Revert "Updated bundled fmt to version 10.0.0"

This reverts commit 62e55e7a7f.

include/spdlog/fmt/bundled/os.h

@@ -71,7 +71,7 @@
 #define FMT_RETRY(result, expression) FMT_RETRY_VAL(result, expression, -1)
 
 FMT_BEGIN_NAMESPACE
-FMT_BEGIN_EXPORT
+FMT_MODULE_EXPORT_BEGIN
 
 /**
   \rst
@@ -120,10 +120,48 @@ template <typename Char> class basic_cstring_view {
 using cstring_view = basic_cstring_view<char>;
 using wcstring_view = basic_cstring_view<wchar_t>;
 
+template <typename Char> struct formatter<std::error_code, Char> {
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    out = detail::write_bytes(out, ec.category().name(),
+                              basic_format_specs<Char>());
+    out = detail::write<Char>(out, Char(':'));
+    out = detail::write<Char>(out, ec.value());
+    return out;
+  }
+};
+
 #ifdef _WIN32
 FMT_API const std::error_category& system_category() noexcept;
 
 FMT_BEGIN_DETAIL_NAMESPACE
+// A converter from UTF-16 to UTF-8.
+// It is only provided for Windows since other systems support UTF-8 natively.
+class utf16_to_utf8 {
+ private:
+  memory_buffer buffer_;
+
+ public:
+  utf16_to_utf8() {}
+  FMT_API explicit utf16_to_utf8(basic_string_view<wchar_t> s);
+  operator string_view() const { return string_view(&buffer_[0], size()); }
+  size_t size() const { return buffer_.size() - 1; }
+  const char* c_str() const { return &buffer_[0]; }
+  std::string str() const { return std::string(&buffer_[0], size()); }
+
+  // Performs conversion returning a system error code instead of
+  // throwing exception on conversion error. This method may still throw
+  // in case of memory allocation error.
+  FMT_API int convert(basic_string_view<wchar_t> s);
+};
+
 FMT_API void format_windows_error(buffer<char>& out, int error_code,
                                   const char* message) noexcept;
 FMT_END_DETAIL_NAMESPACE
@@ -317,12 +355,6 @@ class FMT_API file {
   // Creates a buffered_file object associated with this file and detaches
   // this file object from the file.
   buffered_file fdopen(const char* mode);
-
-#  if defined(_WIN32) && !defined(__MINGW32__)
-  // Opens a file and constructs a file object representing this file by
-  // wcstring_view filename. Windows only.
-  static file open_windows_file(wcstring_view path, int oflag);
-#  endif
 };
 
 // Returns the memory page size.
@@ -365,28 +397,6 @@ struct ostream_params {
 #  endif
 };
 
-class file_buffer final : public buffer<char> {
-  file file_;
-
-  FMT_API void grow(size_t) override;
-
- public:
-  FMT_API file_buffer(cstring_view path, const ostream_params& params);
-  FMT_API file_buffer(file_buffer&& other);
-  FMT_API ~file_buffer();
-
-  void flush() {
-    if (size() == 0) return;
-    file_.write(data(), size() * sizeof(data()[0]));
-    clear();
-  }
-
-  void close() {
-    flush();
-    file_.close();
-  }
-};
-
 FMT_END_DETAIL_NAMESPACE
 
 // Added {} below to work around default constructor error known to
@@ -394,32 +404,49 @@ FMT_END_DETAIL_NAMESPACE
 constexpr detail::buffer_size buffer_size{};
 
 /** A fast output stream which is not thread-safe. */
-class FMT_API ostream {
+class FMT_API ostream final : private detail::buffer<char> {
  private:
-  FMT_MSC_WARNING(suppress : 4251)
-  detail::file_buffer buffer_;
+  file file_;
+
+  void grow(size_t) override;
 
   ostream(cstring_view path, const detail::ostream_params& params)
-      : buffer_(path, params) {}
+      : file_(path, params.oflag) {
+    set(new char[params.buffer_size], params.buffer_size);
+  }
 
  public:
-  ostream(ostream&& other) : buffer_(std::move(other.buffer_)) {}
+  ostream(ostream&& other)
+      : detail::buffer<char>(other.data(), other.size(), other.capacity()),
+        file_(std::move(other.file_)) {
+    other.clear();
+    other.set(nullptr, 0);
+  }
+  ~ostream() {
+    flush();
+    delete[] data();
+  }
 
-  ~ostream();
-
-  void flush() { buffer_.flush(); }
+  void flush() {
+    if (size() == 0) return;
+    file_.write(data(), size());
+    clear();
+  }
 
   template <typename... T>
   friend ostream output_file(cstring_view path, T... params);
 
-  void close() { buffer_.close(); }
+  void close() {
+    flush();
+    file_.close();
+  }
 
   /**
     Formats ``args`` according to specifications in ``fmt`` and writes the
     output to the file.
    */
   template <typename... T> void print(format_string<T...> fmt, T&&... args) {
-    vformat_to(detail::buffer_appender<char>(buffer_), fmt,
+    vformat_to(detail::buffer_appender<char>(*this), fmt,
                fmt::make_format_args(args...));
   }
 };
@@ -445,7 +472,7 @@ inline ostream output_file(cstring_view path, T... params) {
 }
 #endif  // FMT_USE_FCNTL
 
-FMT_END_EXPORT
+FMT_MODULE_EXPORT_END
 FMT_END_NAMESPACE
 
 #endif  // FMT_OS_H_