...> fmt, T&&... args)
     -> OutputIt {
-  return vformat_to(out, fmt::wstring_view(fmt),
-                    fmt::make_wformat_args(args...));
+  return vformat_to(out, fmt.get(), fmt::make_wformat_args(args...));
 }
 
 // Pass char_t as a default template parameter instead of using
@@ -301,11 +300,11 @@ inline void vprint(wstring_view fmt, wformat_args args) {
 
 template <typename... T>
 void print(std::FILE* f, wformat_string<T...> fmt, T&&... args) {
-  return vprint(f, wstring_view(fmt), fmt::make_wformat_args(args...));
+  return vprint(f, fmt.get(), fmt::make_wformat_args(args...));
 }
 
 template <typename... T> void print(wformat_string<T...> fmt, T&&... args) {
-  return vprint(wstring_view(fmt), fmt::make_wformat_args(args...));
+  return vprint(fmt.get(), fmt::make_wformat_args(args...));
 }
 
 template <typename... T>
@@ -327,7 +326,7 @@ inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
 template <typename... T>
 inline auto format(text_style ts, wformat_string<T...> fmt, T&&... args)
     -> std::wstring {
-  return fmt::vformat(ts, fmt, fmt::make_wformat_args(args...));
+  return fmt::vformat(ts, fmt.get(), fmt::make_wformat_args(args...));
 }
 
 inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
@@ -338,7 +337,8 @@ inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
 
 template <typename... T>
 void print(std::wostream& os, wformat_string<T...> fmt, T&&... args) {
-  vprint(os, fmt, fmt::make_format_args<buffered_context<wchar_t>>(args...));
+  vprint(os, fmt.get(),
+         fmt::make_format_args<buffered_context<wchar_t>>(args...));
 }
 
 template <typename... T>