Version 1.16.0

clang-format
Bump fmt to 12.0.0
2025-11-16 09:28:56 +08:00 · 2025-10-11 15:53:05 +03:00 · 2025-10-11 15:50:16 +03:00 · 2025-10-11 15:18:15 +03:00 · 2025-08-07 23:47:11 +03:00 · 2025-08-07 23:38:29 +03:00
26 changed files with 1366 additions and 1118 deletions
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -18,9 +18,8 @@ jobs:
      fail-fast: false
      matrix:
        config:
-          - { compiler: gcc, version: 7, build_type: Release, cppstd: 11 }
-          - { compiler: gcc, version: 9, build_type: Release, cppstd: 17 }
-          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 20 }
+          - { compiler: gcc, version: 9, build_type: Release, cppstd: 11 }
+          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 17 }
          - { compiler: gcc, version: 12, build_type: Release, cppstd: 20 }
          - { compiler: gcc, version: 12, build_type: Debug, cppstd: 20, asan: ON }
          - { compiler: clang, version: 12, build_type: Debug, cppstd: 17 }
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -75,74 +75,5 @@ jobs:
        run: |
          build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe

-  # -----------------------------------------------------------------------
-  # MSVC 2019 build matrix
-  # -----------------------------------------------------------------------
-  build_2019:
-    runs-on: windows-2019
-    strategy:
-      fail-fast: true
-      matrix:
-        config:
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 17
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 14
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 11

-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: CMake ${{ matrix.config.GENERATOR }} CXX=${{matrix.config.CXX_STANDARD}} WCHAR=${{matrix.config.WCHAR_FILES}} STD_FORMAT=${{matrix.config.USE_STD_FORMAT}}
-        shell: pwsh
-        run: |
-          mkdir build
-          cd build
-          cmake -G "${{ matrix.config.GENERATOR }}"  -A x64 `
-            -D CMAKE_BUILD_TYPE=${{ matrix.config.BUILD_TYPE }} `
-            -D BUILD_SHARED_LIBS=${{ matrix.config.BUILD_SHARED }} `
-            -D SPDLOG_WCHAR_SUPPORT=${{ matrix.config.WCHAR }} `
-            -D SPDLOG_WCHAR_FILENAMES=${{ matrix.config.WCHAR_FILES }} `
-            -D SPDLOG_BUILD_EXAMPLE=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_EXAMPLE_HO=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_TESTS=ON `
-            -D SPDLOG_BUILD_TESTS_HO=OFF `
-            -D SPDLOG_BUILD_WARNINGS=${{ matrix.config.FATAL_ERRORS }} `
-            -D SPDLOG_USE_STD_FORMAT=${{ matrix.config.USE_STD_FORMAT }} `
-            -D CMAKE_CXX_STANDARD=${{ matrix.config.CXX_STANDARD }} ..
-
-      - name: Build
-        shell: pwsh
-        run: |
-          cd build
-          cmake --build  . --parallel --config ${{ matrix.config.BUILD_TYPE }}
-
-      - name: Run Tests
-        shell: pwsh
-        env:
-          PATH: ${{ env.PATH }};${{ github.workspace }}\build\_deps\catch2-build\src\${{ matrix.config.BUILD_TYPE }};${{ github.workspace }}\build\${{ matrix.config.BUILD_TYPE }}
-        run: |
-          build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe
+  
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -62,6 +62,9 @@ option(SPDLOG_ENABLE_PCH "Build static or shared library using precompiled heade
 # build position independent code
 option(SPDLOG_BUILD_PIC "Build position independent code (-fPIC)" OFF)

+# debug build postfix
+set(SPDLOG_DEBUG_POSTFIX "d" CACHE STRING "Filename postfix for libraries in debug builds")
+
 # example options
 option(SPDLOG_BUILD_EXAMPLE "Build example" ${SPDLOG_MASTER_PROJECT})
 option(SPDLOG_BUILD_EXAMPLE_HO "Build header only example" OFF)
@@ -191,7 +194,7 @@ spdlog_enable_warnings(spdlog)

 set_target_properties(spdlog PROPERTIES VERSION ${SPDLOG_VERSION} SOVERSION
                                                                  ${SPDLOG_VERSION_MAJOR}.${SPDLOG_VERSION_MINOR})
-set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX d)
+set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX ${SPDLOG_DEBUG_POSTFIX})

 if(COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
    configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/pch.h.in ${PROJECT_BINARY_DIR}/spdlog_pch.h @ONLY)
--- a/README.md
+++ b/README.md
@@ -80,7 +80,7 @@ int main()
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:<30}", "left aligned");
    
-    spdlog::set_level(spdlog::level::debug); // Set global log level to debug
+    spdlog::set_level(spdlog::level::debug); // Set *global* log level to debug
    spdlog::debug("This message should be displayed..");    
    
    // change log pattern
@@ -224,7 +224,7 @@ void binary_example()
 ```c++

 // create a logger with 2 targets, with different log levels and formats.
-// The console will show only warnings or errors, while the file will log all.
+// The console will show only warnings or errors, while the file will log all. 
 void multi_sink_example()
 {
    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
@@ -241,6 +241,29 @@ void multi_sink_example()
 }
 ```

+---
+#### Register several loggers - change global level
+```c++
+
+// Creation of loggers. Set levels to all registered loggers. 
+void set_level_example()
+{
+    auto logger1 = spdlog::basic_logger_mt("logger1", "logs/logger1.txt");
+    auto logger2 = spdlog::basic_logger_mt("logger2", "logs/logger2.txt");
+
+    spdlog::set_default_logger(logger2);
+    spdlog::default_logger()->set_level(spdlog::level::trace); // set level for the default logger (logger2) to trace
+
+    spdlog::trace("trace message to the logger2 (specified as default)");
+
+    spdlog::set_level(spdlog::level::off) // (sic!) set level for *all* registered loggers to off (disable)
+  
+    logger1.warn("warn message will not appear because the level set to off");
+    logger2.warn("warn message will not appear because the level set to off");
+    spdlog::warn("warn message will not appear because the level set to off");
+}
+```
+
 ---
 #### User-defined callbacks about log events
 ```c++
--- a/include/spdlog/details/os-inl.h
+++ b/include/spdlog/details/os-inl.h
@@ -23,7 +23,6 @@

 #ifdef _WIN32
    #include <spdlog/details/windows_include.h>
-    #include <fileapi.h>  // for FlushFileBuffers
    #include <io.h>       // for _get_osfhandle, _isatty, _fileno
    #include <process.h>  // for _get_pid

--- a/include/spdlog/details/tcp_client-windows.h
+++ b/include/spdlog/details/tcp_client-windows.h
@@ -58,8 +58,81 @@ public:

    SOCKET fd() const { return socket_; }

+    int connect_socket_with_timeout(SOCKET sockfd,
+                                    const struct sockaddr *addr,
+                                    int addrlen,
+                                    const timeval &tv) {
+        // If no timeout requested, do a normal blocking connect.
+        if (tv.tv_sec == 0 && tv.tv_usec == 0) {
+            int rv = ::connect(sockfd, addr, addrlen);
+            if (rv == SOCKET_ERROR && WSAGetLastError() == WSAEISCONN) {
+                return 0;
+            }
+            return rv;
+        }
+
+        // Switch to non‐blocking mode
+        u_long mode = 1UL;
+        if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        int rv = ::connect(sockfd, addr, addrlen);
+        int last_error = WSAGetLastError();
+        if (rv == 0 || last_error == WSAEISCONN) {
+            mode = 0UL;
+            if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+                return SOCKET_ERROR;
+            }
+            return 0;
+        }
+        if (last_error != WSAEWOULDBLOCK) {
+            // Real error
+            mode = 0UL;
+            if (::ioctlsocket(sockfd, FIONBIO, &mode)) {
+                return SOCKET_ERROR;
+            }
+            return SOCKET_ERROR;
+        }
+
+        // Wait until socket is writable or timeout expires
+        fd_set wfds;
+        FD_ZERO(&wfds);
+        FD_SET(sockfd, &wfds);
+
+        rv = ::select(0, nullptr, &wfds, nullptr, const_cast<timeval *>(&tv));
+
+        // Restore blocking mode regardless of select result
+        mode = 0UL;
+        if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        if (rv == 0) {
+            WSASetLastError(WSAETIMEDOUT);
+            return SOCKET_ERROR;
+        }
+        if (rv == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        int so_error = 0;
+        int len = sizeof(so_error);
+        if (::getsockopt(sockfd, SOL_SOCKET, SO_ERROR, reinterpret_cast<char *>(&so_error), &len) ==
+            SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+        if (so_error != 0 && so_error != WSAEISCONN) {
+            // connection failed
+            WSASetLastError(so_error);
+            return SOCKET_ERROR;
+        }
+
+        return 0;  // success
+    }
+
    // try to connect or throw on failure
-    void connect(const std::string &host, int port) {
+    void connect(const std::string &host, int port, int timeout_ms = 0) {
        if (is_connected()) {
            close();
        }
@@ -71,6 +144,10 @@ public:
        hints.ai_flags = AI_NUMERICSERV;  // port passed as as numeric value
        hints.ai_protocol = 0;

+        timeval tv;
+        tv.tv_sec = timeout_ms / 1000;
+        tv.tv_usec = (timeout_ms % 1000) * 1000;
+
        auto port_str = std::to_string(port);
        struct addrinfo *addrinfo_result;
        auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
@@ -82,7 +159,6 @@ public:
        }

        // Try each address until we successfully connect(2).
-
        for (auto *rp = addrinfo_result; rp != nullptr; rp = rp->ai_next) {
            socket_ = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
            if (socket_ == INVALID_SOCKET) {
@@ -90,18 +166,24 @@ public:
                WSACleanup();
                continue;
            }
-            if (::connect(socket_, rp->ai_addr, (int)rp->ai_addrlen) == 0) {
+            if (connect_socket_with_timeout(socket_, rp->ai_addr, (int)rp->ai_addrlen, tv) == 0) {
+                last_error = 0;
                break;
-            } else {
-                last_error = ::WSAGetLastError();
-                close();
            }
+            last_error = WSAGetLastError();
+            ::closesocket(socket_);
+            socket_ = INVALID_SOCKET;
        }
        ::freeaddrinfo(addrinfo_result);
        if (socket_ == INVALID_SOCKET) {
            WSACleanup();
            throw_winsock_error_("connect failed", last_error);
        }
+        if (timeout_ms > 0) {
+            DWORD tv = static_cast<DWORD>(timeout_ms);
+            ::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, (const char *)&tv, sizeof(tv));
+            ::setsockopt(socket_, SOL_SOCKET, SO_SNDTIMEO, (const char *)&tv, sizeof(tv));
+        }

        // set TCP_NODELAY
        int enable_flag = 1;
--- a/include/spdlog/details/tcp_client.h
+++ b/include/spdlog/details/tcp_client.h
@@ -39,8 +39,72 @@ public:

    ~tcp_client() { close(); }

+    int connect_socket_with_timeout(int sockfd,
+                                    const struct sockaddr *addr,
+                                    socklen_t addrlen,
+                                    const timeval &tv) {
+        // Blocking connect if timeout is zero
+        if (tv.tv_sec == 0 && tv.tv_usec == 0) {
+            int rv = ::connect(sockfd, addr, addrlen);
+            if (rv < 0 && errno == EISCONN) {
+                // already connected, treat as success
+                return 0;
+            }
+            return rv;
+        }
+
+        // Non-blocking path
+        int orig_flags = ::fcntl(sockfd, F_GETFL, 0);
+        if (orig_flags < 0) {
+            return -1;
+        }
+        if (::fcntl(sockfd, F_SETFL, orig_flags | O_NONBLOCK) < 0) {
+            return -1;
+        }
+
+        int rv = ::connect(sockfd, addr, addrlen);
+        if (rv == 0 || (rv < 0 && errno == EISCONN)) {
+            // immediate connect or already connected
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return 0;
+        }
+        if (errno != EINPROGRESS) {
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return -1;
+        }
+
+        // wait for writability
+        fd_set wfds;
+        FD_ZERO(&wfds);
+        FD_SET(sockfd, &wfds);
+
+        struct timeval tv_copy = tv;
+        rv = ::select(sockfd + 1, nullptr, &wfds, nullptr, &tv_copy);
+        if (rv <= 0) {
+            // timeout or error
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            if (rv == 0) errno = ETIMEDOUT;
+            return -1;
+        }
+
+        // check socket error
+        int so_error = 0;
+        socklen_t len = sizeof(so_error);
+        if (::getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &so_error, &len) < 0) {
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return -1;
+        }
+        ::fcntl(sockfd, F_SETFL, orig_flags);
+        if (so_error != 0 && so_error != EISCONN) {
+            errno = so_error;
+            return -1;
+        }
+
+        return 0;
+    }
+
    // try to connect or throw on failure
-    void connect(const std::string &host, int port) {
+    void connect(const std::string &host, int port, int timeout_ms = 0) {
        close();
        struct addrinfo hints {};
        memset(&hints, 0, sizeof(struct addrinfo));
@@ -49,6 +113,10 @@ public:
        hints.ai_flags = AI_NUMERICSERV;  // port passed as as numeric value
        hints.ai_protocol = 0;

+        struct timeval tv;
+        tv.tv_sec = timeout_ms / 1000;
+        tv.tv_usec = (timeout_ms % 1000) * 1000;
+
        auto port_str = std::to_string(port);
        struct addrinfo *addrinfo_result;
        auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
@@ -69,8 +137,9 @@ public:
                last_errno = errno;
                continue;
            }
-            rv = ::connect(socket_, rp->ai_addr, rp->ai_addrlen);
-            if (rv == 0) {
+            ::fcntl(socket_, F_SETFD, FD_CLOEXEC);
+            if (connect_socket_with_timeout(socket_, rp->ai_addr, rp->ai_addrlen, tv) == 0) {
+                last_errno = 0;
                break;
            }
            last_errno = errno;
@@ -82,6 +151,12 @@ public:
            throw_spdlog_ex("::connect failed", last_errno);
        }

+        if (timeout_ms > 0) {
+            // Set timeouts for send and recv
+            ::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, (const char *)&tv, sizeof(tv));
+            ::setsockopt(socket_, SOL_SOCKET, SO_SNDTIMEO, (const char *)&tv, sizeof(tv));
+        }
+
        // set TCP_NODELAY
        int enable_flag = 1;
        ::setsockopt(socket_, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char *>(&enable_flag),
--- a/include/spdlog/fmt/bundled/args.h
+++ b/include/spdlog/fmt/bundled/args.h
@@ -71,7 +71,7 @@ class dynamic_arg_list {
 * It can be implicitly converted into `fmt::basic_format_args` for passing
 * into type-erased formatting functions such as `fmt::vformat`.
 */
-template <typename Context> class dynamic_format_arg_store {
+FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
 private:
  using char_type = typename Context::char_type;

@@ -212,7 +212,7 @@ template <typename Context> class dynamic_format_arg_store {
  }

  /// Returns the number of elements in the store.
-  size_t size() const noexcept { return data_.size(); }
+  auto size() const noexcept -> size_t { return data_.size(); }
 };

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/base.h
+++ b/include/spdlog/fmt/bundled/base.h
@@ -21,7 +21,7 @@
 #endif

 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 110200
+#define FMT_VERSION 120000

 // Detect compiler versions.
 #if defined(__clang__) && !defined(__ibmxl__)
@@ -201,14 +201,6 @@
 #  define FMT_NODISCARD
 #endif

-#ifdef FMT_DEPRECATED
-// Use the provided definition.
-#elif FMT_HAS_CPP14_ATTRIBUTE(deprecated)
-#  define FMT_DEPRECATED [[deprecated]]
-#else
-#  define FMT_DEPRECATED /* deprecated */
-#endif
-
 #if FMT_GCC_VERSION || FMT_CLANG_VERSION
 #  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
 #else
@@ -260,7 +252,7 @@ FMT_PRAGMA_CLANG(diagnostic push)
 #ifndef FMT_BEGIN_NAMESPACE
 #  define FMT_BEGIN_NAMESPACE \
    namespace fmt {           \
-    inline namespace v11 {
+    inline namespace v12 {
 #  define FMT_END_NAMESPACE \
    }                       \
    }
@@ -356,6 +348,9 @@ template <typename T> constexpr auto max_of(T a, T b) -> T {
  return a > b ? a : b;
 }

+FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
+                                      const char* message);
+
 namespace detail {
 // Suppresses "unused variable" warnings with the method described in
 // https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
@@ -396,7 +391,7 @@ FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
 #  define FMT_ASSERT(condition, message)                                    \
    ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
         ? (void)0                                                          \
-         : fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
+         : ::fmt::assert_fail(__FILE__, __LINE__, (message)))
 #endif

 #ifdef FMT_USE_INT128
@@ -463,12 +458,13 @@ enum { use_utf8 = !FMT_WIN32 || is_utf8_enabled };
 static_assert(!FMT_UNICODE || use_utf8,
              "Unicode support requires compiling with /utf-8");

-template <typename T> constexpr const char* narrow(const T*) { return nullptr; }
-constexpr FMT_ALWAYS_INLINE const char* narrow(const char* s) { return s; }
+template <typename T> constexpr auto narrow(T*) -> char* { return nullptr; }
+constexpr FMT_ALWAYS_INLINE auto narrow(const char* s) -> const char* {
+  return s;
+}

 template <typename Char>
-FMT_CONSTEXPR auto compare(const Char* s1, const Char* s2, std::size_t n)
-    -> int {
+FMT_CONSTEXPR auto compare(const Char* s1, const Char* s2, size_t n) -> int {
  if (!is_constant_evaluated() && sizeof(Char) == 1) return memcmp(s1, s2, n);
  for (; n != 0; ++s1, ++s2, --n) {
    if (*s1 < *s2) return -1;
@@ -540,7 +536,7 @@ template <typename Char> class basic_string_view {
  FMT_CONSTEXPR20 basic_string_view(const Char* s) : data_(s) {
 #if FMT_HAS_BUILTIN(__builtin_strlen) || FMT_GCC_VERSION || FMT_CLANG_VERSION
    if (std::is_same<Char, char>::value && !detail::is_constant_evaluated()) {
-      size_ = __builtin_strlen(detail::narrow(s));  // strlen is not costexpr.
+      size_ = __builtin_strlen(detail::narrow(s));  // strlen is not constexpr.
      return;
    }
 #endif
@@ -616,19 +612,6 @@ template <typename Char> class basic_string_view {

 using string_view = basic_string_view<char>;

-// DEPRECATED! Will be merged with is_char and moved to detail.
-template <typename T> struct is_xchar : std::false_type {};
-template <> struct is_xchar<wchar_t> : std::true_type {};
-template <> struct is_xchar<char16_t> : std::true_type {};
-template <> struct is_xchar<char32_t> : std::true_type {};
-#ifdef __cpp_char8_t
-template <> struct is_xchar<char8_t> : std::true_type {};
-#endif
-
-// Specifies if `T` is a character (code unit) type.
-template <typename T> struct is_char : is_xchar<T> {};
-template <> struct is_char<char> : std::true_type {};
-
 template <typename T> class basic_appender;
 using appender = basic_appender<char>;

@@ -781,7 +764,7 @@ class basic_specs {
            (static_cast<unsigned>(p) << precision_shift);
  }

-  constexpr bool dynamic() const {
+  constexpr auto dynamic() const -> bool {
    return (data_ & (width_mask | precision_mask)) != 0;
  }

@@ -921,14 +904,47 @@ template <typename Char = char> class parse_context {
  FMT_CONSTEXPR void check_dynamic_spec(int arg_id);
 };

+#ifndef FMT_USE_LOCALE
+#  define FMT_USE_LOCALE (FMT_OPTIMIZE_SIZE <= 1)
+#endif
+
+// A type-erased reference to std::locale to avoid the heavy <locale> include.
+class locale_ref {
+#if FMT_USE_LOCALE
+ private:
+  const void* locale_;  // A type-erased pointer to std::locale.
+
+ public:
+  constexpr locale_ref() : locale_(nullptr) {}
+
+  template <typename Locale, FMT_ENABLE_IF(sizeof(Locale::collate) != 0)>
+  locale_ref(const Locale& loc);
+
+  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
+#endif  // FMT_USE_LOCALE
+
+ public:
+  template <typename Locale> auto get() const -> Locale;
+};
+
 FMT_END_EXPORT

 namespace detail {

+// Specifies if `T` is a code unit type.
+template <typename T> struct is_code_unit : std::false_type {};
+template <> struct is_code_unit<char> : std::true_type {};
+template <> struct is_code_unit<wchar_t> : std::true_type {};
+template <> struct is_code_unit<char16_t> : std::true_type {};
+template <> struct is_code_unit<char32_t> : std::true_type {};
+#ifdef __cpp_char8_t
+template <> struct is_code_unit<char8_t> : bool_constant<is_utf8_enabled> {};
+#endif
+
 // Constructs fmt::basic_string_view<Char> from types implicitly convertible
 // to it, deducing Char. Explicitly convertible types such as the ones returned
 // from FMT_STRING are intentionally excluded.
-template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
+template <typename Char, FMT_ENABLE_IF(is_code_unit<Char>::value)>
 constexpr auto to_string_view(const Char* s) -> basic_string_view<Char> {
  return s;
 }
@@ -1057,11 +1073,11 @@ template <bool B1, bool B2, bool... Tail> constexpr auto count() -> int {
  return (B1 ? 1 : 0) + count<B2, Tail...>();
 }

-template <typename... Args> constexpr auto count_named_args() -> int {
-  return count<is_named_arg<Args>::value...>();
+template <typename... T> constexpr auto count_named_args() -> int {
+  return count<is_named_arg<T>::value...>();
 }
-template <typename... Args> constexpr auto count_static_named_args() -> int {
-  return count<is_static_named_arg<Args>::value...>();
+template <typename... T> constexpr auto count_static_named_args() -> int {
+  return count<is_static_named_arg<T>::value...>();
 }

 template <typename Char> struct named_arg_info {
@@ -1069,7 +1085,7 @@ template <typename Char> struct named_arg_info {
  int id;
 };

-// named_args is non-const to suppress a bogus -Wmaybe-uninitalized in gcc 13.
+// named_args is non-const to suppress a bogus -Wmaybe-uninitialized in gcc 13.
 template <typename Char>
 FMT_CONSTEXPR void check_for_duplicate(named_arg_info<Char>* named_args,
                                       int named_arg_index,
@@ -1173,7 +1189,7 @@ template <typename Char> struct type_mapper {
  static auto map(ubitint<N>)
      -> conditional_t<N <= 64, unsigned long long, void>;

-  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  template <typename T, FMT_ENABLE_IF(is_code_unit<T>::value)>
  static auto map(T) -> conditional_t<
      std::is_same<T, char>::value || std::is_same<T, Char>::value, Char, void>;

@@ -1679,12 +1695,12 @@ template <typename... T> struct arg_pack {};
 template <typename Char, int NUM_ARGS, int NUM_NAMED_ARGS, bool DYNAMIC_NAMES>
 class format_string_checker {
 private:
-  type types_[max_of(1, NUM_ARGS)];
-  named_arg_info<Char> named_args_[max_of(1, NUM_NAMED_ARGS)];
+  type types_[max_of<size_t>(1, NUM_ARGS)];
+  named_arg_info<Char> named_args_[max_of<size_t>(1, NUM_NAMED_ARGS)];
  compile_parse_context<Char> context_;

  using parse_func = auto (*)(parse_context<Char>&) -> const Char*;
-  parse_func parse_funcs_[max_of(1, NUM_ARGS)];
+  parse_func parse_funcs_[max_of<size_t>(1, NUM_ARGS)];

 public:
  template <typename... T>
@@ -2033,6 +2049,17 @@ struct has_back_insert_iterator_container_append<
                        .append(std::declval<InputIt>(),
                                std::declval<InputIt>()))>> : std::true_type {};

+template <typename OutputIt, typename InputIt, typename = void>
+struct has_back_insert_iterator_container_insert_at_end : std::false_type {};
+
+template <typename OutputIt, typename InputIt>
+struct has_back_insert_iterator_container_insert_at_end<
+    OutputIt, InputIt,
+    void_t<decltype(get_container(std::declval<OutputIt>())
+                        .insert(get_container(std::declval<OutputIt>()).end(),
+                                std::declval<InputIt>(),
+                                std::declval<InputIt>()))>> : std::true_type {};
+
 // An optimized version of std::copy with the output value type (T).
 template <typename T, typename InputIt, typename OutputIt,
          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
@@ -2047,6 +2074,8 @@ FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
 template <typename T, typename InputIt, typename OutputIt,
          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value &&
                        !has_back_insert_iterator_container_append<
+                            OutputIt, InputIt>::value &&
+                        has_back_insert_iterator_container_insert_at_end<
                            OutputIt, InputIt>::value)>
 FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
    -> OutputIt {
@@ -2056,7 +2085,11 @@ FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
 }

 template <typename T, typename InputIt, typename OutputIt,
-          FMT_ENABLE_IF(!is_back_insert_iterator<OutputIt>::value)>
+          FMT_ENABLE_IF(!(is_back_insert_iterator<OutputIt>::value &&
+                          (has_back_insert_iterator_container_append<
+                               OutputIt, InputIt>::value ||
+                           has_back_insert_iterator_container_insert_at_end<
+                               OutputIt, InputIt>::value)))>
 FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
  while (begin != end) *out++ = static_cast<T>(*begin++);
  return out;
@@ -2176,7 +2209,7 @@ template <typename Context> class value {
    static_assert(N <= 64, "unsupported _BitInt");
  }

-  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  template <typename T, FMT_ENABLE_IF(is_code_unit<T>::value)>
  constexpr FMT_INLINE value(T x FMT_BUILTIN) : char_value(x) {
    static_assert(
        std::is_same<T, char>::value || std::is_same<T, char_type>::value,
@@ -2252,7 +2285,7 @@ template <typename Context> class value {
        custom.value = const_cast<value_type*>(&x);
 #endif
    }
-    custom.format = format_custom<value_type, formatter<value_type, char_type>>;
+    custom.format = format_custom<value_type>;
  }

  template <typename T, FMT_ENABLE_IF(!has_formatter<T, char_type>())>
@@ -2263,10 +2296,10 @@ template <typename Context> class value {
  }

  // Formats an argument of a custom type, such as a user-defined class.
-  template <typename T, typename Formatter>
+  template <typename T>
  static void format_custom(void* arg, parse_context<char_type>& parse_ctx,
                            Context& ctx) {
-    auto f = Formatter();
+    auto f = formatter<T, char_type>();
    parse_ctx.advance_to(f.parse(parse_ctx));
    using qualified_type =
        conditional_t<has_formatter<const T, char_type>(), const T, T>;
@@ -2293,35 +2326,14 @@ struct is_output_iterator<
    enable_if_t<std::is_assignable<decltype(*std::declval<decay_t<It>&>()++),
                                   T>::value>> : std::true_type {};

-#ifndef FMT_USE_LOCALE
-#  define FMT_USE_LOCALE (FMT_OPTIMIZE_SIZE <= 1)
-#endif
-
-// A type-erased reference to an std::locale to avoid a heavy <locale> include.
-class locale_ref {
-#if FMT_USE_LOCALE
- private:
-  const void* locale_;  // A type-erased pointer to std::locale.
-
- public:
-  constexpr locale_ref() : locale_(nullptr) {}
-  template <typename Locale> locale_ref(const Locale& loc);
-
-  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
-#endif  // FMT_USE_LOCALE
-
- public:
-  template <typename Locale> auto get() const -> Locale;
-};
-
 template <typename> constexpr auto encode_types() -> unsigned long long {
  return 0;
 }

-template <typename Context, typename Arg, typename... Args>
+template <typename Context, typename First, typename... T>
 constexpr auto encode_types() -> unsigned long long {
-  return static_cast<unsigned>(stored_type_constant<Arg, Context>::value) |
-         (encode_types<Context, Args...>() << packed_arg_bits);
+  return static_cast<unsigned>(stored_type_constant<First, Context>::value) |
+         (encode_types<Context, T...>() << packed_arg_bits);
 }

 template <typename Context, typename... T, size_t NUM_ARGS = sizeof...(T)>
@@ -2338,8 +2350,9 @@ template <typename Context, int NUM_ARGS, int NUM_NAMED_ARGS,
          unsigned long long DESC>
 struct named_arg_store {
  // args_[0].named_args points to named_args to avoid bloating format_args.
-  arg_t<Context, NUM_ARGS> args[1 + NUM_ARGS];
-  named_arg_info<typename Context::char_type> named_args[NUM_NAMED_ARGS];
+  arg_t<Context, NUM_ARGS> args[1u + NUM_ARGS];
+  named_arg_info<typename Context::char_type>
+      named_args[static_cast<size_t>(NUM_NAMED_ARGS)];

  template <typename... T>
  FMT_CONSTEXPR FMT_ALWAYS_INLINE named_arg_store(T&... values)
@@ -2358,8 +2371,8 @@ struct named_arg_store {
  }

  named_arg_store(const named_arg_store& rhs) = delete;
-  named_arg_store& operator=(const named_arg_store& rhs) = delete;
-  named_arg_store& operator=(named_arg_store&& rhs) = delete;
+  auto operator=(const named_arg_store& rhs) -> named_arg_store& = delete;
+  auto operator=(named_arg_store&& rhs) -> named_arg_store& = delete;
  operator const arg_t<Context, NUM_ARGS>*() const { return args + 1; }
 };

@@ -2372,7 +2385,7 @@ struct format_arg_store {
  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
  using type =
      conditional_t<NUM_NAMED_ARGS == 0,
-                    arg_t<Context, NUM_ARGS>[max_of(1, NUM_ARGS)],
+                    arg_t<Context, NUM_ARGS>[max_of<size_t>(1, NUM_ARGS)],
                    named_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>>;
  type args;
 };
@@ -2656,22 +2669,17 @@ class context {
 private:
  appender out_;
  format_args args_;
-  FMT_NO_UNIQUE_ADDRESS detail::locale_ref loc_;
+  FMT_NO_UNIQUE_ADDRESS locale_ref loc_;

 public:
-  /// The character type for the output.
-  using char_type = char;
-
+  using char_type = char;  ///< The character type for the output.
  using iterator = appender;
  using format_arg = basic_format_arg<context>;
-  using parse_context_type FMT_DEPRECATED = parse_context<>;
-  template <typename T> using formatter_type FMT_DEPRECATED = formatter<T>;
  enum { builtin_types = FMT_BUILTIN_TYPES };

  /// Constructs a `context` object. References to the arguments are stored
  /// in the object so make sure they have appropriate lifetimes.
-  FMT_CONSTEXPR context(iterator out, format_args args,
-                        detail::locale_ref loc = {})
+  FMT_CONSTEXPR context(iterator out, format_args args, locale_ref loc = {})
      : out_(out), args_(args), loc_(loc) {}
  context(context&&) = default;
  context(const context&) = delete;
@@ -2692,7 +2700,7 @@ class context {
  // Advances the begin iterator to `it`.
  FMT_CONSTEXPR void advance_to(iterator) {}

-  FMT_CONSTEXPR auto locale() const -> detail::locale_ref { return loc_; }
+  FMT_CONSTEXPR auto locale() const -> locale_ref { return loc_; }
 };

 template <typename Char = char> struct runtime_format_string {
@@ -2779,9 +2787,6 @@ template <typename T, typename Char = char>
 concept formattable = is_formattable<remove_reference_t<T>, Char>::value;
 #endif

-template <typename T, typename Char>
-using has_formatter FMT_DEPRECATED = std::is_constructible<formatter<T, Char>>;
-
 // A formatter specialization for natively supported types.
 template <typename T, typename Char>
 struct formatter<T, Char,
@@ -2978,9 +2983,9 @@ FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
  return fmt::println(stdout, fmt, static_cast<T&&>(args)...);
 }

-FMT_END_EXPORT
 FMT_PRAGMA_CLANG(diagnostic pop)
 FMT_PRAGMA_GCC(pop_options)
+FMT_END_EXPORT
 FMT_END_NAMESPACE

 #ifdef FMT_HEADER_ONLY
--- a/include/spdlog/fmt/bundled/chrono.h
+++ b/include/spdlog/fmt/bundled/chrono.h
@@ -38,6 +38,7 @@ FMT_BEGIN_NAMESPACE
 // Copyright Paul Dreik 2019
 namespace safe_duration_cast {

+// DEPRECATED!
 template <typename To, typename From,
          FMT_ENABLE_IF(!std::is_same<From, To>::value &&
                        std::numeric_limits<From>::is_signed ==
@@ -161,17 +162,6 @@ auto safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
                        int& ec) -> To {
  using From = std::chrono::duration<FromRep, FromPeriod>;
  ec = 0;
-  if (std::isnan(from.count())) {
-    // nan in, gives nan out. easy.
-    return To{std::numeric_limits<typename To::rep>::quiet_NaN()};
-  }
-  // maybe we should also check if from is denormal, and decide what to do about
-  // it.
-
-  // +-inf should be preserved.
-  if (std::isinf(from.count())) {
-    return To{from.count()};
-  }

  // the basic idea is that we need to convert from count() in the from type
  // to count() in the To type, by multiplying it with this:
@@ -282,8 +272,6 @@ namespace detail {
 #define FMT_NOMACRO

 template <typename T = void> struct null {};
-inline auto localtime_r FMT_NOMACRO(...) -> null<> { return null<>(); }
-inline auto localtime_s(...) -> null<> { return null<>(); }
 inline auto gmtime_r(...) -> null<> { return null<>(); }
 inline auto gmtime_s(...) -> null<> { return null<>(); }

@@ -326,7 +314,7 @@ inline auto get_classic_locale() -> const std::locale& {
 }

 template <typename CodeUnit> struct codecvt_result {
-  static constexpr const size_t max_size = 32;
+  static constexpr size_t max_size = 32;
  CodeUnit buf[max_size];
  CodeUnit* end;
 };
@@ -443,11 +431,7 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {

  using common_rep = typename std::common_type<FromRep, typename To::rep,
                                               decltype(factor::num)>::type;
-
-  int ec = 0;
-  auto count = safe_duration_cast::lossless_integral_conversion<common_rep>(
-      from.count(), ec);
-  if (ec) throw_duration_error();
+  common_rep count = from.count();  // This conversion is lossless.

  // Multiply from.count() by factor and check for overflow.
  if (const_check(factor::num != 1)) {
@@ -458,6 +442,7 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
    count *= factor::num;
  }
  if (const_check(factor::den != 1)) count /= factor::den;
+  int ec = 0;
  auto to =
      To(safe_duration_cast::lossless_integral_conversion<typename To::rep>(
          count, ec));
@@ -471,6 +456,8 @@ template <typename To, typename FromRep, typename FromPeriod,
                            std::is_floating_point<typename To::rep>::value)>
 auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
 #if FMT_SAFE_DURATION_CAST
+  // Preserve infinity and NaN.
+  if (!isfinite(from.count())) return static_cast<To>(from.count());
  // Throwing version of safe_duration_cast is only available for
  // integer to integer or float to float casts.
  int ec;
@@ -487,7 +474,7 @@ template <typename To, typename FromRep, typename FromPeriod,
          FMT_ENABLE_IF(
              !is_similar_arithmetic_type<FromRep, typename To::rep>::value)>
 auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
-  // Mixed integer <-> float cast is not supported by safe_duration_cast.
+  // Mixed integer <-> float cast is not supported by safe duration_cast.
  return std::chrono::duration_cast<To>(from);
 }

@@ -501,86 +488,10 @@ auto to_time_t(sys_time<Duration> time_point) -> std::time_t {
      .count();
 }

-namespace tz {
-
-// DEPRECATED!
-struct time_zone {
-  template <typename Duration, typename LocalTime>
-  auto to_sys(LocalTime) -> sys_time<Duration> {
-    return {};
-  }
-};
-template <typename... T> auto current_zone(T...) -> time_zone* {
-  return nullptr;
-}
-
-template <typename... T> void _tzset(T...) {}
-}  // namespace tz
-
-// DEPRECATED!
-inline void tzset_once() {
-  static bool init = []() {
-    using namespace tz;
-    _tzset();
-    return false;
-  }();
-  ignore_unused(init);
-}
 }  // namespace detail

 FMT_BEGIN_EXPORT

-/**
- * Converts given time since epoch as `std::time_t` value into calendar time,
- * expressed in local time. Unlike `std::localtime`, this function is
- * thread-safe on most platforms.
- */
-FMT_DEPRECATED inline auto localtime(std::time_t time) -> std::tm {
-  struct dispatcher {
-    std::time_t time_;
-    std::tm tm_;
-
-    inline dispatcher(std::time_t t) : time_(t) {}
-
-    inline auto run() -> bool {
-      using namespace fmt::detail;
-      return handle(localtime_r(&time_, &tm_));
-    }
-
-    inline auto handle(std::tm* tm) -> bool { return tm != nullptr; }
-
-    inline auto handle(detail::null<>) -> bool {
-      using namespace fmt::detail;
-      return fallback(localtime_s(&tm_, &time_));
-    }
-
-    inline auto fallback(int res) -> bool { return res == 0; }
-
-#if !FMT_MSC_VERSION
-    inline auto fallback(detail::null<>) -> bool {
-      using namespace fmt::detail;
-      std::tm* tm = std::localtime(&time_);
-      if (tm) tm_ = *tm;
-      return tm != nullptr;
-    }
-#endif
-  };
-  dispatcher lt(time);
-  // Too big time values may be unsupported.
-  if (!lt.run()) FMT_THROW(format_error("time_t value out of range"));
-  return lt.tm_;
-}
-
-#if FMT_USE_LOCAL_TIME
-template <typename Duration>
-FMT_DEPRECATED auto localtime(std::chrono::local_time<Duration> time)
-    -> std::tm {
-  using namespace std::chrono;
-  using namespace detail::tz;
-  return localtime(detail::to_time_t(current_zone()->to_sys<Duration>(time)));
-}
-#endif
-
 /**
 * Converts given time since epoch as `std::time_t` value into calendar time,
 * expressed in Coordinated Universal Time (UTC). Unlike `std::gmtime`, this
@@ -652,7 +563,7 @@ inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
  // Add ASCII '0' to each digit byte and insert separators.
  digits |= 0x3030003030003030 | (usep << 16) | (usep << 40);

-  constexpr const size_t len = 8;
+  constexpr size_t len = 8;
  if (const_check(is_big_endian())) {
    char tmp[len];
    std::memcpy(tmp, &digits, len);
@@ -1000,16 +911,16 @@ template <typename T>
 struct has_tm_zone<T, void_t<decltype(T::tm_zone)>> : std::true_type {};

 template <typename T, FMT_ENABLE_IF(has_tm_zone<T>::value)>
-bool set_tm_zone(T& time, char* tz) {
+auto set_tm_zone(T& time, char* tz) -> bool {
  time.tm_zone = tz;
  return true;
 }
 template <typename T, FMT_ENABLE_IF(!has_tm_zone<T>::value)>
-bool set_tm_zone(T&, char*) {
+auto set_tm_zone(T&, char*) -> bool {
  return false;
 }

-inline char* utc() {
+inline auto utc() -> char* {
  static char tz[] = "UTC";
  return tz;
 }
@@ -2230,7 +2141,7 @@ template <typename Char> struct formatter<std::tm, Char> {
    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
                                ctx);

-    auto loc_ref = specs.localized() ? ctx.locale() : detail::locale_ref();
+    auto loc_ref = specs.localized() ? ctx.locale() : locale_ref();
    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
    auto w = detail::tm_writer<basic_appender<Char>, Char, Duration>(
        loc, out, tm, subsecs);
--- a/include/spdlog/fmt/bundled/color.h
+++ b/include/spdlog/fmt/bundled/color.h
@@ -375,19 +375,17 @@ template <typename Char> struct ansi_color_escape {
      // 10 more.
      if (is_background) value += 10u;

-      size_t index = 0;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
+      buffer[size++] = static_cast<Char>('\x1b');
+      buffer[size++] = static_cast<Char>('[');

      if (value >= 100u) {
-        buffer[index++] = static_cast<Char>('1');
+        buffer[size++] = static_cast<Char>('1');
        value %= 100u;
      }
-      buffer[index++] = static_cast<Char>('0' + value / 10u);
-      buffer[index++] = static_cast<Char>('0' + value % 10u);
+      buffer[size++] = static_cast<Char>('0' + value / 10u);
+      buffer[size++] = static_cast<Char>('0' + value % 10u);

-      buffer[index++] = static_cast<Char>('m');
-      buffer[index++] = static_cast<Char>('\0');
+      buffer[size++] = static_cast<Char>('m');
      return;
    }

@@ -398,7 +396,7 @@ template <typename Char> struct ansi_color_escape {
    to_esc(color.r, buffer + 7, ';');
    to_esc(color.g, buffer + 11, ';');
    to_esc(color.b, buffer + 15, 'm');
-    buffer[19] = static_cast<Char>(0);
+    size = 19;
  }
  FMT_CONSTEXPR ansi_color_escape(emphasis em) noexcept {
    uint8_t em_codes[num_emphases] = {};
@@ -411,26 +409,28 @@ template <typename Char> struct ansi_color_escape {
    if (has_emphasis(em, emphasis::conceal)) em_codes[6] = 8;
    if (has_emphasis(em, emphasis::strikethrough)) em_codes[7] = 9;

-    size_t index = 0;
+    buffer[size++] = static_cast<Char>('\x1b');
+    buffer[size++] = static_cast<Char>('[');
+
    for (size_t i = 0; i < num_emphases; ++i) {
      if (!em_codes[i]) continue;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
-      buffer[index++] = static_cast<Char>('0' + em_codes[i]);
-      buffer[index++] = static_cast<Char>('m');
+      buffer[size++] = static_cast<Char>('0' + em_codes[i]);
+      buffer[size++] = static_cast<Char>(';');
    }
-    buffer[index++] = static_cast<Char>(0);
+
+    buffer[size - 1] = static_cast<Char>('m');
  }
  FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }

  FMT_CONSTEXPR auto begin() const noexcept -> const Char* { return buffer; }
-  FMT_CONSTEXPR20 auto end() const noexcept -> const Char* {
-    return buffer + basic_string_view<Char>(buffer).size();
+  FMT_CONSTEXPR auto end() const noexcept -> const Char* {
+    return buffer + size;
  }

 private:
  static constexpr size_t num_emphases = 8;
-  Char buffer[7u + 3u * num_emphases + 1u];
+  Char buffer[7u + 4u * num_emphases];
+  size_t size = 0;

  static FMT_CONSTEXPR void to_esc(uint8_t c, Char* out,
                                   char delimiter) noexcept {
--- a/include/spdlog/fmt/bundled/compile.h
+++ b/include/spdlog/fmt/bundled/compile.h
@@ -22,8 +22,6 @@ FMT_EXPORT class compiled_string {};
 template <typename S>
 struct is_compiled_string : std::is_base_of<compiled_string, S> {};

-namespace detail {
-
 /**
 * Converts a string literal `s` into a format string that will be parsed at
 * compile time and converted into efficient formatting code. Requires C++17
@@ -41,18 +39,40 @@ namespace detail {
 #  define FMT_COMPILE(s) FMT_STRING(s)
 #endif

+/**
+ * Converts a string literal into a format string that will be parsed at
+ * compile time and converted into efficient formatting code. Requires support
+ * for class types in constant template parameters (a C++20 feature).
+ *
+ *  **Example**:
+ *
+ *     // Converts 42 into std::string using the most efficient method and no
+ *     // runtime format string processing.
+ *     using namespace fmt::literals;
+ *     std::string s = fmt::format("{}"_cf, 42);
+ */
+#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+inline namespace literals {
+template <detail::fixed_string Str> constexpr auto operator""_cf() {
+  return FMT_COMPILE(Str.data);
+}
+}  // namespace literals
+#endif
+
+namespace detail {
+
 template <typename T, typename... Tail>
-auto first(const T& value, const Tail&...) -> const T& {
+constexpr auto first(const T& value, const Tail&...) -> const T& {
  return value;
 }

 #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-template <typename... Args> struct type_list {};
+template <typename... T> struct type_list {};

 // Returns a reference to the argument at index N from [first, rest...].
 template <int N, typename T, typename... Args>
-constexpr const auto& get([[maybe_unused]] const T& first,
-                          [[maybe_unused]] const Args&... rest) {
+constexpr auto get([[maybe_unused]] const T& first,
+                   [[maybe_unused]] const Args&... rest) -> const auto& {
  static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
  if constexpr (N == 0)
    return first;
@@ -84,8 +104,8 @@ FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
 }

 template <typename Char, typename... Args>
-constexpr int get_arg_index_by_name(basic_string_view<Char> name,
-                                    type_list<Args...>) {
+constexpr auto get_arg_index_by_name(basic_string_view<Char> name,
+                                     type_list<Args...>) -> int {
  return get_arg_index_by_name<Args...>(name);
 }

@@ -105,8 +125,8 @@ template <typename Char> struct text {
  basic_string_view<Char> data;
  using char_type = Char;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
    return write<Char>(out, data);
  }
 };
@@ -115,8 +135,8 @@ template <typename Char>
 struct is_compiled_format<text<Char>> : std::true_type {};

 template <typename Char>
-constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
-                               size_t size) {
+constexpr auto make_text(basic_string_view<Char> s, size_t pos, size_t size)
+    -> text<Char> {
  return {{&s[pos], size}};
 }

@@ -124,8 +144,8 @@ template <typename Char> struct code_unit {
  Char value;
  using char_type = Char;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
    *out++ = value;
    return out;
  }
@@ -133,7 +153,7 @@ template <typename Char> struct code_unit {

 // This ensures that the argument type is convertible to `const T&`.
 template <typename T, int N, typename... Args>
-constexpr const T& get_arg_checked(const Args&... args) {
+constexpr auto get_arg_checked(const Args&... args) -> const T& {
  const auto& arg = detail::get<N>(args...);
  if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>()) {
    return arg.value;
@@ -146,13 +166,13 @@ template <typename Char>
 struct is_compiled_format<code_unit<Char>> : std::true_type {};

 // A replacement field that refers to argument N.
-template <typename Char, typename T, int N> struct field {
+template <typename Char, typename V, int N> struct field {
  using char_type = Char;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    const T& arg = get_arg_checked<T, N>(args...);
-    if constexpr (std::is_convertible<T, basic_string_view<Char>>::value) {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
+    const V& arg = get_arg_checked<V, N>(args...);
+    if constexpr (std::is_convertible<V, basic_string_view<Char>>::value) {
      auto s = basic_string_view<Char>(arg);
      return copy<Char>(s.begin(), s.end(), out);
    } else {
@@ -170,10 +190,10 @@ template <typename Char> struct runtime_named_field {
  basic_string_view<Char> name;

  template <typename OutputIt, typename T>
-  constexpr static bool try_format_argument(
+  constexpr static auto try_format_argument(
      OutputIt& out,
      // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
-      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) {
+      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) -> bool {
    if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
      if (arg_name == arg.name) {
        out = write<Char>(out, arg.value);
@@ -183,8 +203,8 @@ template <typename Char> struct runtime_named_field {
    return false;
  }

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
    bool found = (try_format_argument(out, name, args) || ...);
    if (!found) {
      FMT_THROW(format_error("argument with specified name is not found"));
@@ -197,17 +217,17 @@ template <typename Char>
 struct is_compiled_format<runtime_named_field<Char>> : std::true_type {};

 // A replacement field that refers to argument N and has format specifiers.
-template <typename Char, typename T, int N> struct spec_field {
+template <typename Char, typename V, int N> struct spec_field {
  using char_type = Char;
-  formatter<T, Char> fmt;
+  formatter<V, Char> fmt;

-  template <typename OutputIt, typename... Args>
-  constexpr FMT_INLINE OutputIt format(OutputIt out,
-                                       const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr FMT_INLINE auto format(OutputIt out, const T&... args) const
+      -> OutputIt {
    const auto& vargs =
        fmt::make_format_args<basic_format_context<OutputIt, Char>>(args...);
    basic_format_context<OutputIt, Char> ctx(out, vargs);
-    return fmt.format(get_arg_checked<T, N>(args...), ctx);
+    return fmt.format(get_arg_checked<V, N>(args...), ctx);
  }
 };

@@ -219,8 +239,8 @@ template <typename L, typename R> struct concat {
  R rhs;
  using char_type = typename L::char_type;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
    out = lhs.format(out, args...);
    return rhs.format(out, args...);
  }
@@ -230,14 +250,14 @@ template <typename L, typename R>
 struct is_compiled_format<concat<L, R>> : std::true_type {};

 template <typename L, typename R>
-constexpr concat<L, R> make_concat(L lhs, R rhs) {
+constexpr auto make_concat(L lhs, R rhs) -> concat<L, R> {
  return {lhs, rhs};
 }

 struct unknown_format {};

 template <typename Char>
-constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
+constexpr auto parse_text(basic_string_view<Char> str, size_t pos) -> size_t {
  for (size_t size = str.size(); pos != size; ++pos) {
    if (str[pos] == '{' || str[pos] == '}') break;
  }
@@ -270,8 +290,8 @@ template <typename T, typename Char> struct parse_specs_result {
 enum { manual_indexing_id = -1 };

 template <typename T, typename Char>
-constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
-                                                  size_t pos, int next_arg_id) {
+constexpr auto parse_specs(basic_string_view<Char> str, size_t pos,
+                           int next_arg_id) -> parse_specs_result<T, Char> {
  str.remove_prefix(pos);
  auto ctx =
      compile_parse_context<Char>(str, max_value<int>(), nullptr, next_arg_id);
@@ -285,16 +305,16 @@ template <typename Char> struct arg_id_handler {
  arg_id_kind kind;
  arg_ref<Char> arg_id;

-  constexpr int on_auto() {
+  constexpr auto on_auto() -> int {
    FMT_ASSERT(false, "handler cannot be used with automatic indexing");
    return 0;
  }
-  constexpr int on_index(int id) {
+  constexpr auto on_index(int id) -> int {
    kind = arg_id_kind::index;
    arg_id = arg_ref<Char>(id);
    return 0;
  }
-  constexpr int on_name(basic_string_view<Char> id) {
+  constexpr auto on_name(basic_string_view<Char> id) -> int {
    kind = arg_id_kind::name;
    arg_id = arg_ref<Char>(id);
    return 0;
@@ -433,27 +453,28 @@ FMT_BEGIN_EXPORT

 #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)

-template <typename CompiledFormat, typename... Args,
+template <typename CompiledFormat, typename... T,
          typename Char = typename CompiledFormat::char_type,
          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
-                                          const Args&... args) {
+FMT_INLINE FMT_CONSTEXPR_STRING auto format(const CompiledFormat& cf,
+                                            const T&... args)
+    -> std::basic_string<Char> {
  auto s = std::basic_string<Char>();
  cf.format(std::back_inserter(s), args...);
  return s;
 }

-template <typename OutputIt, typename CompiledFormat, typename... Args,
+template <typename OutputIt, typename CompiledFormat, typename... T,
          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
-                                        const Args&... args) {
+constexpr FMT_INLINE auto format_to(OutputIt out, const CompiledFormat& cf,
+                                    const T&... args) -> OutputIt {
  return cf.format(out, args...);
 }

-template <typename S, typename... Args,
+template <typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
-                                                           Args&&... args) {
+FMT_INLINE FMT_CONSTEXPR_STRING auto format(const S&, T&&... args)
+    -> std::basic_string<typename S::char_type> {
  if constexpr (std::is_same<typename S::char_type, char>::value) {
    constexpr auto str = basic_string_view<typename S::char_type>(S());
    if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
@@ -466,72 +487,97 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
      }
    }
  }
-  constexpr auto compiled = detail::compile<Args...>(S());
+  constexpr auto compiled = detail::compile<T...>(S());
  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
                             detail::unknown_format>()) {
    return fmt::format(
        static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
+        std::forward<T>(args)...);
  } else {
-    return fmt::format(compiled, std::forward<Args>(args)...);
+    return fmt::format(compiled, std::forward<T>(args)...);
  }
 }

-template <typename OutputIt, typename S, typename... Args,
+template <typename OutputIt, typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
-  constexpr auto compiled = detail::compile<Args...>(S());
+FMT_CONSTEXPR auto format_to(OutputIt out, const S&, T&&... args) -> OutputIt {
+  constexpr auto compiled = detail::compile<T...>(S());
  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
                             detail::unknown_format>()) {
    return fmt::format_to(
        out, static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
+        std::forward<T>(args)...);
  } else {
-    return fmt::format_to(out, compiled, std::forward<Args>(args)...);
+    return fmt::format_to(out, compiled, std::forward<T>(args)...);
  }
 }
 #endif

-template <typename OutputIt, typename S, typename... Args,
+template <typename OutputIt, typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
+auto format_to_n(OutputIt out, size_t n, const S& fmt, T&&... args)
    -> format_to_n_result<OutputIt> {
  using traits = detail::fixed_buffer_traits;
  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
-  fmt::format_to(std::back_inserter(buf), fmt, std::forward<Args>(args)...);
+  fmt::format_to(std::back_inserter(buf), fmt, std::forward<T>(args)...);
  return {buf.out(), buf.count()};
 }

-template <typename S, typename... Args,
+template <typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
-    -> size_t {
+FMT_CONSTEXPR20 auto formatted_size(const S& fmt, T&&... args) -> size_t {
  auto buf = detail::counting_buffer<>();
-  fmt::format_to(appender(buf), fmt, args...);
+  fmt::format_to(appender(buf), fmt, std::forward<T>(args)...);
  return buf.count();
 }

-template <typename S, typename... Args,
+template <typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-void print(std::FILE* f, const S& fmt, const Args&... args) {
+void print(std::FILE* f, const S& fmt, T&&... args) {
  auto buf = memory_buffer();
-  fmt::format_to(appender(buf), fmt, args...);
+  fmt::format_to(appender(buf), fmt, std::forward<T>(args)...);
  detail::print(f, {buf.data(), buf.size()});
 }

-template <typename S, typename... Args,
+template <typename S, typename... T,
          FMT_ENABLE_IF(is_compiled_string<S>::value)>
-void print(const S& fmt, const Args&... args) {
-  print(stdout, fmt, args...);
+void print(const S& fmt, T&&... args) {
+  print(stdout, fmt, std::forward<T>(args)...);
 }

-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-inline namespace literals {
-template <detail::fixed_string Str> constexpr auto operator""_cf() {
-  return FMT_COMPILE(Str.data);
-}
-}  // namespace literals
-#endif
+template <size_t N> class static_format_result {
+ private:
+  char data[N];
+
+ public:
+  template <typename S, typename... T,
+            FMT_ENABLE_IF(is_compiled_string<S>::value)>
+  explicit FMT_CONSTEXPR static_format_result(const S& fmt, T&&... args) {
+    *fmt::format_to(data, fmt, std::forward<T>(args)...) = '\0';
+  }
+
+  auto str() const -> fmt::string_view { return {data, N - 1}; }
+  auto c_str() const -> const char* { return data; }
+};
+
+/**
+ * Formats arguments according to the format string `fmt_str` and produces
+ * a string of the exact required size at compile time. Both the format string
+ * and the arguments must be compile-time expressions.
+ *
+ * The resulting string can be accessed as a C string via `c_str()` or as
+ * a `fmt::string_view` via `str()`.
+ *
+ * **Example**:
+ *
+ *     // Produces the static string "42" at compile time.
+ *     static constexpr auto result = FMT_STATIC_FORMAT("{}", 42);
+ *     const char* s = result.c_str();
+ */
+#define FMT_STATIC_FORMAT(fmt_str, ...)                            \
+  fmt::static_format_result<                                       \
+      fmt::formatted_size(FMT_COMPILE(fmt_str), __VA_ARGS__) + 1>( \
+      FMT_COMPILE(fmt_str), __VA_ARGS__)

 FMT_END_EXPORT
 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/format-inl.h
+++ b/include/spdlog/fmt/bundled/format-inl.h
@@ -22,7 +22,7 @@

 #include "format.h"

-#if FMT_USE_LOCALE
+#if FMT_USE_LOCALE && !defined(FMT_MODULE)
 #  include <locale>
 #endif

@@ -31,14 +31,49 @@
 #endif

 FMT_BEGIN_NAMESPACE
-namespace detail {

+#ifndef FMT_CUSTOM_ASSERT_FAIL
 FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
  // Use unchecked std::fprintf to avoid triggering another assertion when
  // writing to stderr fails.
  fprintf(stderr, "%s:%d: assertion failed: %s", file, line, message);
  abort();
 }
+#endif
+
+#if FMT_USE_LOCALE
+namespace detail {
+using std::locale;
+using std::numpunct;
+using std::use_facet;
+}  // namespace detail
+
+template <typename Locale, enable_if_t<(sizeof(Locale::collate) != 0), int>>
+locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
+  static_assert(std::is_same<Locale, std::locale>::value, "");
+}
+#else
+namespace detail {
+struct locale {};
+template <typename Char> struct numpunct {
+  auto grouping() const -> std::string { return "\03"; }
+  auto thousands_sep() const -> Char { return ','; }
+  auto decimal_point() const -> Char { return '.'; }
+};
+template <typename Facet> Facet use_facet(locale) { return {}; }
+}  // namespace detail
+#endif  // FMT_USE_LOCALE
+
+template <typename Locale> auto locale_ref::get() const -> Locale {
+  using namespace detail;
+  static_assert(std::is_same<Locale, locale>::value, "");
+#if FMT_USE_LOCALE
+  if (locale_) return *static_cast<const locale*>(locale_);
+#endif
+  return locale();
+}
+
+namespace detail {

 FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
                                string_view message) noexcept {
@@ -79,33 +114,6 @@ inline void fwrite_all(const void* ptr, size_t count, FILE* stream) {
    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
 }

-#if FMT_USE_LOCALE
-using std::locale;
-using std::numpunct;
-using std::use_facet;
-
-template <typename Locale>
-locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
-  static_assert(std::is_same<Locale, locale>::value, "");
-}
-#else
-struct locale {};
-template <typename Char> struct numpunct {
-  auto grouping() const -> std::string { return "\03"; }
-  auto thousands_sep() const -> Char { return ','; }
-  auto decimal_point() const -> Char { return '.'; }
-};
-template <typename Facet> Facet use_facet(locale) { return {}; }
-#endif  // FMT_USE_LOCALE
-
-template <typename Locale> auto locale_ref::get() const -> Locale {
-  static_assert(std::is_same<Locale, locale>::value, "");
-#if FMT_USE_LOCALE
-  if (locale_) return *static_cast<const locale*>(locale_);
-#endif
-  return locale();
-}
-
 template <typename Char>
 FMT_FUNC auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char> {
  auto&& facet = use_facet<numpunct<Char>>(loc.get<locale>());
@@ -133,14 +141,13 @@ FMT_FUNC auto write_loc(appender out, loc_value value,
 }  // namespace detail

 FMT_FUNC void report_error(const char* message) {
-#if FMT_USE_EXCEPTIONS
-  // Use FMT_THROW instead of throw to avoid bogus unreachable code warnings
-  // from MSVC.
-  FMT_THROW(format_error(message));
-#else
-  fputs(message, stderr);
-  abort();
+#if FMT_MSC_VERSION || defined(__NVCC__)
+  // Silence unreachable code warnings in MSVC and NVCC because these
+  // are nearly impossible to fix in a generic code.
+  volatile bool b = true;
+  if (!b) return;
 #endif
+  FMT_THROW(format_error(message));
 }

 template <typename Locale> typename Locale::id format_facet<Locale>::id;
@@ -174,11 +181,11 @@ inline auto operator==(basic_fp<F> x, basic_fp<F> y) -> bool {
 }

 // Compilers should be able to optimize this into the ror instruction.
-FMT_CONSTEXPR inline auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
+FMT_INLINE auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
  r &= 31;
  return (n >> r) | (n << (32 - r));
 }
-FMT_CONSTEXPR inline auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
+FMT_INLINE auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
  r &= 63;
  return (n >> r) | (n << (64 - r));
 }
@@ -275,7 +282,7 @@ template <> struct cache_accessor<float> {
  static auto get_cached_power(int k) noexcept -> uint64_t {
    FMT_ASSERT(k >= float_info<float>::min_k && k <= float_info<float>::max_k,
               "k is out of range");
-    static constexpr const uint64_t pow10_significands[] = {
+    static constexpr uint64_t pow10_significands[] = {
        0x81ceb32c4b43fcf5, 0xa2425ff75e14fc32, 0xcad2f7f5359a3b3f,
        0xfd87b5f28300ca0e, 0x9e74d1b791e07e49, 0xc612062576589ddb,
        0xf79687aed3eec552, 0x9abe14cd44753b53, 0xc16d9a0095928a28,
@@ -370,7 +377,7 @@ template <> struct cache_accessor<double> {
    FMT_ASSERT(k >= float_info<double>::min_k && k <= float_info<double>::max_k,
               "k is out of range");

-    static constexpr const uint128_fallback pow10_significands[] = {
+    static constexpr uint128_fallback pow10_significands[] = {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
      {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
      {0x9faacf3df73609b1, 0x77b191618c54e9ad},
@@ -1037,7 +1044,7 @@ template <> struct cache_accessor<double> {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
    return pow10_significands[k - float_info<double>::min_k];
 #else
-    static constexpr const uint64_t powers_of_5_64[] = {
+    static constexpr uint64_t powers_of_5_64[] = {
        0x0000000000000001, 0x0000000000000005, 0x0000000000000019,
        0x000000000000007d, 0x0000000000000271, 0x0000000000000c35,
        0x0000000000003d09, 0x000000000001312d, 0x000000000005f5e1,
@@ -1149,8 +1156,8 @@ auto is_left_endpoint_integer_shorter_interval(int exponent) noexcept -> bool {
         exponent <= case_shorter_interval_left_endpoint_upper_threshold;
 }

-// Remove trailing zeros from n and return the number of zeros removed (float)
-FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
+// Remove trailing zeros from n and return the number of zeros removed (float).
+FMT_INLINE auto remove_trailing_zeros(uint32_t& n, int s = 0) noexcept -> int {
  FMT_ASSERT(n != 0, "");
  // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
  constexpr uint32_t mod_inv_5 = 0xcccccccd;
@@ -1170,22 +1177,19 @@ FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
  return s;
 }

-// Removes trailing zeros and returns the number of zeros removed (double)
-FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
+// Removes trailing zeros and returns the number of zeros removed (double).
+FMT_INLINE auto remove_trailing_zeros(uint64_t& n) noexcept -> int {
  FMT_ASSERT(n != 0, "");

-  // This magic number is ceil(2^90 / 10^8).
-  constexpr uint64_t magic_number = 12379400392853802749ull;
-  auto nm = umul128(n, magic_number);
-
  // Is n is divisible by 10^8?
-  if ((nm.high() & ((1ull << (90 - 64)) - 1)) == 0 && nm.low() < magic_number) {
+  constexpr uint32_t ten_pow_8 = 100000000u;
+  if ((n % ten_pow_8) == 0) {
    // If yes, work with the quotient...
-    auto n32 = static_cast<uint32_t>(nm.high() >> (90 - 64));
+    auto n32 = static_cast<uint32_t>(n / ten_pow_8);
    // ... and use the 32 bit variant of the function
-    int s = remove_trailing_zeros(n32, 8);
+    int num_zeros = remove_trailing_zeros(n32, 8);
    n = n32;
-    return s;
+    return num_zeros;
  }

  // If n is not divisible by 10^8, work with n itself.
@@ -1210,7 +1214,7 @@ FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {

 // The main algorithm for shorter interval case
 template <typename T>
-FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
+FMT_INLINE auto shorter_interval_case(int exponent) noexcept -> decimal_fp<T> {
  decimal_fp<T> ret_value;
  // Compute k and beta
  const int minus_k = floor_log10_pow2_minus_log10_4_over_3(exponent);
@@ -1454,8 +1458,8 @@ FMT_FUNC void vformat_to(buffer<char>& buf, string_view fmt, format_args args,
  auto out = appender(buf);
  if (fmt.size() == 2 && equal2(fmt.data(), "{}"))
    return args.get(0).visit(default_arg_formatter<char>{out});
-  parse_format_string(
-      fmt, format_handler<char>{parse_context<char>(fmt), {out, args, loc}});
+  parse_format_string(fmt,
+                      format_handler<>{parse_context<>(fmt), {out, args, loc}});
 }

 template <typename T> struct span {
@@ -1546,10 +1550,11 @@ template <typename F> class glibc_file : public file_base<F> {

  void advance_write_buffer(size_t size) { this->file_->_IO_write_ptr += size; }

-  bool needs_flush() const {
+  auto needs_flush() const -> bool {
    if ((this->file_->_flags & line_buffered) == 0) return false;
    char* end = this->file_->_IO_write_end;
-    return memchr(end, '\n', to_unsigned(this->file_->_IO_write_ptr - end));
+    auto size = max_of<ptrdiff_t>(this->file_->_IO_write_ptr - end, 0);
+    return memchr(end, '\n', static_cast<size_t>(size));
  }

  void flush() { fflush_unlocked(this->file_); }
@@ -1573,7 +1578,7 @@ template <typename F> class apple_file : public file_base<F> {
  void init_buffer() {
    if (this->file_->_p) return;
    // Force buffer initialization by placing and removing a char in a buffer.
-    putc_unlocked(0, this->file_);
+    if (!FMT_CLANG_ANALYZER) putc_unlocked(0, this->file_);
    --this->file_->_p;
    ++this->file_->_w;
  }
@@ -1594,7 +1599,7 @@ template <typename F> class apple_file : public file_base<F> {
    this->file_->_w -= size;
  }

-  bool needs_flush() const {
+  auto needs_flush() const -> bool {
    if ((this->file_->_flags & line_buffered) == 0) return false;
    return memchr(this->file_->_p + this->file_->_w, '\n',
                  to_unsigned(-this->file_->_w));
--- a/include/spdlog/fmt/bundled/format.h
+++ b/include/spdlog/fmt/bundled/format.h
--- a/include/spdlog/fmt/bundled/os.h
+++ b/include/spdlog/fmt/bundled/os.h
@@ -29,7 +29,8 @@
 #  if (FMT_HAS_INCLUDE(<fcntl.h>) || defined(__APPLE__) || \
       defined(__linux__)) &&                              \
      (!defined(WINAPI_FAMILY) ||                          \
-       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)) &&    \
+      !defined(__wasm__)
 #    include <fcntl.h>  // for O_RDONLY
 #    define FMT_USE_FCNTL 1
 #  else
--- a/include/spdlog/fmt/bundled/ostream.h
+++ b/include/spdlog/fmt/bundled/ostream.h
@@ -33,8 +33,8 @@
 FMT_BEGIN_NAMESPACE
 namespace detail {

-// Generate a unique explicit instantion in every translation unit using a tag
-// type in an anonymous namespace.
+// Generate a unique explicit instantiation in every translation unit using a
+// tag type in an anonymous namespace.
 namespace {
 struct file_access_tag {};
 }  // namespace
--- a/include/spdlog/fmt/bundled/printf.h
+++ b/include/spdlog/fmt/bundled/printf.h
@@ -9,7 +9,7 @@
 #define FMT_PRINTF_H_

 #ifndef FMT_MODULE
-#  include <algorithm>  // std::max
+#  include <algorithm>  // std::find
 #  include <limits>     // std::numeric_limits
 #endif

@@ -18,10 +18,6 @@
 FMT_BEGIN_NAMESPACE
 FMT_BEGIN_EXPORT

-template <typename T> struct printf_formatter {
-  printf_formatter() = delete;
-};
-
 template <typename Char> class basic_printf_context {
 private:
  basic_appender<Char> out_;
@@ -33,8 +29,6 @@ template <typename Char> class basic_printf_context {

 public:
  using char_type = Char;
-  using parse_context_type = parse_context<Char>;
-  template <typename T> using formatter_type = printf_formatter<T>;
  enum { builtin_types = 1 };

  /// Constructs a `printf_context` object. References to the arguments are
@@ -46,7 +40,7 @@ template <typename Char> class basic_printf_context {
  auto out() -> basic_appender<Char> { return out_; }
  void advance_to(basic_appender<Char>) {}

-  auto locale() -> detail::locale_ref { return {}; }
+  auto locale() -> locale_ref { return {}; }

  auto arg(int id) const -> basic_format_arg<basic_printf_context> {
    return args_.get(id);
@@ -74,10 +68,9 @@ inline auto find<false, char>(const char* first, const char* last, char value,

 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
-template <bool IsSigned> struct int_checker {
+template <bool IS_SIGNED> struct int_checker {
  template <typename T> static auto fits_in_int(T value) -> bool {
-    unsigned max = to_unsigned(max_value<int>());
-    return value <= max;
+    return value <= to_unsigned(max_value<int>());
  }
  inline static auto fits_in_int(bool) -> bool { return true; }
 };
@@ -95,7 +88,7 @@ struct printf_precision_handler {
  auto operator()(T value) -> int {
    if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
      report_error("number is too big");
-    return (std::max)(static_cast<int>(value), 0);
+    return max_of(static_cast<int>(value), 0);
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
@@ -410,7 +403,9 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
      arg_index = parse_ctx.next_arg_id();
    else
      parse_ctx.check_arg_id(--arg_index);
-    return detail::get_arg(context, arg_index);
+    auto arg = context.arg(arg_index);
+    if (!arg) report_error("argument not found");
+    return arg;
  };

  const Char* start = parse_ctx.begin();
@@ -571,15 +566,19 @@ inline auto vsprintf(basic_string_view<Char> fmt,
 *
 *     std::string message = fmt::sprintf("The answer is %d", 42);
 */
-template <typename S, typename... T, typename Char = detail::char_t<S>>
-inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
-  return vsprintf(detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
+template <typename... T>
+inline auto sprintf(string_view fmt, const T&... args) -> std::string {
+  return vsprintf(fmt, make_printf_args(args...));
+}
+template <typename... T>
+FMT_DEPRECATED auto sprintf(basic_string_view<wchar_t> fmt, const T&... args)
+    -> std::wstring {
+  return vsprintf(fmt, make_printf_args<wchar_t>(args...));
 }

 template <typename Char>
-inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
-                     typename vprintf_args<Char>::type args) -> int {
+auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
+              typename vprintf_args<Char>::type args) -> int {
  auto buf = basic_memory_buffer<Char>();
  detail::vprintf(buf, fmt, args);
  size_t size = buf.size();
@@ -596,17 +595,14 @@ inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
 *
 *     fmt::fprintf(stderr, "Don't %s!", "panic");
 */
-template <typename S, typename... T, typename Char = detail::char_t<S>>
-inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
-  return vfprintf(f, detail::to_string_view(fmt),
-                  make_printf_args<Char>(args...));
+template <typename... T>
+inline auto fprintf(std::FILE* f, string_view fmt, const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args(args...));
 }
-
-template <typename Char>
-FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
-                                   typename vprintf_args<Char>::type args)
-    -> int {
-  return vfprintf(stdout, fmt, args);
+template <typename... T>
+FMT_DEPRECATED auto fprintf(std::FILE* f, basic_string_view<wchar_t> fmt,
+                            const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args<wchar_t>(args...));
 }

 /**
@@ -621,11 +617,6 @@ template <typename... T>
 inline auto printf(string_view fmt, const T&... args) -> int {
  return vfprintf(stdout, fmt, make_printf_args(args...));
 }
-template <typename... T>
-FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
-                                  const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
-}

 FMT_END_EXPORT
 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/ranges.h
+++ b/include/spdlog/fmt/bundled/ranges.h
@@ -11,7 +11,6 @@
 #ifndef FMT_MODULE
 #  include <initializer_list>
 #  include <iterator>
-#  include <string>
 #  include <tuple>
 #  include <type_traits>
 #  include <utility>
@@ -31,7 +30,7 @@ template <typename T> class is_map {
  template <typename> static void check(...);

 public:
-  static constexpr const bool value =
+  static constexpr bool value =
      !std::is_void<decltype(check<T>(nullptr))>::value;
 };

@@ -40,17 +39,16 @@ template <typename T> class is_set {
  template <typename> static void check(...);

 public:
-  static constexpr const bool value =
+  static constexpr bool value =
      !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
 };

 // C array overload
-template <typename T, std::size_t N>
+template <typename T, size_t N>
 auto range_begin(const T (&arr)[N]) -> const T* {
  return arr;
 }
-template <typename T, std::size_t N>
-auto range_end(const T (&arr)[N]) -> const T* {
+template <typename T, size_t N> auto range_end(const T (&arr)[N]) -> const T* {
  return arr + N;
 }

@@ -120,7 +118,7 @@ template <typename T> class is_tuple_like_ {
  template <typename> static void check(...);

 public:
-  static constexpr const bool value =
+  static constexpr bool value =
      !std::is_void<decltype(check<T>(nullptr))>::value;
 };

@@ -154,7 +152,7 @@ using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 class is_tuple_formattable_ {
 public:
-  static constexpr const bool value = false;
+  static constexpr bool value = false;
 };
 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
  template <size_t... Is>
@@ -170,7 +168,7 @@ template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
                                       C>::value)...>{}));

 public:
-  static constexpr const bool value =
+  static constexpr bool value =
      decltype(check(tuple_index_sequence<T>{}))::value;
 };

@@ -208,7 +206,7 @@ template <typename Char, typename... T>
 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;

 using std::get;
-template <typename Tuple, typename Char, std::size_t... Is>
+template <typename Tuple, typename Char, size_t... Is>
 auto get_formatters(index_sequence<Is...>)
    -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 }  // namespace tuple
@@ -219,7 +217,7 @@ template <typename R> struct range_reference_type_impl {
  using type = decltype(*detail::range_begin(std::declval<R&>()));
 };

-template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
+template <typename T, size_t N> struct range_reference_type_impl<T[N]> {
  using type = T&;
 };

@@ -281,14 +279,15 @@ template <typename FormatContext> struct format_tuple_element {

 }  // namespace detail

+FMT_EXPORT
 template <typename T> struct is_tuple_like {
-  static constexpr const bool value =
+  static constexpr bool value =
      detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 };

+FMT_EXPORT
 template <typename T, typename C> struct is_tuple_formattable {
-  static constexpr const bool value =
-      detail::is_tuple_formattable_<T, C>::value;
+  static constexpr bool value = detail::is_tuple_formattable_<T, C>::value;
 };

 template <typename Tuple, typename Char>
@@ -343,8 +342,9 @@ struct formatter<Tuple, Char,
  }
 };

+FMT_EXPORT
 template <typename T, typename Char> struct is_range {
-  static constexpr const bool value =
+  static constexpr bool value =
      detail::is_range_<T>::value && !detail::has_to_string_view<T>::value;
 };

@@ -368,6 +368,7 @@ template <typename P1, typename... Pn>
 struct conjunction<P1, Pn...>
    : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};

+FMT_EXPORT
 template <typename T, typename Char, typename Enable = void>
 struct range_formatter;

@@ -670,7 +671,8 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
  }
 };

-template <typename Char, typename Tuple> struct tuple_join_view : detail::view {
+FMT_EXPORT
+template <typename Tuple, typename Char> struct tuple_join_view : detail::view {
  const Tuple& tuple;
  basic_string_view<Char> sep;

@@ -685,15 +687,15 @@ template <typename Char, typename Tuple> struct tuple_join_view : detail::view {
 #  define FMT_TUPLE_JOIN_SPECIFIERS 0
 #endif

-template <typename Char, typename Tuple>
-struct formatter<tuple_join_view<Char, Tuple>, Char,
+template <typename Tuple, typename Char>
+struct formatter<tuple_join_view<Tuple, Char>, Char,
                 enable_if_t<is_tuple_like<Tuple>::value>> {
  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    return do_parse(ctx, std::tuple_size<Tuple>());
  }

  template <typename FormatContext>
-  auto format(const tuple_join_view<Char, Tuple>& value,
+  auto format(const tuple_join_view<Tuple, Char>& value,
              FormatContext& ctx) const -> typename FormatContext::iterator {
    return do_format(value, ctx, std::tuple_size<Tuple>());
  }
@@ -725,14 +727,14 @@ struct formatter<tuple_join_view<Char, Tuple>, Char,
  }

  template <typename FormatContext>
-  auto do_format(const tuple_join_view<Char, Tuple>&, FormatContext& ctx,
+  auto do_format(const tuple_join_view<Tuple, Char>&, FormatContext& ctx,
                 std::integral_constant<size_t, 0>) const ->
      typename FormatContext::iterator {
    return ctx.out();
  }

  template <typename FormatContext, size_t N>
-  auto do_format(const tuple_join_view<Char, Tuple>& value, FormatContext& ctx,
+  auto do_format(const tuple_join_view<Tuple, Char>& value, FormatContext& ctx,
                 std::integral_constant<size_t, N>) const ->
      typename FormatContext::iterator {
    using std::get;
@@ -754,7 +756,7 @@ template <typename T> class is_container_adaptor_like {
  template <typename> static void check(...);

 public:
-  static constexpr const bool value =
+  static constexpr bool value =
      !std::is_void<decltype(check<T>(nullptr))>::value;
 };

@@ -825,7 +827,7 @@ auto join(Range&& r, string_view sep)
 */
 template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
 FMT_CONSTEXPR auto join(const Tuple& tuple, string_view sep)
-    -> tuple_join_view<char, Tuple> {
+    -> tuple_join_view<Tuple, char> {
  return {tuple, sep};
 }

--- a/include/spdlog/fmt/bundled/std.h
+++ b/include/spdlog/fmt/bundled/std.h
@@ -15,15 +15,13 @@
 #  include <atomic>
 #  include <bitset>
 #  include <complex>
-#  include <cstdlib>
 #  include <exception>
-#  include <functional>
+#  include <functional>  // std::reference_wrapper
 #  include <memory>
 #  include <thread>
 #  include <type_traits>
-#  include <typeinfo>
-#  include <utility>
-#  include <vector>
+#  include <typeinfo>  // std::type_info
+#  include <utility>   // std::make_index_sequence

 // Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
@@ -62,27 +60,26 @@
 #  endif
 #endif

-// For older Xcode versions, __cpp_lib_xxx flags are inaccurately defined.
-#ifndef FMT_CPP_LIB_FILESYSTEM
-#  ifdef __cpp_lib_filesystem
-#    define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
-#  else
-#    define FMT_CPP_LIB_FILESYSTEM 0
-#  endif
+#ifdef FMT_CPP_LIB_FILESYSTEM
+// Use the provided definition.
+#elif defined(__cpp_lib_filesystem)
+#  define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
+#else
+#  define FMT_CPP_LIB_FILESYSTEM 0
 #endif

-#ifndef FMT_CPP_LIB_VARIANT
-#  ifdef __cpp_lib_variant
-#    define FMT_CPP_LIB_VARIANT __cpp_lib_variant
-#  else
-#    define FMT_CPP_LIB_VARIANT 0
-#  endif
+#ifdef FMT_CPP_LIB_VARIANT
+// Use the provided definition.
+#elif defined(__cpp_lib_variant)
+#  define FMT_CPP_LIB_VARIANT __cpp_lib_variant
+#else
+#  define FMT_CPP_LIB_VARIANT 0
 #endif

+FMT_BEGIN_NAMESPACE
+namespace detail {
+
 #if FMT_CPP_LIB_FILESYSTEM
-FMT_BEGIN_NAMESPACE
-
-namespace detail {

 template <typename Char, typename PathChar>
 auto get_path_string(const std::filesystem::path& p,
@@ -111,8 +108,168 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
  }
 }

+#endif  // FMT_CPP_LIB_FILESYSTEM
+
+#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
+template <typename Char, typename OutputIt, typename T>
+auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
+  if constexpr (has_to_string_view<T>::value)
+    return write_escaped_string<Char>(out, detail::to_string_view(v));
+  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
+  return write<Char>(out, v);
+}
+#endif
+
+#if FMT_CPP_LIB_VARIANT
+
+template <typename> struct is_variant_like_ : std::false_type {};
+template <typename... Types>
+struct is_variant_like_<std::variant<Types...>> : std::true_type {};
+
+template <typename Variant, typename Char> class is_variant_formattable {
+  template <size_t... Is>
+  static auto check(std::index_sequence<Is...>) -> std::conjunction<
+      is_formattable<std::variant_alternative_t<Is, Variant>, Char>...>;
+
+ public:
+  static constexpr bool value = decltype(check(
+      std::make_index_sequence<std::variant_size<Variant>::value>()))::value;
+};
+
+#endif  // FMT_CPP_LIB_VARIANT
+
+#if FMT_USE_RTTI
+
+template <typename OutputIt>
+auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
+#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
+  int status = 0;
+  size_t size = 0;
+  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
+      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
+
+  string_view demangled_name_view;
+  if (demangled_name_ptr) {
+    demangled_name_view = demangled_name_ptr.get();
+
+    // Normalization of stdlib inline namespace names.
+    // libc++ inline namespaces.
+    //  std::__1::*       -> std::*
+    //  std::__1::__fs::* -> std::*
+    // libstdc++ inline namespaces.
+    //  std::__cxx11::*             -> std::*
+    //  std::filesystem::__cxx11::* -> std::filesystem::*
+    if (demangled_name_view.starts_with("std::")) {
+      char* begin = demangled_name_ptr.get();
+      char* to = begin + 5;  // std::
+      for (char *from = to, *end = begin + demangled_name_view.size();
+           from < end;) {
+        // This is safe, because demangled_name is NUL-terminated.
+        if (from[0] == '_' && from[1] == '_') {
+          char* next = from + 1;
+          while (next < end && *next != ':') next++;
+          if (next[0] == ':' && next[1] == ':') {
+            from = next + 2;
+            continue;
+          }
+        }
+        *to++ = *from++;
+      }
+      demangled_name_view = {begin, detail::to_unsigned(to - begin)};
+    }
+  } else {
+    demangled_name_view = string_view(ti.name());
+  }
+  return detail::write_bytes<char>(out, demangled_name_view);
+#  elif FMT_MSC_VERSION
+  const string_view demangled_name(ti.name());
+  for (size_t i = 0; i < demangled_name.size(); ++i) {
+    auto sub = demangled_name;
+    sub.remove_prefix(i);
+    if (sub.starts_with("enum ")) {
+      i += 4;
+      continue;
+    }
+    if (sub.starts_with("class ") || sub.starts_with("union ")) {
+      i += 5;
+      continue;
+    }
+    if (sub.starts_with("struct ")) {
+      i += 6;
+      continue;
+    }
+    if (*sub.begin() != ' ') *out++ = *sub.begin();
+  }
+  return out;
+#  else
+  return detail::write_bytes<char>(out, string_view(ti.name()));
+#  endif
+}
+
+#endif  // FMT_USE_RTTI
+
+template <typename T, typename Enable = void>
+struct has_flip : std::false_type {};
+
+template <typename T>
+struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
+    : std::true_type {};
+
+template <typename T> struct is_bit_reference_like {
+  static constexpr bool value = std::is_convertible<T, bool>::value &&
+                                std::is_nothrow_assignable<T, bool>::value &&
+                                has_flip<T>::value;
+};
+
+// Workaround for libc++ incompatibility with C++ standard.
+// According to the Standard, `bitset::operator[] const` returns bool.
+#if defined(_LIBCPP_VERSION) && !defined(FMT_IMPORT_STD)
+template <typename C>
+struct is_bit_reference_like<std::__bit_const_reference<C>> {
+  static constexpr bool value = true;
+};
+#endif
+
+template <typename T, typename Enable = void>
+struct has_format_as : std::false_type {};
+template <typename T>
+struct has_format_as<T, void_t<decltype(format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
+template <typename T, typename Enable = void>
+struct has_format_as_member : std::false_type {};
+template <typename T>
+struct has_format_as_member<
+    T, void_t<decltype(formatter<T>::format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
 }  // namespace detail

+template <typename T, typename Deleter>
+auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
+  return p.get();
+}
+template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
+  return p.get();
+}
+
+#if FMT_CPP_LIB_FILESYSTEM
+
+class path : public std::filesystem::path {
+ public:
+  auto display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{}"), base);
+  }
+  auto system_string() const -> std::string { return string(); }
+
+  auto generic_display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{:g}"), base);
+  }
+  auto generic_system_string() const -> std::string { return generic_string(); }
+};
+
 template <typename Char> struct formatter<std::filesystem::path, Char> {
 private:
  format_specs specs_;
@@ -162,39 +319,20 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
  }
 };

-class path : public std::filesystem::path {
- public:
-  auto display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{}"), base);
-  }
-  auto system_string() const -> std::string { return string(); }
-
-  auto generic_display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{:g}"), base);
-  }
-  auto generic_system_string() const -> std::string { return generic_string(); }
-};
-
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_FILESYSTEM

-FMT_BEGIN_NAMESPACE
-template <std::size_t N, typename Char>
+template <size_t N, typename Char>
 struct formatter<std::bitset<N>, Char>
    : nested_formatter<basic_string_view<Char>, Char> {
 private:
-  // Functor because C++11 doesn't support generic lambdas.
+  // This is a functor because C++11 doesn't support generic lambdas.
  struct writer {
    const std::bitset<N>& bs;

    template <typename OutputIt>
    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
-      for (auto pos = N; pos > 0; --pos) {
+      for (auto pos = N; pos > 0; --pos)
        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
-      }
-
      return out;
    }
  };
@@ -209,10 +347,8 @@ struct formatter<std::bitset<N>, Char>

 template <typename Char>
 struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
-FMT_END_NAMESPACE

 #ifdef __cpp_lib_optional
-FMT_BEGIN_NAMESPACE
 template <typename T, typename Char>
 struct formatter<std::optional<T>, Char,
                 std::enable_if_t<is_formattable<T, Char>::value>> {
@@ -251,30 +387,9 @@ struct formatter<std::optional<T>, Char,
    return detail::write(out, ')');
  }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_optional

-#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename Char, typename OutputIt, typename T>
-auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
-  if constexpr (has_to_string_view<T>::value)
-    return write_escaped_string<Char>(out, detail::to_string_view(v));
-  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
-  return write<Char>(out, v);
-}
-
-}  // namespace detail
-
-FMT_END_NAMESPACE
-#endif
-
 #ifdef __cpp_lib_expected
-FMT_BEGIN_NAMESPACE
-
 template <typename T, typename E, typename Char>
 struct formatter<std::expected<T, E>, Char,
                 std::enable_if_t<(std::is_void<T>::value ||
@@ -301,11 +416,9 @@ struct formatter<std::expected<T, E>, Char,
    return out;
  }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_expected

 #ifdef __cpp_lib_source_location
-FMT_BEGIN_NAMESPACE
 template <> struct formatter<std::source_location> {
  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }

@@ -323,42 +436,12 @@ template <> struct formatter<std::source_location> {
    return out;
  }
 };
-FMT_END_NAMESPACE
 #endif

 #if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using variant_index_sequence =
-    std::make_index_sequence<std::variant_size<T>::value>;
-
-template <typename> struct is_variant_like_ : std::false_type {};
-template <typename... Types>
-struct is_variant_like_<std::variant<Types...>> : std::true_type {};
-
-// formattable element check.
-template <typename T, typename C> class is_variant_formattable_ {
-  template <std::size_t... Is>
-  static std::conjunction<
-      is_formattable<std::variant_alternative_t<Is, T>, C>...>
-      check(std::index_sequence<Is...>);
-
- public:
-  static constexpr const bool value =
-      decltype(check(variant_index_sequence<T>{}))::value;
-};
-
-}  // namespace detail

 template <typename T> struct is_variant_like {
-  static constexpr const bool value = detail::is_variant_like_<T>::value;
-};
-
-template <typename T, typename C> struct is_variant_formattable {
-  static constexpr const bool value =
-      detail::is_variant_formattable_<T, C>::value;
+  static constexpr bool value = detail::is_variant_like_<T>::value;
 };

 template <typename Char> struct formatter<std::monostate, Char> {
@@ -374,10 +457,10 @@ template <typename Char> struct formatter<std::monostate, Char> {
 };

 template <typename Variant, typename Char>
-struct formatter<
-    Variant, Char,
-    std::enable_if_t<std::conjunction_v<
-        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
+struct formatter<Variant, Char,
+                 std::enable_if_t<std::conjunction_v<
+                     is_variant_like<Variant>,
+                     detail::is_variant_formattable<Variant, Char>>>> {
  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    return ctx.begin();
  }
@@ -402,10 +485,9 @@ struct formatter<
    return out;
  }
 };
-FMT_END_NAMESPACE
+
 #endif  // FMT_CPP_LIB_VARIANT

-FMT_BEGIN_NAMESPACE
 template <> struct formatter<std::error_code> {
 private:
  format_specs specs_;
@@ -459,101 +541,29 @@ template <> struct formatter<std::error_code> {
 };

 #if FMT_USE_RTTI
-namespace detail {
-
-template <typename Char, typename OutputIt>
-auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
-#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
-  int status = 0;
-  std::size_t size = 0;
-  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
-      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
-
-  string_view demangled_name_view;
-  if (demangled_name_ptr) {
-    demangled_name_view = demangled_name_ptr.get();
-
-    // Normalization of stdlib inline namespace names.
-    // libc++ inline namespaces.
-    //  std::__1::*       -> std::*
-    //  std::__1::__fs::* -> std::*
-    // libstdc++ inline namespaces.
-    //  std::__cxx11::*             -> std::*
-    //  std::filesystem::__cxx11::* -> std::filesystem::*
-    if (demangled_name_view.starts_with("std::")) {
-      char* begin = demangled_name_ptr.get();
-      char* to = begin + 5;  // std::
-      for (char *from = to, *end = begin + demangled_name_view.size();
-           from < end;) {
-        // This is safe, because demangled_name is NUL-terminated.
-        if (from[0] == '_' && from[1] == '_') {
-          char* next = from + 1;
-          while (next < end && *next != ':') next++;
-          if (next[0] == ':' && next[1] == ':') {
-            from = next + 2;
-            continue;
-          }
-        }
-        *to++ = *from++;
-      }
-      demangled_name_view = {begin, detail::to_unsigned(to - begin)};
-    }
-  } else {
-    demangled_name_view = string_view(ti.name());
-  }
-  return detail::write_bytes<Char>(out, demangled_name_view);
-#  elif FMT_MSC_VERSION
-  const string_view demangled_name(ti.name());
-  for (std::size_t i = 0; i < demangled_name.size(); ++i) {
-    auto sub = demangled_name;
-    sub.remove_prefix(i);
-    if (sub.starts_with("enum ")) {
-      i += 4;
-      continue;
-    }
-    if (sub.starts_with("class ") || sub.starts_with("union ")) {
-      i += 5;
-      continue;
-    }
-    if (sub.starts_with("struct ")) {
-      i += 6;
-      continue;
-    }
-    if (*sub.begin() != ' ') *out++ = *sub.begin();
-  }
-  return out;
-#  else
-  return detail::write_bytes<Char>(out, string_view(ti.name()));
-#  endif
-}
-
-}  // namespace detail
-
-template <typename Char>
-struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
-                 > {
+template <> struct formatter<std::type_info> {
 public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
    return ctx.begin();
  }

  template <typename Context>
  auto format(const std::type_info& ti, Context& ctx) const
      -> decltype(ctx.out()) {
-    return detail::write_demangled_name<Char>(ctx.out(), ti);
+    return detail::write_demangled_name(ctx.out(), ti);
  }
 };
-#endif
+#endif  // FMT_USE_RTTI

-template <typename T, typename Char>
+template <typename T>
 struct formatter<
-    T, Char,  // DEPRECATED! Mixing code unit types.
+    T, char,
    typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
 private:
  bool with_typename_ = false;

 public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
    auto it = ctx.begin();
    auto end = ctx.end();
    if (it == end || *it == '}') return it;
@@ -570,43 +580,15 @@ struct formatter<
    auto out = ctx.out();
 #if FMT_USE_RTTI
    if (with_typename_) {
-      out = detail::write_demangled_name<Char>(out, typeid(ex));
+      out = detail::write_demangled_name(out, typeid(ex));
      *out++ = ':';
      *out++ = ' ';
    }
 #endif
-    return detail::write_bytes<Char>(out, string_view(ex.what()));
+    return detail::write_bytes<char>(out, string_view(ex.what()));
  }
 };

-namespace detail {
-
-template <typename T, typename Enable = void>
-struct has_flip : std::false_type {};
-
-template <typename T>
-struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
-    : std::true_type {};
-
-template <typename T> struct is_bit_reference_like {
-  static constexpr const bool value =
-      std::is_convertible<T, bool>::value &&
-      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
-};
-
-#ifdef _LIBCPP_VERSION
-
-// Workaround for libc++ incompatibility with C++ standard.
-// According to the Standard, `bitset::operator[] const` returns bool.
-template <typename C>
-struct is_bit_reference_like<std::__bit_const_reference<C>> {
-  static constexpr const bool value = true;
-};
-
-#endif
-
-}  // namespace detail
-
 // We can't use std::vector<bool, Allocator>::reference and
 // std::bitset<N>::reference because the compiler can't deduce Allocator and N
 // in partial specialization.
@@ -621,14 +603,6 @@ struct formatter<BitRef, Char,
  }
 };

-template <typename T, typename Deleter>
-auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
-  return p.get();
-}
-template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
-  return p.get();
-}
-
 template <typename T, typename Char>
 struct formatter<std::atomic<T>, Char,
                 enable_if_t<is_formattable<T, Char>::value>>
@@ -715,7 +689,11 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {

 template <typename T, typename Char>
 struct formatter<std::reference_wrapper<T>, Char,
-                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value>>
+                 // Guard against format_as because reference_wrapper is
+                 // implicitly convertible to T&.
+                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value &&
+                             !detail::has_format_as<T>::value &&
+                             !detail::has_format_as_member<T>::value>>
    : formatter<remove_cvref_t<T>, Char> {
  template <typename FormatContext>
  auto format(std::reference_wrapper<T> ref, FormatContext& ctx) const
@@ -725,4 +703,5 @@ struct formatter<std::reference_wrapper<T>, Char,
 };

 FMT_END_NAMESPACE
+
 #endif  // FMT_STD_H_
--- a/include/spdlog/fmt/bundled/xchar.h
+++ b/include/spdlog/fmt/bundled/xchar.h
@@ -55,6 +55,16 @@ inline auto write_loc(basic_appender<wchar_t> out, loc_value value,
 #endif
  return false;
 }
+
+template <typename Char>
+void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
+                basic_format_args<buffered_context<Char>> args,
+                locale_ref loc = {}) {
+  static_assert(!std::is_same<Char, char>::value, "");
+  auto out = basic_appender<Char>(buf);
+  parse_format_string(
+      fmt, format_handler<Char>{parse_context<Char>(fmt), {out, args, loc}});
+}
 }  // namespace detail

 FMT_BEGIN_EXPORT
@@ -112,10 +122,6 @@ inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
  return {{s}};
 }

-#ifdef __cpp_char8_t
-template <> struct is_char<char8_t> : bool_constant<detail::is_utf8_enabled> {};
-#endif
-
 template <typename... T>
 constexpr auto make_wformat_args(T&... args)
    -> decltype(fmt::make_format_args<wformat_context>(args...)) {
@@ -151,13 +157,13 @@ auto join(std::initializer_list<T> list, wstring_view sep)

 template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
 auto join(const Tuple& tuple, basic_string_view<wchar_t> sep)
-    -> tuple_join_view<wchar_t, Tuple> {
+    -> tuple_join_view<Tuple, wchar_t> {
  return {tuple, sep};
 }

 template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
 auto vformat(basic_string_view<Char> fmt,
-             typename detail::vformat_args<Char>::type args)
+             basic_format_args<buffered_context<Char>> args)
    -> std::basic_string<Char> {
  auto buf = basic_memory_buffer<Char>();
  detail::vformat_to(buf, fmt, args);
@@ -187,24 +193,20 @@ auto format(const S& fmt, T&&... args) -> std::basic_string<Char> {
                 fmt::make_format_args<buffered_context<Char>>(args...));
 }

-template <typename Locale, typename S,
-          typename Char = detail::format_string_char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto vformat(const Locale& loc, const S& fmt,
-                    typename detail::vformat_args<Char>::type args)
+template <typename S, typename Char = detail::format_string_char_t<S>,
+          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+inline auto vformat(locale_ref loc, const S& fmt,
+                    basic_format_args<buffered_context<Char>> args)
    -> std::basic_string<Char> {
  auto buf = basic_memory_buffer<Char>();
-  detail::vformat_to(buf, detail::to_string_view(fmt), args,
-                     detail::locale_ref(loc));
+  detail::vformat_to(buf, detail::to_string_view(fmt), args, loc);
  return {buf.data(), buf.size()};
 }

-template <typename Locale, typename S, typename... T,
+template <typename S, typename... T,
          typename Char = detail::format_string_char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format(const Locale& loc, const S& fmt, T&&... args)
+          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+inline auto format(locale_ref loc, const S& fmt, T&&... args)
    -> std::basic_string<Char> {
  return vformat(loc, detail::to_string_view(fmt),
                 fmt::make_format_args<buffered_context<Char>>(args...));
@@ -215,7 +217,7 @@ template <typename OutputIt, typename S,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                            detail::is_exotic_char<Char>::value)>
 auto vformat_to(OutputIt out, const S& fmt,
-                typename detail::vformat_args<Char>::type args) -> OutputIt {
+                basic_format_args<buffered_context<Char>> args) -> OutputIt {
  auto&& buf = detail::get_buffer<Char>(out);
  detail::vformat_to(buf, detail::to_string_view(fmt), args);
  return detail::get_iterator(buf, out);
@@ -231,27 +233,24 @@ inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
                    fmt::make_format_args<buffered_context<Char>>(args...));
 }

-template <typename Locale, typename S, typename OutputIt, typename... Args,
+template <typename S, typename OutputIt, typename... Args,
          typename Char = detail::format_string_char_t<S>,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_locale<Locale>::value&&
-                                detail::is_exotic_char<Char>::value)>
-inline auto vformat_to(OutputIt out, const Locale& loc, const S& fmt,
-                       typename detail::vformat_args<Char>::type args)
+                            detail::is_exotic_char<Char>::value)>
+inline auto vformat_to(OutputIt out, locale_ref loc, const S& fmt,
+                       basic_format_args<buffered_context<Char>> args)
    -> OutputIt {
  auto&& buf = detail::get_buffer<Char>(out);
-  vformat_to(buf, detail::to_string_view(fmt), args, detail::locale_ref(loc));
+  vformat_to(buf, detail::to_string_view(fmt), args, loc);
  return detail::get_iterator(buf, out);
 }

-template <typename Locale, typename OutputIt, typename S, typename... T,
+template <typename OutputIt, typename S, typename... T,
          typename Char = detail::format_string_char_t<S>,
          bool enable = detail::is_output_iterator<OutputIt, Char>::value &&
-                        detail::is_locale<Locale>::value &&
                        detail::is_exotic_char<Char>::value>
-inline auto format_to(OutputIt out, const Locale& loc, const S& fmt,
-                      T&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
+inline auto format_to(OutputIt out, locale_ref loc, const S& fmt, T&&... args)
+    -> typename std::enable_if<enable, OutputIt>::type {
  return vformat_to(out, loc, detail::to_string_view(fmt),
                    fmt::make_format_args<buffered_context<Char>>(args...));
 }
@@ -260,7 +259,7 @@ template <typename OutputIt, typename Char, typename... Args,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                            detail::is_exotic_char<Char>::value)>
 inline auto vformat_to_n(OutputIt out, size_t n, basic_string_view<Char> fmt,
-                         typename detail::vformat_args<Char>::type args)
+                         basic_format_args<buffered_context<Char>> args)
    -> format_to_n_result<OutputIt> {
  using traits = detail::fixed_buffer_traits;
  auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
@@ -331,18 +330,6 @@ inline auto format(text_style ts, wformat_string<T...> fmt, T&&... args)
  return fmt::vformat(ts, fmt, fmt::make_wformat_args(args...));
 }

-template <typename... T>
-FMT_DEPRECATED void print(std::FILE* f, text_style ts, wformat_string<T...> fmt,
-                          const T&... args) {
-  vprint(f, ts, fmt, fmt::make_wformat_args(args...));
-}
-
-template <typename... T>
-FMT_DEPRECATED void print(text_style ts, wformat_string<T...> fmt,
-                          const T&... args) {
-  return print(stdout, ts, fmt, args...);
-}
-
 inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
  auto buffer = basic_memory_buffer<wchar_t>();
  detail::vformat_to(buffer, fmt, args);
--- a/include/spdlog/sinks/ringbuffer_sink.h
+++ b/include/spdlog/sinks/ringbuffer_sink.h
@@ -21,7 +21,11 @@ template <typename Mutex>
 class ringbuffer_sink final : public base_sink<Mutex> {
 public:
    explicit ringbuffer_sink(size_t n_items)
-        : q_{n_items} {}
+        : q_{n_items} {
+        if (n_items == 0) {
+            throw_spdlog_ex("ringbuffer_sink: n_items cannot be zero");
+        }
+    }

    std::vector<details::log_msg_buffer> last_raw(size_t lim = 0) {
        std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
--- a/include/spdlog/sinks/tcp_sink.h
+++ b/include/spdlog/sinks/tcp_sink.h
@@ -31,6 +31,8 @@ namespace sinks {
 struct tcp_sink_config {
    std::string server_host;
    int server_port;
+    int timeout_ms =
+        0;  // The timeout for all 3 major socket operations that is connect, send, and recv
    bool lazy_connect = false;  // if true connect on first log call instead of on construction

    tcp_sink_config(std::string host, int port)
@@ -44,10 +46,22 @@ public:
    // connect to tcp host/port or throw if failed
    // host can be hostname or ip address

+    explicit tcp_sink(const std::string &host,
+                      int port,
+                      int timeout_ms = 0,
+                      bool lazy_connect = false)
+        : config_{host, port} {
+        config_.timeout_ms = timeout_ms;
+        config_.lazy_connect = lazy_connect;
+        if (!config_.lazy_connect) {
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
+        }
+    }
+
    explicit tcp_sink(tcp_sink_config sink_config)
        : config_{std::move(sink_config)} {
        if (!config_.lazy_connect) {
-            this->client_.connect(config_.server_host, config_.server_port);
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
        }
    }

@@ -58,7 +72,7 @@ protected:
        spdlog::memory_buf_t formatted;
        spdlog::sinks::base_sink<Mutex>::formatter_->format(msg, formatted);
        if (!client_.is_connected()) {
-            client_.connect(config_.server_host, config_.server_port);
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
        }
        client_.send(formatted.data(), formatted.size());
    }
--- a/include/spdlog/version.h
+++ b/include/spdlog/version.h
@@ -4,8 +4,8 @@
 #pragma once

 #define SPDLOG_VER_MAJOR 1
-#define SPDLOG_VER_MINOR 15
-#define SPDLOG_VER_PATCH 3
+#define SPDLOG_VER_MINOR 16
+#define SPDLOG_VER_PATCH 0

 #define SPDLOG_TO_VERSION(major, minor, patch) (major * 10000 + minor * 100 + patch)
 #define SPDLOG_VERSION SPDLOG_TO_VERSION(SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR, SPDLOG_VER_PATCH)
--- a/src/bundled_fmtlib_format.cpp
+++ b/src/bundled_fmtlib_format.cpp
@@ -11,36 +11,35 @@
    #include <spdlog/fmt/bundled/format-inl.h>

 FMT_BEGIN_NAMESPACE
-namespace detail {

-template FMT_API auto dragonbox::to_decimal(float x) noexcept -> dragonbox::decimal_fp<float>;
-template FMT_API auto dragonbox::to_decimal(double x) noexcept -> dragonbox::decimal_fp<double>;
-
-    #if FMT_USE_LOCALE
-// DEPRECATED! locale_ref in the detail namespace
+#if FMT_USE_LOCALE
 template FMT_API locale_ref::locale_ref(const std::locale& loc);
 template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
-    #endif
+#endif
+
+namespace detail {
+
+template FMT_API auto dragonbox::to_decimal(float x) noexcept
+    -> dragonbox::decimal_fp<float>;
+template FMT_API auto dragonbox::to_decimal(double x) noexcept
+    -> dragonbox::decimal_fp<double>;

 // Explicit instantiations for char.

-template FMT_API auto thousands_sep_impl(locale_ref) -> thousands_sep_result<char>;
+template FMT_API auto thousands_sep_impl(locale_ref)
+    -> thousands_sep_result<char>;
 template FMT_API auto decimal_point_impl(locale_ref) -> char;

 // DEPRECATED!
 template FMT_API void buffer<char>::append(const char*, const char*);

-// DEPRECATED!
-template FMT_API void vformat_to(buffer<char>&,
-                                 string_view,
-                                 typename vformat_args<>::type,
-                                 locale_ref);
-
 // Explicit instantiations for wchar_t.

-template FMT_API auto thousands_sep_impl(locale_ref) -> thousands_sep_result<wchar_t>;
+template FMT_API auto thousands_sep_impl(locale_ref)
+    -> thousands_sep_result<wchar_t>;
 template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;

+// DEPRECATED!
 template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);

 }  // namespace detail
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -49,7 +49,8 @@ set(SPDLOG_UTESTS_SOURCES
    test_time_point.cpp
    test_stopwatch.cpp
    test_circular_q.cpp
-    test_bin_to_hex.cpp)
+    test_bin_to_hex.cpp
+    test_ringbuffer.cpp)

 if(NOT SPDLOG_NO_EXCEPTIONS)
    list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
@@ -74,7 +75,7 @@ function(spdlog_prepare_test test_target spdlog_lib)
    elseif(SPDLOG_SANITIZE_THREAD)
        spdlog_enable_thread_sanitizer(${test_target})
    endif()
-    add_test(NAME ${test_target} COMMAND ${test_target})
+    add_test(NAME ${test_target} COMMAND ${test_target} --order decl)
    set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()

--- a/tests/test_ringbuffer.cpp
+++ b/tests/test_ringbuffer.cpp
@@ -0,0 +1,52 @@
+#include "includes.h"
+#include "spdlog/sinks/ringbuffer_sink.h"
+
+TEST_CASE("ringbuffer invalid size", "[ringbuffer]") {
+    REQUIRE_THROWS_AS(spdlog::sinks::ringbuffer_sink_mt(0), spdlog::spdlog_ex);
+}
+
+TEST_CASE("ringbuffer stores formatted messages", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg1"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg2"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg3"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 3);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("msg1{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("msg2{}", default_eol));
+    REQUIRE(formatted[2] == spdlog::fmt_lib::format("msg3{}", default_eol));
+}
+
+TEST_CASE("ringbuffer overrun keeps last items", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(2);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "first"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "second"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "third"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("second{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("third{}", default_eol));
+}
+
+TEST_CASE("ringbuffer retrieval limit", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "A"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "B"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "C"});
+
+    auto formatted = sink.last_formatted(2);
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("B{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("C{}", default_eol));
+}
Author	SHA1	Message	Date
gabime	486b55554f	Version 1.16.0	2025-10-11 15:53:05 +03:00
gabime	1bea38edcc	clang-format	2025-10-11 15:50:16 +03:00
gabime	4418909af2	Bump fmt to 12.0.0	2025-10-11 15:18:15 +03:00
Angelio Mason	f1d748e5e3	Remove the fileapi.h include in os-inl.h (#3444 ) * Replaced fileapi.h include with windows.h, as instructed in https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-flushfilebuffers Otherwise this causes compilation error on older sdks. * Removed the fileapi.h include entirely, since windows.h is already included before --------- Co-authored-by: MasonAngelio <MasonAngelio>	2025-08-07 23:47:11 +03:00
Vitaly	3edc8036db	Run tests in the order they are declared in the source file. (#3451 ) Fixes an issue with running tests in random order in Catch2 3.9.0+.	2025-08-07 23:38:29 +03:00
Mihir Patel	9ecdf5c8a1	Added timeout for TCP calls such as connect, send, recv (#3432 ) * Now lets test on windows * I guess testing on windows passes. * Update tcp_client-windows.h Added default value to argument * Final edit * Update tcp_client-windows.h Changed improper misplaced includes.	2025-07-17 23:47:35 +03:00
Gabi Melman	737347d2df	Update linux.yml	2025-07-16 09:55:57 +03:00
Alexander	4f2b3d52f9	Update README.md (#3437 ) * Update README.md add example showcasing 2 loggers and `spdlog::set_level()` which set level not only to default logger, but to all registed loggers * Update README.md * simplify * simplify	2025-07-16 08:59:51 +03:00
Joshua Chapman	4397dac510	chore(cmake): add option to override CMAKE_DEBUG_POSTFIX (#3433 ) This will make it possible to use the pkg-config with CMake debug build.	2025-07-08 22:52:42 +03:00
Gabi Melman	6fd67ce169	Update windows.yml remove msvc 2019 build	2025-07-06 10:08:55 +03:00
Gabi Melman	4619e18a16	Update windows.yml	2025-07-06 09:53:42 +03:00
Gabi Melman	a6215527f4	Fix ringbuffer tests for newline (#3436 )	2025-07-06 08:38:48 +03:00