Fixed issue #3360

2025-09-28 17:19:34 +08:00 · 2025-03-17 15:31:40 +02:00
45 changed files with 673 additions and 848 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,38 +18,39 @@ include(GNUInstallDirs)
 # ---------------------------------------------------------------------------------------
 # Set default build to release
 # ---------------------------------------------------------------------------------------
-if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Compiler config
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_USE_STD_FORMAT)
+if (SPDLOG_USE_STD_FORMAT)
    set(CMAKE_CXX_STANDARD 20)
    set(CMAKE_CXX_STANDARD_REQUIRED ON)
-elseif(NOT CMAKE_CXX_STANDARD)
+elseif (NOT CMAKE_CXX_STANDARD)
    set(CMAKE_CXX_STANDARD 11)
    set(CMAKE_CXX_STANDARD_REQUIRED ON)
-endif()
+endif ()
+

 set(CMAKE_CXX_EXTENSIONS OFF)

-if(CMAKE_SYSTEM_NAME MATCHES "CYGWIN" OR CMAKE_SYSTEM_NAME MATCHES "MSYS" OR CMAKE_SYSTEM_NAME MATCHES "MINGW")
+if (CMAKE_SYSTEM_NAME MATCHES "CYGWIN" OR CMAKE_SYSTEM_NAME MATCHES "MSYS" OR CMAKE_SYSTEM_NAME MATCHES "MINGW")
    set(CMAKE_CXX_EXTENSIONS ON)
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Set SPDLOG_MASTER_PROJECT to ON if we are building spdlog
 # ---------------------------------------------------------------------------------------
 # Check if spdlog is being used directly or via add_subdirectory, but allow overriding
-if(NOT DEFINED SPDLOG_MASTER_PROJECT)
-    if(CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+if (NOT DEFINED SPDLOG_MASTER_PROJECT)
+    if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
        set(SPDLOG_MASTER_PROJECT ON)
-    else()
+    else ()
        set(SPDLOG_MASTER_PROJECT OFF)
-    endif()
-endif()
+    endif ()
+endif ()

 option(SPDLOG_BUILD_ALL "Build all artifacts" OFF)

@@ -76,9 +77,9 @@ option(SPDLOG_BUILD_BENCH "Build benchmarks (Requires https://github.com/google/
 # sanitizer options
 option(SPDLOG_SANITIZE_ADDRESS "Enable address sanitizer in tests" OFF)
 option(SPDLOG_SANITIZE_THREAD "Enable thread sanitizer in tests" OFF)
-if(SPDLOG_SANITIZE_ADDRESS AND SPDLOG_SANITIZE_THREAD)
+if (SPDLOG_SANITIZE_ADDRESS AND SPDLOG_SANITIZE_THREAD)
    message(FATAL_ERROR "SPDLOG_SANITIZE_ADDRESS and SPDLOG_SANITIZE_THREAD are mutually exclusive")
-endif()
+endif ()

 # warning options
 option(SPDLOG_BUILD_WARNINGS "Enable compiler warnings" OFF)
@@ -91,61 +92,61 @@ option(SPDLOG_FMT_EXTERNAL "Use external fmt library instead of bundled" OFF)
 option(SPDLOG_FMT_EXTERNAL_HO "Use external fmt header-only library instead of bundled" OFF)
 option(SPDLOG_NO_EXCEPTIONS "Compile with -fno-exceptions. Call abort() on any spdlog exceptions" OFF)

-if(SPDLOG_FMT_EXTERNAL AND SPDLOG_FMT_EXTERNAL_HO)
+if (SPDLOG_FMT_EXTERNAL AND SPDLOG_FMT_EXTERNAL_HO)
    message(FATAL_ERROR "SPDLOG_FMT_EXTERNAL and SPDLOG_FMT_EXTERNAL_HO are mutually exclusive")
-endif()
+endif ()

-if(SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL_HO)
+if (SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL_HO)
    message(FATAL_ERROR "SPDLOG_USE_STD_FORMAT and SPDLOG_FMT_EXTERNAL_HO are mutually exclusive")
-endif()
+endif ()

-if(SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL)
+if (SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL)
    message(FATAL_ERROR "SPDLOG_USE_STD_FORMAT and SPDLOG_FMT_EXTERNAL are mutually exclusive")
-endif()
+endif ()

 # misc tweakme options
-if(WIN32)
+if (WIN32)
    option(SPDLOG_WCHAR_SUPPORT "Support wchar api" OFF)
    option(SPDLOG_WCHAR_FILENAMES "Support wchar filenames" OFF)
    option(SPDLOG_WCHAR_CONSOLE "Support wchar output to console" OFF)
-else()
+else ()
    set(SPDLOG_WCHAR_SUPPORT OFF CACHE BOOL "non supported option" FORCE)
    set(SPDLOG_WCHAR_FILENAMES OFF CACHE BOOL "non supported option" FORCE)
    set(SPDLOG_WCHAR_CONSOLE OFF CACHE BOOL "non supported option" FORCE)
-endif()
+endif ()

-if(MSVC)
+if (MSVC)
    option(SPDLOG_MSVC_UTF8 "Enable/disable msvc /utf-8 flag required by fmt lib" ON)
-endif()
+endif ()

-if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
    option(SPDLOG_CLOCK_COARSE "Use CLOCK_REALTIME_COARSE instead of the regular clock," OFF)
-else()
+else ()
    set(SPDLOG_CLOCK_COARSE OFF CACHE BOOL "non supported option" FORCE)
-endif()
+endif ()

 option(SPDLOG_PREVENT_CHILD_FD "Prevent from child processes to inherit log file descriptors" OFF)
 option(SPDLOG_NO_THREAD_ID "prevent spdlog from querying the thread id on each log call if thread id is not needed" OFF)
 option(SPDLOG_NO_TLS "prevent spdlog from using thread local storage" OFF)
 option(
-    SPDLOG_NO_ATOMIC_LEVELS
-    "prevent spdlog from using of std::atomic log levels (use only if your code never modifies log levels concurrently"
-    OFF)
+        SPDLOG_NO_ATOMIC_LEVELS
+        "prevent spdlog from using of std::atomic log levels (use only if your code never modifies log levels concurrently"
+        OFF)
 option(SPDLOG_DISABLE_DEFAULT_LOGGER "Disable default logger creation" OFF)
 option(SPDLOG_FWRITE_UNLOCKED "Use the unlocked variant of fwrite. Leave this on unless your libc doesn't have it" ON)

 # clang-tidy
 option(SPDLOG_TIDY "run clang-tidy" OFF)

-if(SPDLOG_TIDY)
+if (SPDLOG_TIDY)
    set(CMAKE_CXX_CLANG_TIDY "clang-tidy")
    set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
    message(STATUS "Enabled clang-tidy")
-endif()
+endif ()

-if(SPDLOG_BUILD_PIC)
+if (SPDLOG_BUILD_PIC)
    set(CMAKE_POSITION_INDEPENDENT_CODE ON)
-endif()
+endif ()

 find_package(Threads REQUIRED)
 message(STATUS "Build type: " ${CMAKE_BUILD_TYPE})
@@ -154,56 +155,56 @@ message(STATUS "Build type: " ${CMAKE_BUILD_TYPE})
 # ---------------------------------------------------------------------------------------
 set(SPDLOG_SRCS src/spdlog.cpp src/stdout_sinks.cpp src/color_sinks.cpp src/file_sinks.cpp src/async.cpp src/cfg.cpp)

-if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
    list(APPEND SPDLOG_SRCS src/bundled_fmtlib_format.cpp)
-endif()
+endif ()

-if(SPDLOG_BUILD_SHARED OR BUILD_SHARED_LIBS)
-    if(WIN32)
+if (SPDLOG_BUILD_SHARED OR BUILD_SHARED_LIBS)
+    if (WIN32)
        configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/version.rc.in ${CMAKE_CURRENT_BINARY_DIR}/version.rc @ONLY)
        list(APPEND SPDLOG_SRCS ${CMAKE_CURRENT_BINARY_DIR}/version.rc)
-    endif()
+    endif ()
    add_library(spdlog SHARED ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
    target_compile_definitions(spdlog PUBLIC SPDLOG_SHARED_LIB)
-    if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
        target_compile_options(spdlog PUBLIC $<$<AND:$<CXX_COMPILER_ID:MSVC>,$<NOT:$<COMPILE_LANGUAGE:CUDA>>>:/wd4251
-                                             /wd4275>)
-    endif()
-    if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+                /wd4275>)
+    endif ()
+    if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
        target_compile_definitions(spdlog PRIVATE FMT_LIB_EXPORT PUBLIC FMT_SHARED)
-    endif()
-else()
+    endif ()
+else ()
    add_library(spdlog STATIC ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
-endif()
+endif ()

 add_library(spdlog::spdlog ALIAS spdlog)

 set(SPDLOG_INCLUDES_LEVEL "")
-if(SPDLOG_SYSTEM_INCLUDES)
+if (SPDLOG_SYSTEM_INCLUDES)
    set(SPDLOG_INCLUDES_LEVEL "SYSTEM")
-endif()
+endif ()

 target_compile_definitions(spdlog PUBLIC SPDLOG_COMPILED_LIB)
 target_include_directories(spdlog ${SPDLOG_INCLUDES_LEVEL} PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
-                                                                  "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
+        "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
 target_link_libraries(spdlog PUBLIC Threads::Threads)
 spdlog_enable_warnings(spdlog)

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

-if(COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
+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)
    target_precompile_headers(spdlog PRIVATE ${PROJECT_BINARY_DIR}/spdlog_pch.h)
-endif()
+endif ()

 # sanitizer support
-if(SPDLOG_SANITIZE_ADDRESS)
+if (SPDLOG_SANITIZE_ADDRESS)
    spdlog_enable_addr_sanitizer(spdlog)
-elseif(SPDLOG_SANITIZE_THREAD)
+elseif (SPDLOG_SANITIZE_THREAD)
    spdlog_enable_thread_sanitizer(spdlog)
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Header only version
@@ -212,134 +213,132 @@ add_library(spdlog_header_only INTERFACE)
 add_library(spdlog::spdlog_header_only ALIAS spdlog_header_only)

 target_include_directories(
-    spdlog_header_only ${SPDLOG_INCLUDES_LEVEL} INTERFACE "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
-                                                          "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
+        spdlog_header_only ${SPDLOG_INCLUDES_LEVEL} INTERFACE "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+        "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
 target_link_libraries(spdlog_header_only INTERFACE Threads::Threads)

 # ---------------------------------------------------------------------------------------
 # Use fmt package if using external fmt
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_FMT_EXTERNAL OR SPDLOG_FMT_EXTERNAL_HO)
-    if(NOT TARGET fmt::fmt)
+if (SPDLOG_FMT_EXTERNAL OR SPDLOG_FMT_EXTERNAL_HO)
+    if (NOT TARGET fmt::fmt)
        find_package(fmt CONFIG REQUIRED)
-    endif()
+    endif ()
    target_compile_definitions(spdlog PUBLIC SPDLOG_FMT_EXTERNAL)
    target_compile_definitions(spdlog_header_only INTERFACE SPDLOG_FMT_EXTERNAL)

    # use external fmt-header-only
-    if(SPDLOG_FMT_EXTERNAL_HO)
+    if (SPDLOG_FMT_EXTERNAL_HO)
        target_link_libraries(spdlog PUBLIC fmt::fmt-header-only)
        target_link_libraries(spdlog_header_only INTERFACE fmt::fmt-header-only)
-    else() # use external compile fmt
+    else () # use external compile fmt
        target_link_libraries(spdlog PUBLIC fmt::fmt)
        target_link_libraries(spdlog_header_only INTERFACE fmt::fmt)
-    endif()
+    endif ()

    set(PKG_CONFIG_REQUIRES fmt) # add dependency to pkg-config
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Check if fwrite_unlocked/_fwrite_nolock is available
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_FWRITE_UNLOCKED)
+if (SPDLOG_FWRITE_UNLOCKED)
    include(CheckSymbolExists)
-    if(WIN32)
+    if (WIN32)
        check_symbol_exists(_fwrite_nolock "stdio.h" HAVE_FWRITE_UNLOCKED)
-    else()
+    else ()
        check_symbol_exists(fwrite_unlocked "stdio.h" HAVE_FWRITE_UNLOCKED)
-    endif()
-    if(HAVE_FWRITE_UNLOCKED)
+    endif ()
+    if (HAVE_FWRITE_UNLOCKED)
        target_compile_definitions(spdlog PRIVATE SPDLOG_FWRITE_UNLOCKED)
        target_compile_definitions(spdlog_header_only INTERFACE SPDLOG_FWRITE_UNLOCKED)
-    endif()
-endif()
+    endif ()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Add required libraries for Android CMake build
 # ---------------------------------------------------------------------------------------
-if(ANDROID)
+if (ANDROID)
    target_link_libraries(spdlog PUBLIC log)
    target_link_libraries(spdlog_header_only INTERFACE log)
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Misc definitions according to tweak options
 # ---------------------------------------------------------------------------------------
 set(SPDLOG_WCHAR_TO_UTF8_SUPPORT ${SPDLOG_WCHAR_SUPPORT})
 set(SPDLOG_UTF8_TO_WCHAR_CONSOLE ${SPDLOG_WCHAR_CONSOLE})
-foreach(
-    SPDLOG_OPTION
-    SPDLOG_WCHAR_TO_UTF8_SUPPORT
-    SPDLOG_UTF8_TO_WCHAR_CONSOLE
-    SPDLOG_WCHAR_FILENAMES
-    SPDLOG_NO_EXCEPTIONS
-    SPDLOG_CLOCK_COARSE
-    SPDLOG_PREVENT_CHILD_FD
-    SPDLOG_NO_THREAD_ID
-    SPDLOG_NO_TLS
-    SPDLOG_NO_ATOMIC_LEVELS
-    SPDLOG_DISABLE_DEFAULT_LOGGER
-    SPDLOG_USE_STD_FORMAT)
-    if(${SPDLOG_OPTION})
+foreach (
+        SPDLOG_OPTION
+        SPDLOG_WCHAR_TO_UTF8_SUPPORT
+        SPDLOG_UTF8_TO_WCHAR_CONSOLE
+        SPDLOG_WCHAR_FILENAMES
+        SPDLOG_NO_EXCEPTIONS
+        SPDLOG_CLOCK_COARSE
+        SPDLOG_PREVENT_CHILD_FD
+        SPDLOG_NO_THREAD_ID
+        SPDLOG_NO_TLS
+        SPDLOG_NO_ATOMIC_LEVELS
+        SPDLOG_DISABLE_DEFAULT_LOGGER
+        SPDLOG_USE_STD_FORMAT)
+    if (${SPDLOG_OPTION})
        target_compile_definitions(spdlog PUBLIC ${SPDLOG_OPTION})
        target_compile_definitions(spdlog_header_only INTERFACE ${SPDLOG_OPTION})
-    endif()
-endforeach()
+    endif ()
+endforeach ()

-if(MSVC)
+if (MSVC)
    target_compile_options(spdlog PRIVATE "/Zc:__cplusplus")
    target_compile_options(spdlog_header_only INTERFACE "/Zc:__cplusplus")
-    if(SPDLOG_MSVC_UTF8)
-        # fmtlib requires the /utf-8 flag when building with msvc. see https://github.com/fmtlib/fmt/pull/4159 on the
-        # purpose of the additional
+    if (SPDLOG_MSVC_UTF8)
+        # fmtlib requires the /utf-8 flag when building with msvc.
+        # see https://github.com/fmtlib/fmt/pull/4159 on the purpose of the additional
        # "$<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:MSVC>>"
        target_compile_options(spdlog PUBLIC $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:MSVC>>:/utf-8>)
-        target_compile_options(spdlog_header_only
-                               INTERFACE $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:MSVC>>:/utf-8>)
-    endif()
-endif()
+        target_compile_options(spdlog_header_only INTERFACE $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:MSVC>>:/utf-8>)
+    endif ()
+endif ()

 # ---------------------------------------------------------------------------------------
 # If exceptions are disabled, disable them in the bundled fmt as well
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_NO_EXCEPTIONS)
-    if(NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
-        target_compile_definitions(spdlog PUBLIC FMT_USE_EXCEPTIONS=0)
-    endif()
-    if(NOT MSVC)
+if (SPDLOG_NO_EXCEPTIONS)
+    if (NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+        target_compile_definitions(spdlog PUBLIC FMT_EXCEPTIONS=0)
+    endif ()
+    if (NOT MSVC)
        target_compile_options(spdlog PRIVATE -fno-exceptions)
-    else()
+    else ()
        target_compile_options(spdlog PRIVATE /EHs-c-)
-        target_compile_definitions(spdlog PRIVATE _HAS_EXCEPTIONS=0)
-    endif()
-endif()
+    endif ()
+endif ()
 # ---------------------------------------------------------------------------------------
 # Build binaries
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_BUILD_EXAMPLE OR SPDLOG_BUILD_EXAMPLE_HO OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_EXAMPLE OR SPDLOG_BUILD_EXAMPLE_HO OR SPDLOG_BUILD_ALL)
    message(STATUS "Generating example(s)")
    add_subdirectory(example)
    spdlog_enable_warnings(example)
-    if(SPDLOG_BUILD_EXAMPLE_HO)
+    if (SPDLOG_BUILD_EXAMPLE_HO)
        spdlog_enable_warnings(example_header_only)
-    endif()
-endif()
+    endif ()
+endif ()

-if(SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
    message(STATUS "Generating tests")
    enable_testing()
    add_subdirectory(tests)
-endif()
+endif ()

-if(SPDLOG_BUILD_BENCH OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_BENCH OR SPDLOG_BUILD_ALL)
    message(STATUS "Generating benchmarks")
    add_subdirectory(bench)
-endif()
+endif ()

 # ---------------------------------------------------------------------------------------
 # Install
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_INSTALL)
+if (SPDLOG_INSTALL)
    message(STATUS "Generating install")
    set(project_config_in "${CMAKE_CURRENT_LIST_DIR}/cmake/spdlogConfig.cmake.in")
    set(project_config_out "${CMAKE_CURRENT_BINARY_DIR}/spdlogConfig.cmake")
@@ -354,30 +353,30 @@ if(SPDLOG_INSTALL)
    # ---------------------------------------------------------------------------------------
    install(DIRECTORY include/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}" PATTERN "fmt/bundled" EXCLUDE)
    install(
-        TARGETS spdlog spdlog_header_only
-        EXPORT spdlog
-        LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+            TARGETS spdlog spdlog_header_only
+            EXPORT spdlog
+            LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})

-    if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+    if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
        install(DIRECTORY include/${PROJECT_NAME}/fmt/bundled/
                DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}/fmt/bundled/")
-    endif()
+    endif ()

    # ---------------------------------------------------------------------------------------
    # Install pkg-config file
    # ---------------------------------------------------------------------------------------
-    if(IS_ABSOLUTE "${CMAKE_INSTALL_INCLUDEDIR}")
+    if (IS_ABSOLUTE "${CMAKE_INSTALL_INCLUDEDIR}")
        set(PKG_CONFIG_INCLUDEDIR "${CMAKE_INSTALL_INCLUDEDIR}")
-    else()
+    else ()
        set(PKG_CONFIG_INCLUDEDIR "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
-    endif()
-    if(IS_ABSOLUTE "${CMAKE_INSTALL_LIBDIR}")
+    endif ()
+    if (IS_ABSOLUTE "${CMAKE_INSTALL_LIBDIR}")
        set(PKG_CONFIG_LIBDIR "${CMAKE_INSTALL_LIBDIR}")
-    else()
+    else ()
        set(PKG_CONFIG_LIBDIR "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
-    endif()
+    endif ()
    get_target_property(PKG_CONFIG_DEFINES spdlog INTERFACE_COMPILE_DEFINITIONS)
    string(REPLACE ";" " -D" PKG_CONFIG_DEFINES "${PKG_CONFIG_DEFINES}")
    string(CONCAT PKG_CONFIG_DEFINES "-D" "${PKG_CONFIG_DEFINES}")
@@ -388,7 +387,7 @@ if(SPDLOG_INSTALL)
    # Install CMake config files
    # ---------------------------------------------------------------------------------------
    export(TARGETS spdlog spdlog_header_only NAMESPACE spdlog::
-           FILE "${CMAKE_CURRENT_BINARY_DIR}/${config_targets_file}")
+            FILE "${CMAKE_CURRENT_BINARY_DIR}/${config_targets_file}")
    install(EXPORT spdlog DESTINATION ${export_dest_dir} NAMESPACE spdlog:: FILE ${config_targets_file})

    include(CMakePackageConfigHelpers)
@@ -401,4 +400,4 @@ if(SPDLOG_INSTALL)
    # Support creation of installable packages
    # ---------------------------------------------------------------------------------------
    include(cmake/spdlogCPack.cmake)
-endif()
+endif ()
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Fast C++ logging library

 ## Install
 #### Header-only version
-Copy the include [folder](include/spdlog) to your build tree and use a C++11 compiler.
+Copy the include [folder](https://github.com/gabime/spdlog/tree/v1.x/include/spdlog) to your build tree and use a C++11 compiler.

 #### Compiled version (recommended - much faster compile times)
 ```console
@@ -19,7 +19,7 @@ $ git clone https://github.com/gabime/spdlog.git
 $ cd spdlog && mkdir build && cd build
 $ cmake .. && cmake --build .
 ```
-see example [CMakeLists.txt](example/CMakeLists.txt) on how to use.
+see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/CMakeLists.txt) on how to use.

 ## Platforms
 * Linux, FreeBSD, OpenBSD, Solaris, AIX
@@ -48,7 +48,7 @@ see example [CMakeLists.txt](example/CMakeLists.txt) on how to use.
 * Headers only or compiled
 * Feature-rich formatting, using the excellent [fmt](https://github.com/fmtlib/fmt) library.
 * Asynchronous mode (optional)
-* [Custom](https://github.com/gabime/spdlog/wiki/Custom-formatting) formatting.
+* [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) formatting.
 * Multi/Single threaded loggers.
 * Various log targets:
  * Rotating log files.
@@ -58,7 +58,7 @@ see example [CMakeLists.txt](example/CMakeLists.txt) on how to use.
  * Windows event log.
  * Windows debugger (```OutputDebugString(..)```).
  * Log to Qt widgets ([example](#log-to-qt-with-nice-colors)).
-  * Easily [extendable](https://github.com/gabime/spdlog/wiki/Sinks#implementing-your-own-sink) with custom log targets.
+  * Easily [extendable](https://github.com/gabime/spdlog/wiki/4.-Sinks#implementing-your-own-sink) with custom log targets.
 * Log filtering - log levels can be modified at runtime as well as compile time.
 * Support for loading log levels from argv or environment var.
 * [Backtrace](#backtrace-support) support - store debug messages in a ring buffer and display them later on demand.
@@ -467,7 +467,7 @@ void mdc_example()
 ---
 ## Benchmarks

-Below are some [benchmarks](bench/bench.cpp) done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
+Below are some [benchmarks](https://github.com/gabime/spdlog/blob/v1.x/bench/bench.cpp) done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz

 #### Synchronous mode
 ```
@@ -519,8 +519,7 @@ Below are some [benchmarks](bench/bench.cpp) done in Ubuntu 64 bit, Intel i7-477
 ```

 ## Documentation
-
-Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki) pages.
+Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.

 ---

--- a/cmake/pch.h.in
+++ b/cmake/pch.h.in
@@ -10,6 +10,7 @@

 // details/file_helper-inl.h
 // details/os-inl.h
+// fmt/bundled/core.h
 // fmt/bundled/posix.h
 // logger-inl.h
 // sinks/daily_file_sink.h
@@ -22,6 +23,7 @@

 // details/os-inl.h
 // details/pattern_formatter-inl.h
+// fmt/bundled/core.h
 // fmt/bundled/format-inl.h
 #include <cstring>

@@ -71,6 +73,7 @@
 // details/registry.h
 // details/tcp_client-windows.h
 // details/tcp_client.h
+// fmt/bundled/core.h
 // sinks/android_sink.h
 // sinks/ansicolor_sink.h
 // sinks/basic_file_sink.h
@@ -147,6 +150,7 @@

 // common.h
 // details/fmt_helper.h
+// fmt/bundled/core.h
 // fmt/bundled/ranges.h
 #include <type_traits>

@@ -251,4 +255,4 @@
 #include <mutex>

 // spdlog
-#include <spdlog/common.h>
+#include <spdlog/common.h>
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -269,7 +269,7 @@ void multi_sink_example() {
 struct my_type {
    int i = 0;
    explicit my_type(int i)
-        : i(i) {}
+        : i(i){}
 };

 #ifndef SPDLOG_USE_STD_FORMAT  // when using fmtlib
@@ -382,14 +382,14 @@ void replace_default_logger_example() {
    spdlog::set_default_logger(old_logger);
 }

-// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread
-// local storage. Each thread maintains its own MDC, which loggers use to append diagnostic
-// information to log outputs. Note: it is not supported in asynchronous mode due to its reliance on
-// thread-local storage.
+// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
+// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
+// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.

 #ifndef SPDLOG_NO_TLS
    #include "spdlog/mdc.h"
-void mdc_example() {
+void mdc_example()
+{
    spdlog::mdc::put("key1", "value1");
    spdlog::mdc::put("key2", "value2");
    // if not using the default format, you can use the %& formatter to print mdc data as well
--- a/include/spdlog/async.h
+++ b/include/spdlog/async.h
@@ -89,7 +89,8 @@ inline void init_thread_pool(size_t q_size,
 }

 inline void init_thread_pool(size_t q_size, size_t thread_count) {
-    init_thread_pool(q_size, thread_count, [] {}, [] {});
+    init_thread_pool(
+        q_size, thread_count, [] {}, [] {});
 }

 // get the global thread pool.
--- a/include/spdlog/async_logger-inl.h
+++ b/include/spdlog/async_logger-inl.h
@@ -33,7 +33,7 @@ SPDLOG_INLINE spdlog::async_logger::async_logger(std::string logger_name,
 // send the log message to the thread pool
 SPDLOG_INLINE void spdlog::async_logger::sink_it_(const details::log_msg &msg){
    SPDLOG_TRY{if (auto pool_ptr = thread_pool_.lock()){
-        pool_ptr -> post_log(shared_from_this(), msg, overflow_policy_);
+        pool_ptr->post_log(shared_from_this(), msg, overflow_policy_);
 }
 else {
    throw_spdlog_ex("async log: thread pool doesn't exist anymore");
@@ -45,7 +45,7 @@ SPDLOG_LOGGER_CATCH(msg.source)
 // send flush request to the thread pool
 SPDLOG_INLINE void spdlog::async_logger::flush_(){
    SPDLOG_TRY{if (auto pool_ptr = thread_pool_.lock()){
-        pool_ptr -> post_flush(shared_from_this(), overflow_policy_);
+        pool_ptr->post_flush(shared_from_this(), overflow_policy_);
 }
 else {
    throw_spdlog_ex("async flush: thread pool doesn't exist anymore");
--- a/include/spdlog/common.h
+++ b/include/spdlog/common.h
@@ -364,7 +364,7 @@ SPDLOG_CONSTEXPR_FUNC spdlog::wstring_view_t to_string_view(spdlog::wstring_view
 }
 #endif

-#if defined(SPDLOG_USE_STD_FORMAT) && __cpp_lib_format >= 202207L
+#if defined(SPDLOG_USE_STD_FORMAT) &&  __cpp_lib_format >= 202207L
 template <typename T, typename... Args>
 SPDLOG_CONSTEXPR_FUNC std::basic_string_view<T> to_string_view(
    std::basic_format_string<T, Args...> fmt) SPDLOG_NOEXCEPT {
--- a/include/spdlog/details/os-inl.h
+++ b/include/spdlog/details/os-inl.h
@@ -265,10 +265,9 @@ SPDLOG_INLINE int utc_minutes_offset(const std::tm &tm) {
    return offset;
 #else

-    #if defined(sun) || defined(__sun) || defined(_AIX) ||                        \
-        (defined(__NEWLIB__) && !defined(__TM_GMTOFF)) ||                         \
-        (!defined(__APPLE__) && !defined(_BSD_SOURCE) && !defined(_GNU_SOURCE) && \
-         (!defined(_POSIX_VERSION) || (_POSIX_VERSION < 202405L)))
+    #if defined(sun) || defined(__sun) || defined(_AIX) || \
+        (defined(__NEWLIB__) && !defined(__TM_GMTOFF)) ||  \
+        (!defined(_BSD_SOURCE) && !defined(_GNU_SOURCE))
    // 'tm_gmtoff' field is BSD extension and it's missing on SunOS/Solaris
    struct helper {
        static long int calculate_gmt_offset(const std::tm &localtm = details::os::localtime(),
@@ -483,12 +482,13 @@ SPDLOG_INLINE void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target) {
    }

    // find the size to allocate for the result buffer
-    int result_size = ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, NULL, 0);
+    int result_size =
+        ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, NULL, 0);

    if (result_size > 0) {
        target.resize(result_size);
-        result_size =
-            ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(), result_size);
+        result_size = ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(),
+                                            result_size);
        if (result_size > 0) {
            assert(result_size == target.size());
            return;
@@ -592,13 +592,13 @@ SPDLOG_INLINE bool fsync(FILE *fp) {
 // Do non-locking fwrite if possible by the os or use the regular locking fwrite
 // Return true on success.
 SPDLOG_INLINE bool fwrite_bytes(const void *ptr, const size_t n_bytes, FILE *fp) {
-#if defined(_WIN32) && defined(SPDLOG_FWRITE_UNLOCKED)
+    #if defined(_WIN32) && defined(SPDLOG_FWRITE_UNLOCKED)
    return _fwrite_nolock(ptr, 1, n_bytes, fp) == n_bytes;
-#elif defined(SPDLOG_FWRITE_UNLOCKED)
+    #elif defined(SPDLOG_FWRITE_UNLOCKED)
    return ::fwrite_unlocked(ptr, 1, n_bytes, fp) == n_bytes;
-#else
+    #else
    return std::fwrite(ptr, 1, n_bytes, fp) == n_bytes;
-#endif
+    #endif
 }

 }  // namespace os
--- a/include/spdlog/details/registry-inl.h
+++ b/include/spdlog/details/registry-inl.h
@@ -54,11 +54,6 @@ SPDLOG_INLINE void registry::register_logger(std::shared_ptr<logger> new_logger)
    register_logger_(std::move(new_logger));
 }

-SPDLOG_INLINE void registry::register_or_replace(std::shared_ptr<logger> new_logger) {
-    std::lock_guard<std::mutex> lock(logger_map_mutex_);
-    register_or_replace_(std::move(new_logger));
-}
-
 SPDLOG_INLINE void registry::initialize_logger(std::shared_ptr<logger> new_logger) {
    std::lock_guard<std::mutex> lock(logger_map_mutex_);
    new_logger->set_formatter(formatter_->clone());
@@ -257,14 +252,10 @@ SPDLOG_INLINE void registry::throw_if_exists_(const std::string &logger_name) {
 }

 SPDLOG_INLINE void registry::register_logger_(std::shared_ptr<logger> new_logger) {
-    auto &logger_name = new_logger->name();
+    auto logger_name = new_logger->name();
    throw_if_exists_(logger_name);
    loggers_[logger_name] = std::move(new_logger);
 }

-SPDLOG_INLINE void registry::register_or_replace_(std::shared_ptr<logger> new_logger) {
-    loggers_[new_logger->name()] = std::move(new_logger);
-}
-
 }  // namespace details
 }  // namespace spdlog
--- a/include/spdlog/details/registry.h
+++ b/include/spdlog/details/registry.h
@@ -31,7 +31,6 @@ public:
    registry &operator=(const registry &) = delete;

    void register_logger(std::shared_ptr<logger> new_logger);
-    void register_or_replace(std::shared_ptr<logger> new_logger);
    void initialize_logger(std::shared_ptr<logger> new_logger);
    std::shared_ptr<logger> get(const std::string &logger_name);
    std::shared_ptr<logger> default_logger();
@@ -106,7 +105,6 @@ private:

    void throw_if_exists_(const std::string &logger_name);
    void register_logger_(std::shared_ptr<logger> new_logger);
-    void register_or_replace_(std::shared_ptr<logger> new_logger);
    bool set_level_from_cfg_(logger *logger);
    std::mutex logger_map_mutex_, flusher_mutex_;
    std::recursive_mutex tp_mutex_;
--- a/include/spdlog/details/thread_pool-inl.h
+++ b/include/spdlog/details/thread_pool-inl.h
@@ -38,7 +38,8 @@ SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
    : thread_pool(q_max_items, threads_n, on_thread_start, [] {}) {}

 SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items, size_t threads_n)
-    : thread_pool(q_max_items, threads_n, [] {}, [] {}) {}
+    : thread_pool(
+          q_max_items, threads_n, [] {}, [] {}) {}

 // message all threads to terminate gracefully join them
 SPDLOG_INLINE thread_pool::~thread_pool() {
--- a/include/spdlog/fmt/bin_to_hex.h
+++ b/include/spdlog/fmt/bin_to_hex.h
@@ -142,8 +142,8 @@ struct formatter<spdlog::details::dump_info<T>, char> {

    // format the given bytes range as hex
    template <typename FormatContext, typename Container>
-    auto format(const spdlog::details::dump_info<Container> &the_range,
-                FormatContext &ctx) const -> decltype(ctx.out()) {
+    auto format(const spdlog::details::dump_info<Container> &the_range, FormatContext &ctx) const
+        -> decltype(ctx.out()) {
        SPDLOG_CONSTEXPR const char *hex_upper = "0123456789ABCDEF";
        SPDLOG_CONSTEXPR const char *hex_lower = "0123456789abcdef";
        const char *hex_chars = use_uppercase ? hex_upper : hex_lower;
--- 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 110103

 // Detect compiler versions.
 #if defined(__clang__) && !defined(__ibmxl__)
@@ -209,6 +209,20 @@
 #  define FMT_DEPRECATED /* deprecated */
 #endif

+#ifdef FMT_ALWAYS_INLINE
+// Use the provided definition.
+#elif FMT_GCC_VERSION || FMT_CLANG_VERSION
+#  define FMT_ALWAYS_INLINE inline __attribute__((always_inline))
+#else
+#  define FMT_ALWAYS_INLINE inline
+#endif
+// A version of FMT_ALWAYS_INLINE to prevent code bloat in debug mode.
+#ifdef NDEBUG
+#  define FMT_INLINE FMT_ALWAYS_INLINE
+#else
+#  define FMT_INLINE inline
+#endif
+
 #if FMT_GCC_VERSION || FMT_CLANG_VERSION
 #  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
 #else
@@ -235,28 +249,6 @@
 #  define FMT_MSC_WARNING(...)
 #endif

-// Enable minimal optimizations for more compact code in debug mode.
-FMT_PRAGMA_GCC(push_options)
-#if !defined(__OPTIMIZE__) && !defined(__CUDACC__) && !defined(FMT_MODULE)
-FMT_PRAGMA_GCC(optimize("Og"))
-#  define FMT_GCC_OPTIMIZED
-#endif
-FMT_PRAGMA_CLANG(diagnostic push)
-
-#ifdef FMT_ALWAYS_INLINE
-// Use the provided definition.
-#elif FMT_GCC_VERSION || FMT_CLANG_VERSION
-#  define FMT_ALWAYS_INLINE inline __attribute__((always_inline))
-#else
-#  define FMT_ALWAYS_INLINE inline
-#endif
-// A version of FMT_ALWAYS_INLINE to prevent code bloat in debug mode.
-#if defined(NDEBUG) || defined(FMT_GCC_OPTIMIZED)
-#  define FMT_INLINE FMT_ALWAYS_INLINE
-#else
-#  define FMT_INLINE inline
-#endif
-
 #ifndef FMT_BEGIN_NAMESPACE
 #  define FMT_BEGIN_NAMESPACE \
    namespace fmt {           \
@@ -302,8 +294,15 @@ FMT_PRAGMA_CLANG(diagnostic push)
 #endif

 #define FMT_APPLY_VARIADIC(expr) \
-  using unused = int[];          \
-  (void)unused { 0, (expr, 0)... }
+  using ignore = int[];          \
+  (void)ignore { 0, (expr, 0)... }
+
+// Enable minimal optimizations for more compact code in debug mode.
+FMT_PRAGMA_GCC(push_options)
+#if !defined(__OPTIMIZE__) && !defined(__CUDACC__) && !defined(FMT_MODULE)
+FMT_PRAGMA_GCC(optimize("Og"))
+#endif
+FMT_PRAGMA_CLANG(diagnostic push)

 FMT_BEGIN_NAMESPACE

@@ -326,8 +325,8 @@ using underlying_t = typename std::underlying_type<T>::type;
 template <typename T> using decay_t = typename std::decay<T>::type;
 using nullptr_t = decltype(nullptr);

-#if (FMT_GCC_VERSION && FMT_GCC_VERSION < 500) || FMT_MSC_VERSION
-// A workaround for gcc 4.9 & MSVC v141 to make void_t work in a SFINAE context.
+#if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
+// A workaround for gcc 4.9 to make void_t work in a SFINAE context.
 template <typename...> struct void_t_impl {
  using type = void;
 };
@@ -527,20 +526,20 @@ template <typename Char> class basic_string_view {

  constexpr basic_string_view() noexcept : data_(nullptr), size_(0) {}

-  /// Constructs a string view object from a C string and a size.
+  /// Constructs a string reference object from a C string and a size.
  constexpr basic_string_view(const Char* s, size_t count) noexcept
      : data_(s), size_(count) {}

  constexpr basic_string_view(nullptr_t) = delete;

-  /// Constructs a string view object from a C string.
+  /// Constructs a string reference object from a C string.
 #if FMT_GCC_VERSION
  FMT_ALWAYS_INLINE
 #endif
  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.
+#if FMT_HAS_BUILTIN(__buitin_strlen) || FMT_GCC_VERSION || FMT_CLANG_VERSION
+    if (std::is_same<Char, char>::value) {
+      size_ = __builtin_strlen(detail::narrow(s));
      return;
    }
 #endif
@@ -549,7 +548,7 @@ template <typename Char> class basic_string_view {
    size_ = len;
  }

-  /// Constructs a string view from a `std::basic_string` or a
+  /// Constructs a string reference from a `std::basic_string` or a
  /// `std::basic_string_view` object.
  template <typename S,
            FMT_ENABLE_IF(detail::is_std_string_like<S>::value&& std::is_same<
@@ -586,6 +585,7 @@ template <typename Char> class basic_string_view {
    return starts_with(basic_string_view<Char>(s));
  }

+  // Lexicographically compare this string reference to other.
  FMT_CONSTEXPR auto compare(basic_string_view other) const -> int {
    int result =
        detail::compare(data_, other.data_, min_of(size_, other.size_));
@@ -616,7 +616,7 @@ 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.
+/// Specifies if `T` is an extended character type. Can be specialized by users.
 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 {};
@@ -625,7 +625,7 @@ template <> struct is_xchar<char32_t> : std::true_type {};
 template <> struct is_xchar<char8_t> : std::true_type {};
 #endif

-// Specifies if `T` is a character (code unit) type.
+// DEPRECATED! Will be replaced with an alias to prevent specializations.
 template <typename T> struct is_char : is_xchar<T> {};
 template <> struct is_char<char> : std::true_type {};

@@ -740,7 +740,7 @@ class basic_specs {
  };

  unsigned data_ = 1 << fill_size_shift;
-  static_assert(sizeof(basic_specs::data_) * CHAR_BIT >= 18, "");
+  static_assert(sizeof(data_) * CHAR_BIT >= 18, "");

  // Character (code unit) type is erased to prevent template bloat.
  char fill_data_[max_fill_size] = {' '};
@@ -1032,11 +1032,6 @@ enum {

 struct view {};

-template <typename T, typename Enable = std::true_type>
-struct is_view : std::false_type {};
-template <typename T>
-struct is_view<T, bool_constant<sizeof(T) != 0>> : std::is_base_of<view, T> {};
-
 template <typename Char, typename T> struct named_arg;
 template <typename T> struct is_named_arg : std::false_type {};
 template <typename T> struct is_static_named_arg : std::false_type {};
@@ -1069,16 +1064,6 @@ template <typename Char> struct named_arg_info {
  int id;
 };

-// named_args is non-const to suppress a bogus -Wmaybe-uninitalized in gcc 13.
-template <typename Char>
-FMT_CONSTEXPR void check_for_duplicate(named_arg_info<Char>* named_args,
-                                       int named_arg_index,
-                                       basic_string_view<Char> arg_name) {
-  for (int i = 0; i < named_arg_index; ++i) {
-    if (named_args[i].name == arg_name) report_error("duplicate named arg");
-  }
-}
-
 template <typename Char, typename T, FMT_ENABLE_IF(!is_named_arg<T>::value)>
 void init_named_arg(named_arg_info<Char>*, int& arg_index, int&, const T&) {
  ++arg_index;
@@ -1086,7 +1071,6 @@ void init_named_arg(named_arg_info<Char>*, int& arg_index, int&, const T&) {
 template <typename Char, typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
 void init_named_arg(named_arg_info<Char>* named_args, int& arg_index,
                    int& named_arg_index, const T& arg) {
-  check_for_duplicate<Char>(named_args, named_arg_index, arg.name);
  named_args[named_arg_index++] = {arg.name, arg_index++};
 }

@@ -1100,13 +1084,12 @@ template <typename T, typename Char,
          FMT_ENABLE_IF(is_static_named_arg<T>::value)>
 FMT_CONSTEXPR void init_static_named_arg(named_arg_info<Char>* named_args,
                                         int& arg_index, int& named_arg_index) {
-  check_for_duplicate<Char>(named_args, named_arg_index, T::name);
  named_args[named_arg_index++] = {T::name, arg_index++};
 }

 // To minimize the number of types we need to deal with, long is translated
 // either to int or to long long depending on its size.
-enum { long_short = sizeof(long) == sizeof(int) && FMT_BUILTIN_TYPES };
+enum { long_short = sizeof(long) == sizeof(int) };
 using long_type = conditional_t<long_short, int, long long>;
 using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;

@@ -1723,17 +1706,7 @@ class format_string_checker {
      -> const Char* {
    context_.advance_to(begin);
    if (id >= 0 && id < NUM_ARGS) return parse_funcs_[id](context_);
-
-    // If id is out of range, it means we do not know the type and cannot parse
-    // the format at compile time. Instead, skip over content until we finish
-    // the format spec, accounting for any nested replacements.
-    for (int bracket_count = 0;
-         begin != end && (bracket_count > 0 || *begin != '}'); ++begin) {
-      if (*begin == '{')
-        ++bracket_count;
-      else if (*begin == '}')
-        --bracket_count;
-    }
+    while (begin != end && *begin != '}') ++begin;
    return begin;
  }

@@ -2290,15 +2263,15 @@ template <> struct is_output_iterator<appender, char> : std::true_type {};
 template <typename It, typename T>
 struct is_output_iterator<
    It, T,
-    enable_if_t<std::is_assignable<decltype(*std::declval<decay_t<It>&>()++),
-                                   T>::value>> : std::true_type {};
+    void_t<decltype(*std::declval<decay_t<It>&>()++ = std::declval<T>())>>
+    : 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 {
+struct locale_ref {
 #if FMT_USE_LOCALE
 private:
  const void* locale_;  // A type-erased pointer to std::locale.
@@ -2310,7 +2283,6 @@ class locale_ref {
  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
 #endif  // FMT_USE_LOCALE

- public:
  template <typename Locale> auto get() const -> Locale;
 };

@@ -2730,7 +2702,7 @@ template <typename... T> struct fstring {
  template <size_t N>
  FMT_CONSTEVAL FMT_ALWAYS_INLINE fstring(const char (&s)[N]) : str(s, N - 1) {
    using namespace detail;
-    static_assert(count<(is_view<remove_cvref_t<T>>::value &&
+    static_assert(count<(std::is_base_of<view, remove_reference_t<T>>::value &&
                         std::is_reference<T>::value)...>() == 0,
                  "passing views as lvalues is disallowed");
    if (FMT_USE_CONSTEVAL) parse_format_string<char>(s, checker(s, arg_pack()));
@@ -2757,9 +2729,9 @@ template <typename... T> struct fstring {
                              std::is_same<typename S::char_type, char>::value)>
  FMT_ALWAYS_INLINE fstring(const S&) : str(S()) {
    FMT_CONSTEXPR auto sv = string_view(S());
-    FMT_CONSTEXPR int unused =
+    FMT_CONSTEXPR int ignore =
        (parse_format_string(sv, checker(sv, arg_pack())), 0);
-    detail::ignore_unused(unused);
+    detail::ignore_unused(ignore);
  }
  fstring(runtime_format_string<> fmt) : str(fmt.str) {}

--- a/include/spdlog/fmt/bundled/chrono.h
+++ b/include/spdlog/fmt/bundled/chrono.h
@@ -22,6 +22,21 @@

 #include "format.h"

+namespace fmt_detail {
+struct time_zone {
+  template <typename Duration, typename T>
+  auto to_sys(T)
+      -> std::chrono::time_point<std::chrono::system_clock, Duration> {
+    return {};
+  }
+};
+template <typename... T> inline auto current_zone(T...) -> time_zone* {
+  return nullptr;
+}
+
+template <typename... T> inline void _tzset(T...) {}
+}  // namespace fmt_detail
+
 FMT_BEGIN_NAMESPACE

 // Enable safe chrono durations, unless explicitly disabled.
@@ -420,11 +435,14 @@ auto write(OutputIt out, const std::tm& time, const std::locale& loc,
  return write_encoded_tm_str(out, string_view(buf.data(), buf.size()), loc);
 }

-template <typename T, typename U>
-using is_similar_arithmetic_type =
-    bool_constant<(std::is_integral<T>::value && std::is_integral<U>::value) ||
-                  (std::is_floating_point<T>::value &&
-                   std::is_floating_point<U>::value)>;
+template <typename Rep1, typename Rep2>
+struct is_same_arithmetic_type
+    : public std::integral_constant<bool,
+                                    (std::is_integral<Rep1>::value &&
+                                     std::is_integral<Rep2>::value) ||
+                                        (std::is_floating_point<Rep1>::value &&
+                                         std::is_floating_point<Rep2>::value)> {
+};

 FMT_NORETURN inline void throw_duration_error() {
  FMT_THROW(format_error("cannot format duration"));
@@ -483,9 +501,9 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
 #endif
 }

-template <typename To, typename FromRep, typename FromPeriod,
-          FMT_ENABLE_IF(
-              !is_similar_arithmetic_type<FromRep, typename To::rep>::value)>
+template <
+    typename To, typename FromRep, typename FromPeriod,
+    FMT_ENABLE_IF(!is_same_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.
  return std::chrono::duration_cast<To>(from);
@@ -501,30 +519,12 @@ 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);
+// Workaround a bug in libstdc++ which sets __cpp_lib_chrono to 201907 without
+// providing current_zone(): https://github.com/fmtlib/fmt/issues/4160.
+template <typename T> FMT_CONSTEXPR auto has_current_zone() -> bool {
+  using namespace std::chrono;
+  using namespace fmt_detail;
+  return !std::is_same<decltype(current_zone()), fmt_detail::time_zone*>::value;
 }
 }  // namespace detail

@@ -535,7 +535,7 @@ FMT_BEGIN_EXPORT
 * 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 {
+inline auto localtime(std::time_t time) -> std::tm {
  struct dispatcher {
    std::time_t time_;
    std::tm tm_;
@@ -572,11 +572,11 @@ FMT_DEPRECATED inline auto localtime(std::time_t time) -> std::tm {
 }

 #if FMT_USE_LOCAL_TIME
-template <typename Duration>
-FMT_DEPRECATED auto localtime(std::chrono::local_time<Duration> time)
-    -> std::tm {
+template <typename Duration,
+          FMT_ENABLE_IF(detail::has_current_zone<Duration>())>
+inline auto localtime(std::chrono::local_time<Duration> time) -> std::tm {
  using namespace std::chrono;
-  using namespace detail::tz;
+  using namespace fmt_detail;
  return localtime(detail::to_time_t(current_zone()->to_sys<Duration>(time)));
 }
 #endif
@@ -911,14 +911,7 @@ template <typename Derived> struct null_chrono_spec_handler {
  FMT_CONSTEXPR void on_tz_name() { unsupported(); }
 };

-class tm_format_checker : public null_chrono_spec_handler<tm_format_checker> {
- private:
-  bool has_timezone_ = false;
-
- public:
-  constexpr explicit tm_format_checker(bool has_timezone)
-      : has_timezone_(has_timezone) {}
-
+struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
  FMT_NORETURN inline void unsupported() {
    FMT_THROW(format_error("no format"));
  }
@@ -956,12 +949,8 @@ class tm_format_checker : public null_chrono_spec_handler<tm_format_checker> {
  FMT_CONSTEXPR void on_24_hour_time() {}
  FMT_CONSTEXPR void on_iso_time() {}
  FMT_CONSTEXPR void on_am_pm() {}
-  FMT_CONSTEXPR void on_utc_offset(numeric_system) {
-    if (!has_timezone_) FMT_THROW(format_error("no timezone"));
-  }
-  FMT_CONSTEXPR void on_tz_name() {
-    if (!has_timezone_) FMT_THROW(format_error("no timezone"));
-  }
+  FMT_CONSTEXPR void on_utc_offset(numeric_system) {}
+  FMT_CONSTEXPR void on_tz_name() {}
 };

 inline auto tm_wday_full_name(int wday) -> const char* {
@@ -991,27 +980,24 @@ inline auto tm_mon_short_name(int mon) -> const char* {
 }

 template <typename T, typename = void>
-struct has_tm_gmtoff : std::false_type {};
+struct has_member_data_tm_gmtoff : std::false_type {};
 template <typename T>
-struct has_tm_gmtoff<T, void_t<decltype(T::tm_gmtoff)>> : std::true_type {};
+struct has_member_data_tm_gmtoff<T, void_t<decltype(T::tm_gmtoff)>>
+    : std::true_type {};

-template <typename T, typename = void> struct has_tm_zone : std::false_type {};
+template <typename T, typename = void>
+struct has_member_data_tm_zone : std::false_type {};
 template <typename T>
-struct has_tm_zone<T, void_t<decltype(T::tm_zone)>> : std::true_type {};
+struct has_member_data_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) {
-  time.tm_zone = tz;
-  return true;
-}
-template <typename T, FMT_ENABLE_IF(!has_tm_zone<T>::value)>
-bool set_tm_zone(T&, char*) {
-  return false;
-}
-
-inline char* utc() {
-  static char tz[] = "UTC";
-  return tz;
+inline void tzset_once() {
+  static bool init = []() {
+    using namespace fmt_detail;
+    _tzset();
+    return false;
+  }();
+  ignore_unused(init);
 }

 // Converts value to Int and checks that it's in the range [0, upper).
@@ -1019,7 +1005,7 @@ template <typename T, typename Int, FMT_ENABLE_IF(std::is_integral<T>::value)>
 inline auto to_nonnegative_int(T value, Int upper) -> Int {
  if (!std::is_unsigned<Int>::value &&
      (value < 0 || to_unsigned(value) > to_unsigned(upper))) {
-    FMT_THROW(format_error("chrono value is out of range"));
+    FMT_THROW(fmt::format_error("chrono value is out of range"));
  }
  return static_cast<Int>(value);
 }
@@ -1104,7 +1090,7 @@ void write_fractional_seconds(OutputIt& out, Duration d, int precision = -1) {

 // Format subseconds which are given as a floating point type with an
 // appropriate number of digits. We cannot pass the Duration here, as we
-// explicitly need to pass the Rep value in the duration_formatter.
+// explicitly need to pass the Rep value in the chrono_formatter.
 template <typename Duration>
 void write_floating_seconds(memory_buffer& buf, Duration duration,
                            int num_fractional_digits = -1) {
@@ -1138,7 +1124,7 @@ class tm_writer {
  static constexpr int days_per_week = 7;

  const std::locale& loc_;
-  bool is_classic_;
+  const bool is_classic_;
  OutputIt out_;
  const Duration* subsecs_;
  const std::tm& tm_;
@@ -1174,8 +1160,8 @@ class tm_writer {
  }

  auto tm_hour12() const noexcept -> int {
-    auto h = tm_hour();
-    auto z = h < 12 ? h : h - 12;
+    const auto h = tm_hour();
+    const auto z = h < 12 ? h : h - 12;
    return z == 0 ? 12 : z;
  }

@@ -1191,11 +1177,11 @@ class tm_writer {

  // Algorithm: https://en.wikipedia.org/wiki/ISO_week_date.
  auto iso_year_weeks(long long curr_year) const noexcept -> int {
-    auto prev_year = curr_year - 1;
-    auto curr_p =
+    const auto prev_year = curr_year - 1;
+    const auto curr_p =
        (curr_year + curr_year / 4 - curr_year / 100 + curr_year / 400) %
        days_per_week;
-    auto prev_p =
+    const auto prev_p =
        (prev_year + prev_year / 4 - prev_year / 100 + prev_year / 400) %
        days_per_week;
    return 52 + ((curr_p == 4 || prev_p == 3) ? 1 : 0);
@@ -1205,15 +1191,15 @@ class tm_writer {
           days_per_week;
  }
  auto tm_iso_week_year() const noexcept -> long long {
-    auto year = tm_year();
-    auto w = iso_week_num(tm_yday(), tm_wday());
+    const auto year = tm_year();
+    const auto w = iso_week_num(tm_yday(), tm_wday());
    if (w < 1) return year - 1;
    if (w > iso_year_weeks(year)) return year + 1;
    return year;
  }
  auto tm_iso_week_of_year() const noexcept -> int {
-    auto year = tm_year();
-    auto w = iso_week_num(tm_yday(), tm_wday());
+    const auto year = tm_year();
+    const auto w = iso_week_num(tm_yday(), tm_wday());
    if (w < 1) return iso_year_weeks(year - 1);
    if (w > iso_year_weeks(year)) return 1;
    return w;
@@ -1250,8 +1236,9 @@ class tm_writer {
    uint32_or_64_or_128_t<long long> n = to_unsigned(year);
    const int num_digits = count_digits(n);
    if (negative && pad == pad_type::zero) *out_++ = '-';
-    if (width > num_digits)
+    if (width > num_digits) {
      out_ = detail::write_padding(out_, pad, width - num_digits);
+    }
    if (negative && pad != pad_type::zero) *out_++ = '-';
    out_ = format_decimal<Char>(out_, n, num_digits);
  }
@@ -1272,22 +1259,45 @@ class tm_writer {
    write2(static_cast<int>(offset % 60));
  }

-  template <typename T, FMT_ENABLE_IF(has_tm_gmtoff<T>::value)>
-  void format_utc_offset(const T& tm, numeric_system ns) {
+  template <typename T, FMT_ENABLE_IF(has_member_data_tm_gmtoff<T>::value)>
+  void format_utc_offset_impl(const T& tm, numeric_system ns) {
    write_utc_offset(tm.tm_gmtoff, ns);
  }
-  template <typename T, FMT_ENABLE_IF(!has_tm_gmtoff<T>::value)>
-  void format_utc_offset(const T&, numeric_system ns) {
-    write_utc_offset(0, ns);
+  template <typename T, FMT_ENABLE_IF(!has_member_data_tm_gmtoff<T>::value)>
+  void format_utc_offset_impl(const T& tm, numeric_system ns) {
+#if defined(_WIN32) && defined(_UCRT)
+    tzset_once();
+    long offset = 0;
+    _get_timezone(&offset);
+    if (tm.tm_isdst) {
+      long dstbias = 0;
+      _get_dstbias(&dstbias);
+      offset += dstbias;
+    }
+    write_utc_offset(-offset, ns);
+#else
+    if (ns == numeric_system::standard) return format_localized('z');
+
+    // Extract timezone offset from timezone conversion functions.
+    std::tm gtm = tm;
+    std::time_t gt = std::mktime(&gtm);
+    std::tm ltm = gmtime(gt);
+    std::time_t lt = std::mktime(&ltm);
+    long long offset = gt - lt;
+    write_utc_offset(offset, ns);
+#endif
  }

-  template <typename T, FMT_ENABLE_IF(has_tm_zone<T>::value)>
-  void format_tz_name(const T& tm) {
-    out_ = write_tm_str<Char>(out_, tm.tm_zone, loc_);
+  template <typename T, FMT_ENABLE_IF(has_member_data_tm_zone<T>::value)>
+  void format_tz_name_impl(const T& tm) {
+    if (is_classic_)
+      out_ = write_tm_str<Char>(out_, tm.tm_zone, loc_);
+    else
+      format_localized('Z');
  }
-  template <typename T, FMT_ENABLE_IF(!has_tm_zone<T>::value)>
-  void format_tz_name(const T&) {
-    out_ = std::copy_n(utc(), 3, out_);
+  template <typename T, FMT_ENABLE_IF(!has_member_data_tm_zone<T>::value)>
+  void format_tz_name_impl(const T&) {
+    format_localized('Z');
  }

  void format_localized(char format, char modifier = 0) {
@@ -1398,8 +1408,8 @@ class tm_writer {
    out_ = copy<Char>(std::begin(buf) + offset, std::end(buf), out_);
  }

-  void on_utc_offset(numeric_system ns) { format_utc_offset(tm_, ns); }
-  void on_tz_name() { format_tz_name(tm_); }
+  void on_utc_offset(numeric_system ns) { format_utc_offset_impl(tm_, ns); }
+  void on_tz_name() { format_tz_name_impl(tm_); }

  void on_year(numeric_system ns, pad_type pad) {
    if (is_classic_ || ns == numeric_system::standard)
@@ -1473,10 +1483,11 @@ class tm_writer {
  void on_day_of_year(pad_type pad) {
    auto yday = tm_yday() + 1;
    auto digit1 = yday / 100;
-    if (digit1 != 0)
+    if (digit1 != 0) {
      write1(digit1);
-    else
+    } else {
      out_ = detail::write_padding(out_, pad);
+    }
    write2(yday % 100, pad);
  }

@@ -1613,16 +1624,18 @@ template <typename Rep, typename Period,
          FMT_ENABLE_IF(std::is_integral<Rep>::value)>
 inline auto get_milliseconds(std::chrono::duration<Rep, Period> d)
    -> std::chrono::duration<Rep, std::milli> {
-  // This may overflow and/or the result may not fit in the target type.
+  // this may overflow and/or the result may not fit in the
+  // target type.
 #if FMT_SAFE_DURATION_CAST
-  using common_seconds_type =
+  using CommonSecondsType =
      typename std::common_type<decltype(d), std::chrono::seconds>::type;
-  auto d_as_common = detail::duration_cast<common_seconds_type>(d);
-  auto d_as_whole_seconds =
+  const auto d_as_common = detail::duration_cast<CommonSecondsType>(d);
+  const auto d_as_whole_seconds =
      detail::duration_cast<std::chrono::seconds>(d_as_common);
-  // This conversion should be nonproblematic.
-  auto diff = d_as_common - d_as_whole_seconds;
-  auto ms = detail::duration_cast<std::chrono::duration<Rep, std::milli>>(diff);
+  // this conversion should be nonproblematic
+  const auto diff = d_as_common - d_as_whole_seconds;
+  const auto ms =
+      detail::duration_cast<std::chrono::duration<Rep, std::milli>>(diff);
  return ms;
 #else
  auto s = detail::duration_cast<std::chrono::seconds>(d);
@@ -1694,28 +1707,32 @@ class get_locale {
  }
 };

-template <typename Char, typename Rep, typename Period>
-struct duration_formatter {
-  using iterator = basic_appender<Char>;
-  iterator out;
+template <typename FormatContext, typename OutputIt, typename Rep,
+          typename Period>
+struct chrono_formatter {
+  FormatContext& context;
+  OutputIt out;
+  int precision;
+  bool localized = false;
  // rep is unsigned to avoid overflow.
  using rep =
      conditional_t<std::is_integral<Rep>::value && sizeof(Rep) < sizeof(int),
                    unsigned, typename make_unsigned_or_unchanged<Rep>::type>;
  rep val;
-  int precision;
-  locale_ref locale;
-  bool localized = false;
  using seconds = std::chrono::duration<rep>;
  seconds s;
  using milliseconds = std::chrono::duration<rep, std::milli>;
  bool negative;

-  using tm_writer_type = tm_writer<iterator, Char>;
+  using char_type = typename FormatContext::char_type;
+  using tm_writer_type = tm_writer<OutputIt, char_type>;

-  duration_formatter(iterator o, std::chrono::duration<Rep, Period> d,
-                     locale_ref loc)
-      : out(o), val(static_cast<rep>(d.count())), locale(loc), negative(false) {
+  chrono_formatter(FormatContext& ctx, OutputIt o,
+                   std::chrono::duration<Rep, Period> d)
+      : context(ctx),
+        out(o),
+        val(static_cast<rep>(d.count())),
+        negative(false) {
    if (d.count() < 0) {
      val = 0 - val;
      negative = true;
@@ -1729,16 +1746,19 @@ struct duration_formatter {

  // returns true if nan or inf, writes to out.
  auto handle_nan_inf() -> bool {
-    if (isfinite(val)) return false;
+    if (isfinite(val)) {
+      return false;
+    }
    if (isnan(val)) {
      write_nan();
      return true;
    }
    // must be +-inf
-    if (val > 0)
-      std::copy_n("inf", 3, out);
-    else
-      std::copy_n("-inf", 4, out);
+    if (val > 0) {
+      write_pinf();
+    } else {
+      write_ninf();
+    }
    return true;
  }

@@ -1766,9 +1786,10 @@ struct duration_formatter {
  }

  void write_sign() {
-    if (!negative) return;
-    *out++ = '-';
-    negative = false;
+    if (negative) {
+      *out++ = '-';
+      negative = false;
+    }
  }

  void write(Rep value, int width, pad_type pad = pad_type::zero) {
@@ -1780,22 +1801,24 @@ struct duration_formatter {
    if (width > num_digits) {
      out = detail::write_padding(out, pad, width - num_digits);
    }
-    out = format_decimal<Char>(out, n, num_digits);
+    out = format_decimal<char_type>(out, n, num_digits);
  }

  void write_nan() { std::copy_n("nan", 3, out); }
+  void write_pinf() { std::copy_n("inf", 3, out); }
+  void write_ninf() { std::copy_n("-inf", 4, out); }

  template <typename Callback, typename... Args>
  void format_tm(const tm& time, Callback cb, Args... args) {
    if (isnan(val)) return write_nan();
-    get_locale loc(localized, locale);
+    get_locale loc(localized, context.locale());
    auto w = tm_writer_type(loc, out, time);
    (w.*cb)(args...);
    out = w.out();
  }

-  void on_text(const Char* begin, const Char* end) {
-    copy<Char>(begin, end, out);
+  void on_text(const char_type* begin, const char_type* end) {
+    copy<char_type>(begin, end, out);
  }

  // These are not implemented because durations don't have date information.
@@ -1865,12 +1888,13 @@ struct duration_formatter {
        write_floating_seconds(buf, std::chrono::duration<rep, Period>(val),
                               precision);
        if (negative) *out++ = '-';
-        if (buf.size() < 2 || buf[1] == '.')
+        if (buf.size() < 2 || buf[1] == '.') {
          out = detail::write_padding(out, pad);
-        out = copy<Char>(buf.begin(), buf.end(), out);
+        }
+        out = copy<char_type>(buf.begin(), buf.end(), out);
      } else {
        write(second(), 2, pad);
-        write_fractional_seconds<Char>(
+        write_fractional_seconds<char_type>(
            out, std::chrono::duration<rep, Period>(val), precision);
      }
      return;
@@ -1912,10 +1936,12 @@ struct duration_formatter {
  void on_duration_value() {
    if (handle_nan_inf()) return;
    write_sign();
-    out = format_duration_value<Char>(out, val, precision);
+    out = format_duration_value<char_type>(out, val, precision);
  }

-  void on_duration_unit() { out = format_duration_unit<Char, Period>(out); }
+  void on_duration_unit() {
+    out = format_duration_unit<char_type, Period>(out);
+  }
 };

 }  // namespace detail
@@ -1985,11 +2011,12 @@ class year_month_day {
  constexpr auto month() const noexcept -> fmt::month { return month_; }
  constexpr auto day() const noexcept -> fmt::day { return day_; }
 };
-#endif  // __cpp_lib_chrono >= 201907
+#endif

 template <typename Char>
 struct formatter<weekday, Char> : private formatter<std::tm, Char> {
 private:
+  bool localized_ = false;
  bool use_tm_formatter_ = false;

 public:
@@ -1997,7 +2024,8 @@ struct formatter<weekday, Char> : private formatter<std::tm, Char> {
    auto it = ctx.begin(), end = ctx.end();
    if (it != end && *it == 'L') {
      ++it;
-      this->set_localized();
+      localized_ = true;
+      return it;
    }
    use_tm_formatter_ = it != end && *it != '}';
    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2008,7 +2036,7 @@ struct formatter<weekday, Char> : private formatter<std::tm, Char> {
    auto time = std::tm();
    time.tm_wday = static_cast<int>(wd.c_encoding());
    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
-    detail::get_locale loc(this->localized(), ctx.locale());
+    detail::get_locale loc(localized_, ctx.locale());
    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
    w.on_abbr_weekday();
    return w.out();
@@ -2042,6 +2070,7 @@ struct formatter<day, Char> : private formatter<std::tm, Char> {
 template <typename Char>
 struct formatter<month, Char> : private formatter<std::tm, Char> {
 private:
+  bool localized_ = false;
  bool use_tm_formatter_ = false;

 public:
@@ -2049,7 +2078,8 @@ struct formatter<month, Char> : private formatter<std::tm, Char> {
    auto it = ctx.begin(), end = ctx.end();
    if (it != end && *it == 'L') {
      ++it;
-      this->set_localized();
+      localized_ = true;
+      return it;
    }
    use_tm_formatter_ = it != end && *it != '}';
    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2060,7 +2090,7 @@ struct formatter<month, Char> : private formatter<std::tm, Char> {
    auto time = std::tm();
    time.tm_mon = static_cast<int>(static_cast<unsigned>(m)) - 1;
    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
-    detail::get_locale loc(this->localized(), ctx.locale());
+    detail::get_locale loc(localized_, ctx.locale());
    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
    w.on_abbr_month();
    return w.out();
@@ -2124,6 +2154,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
  format_specs specs_;
  detail::arg_ref<Char> width_ref_;
  detail::arg_ref<Char> precision_ref_;
+  bool localized_ = false;
  basic_string_view<Char> fmt_;

 public:
@@ -2146,7 +2177,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
      it = detail::parse_precision(it, end, specs_, precision_ref_, ctx);
    }
    if (it != end && *it == 'L') {
-      specs_.set_localized();
+      localized_ = true;
      ++it;
    }
    end = detail::parse_chrono_format(it, end, checker);
@@ -2173,10 +2204,11 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
      out = detail::format_duration_value<Char>(out, d.count(), precision);
      detail::format_duration_unit<Char, Period>(out);
    } else {
-      auto f =
-          detail::duration_formatter<Char, Rep, Period>(out, d, ctx.locale());
+      using chrono_formatter =
+          detail::chrono_formatter<FormatContext, decltype(out), Rep, Period>;
+      auto f = chrono_formatter(ctx, out, d);
      f.precision = precision;
-      f.localized = specs_.localized();
+      f.localized = localized_;
      detail::parse_chrono_format(begin, end, f);
    }
    return detail::write(
@@ -2188,15 +2220,30 @@ template <typename Char> struct formatter<std::tm, Char> {
 private:
  format_specs specs_;
  detail::arg_ref<Char> width_ref_;
-  basic_string_view<Char> fmt_ =
-      detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();

 protected:
-  auto localized() const -> bool { return specs_.localized(); }
-  FMT_CONSTEXPR void set_localized() { specs_.set_localized(); }
+  basic_string_view<Char> fmt_;

-  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx, bool has_timezone)
-      -> const Char* {
+  template <typename Duration, typename FormatContext>
+  auto do_format(const std::tm& tm, FormatContext& ctx,
+                 const Duration* subsecs) const -> decltype(ctx.out()) {
+    auto specs = specs_;
+    auto buf = basic_memory_buffer<Char>();
+    auto out = basic_appender<Char>(buf);
+    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
+                                ctx);
+
+    auto loc_ref = ctx.locale();
+    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
+    auto w =
+        detail::tm_writer<decltype(out), Char, Duration>(loc, out, tm, subsecs);
+    detail::parse_chrono_format(fmt_.begin(), fmt_.end(), w);
+    return detail::write(
+        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
+  }
+
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    auto it = ctx.begin(), end = ctx.end();
    if (it == end || *it == '}') return it;

@@ -2209,41 +2256,12 @@ template <typename Char> struct formatter<std::tm, Char> {
      if (it == end) return it;
    }

-    if (*it == 'L') {
-      specs_.set_localized();
-      ++it;
-    }
-
-    end = detail::parse_chrono_format(it, end,
-                                      detail::tm_format_checker(has_timezone));
+    end = detail::parse_chrono_format(it, end, detail::tm_format_checker());
    // Replace the default format string only if the new spec is not empty.
    if (end != it) fmt_ = {it, detail::to_unsigned(end - it)};
    return end;
  }

-  template <typename Duration, typename FormatContext>
-  auto do_format(const std::tm& tm, FormatContext& ctx,
-                 const Duration* subsecs) const -> decltype(ctx.out()) {
-    auto specs = specs_;
-    auto buf = basic_memory_buffer<Char>();
-    auto out = basic_appender<Char>(buf);
-    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
-                                ctx);
-
-    auto loc_ref = specs.localized() ? ctx.locale() : detail::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);
-    detail::parse_chrono_format(fmt_.begin(), fmt_.end(), w);
-    return detail::write(
-        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
-  }
-
- public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return do_parse(ctx, detail::has_tm_gmtoff<std::tm>::value);
-  }
-
  template <typename FormatContext>
  auto format(const std::tm& tm, FormatContext& ctx) const
      -> decltype(ctx.out()) {
@@ -2251,11 +2269,10 @@ template <typename Char> struct formatter<std::tm, Char> {
  }
 };

-// DEPRECATED! Reversed order of template parameters.
 template <typename Char, typename Duration>
-struct formatter<sys_time<Duration>, Char> : private formatter<std::tm, Char> {
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return this->do_parse(ctx, true);
+struct formatter<sys_time<Duration>, Char> : formatter<std::tm, Char> {
+  FMT_CONSTEXPR formatter() {
+    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
  }

  template <typename FormatContext>
@@ -2266,7 +2283,6 @@ struct formatter<sys_time<Duration>, Char> : private formatter<std::tm, Char> {
    if (detail::const_check(
            period::num == 1 && period::den == 1 &&
            !std::is_floating_point<typename Duration::rep>::value)) {
-      detail::set_tm_zone(tm, detail::utc());
      return formatter<std::tm, Char>::format(tm, ctx);
    }
    Duration epoch = val.time_since_epoch();
@@ -2274,13 +2290,11 @@ struct formatter<sys_time<Duration>, Char> : private formatter<std::tm, Char> {
        epoch - detail::duration_cast<std::chrono::seconds>(epoch));
    if (subsecs.count() < 0) {
      auto second = detail::duration_cast<Duration>(std::chrono::seconds(1));
-      if (tm.tm_sec != 0) {
+      if (tm.tm_sec != 0)
        --tm.tm_sec;
-      } else {
+      else
        tm = gmtime(val - second);
-        detail::set_tm_zone(tm, detail::utc());
-      }
-      subsecs += second;
+      subsecs += detail::duration_cast<Duration>(std::chrono::seconds(1));
    }
    return formatter<std::tm, Char>::do_format(tm, ctx, &subsecs);
  }
@@ -2298,29 +2312,23 @@ struct formatter<utc_time<Duration>, Char>
 };

 template <typename Duration, typename Char>
-struct formatter<local_time<Duration>, Char>
-    : private formatter<std::tm, Char> {
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return this->do_parse(ctx, false);
+struct formatter<local_time<Duration>, Char> : formatter<std::tm, Char> {
+  FMT_CONSTEXPR formatter() {
+    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
  }

  template <typename FormatContext>
  auto format(local_time<Duration> val, FormatContext& ctx) const
      -> decltype(ctx.out()) {
-    auto time_since_epoch = val.time_since_epoch();
-    auto seconds_since_epoch =
-        detail::duration_cast<std::chrono::seconds>(time_since_epoch);
-    // Use gmtime to prevent time zone conversion since local_time has an
-    // unspecified time zone.
-    std::tm t = gmtime(seconds_since_epoch.count());
    using period = typename Duration::period;
    if (period::num == 1 && period::den == 1 &&
        !std::is_floating_point<typename Duration::rep>::value) {
-      return formatter<std::tm, Char>::format(t, ctx);
+      return formatter<std::tm, Char>::format(localtime(val), ctx);
    }
-    auto subsecs =
-        detail::duration_cast<Duration>(time_since_epoch - seconds_since_epoch);
-    return formatter<std::tm, Char>::do_format(t, ctx, &subsecs);
+    auto epoch = val.time_since_epoch();
+    auto subsecs = detail::duration_cast<Duration>(
+        epoch - detail::duration_cast<std::chrono::seconds>(epoch));
+    return formatter<std::tm, Char>::do_format(localtime(val), ctx, &subsecs);
  }
 };

--- a/include/spdlog/fmt/bundled/color.h
+++ b/include/spdlog/fmt/bundled/color.h
@@ -190,11 +190,11 @@ enum class emphasis : uint8_t {
 // rgb is a struct for red, green and blue colors.
 // Using the name "rgb" makes some editors show the color in a tooltip.
 struct rgb {
-  constexpr rgb() : r(0), g(0), b(0) {}
-  constexpr rgb(uint8_t r_, uint8_t g_, uint8_t b_) : r(r_), g(g_), b(b_) {}
-  constexpr rgb(uint32_t hex)
+  FMT_CONSTEXPR rgb() : r(0), g(0), b(0) {}
+  FMT_CONSTEXPR rgb(uint8_t r_, uint8_t g_, uint8_t b_) : r(r_), g(g_), b(b_) {}
+  FMT_CONSTEXPR rgb(uint32_t hex)
      : r((hex >> 16) & 0xFF), g((hex >> 8) & 0xFF), b(hex & 0xFF) {}
-  constexpr rgb(color hex)
+  FMT_CONSTEXPR rgb(color hex)
      : r((uint32_t(hex) >> 16) & 0xFF),
        g((uint32_t(hex) >> 8) & 0xFF),
        b(uint32_t(hex) & 0xFF) {}
@@ -205,135 +205,97 @@ struct rgb {

 namespace detail {

-// A bit-packed variant of an RGB color, a terminal color, or unset color.
-// see text_style for the bit-packing scheme.
+// color is a struct of either a rgb color or a terminal color.
 struct color_type {
-  constexpr color_type() noexcept = default;
-  constexpr color_type(color rgb_color) noexcept
-      : value_(static_cast<uint32_t>(rgb_color) | (1 << 24)) {}
-  constexpr color_type(rgb rgb_color) noexcept
-      : color_type(static_cast<color>(
-            (static_cast<uint32_t>(rgb_color.r) << 16) |
-            (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b)) {}
-  constexpr color_type(terminal_color term_color) noexcept
-      : value_(static_cast<uint32_t>(term_color) | (3 << 24)) {}
-
-  constexpr auto is_terminal_color() const noexcept -> bool {
-    return (value_ & (1 << 25)) != 0;
+  FMT_CONSTEXPR color_type() noexcept : is_rgb(), value{} {}
+  FMT_CONSTEXPR color_type(color rgb_color) noexcept : is_rgb(true), value{} {
+    value.rgb_color = static_cast<uint32_t>(rgb_color);
  }
-
-  constexpr auto value() const noexcept -> uint32_t {
-    return value_ & 0xFFFFFF;
+  FMT_CONSTEXPR color_type(rgb rgb_color) noexcept : is_rgb(true), value{} {
+    value.rgb_color = (static_cast<uint32_t>(rgb_color.r) << 16) |
+                      (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b;
  }
-
-  constexpr color_type(uint32_t value) noexcept : value_(value) {}
-
-  uint32_t value_ = 0;
+  FMT_CONSTEXPR color_type(terminal_color term_color) noexcept
+      : is_rgb(), value{} {
+    value.term_color = static_cast<uint8_t>(term_color);
+  }
+  bool is_rgb;
+  union color_union {
+    uint8_t term_color;
+    uint32_t rgb_color;
+  } value;
 };
 }  // namespace detail

 /// A text style consisting of foreground and background colors and emphasis.
 class text_style {
-  // The information is packed as follows:
-  // ┌──┐
-  // │ 0│─┐
-  // │..│ ├── foreground color value
-  // │23│─┘
-  // ├──┤
-  // │24│─┬── discriminator for the above value. 00 if unset, 01 if it's
-  // │25│─┘   an RGB color, or 11 if it's a terminal color (10 is unused)
-  // ├──┤
-  // │26│──── overflow bit, always zero (see below)
-  // ├──┤
-  // │27│─┐
-  // │..│ │
-  // │50│ │
-  // ├──┤ │
-  // │51│ ├── background color (same format as the foreground color)
-  // │52│ │
-  // ├──┤ │
-  // │53│─┘
-  // ├──┤
-  // │54│─┐
-  // │..│ ├── emphases
-  // │61│─┘
-  // ├──┤
-  // │62│─┬── unused
-  // │63│─┘
-  // └──┘
-  // The overflow bits are there to make operator|= efficient.
-  // When ORing, we must throw if, for either the foreground or background,
-  // one style specifies a terminal color and the other specifies any color
-  // (terminal or RGB); in other words, if one discriminator is 11 and the
-  // other is 11 or 01.
-  //
-  // We do that check by adding the styles. Consider what adding does to each
-  // possible pair of discriminators:
-  //    00 + 00 = 000
-  //    01 + 00 = 001
-  //    11 + 00 = 011
-  //    01 + 01 = 010
-  //    11 + 01 = 100 (!!)
-  //    11 + 11 = 110 (!!)
-  // In the last two cases, the ones we want to catch, the third bit——the
-  // overflow bit——is set. Bingo.
-  //
-  // We must take into account the possible carry bit from the bits
-  // before the discriminator. The only potentially problematic case is
-  // 11 + 00 = 011 (a carry bit would make it 100, not good!), but a carry
-  // bit is impossible in that case, because 00 (unset color) means the
-  // 24 bits that precede the discriminator are all zero.
-  //
-  // This test can be applied to both colors simultaneously.
-
 public:
  FMT_CONSTEXPR text_style(emphasis em = emphasis()) noexcept
-      : style_(static_cast<uint64_t>(em) << 54) {}
+      : set_foreground_color(), set_background_color(), ems(em) {}

-  FMT_CONSTEXPR auto operator|=(text_style rhs) -> text_style& {
-    if (((style_ + rhs.style_) & ((1ULL << 26) | (1ULL << 53))) != 0)
-      report_error("can't OR a terminal color");
-    style_ |= rhs.style_;
+  FMT_CONSTEXPR auto operator|=(const text_style& rhs) -> text_style& {
+    if (!set_foreground_color) {
+      set_foreground_color = rhs.set_foreground_color;
+      foreground_color = rhs.foreground_color;
+    } else if (rhs.set_foreground_color) {
+      if (!foreground_color.is_rgb || !rhs.foreground_color.is_rgb)
+        report_error("can't OR a terminal color");
+      foreground_color.value.rgb_color |= rhs.foreground_color.value.rgb_color;
+    }
+
+    if (!set_background_color) {
+      set_background_color = rhs.set_background_color;
+      background_color = rhs.background_color;
+    } else if (rhs.set_background_color) {
+      if (!background_color.is_rgb || !rhs.background_color.is_rgb)
+        report_error("can't OR a terminal color");
+      background_color.value.rgb_color |= rhs.background_color.value.rgb_color;
+    }
+
+    ems = static_cast<emphasis>(static_cast<uint8_t>(ems) |
+                                static_cast<uint8_t>(rhs.ems));
    return *this;
  }

-  friend FMT_CONSTEXPR auto operator|(text_style lhs, text_style rhs)
+  friend FMT_CONSTEXPR auto operator|(text_style lhs, const text_style& rhs)
      -> text_style {
    return lhs |= rhs;
  }

-  FMT_CONSTEXPR auto operator==(text_style rhs) const noexcept -> bool {
-    return style_ == rhs.style_;
-  }
-
-  FMT_CONSTEXPR auto operator!=(text_style rhs) const noexcept -> bool {
-    return !(*this == rhs);
-  }
-
  FMT_CONSTEXPR auto has_foreground() const noexcept -> bool {
-    return (style_ & (1 << 24)) != 0;
+    return set_foreground_color;
  }
  FMT_CONSTEXPR auto has_background() const noexcept -> bool {
-    return (style_ & (1ULL << 51)) != 0;
+    return set_background_color;
  }
  FMT_CONSTEXPR auto has_emphasis() const noexcept -> bool {
-    return (style_ >> 54) != 0;
+    return static_cast<uint8_t>(ems) != 0;
  }
  FMT_CONSTEXPR auto get_foreground() const noexcept -> detail::color_type {
    FMT_ASSERT(has_foreground(), "no foreground specified for this style");
-    return style_ & 0x3FFFFFF;
+    return foreground_color;
  }
  FMT_CONSTEXPR auto get_background() const noexcept -> detail::color_type {
    FMT_ASSERT(has_background(), "no background specified for this style");
-    return (style_ >> 27) & 0x3FFFFFF;
+    return background_color;
  }
  FMT_CONSTEXPR auto get_emphasis() const noexcept -> emphasis {
    FMT_ASSERT(has_emphasis(), "no emphasis specified for this style");
-    return static_cast<emphasis>(style_ >> 54);
+    return ems;
  }

 private:
-  FMT_CONSTEXPR text_style(uint64_t style) noexcept : style_(style) {}
+  FMT_CONSTEXPR text_style(bool is_foreground,
+                           detail::color_type text_color) noexcept
+      : set_foreground_color(), set_background_color(), ems() {
+    if (is_foreground) {
+      foreground_color = text_color;
+      set_foreground_color = true;
+    } else {
+      background_color = text_color;
+      set_background_color = true;
+    }
+  }

  friend FMT_CONSTEXPR auto fg(detail::color_type foreground) noexcept
      -> text_style;
@@ -341,19 +303,23 @@ class text_style {
  friend FMT_CONSTEXPR auto bg(detail::color_type background) noexcept
      -> text_style;

-  uint64_t style_ = 0;
+  detail::color_type foreground_color;
+  detail::color_type background_color;
+  bool set_foreground_color;
+  bool set_background_color;
+  emphasis ems;
 };

 /// Creates a text style from the foreground (text) color.
 FMT_CONSTEXPR inline auto fg(detail::color_type foreground) noexcept
    -> text_style {
-  return foreground.value_;
+  return text_style(true, foreground);
 }

 /// Creates a text style from the background color.
 FMT_CONSTEXPR inline auto bg(detail::color_type background) noexcept
    -> text_style {
-  return static_cast<uint64_t>(background.value_) << 27;
+  return text_style(false, background);
 }

 FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept
@@ -368,9 +334,9 @@ template <typename Char> struct ansi_color_escape {
                                  const char* esc) noexcept {
    // If we have a terminal color, we need to output another escape code
    // sequence.
-    if (text_color.is_terminal_color()) {
+    if (!text_color.is_rgb) {
      bool is_background = esc == string_view("\x1b[48;2;");
-      uint32_t value = text_color.value();
+      uint32_t value = text_color.value.term_color;
      // Background ASCII codes are the same as the foreground ones but with
      // 10 more.
      if (is_background) value += 10u;
@@ -394,7 +360,7 @@ template <typename Char> struct ansi_color_escape {
    for (int i = 0; i < 7; i++) {
      buffer[i] = static_cast<Char>(esc[i]);
    }
-    rgb color(text_color.value());
+    rgb color(text_color.value.rgb_color);
    to_esc(color.r, buffer + 7, ';');
    to_esc(color.g, buffer + 11, ';');
    to_esc(color.b, buffer + 15, 'm');
@@ -475,26 +441,32 @@ template <typename T> struct styled_arg : view {
 };

 template <typename Char>
-void vformat_to(buffer<Char>& buf, text_style ts, basic_string_view<Char> fmt,
+void vformat_to(buffer<Char>& buf, const text_style& ts,
+                basic_string_view<Char> fmt,
                basic_format_args<buffered_context<Char>> args) {
+  bool has_style = false;
  if (ts.has_emphasis()) {
+    has_style = true;
    auto emphasis = make_emphasis<Char>(ts.get_emphasis());
    buf.append(emphasis.begin(), emphasis.end());
  }
  if (ts.has_foreground()) {
+    has_style = true;
    auto foreground = make_foreground_color<Char>(ts.get_foreground());
    buf.append(foreground.begin(), foreground.end());
  }
  if (ts.has_background()) {
+    has_style = true;
    auto background = make_background_color<Char>(ts.get_background());
    buf.append(background.begin(), background.end());
  }
  vformat_to(buf, fmt, args);
-  if (ts != text_style()) reset_color<Char>(buf);
+  if (has_style) reset_color<Char>(buf);
 }
 }  // namespace detail

-inline void vprint(FILE* f, text_style ts, string_view fmt, format_args args) {
+inline void vprint(FILE* f, const text_style& ts, string_view fmt,
+                   format_args args) {
  auto buf = memory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
  print(f, FMT_STRING("{}"), string_view(buf.begin(), buf.size()));
@@ -510,7 +482,8 @@ inline void vprint(FILE* f, text_style ts, string_view fmt, format_args args) {
 *                "Elapsed time: {0:.2f} seconds", 1.23);
 */
 template <typename... T>
-void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) {
+void print(FILE* f, const text_style& ts, format_string<T...> fmt,
+           T&&... args) {
  vprint(f, ts, fmt.str, vargs<T...>{{args...}});
 }

@@ -524,11 +497,11 @@ void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) {
 *                "Elapsed time: {0:.2f} seconds", 1.23);
 */
 template <typename... T>
-void print(text_style ts, format_string<T...> fmt, T&&... args) {
+void print(const text_style& ts, format_string<T...> fmt, T&&... args) {
  return print(stdout, ts, fmt, std::forward<T>(args)...);
 }

-inline auto vformat(text_style ts, string_view fmt, format_args args)
+inline auto vformat(const text_style& ts, string_view fmt, format_args args)
    -> std::string {
  auto buf = memory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
@@ -548,7 +521,7 @@ inline auto vformat(text_style ts, string_view fmt, format_args args)
 * ```
 */
 template <typename... T>
-inline auto format(text_style ts, format_string<T...> fmt, T&&... args)
+inline auto format(const text_style& ts, format_string<T...> fmt, T&&... args)
    -> std::string {
  return fmt::vformat(ts, fmt.str, vargs<T...>{{args...}});
 }
@@ -556,8 +529,8 @@ inline auto format(text_style ts, format_string<T...> fmt, T&&... args)
 /// Formats a string with the given text_style and writes the output to `out`.
 template <typename OutputIt,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-auto vformat_to(OutputIt out, text_style ts, string_view fmt, format_args args)
-    -> OutputIt {
+auto vformat_to(OutputIt out, const text_style& ts, string_view fmt,
+                format_args args) -> OutputIt {
  auto&& buf = detail::get_buffer<char>(out);
  detail::vformat_to(buf, ts, fmt, args);
  return detail::get_iterator(buf, out);
@@ -575,8 +548,8 @@ auto vformat_to(OutputIt out, text_style ts, string_view fmt, format_args args)
 */
 template <typename OutputIt, typename... T,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-inline auto format_to(OutputIt out, text_style ts, format_string<T...> fmt,
-                      T&&... args) -> OutputIt {
+inline auto format_to(OutputIt out, const text_style& ts,
+                      format_string<T...> fmt, T&&... args) -> OutputIt {
  return vformat_to(out, ts, fmt.str, vargs<T...>{{args...}});
 }

--- a/include/spdlog/fmt/bundled/compile.h
+++ b/include/spdlog/fmt/bundled/compile.h
@@ -19,11 +19,11 @@ FMT_BEGIN_NAMESPACE
 // A compile-time string which is compiled into fast formatting code.
 FMT_EXPORT class compiled_string {};

+namespace detail {
+
 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
@@ -41,6 +41,16 @@ namespace detail {
 #  define FMT_COMPILE(s) FMT_STRING(s)
 #endif

+#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+template <typename Char, size_t N, fmt::detail::fixed_string<Char, N> Str>
+struct udl_compiled_string : compiled_string {
+  using char_type = Char;
+  constexpr explicit operator basic_string_view<char_type>() const {
+    return {Str.data, N - 1};
+  }
+};
+#endif
+
 template <typename T, typename... Tail>
 auto first(const T& value, const Tail&...) -> const T& {
  return value;
@@ -415,7 +425,7 @@ constexpr auto compile_format_string(S fmt) {
 }

 template <typename... Args, typename S,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 constexpr auto compile(S fmt) {
  constexpr auto str = basic_string_view<typename S::char_type>(fmt);
  if constexpr (str.size() == 0) {
@@ -451,7 +461,7 @@ constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
 }

 template <typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
                                                           Args&&... args) {
  if constexpr (std::is_same<typename S::char_type, char>::value) {
@@ -478,7 +488,7 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
 }

 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
  constexpr auto compiled = detail::compile<Args...>(S());
  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
@@ -493,7 +503,7 @@ FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
 #endif

 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
    -> format_to_n_result<OutputIt> {
  using traits = detail::fixed_buffer_traits;
@@ -503,7 +513,7 @@ auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
 }

 template <typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
    -> size_t {
  auto buf = detail::counting_buffer<>();
@@ -512,7 +522,7 @@ FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
 }

 template <typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 void print(std::FILE* f, const S& fmt, const Args&... args) {
  auto buf = memory_buffer();
  fmt::format_to(appender(buf), fmt, args...);
@@ -520,7 +530,7 @@ void print(std::FILE* f, const S& fmt, const Args&... args) {
 }

 template <typename S, typename... Args,
-          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 void print(const S& fmt, const Args&... args) {
  print(stdout, fmt, args...);
 }
@@ -528,7 +538,9 @@ void print(const S& fmt, const Args&... args) {
 #if FMT_USE_NONTYPE_TEMPLATE_ARGS
 inline namespace literals {
 template <detail::fixed_string Str> constexpr auto operator""_cf() {
-  return FMT_COMPILE(Str.data);
+  using char_t = remove_cvref_t<decltype(Str.data[0])>;
+  return detail::udl_compiled_string<char_t, sizeof(Str.data) / sizeof(char_t),
+                                     Str>();
 }
 }  // namespace literals
 #endif
--- a/include/spdlog/fmt/bundled/fmt.license.rst
+++ b/include/spdlog/fmt/bundled/fmt.license.rst
@@ -1,4 +1,4 @@
-Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
+Copyright (c) 2012 - present, Victor Zverovich

 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
--- a/include/spdlog/fmt/bundled/format-inl.h
+++ b/include/spdlog/fmt/bundled/format-inl.h
@@ -212,7 +212,7 @@ inline auto floor_log10_pow2_minus_log10_4_over_3(int e) noexcept -> int {
  return (e * 631305 - 261663) >> 21;
 }

-FMT_INLINE_VARIABLE constexpr struct div_small_pow10_infos_struct {
+FMT_INLINE_VARIABLE constexpr struct {
  uint32_t divisor;
  int shift_amount;
 } div_small_pow10_infos[] = {{10, 16}, {100, 16}};
@@ -1097,7 +1097,7 @@ template <> struct cache_accessor<double> {
    return {r.high(), r.low() == 0};
  }

-  static auto compute_delta(const cache_entry_type& cache, int beta) noexcept
+  static auto compute_delta(cache_entry_type const& cache, int beta) noexcept
      -> uint32_t {
    return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta));
  }
@@ -1526,8 +1526,9 @@ template <typename F> class glibc_file : public file_base<F> {
  }

  void init_buffer() {
-    if (this->file_->_IO_write_ptr < this->file_->_IO_write_end) return;
+    if (this->file_->_IO_write_ptr) return;
    // Force buffer initialization by placing and removing a char in a buffer.
+    assume(this->file_->_IO_write_ptr >= this->file_->_IO_write_end);
    putc_unlocked(0, this->file_);
    --this->file_->_IO_write_ptr;
  }
--- a/include/spdlog/fmt/bundled/format.h
+++ b/include/spdlog/fmt/bundled/format.h
@@ -117,7 +117,6 @@
 #  define FMT_NOINLINE
 #endif

-// GCC 4.9 doesn't support qualified names in specializations.
 namespace std {
 template <typename T> struct iterator_traits<fmt::basic_appender<T>> {
  using iterator_category = output_iterator_tag;
@@ -706,7 +705,7 @@ using is_integer =

 #if defined(FMT_USE_FLOAT128)
 // Use the provided definition.
-#elif FMT_CLANG_VERSION >= 309 && FMT_HAS_INCLUDE(<quadmath.h>)
+#elif FMT_CLANG_VERSION && FMT_HAS_INCLUDE(<quadmath.h>)
 #  define FMT_USE_FLOAT128 1
 #elif FMT_GCC_VERSION && defined(_GLIBCXX_USE_FLOAT128) && \
    !defined(__STRICT_ANSI__)
@@ -722,10 +721,11 @@ struct float128 {};

 template <typename T> using is_float128 = std::is_same<T, float128>;

-template <typename T> struct is_floating_point : std::is_floating_point<T> {};
-template <> struct is_floating_point<float128> : std::true_type {};
+template <typename T>
+using is_floating_point =
+    bool_constant<std::is_floating_point<T>::value || is_float128<T>::value>;

-template <typename T, bool = is_floating_point<T>::value>
+template <typename T, bool = std::is_floating_point<T>::value>
 struct is_fast_float : bool_constant<std::numeric_limits<T>::is_iec559 &&
                                     sizeof(T) <= sizeof(double)> {};
 template <typename T> struct is_fast_float<T, false> : std::false_type {};
@@ -1613,7 +1613,7 @@ constexpr auto convert_float(T value) -> convert_float_result<T> {
 }

 template <typename Char, typename OutputIt>
-FMT_CONSTEXPR FMT_NOINLINE auto fill(OutputIt it, size_t n,
+FMT_NOINLINE FMT_CONSTEXPR auto fill(OutputIt it, size_t n,
                                     const basic_specs& specs) -> OutputIt {
  auto fill_size = specs.fill_size();
  if (fill_size == 1) return detail::fill_n(it, n, specs.fill_unit<Char>());
@@ -2332,7 +2332,7 @@ template <typename Char, typename OutputIt, typename DecimalFP,
          typename Grouping = digit_grouping<Char>>
 FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
                                    const format_specs& specs, sign s,
-                                    int exp_upper, locale_ref loc) -> OutputIt {
+                                    locale_ref loc) -> OutputIt {
  auto significand = f.significand;
  int significand_size = get_significand_size(f);
  const Char zero = static_cast<Char>('0');
@@ -2348,7 +2348,7 @@ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
    if (specs.type() == presentation_type::fixed) return false;
    // Use the fixed notation if the exponent is in [exp_lower, exp_upper),
    // e.g. 0.0001 instead of 1e-04. Otherwise use the exponent notation.
-    const int exp_lower = -4;
+    const int exp_lower = -4, exp_upper = 16;
    return output_exp < exp_lower ||
           output_exp >= (specs.precision > 0 ? specs.precision : exp_upper);
  };
@@ -2451,13 +2451,12 @@ template <typename Char> class fallback_digit_grouping {
 template <typename Char, typename OutputIt, typename DecimalFP>
 FMT_CONSTEXPR20 auto write_float(OutputIt out, const DecimalFP& f,
                                 const format_specs& specs, sign s,
-                                 int exp_upper, locale_ref loc) -> OutputIt {
+                                 locale_ref loc) -> OutputIt {
  if (is_constant_evaluated()) {
    return do_write_float<Char, OutputIt, DecimalFP,
-                          fallback_digit_grouping<Char>>(out, f, specs, s,
-                                                         exp_upper, loc);
+                          fallback_digit_grouping<Char>>(out, f, specs, s, loc);
  } else {
-    return do_write_float<Char>(out, f, specs, s, exp_upper, loc);
+    return do_write_float<Char>(out, f, specs, s, loc);
  }
 }

@@ -2472,8 +2471,8 @@ template <typename T>
 struct has_isfinite<T, enable_if_t<sizeof(std::isfinite(T())) != 0>>
    : std::true_type {};

-template <typename T,
-          FMT_ENABLE_IF(is_floating_point<T>::value&& has_isfinite<T>::value)>
+template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value&&
+                                        has_isfinite<T>::value)>
 FMT_CONSTEXPR20 auto isfinite(T value) -> bool {
  constexpr T inf = T(std::numeric_limits<double>::infinity());
  if (is_constant_evaluated())
@@ -3289,14 +3288,6 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision,
  return exp;
 }

-// Numbers with exponents greater or equal to the returned value will use
-// the exponential notation.
-template <typename T> constexpr auto exp_upper() -> int {
-  return std::numeric_limits<T>::digits10 != 0
-             ? min_of(16, std::numeric_limits<T>::digits10 + 1)
-             : 16;
-}
-
 template <typename Char, typename OutputIt, typename T>
 FMT_CONSTEXPR20 auto write_float(OutputIt out, T value, format_specs specs,
                                 locale_ref loc) -> OutputIt {
@@ -3312,7 +3303,6 @@ FMT_CONSTEXPR20 auto write_float(OutputIt out, T value, format_specs specs,
    if (specs.width != 0) --specs.width;
  }

-  constexpr int exp_upper = detail::exp_upper<T>();
  int precision = specs.precision;
  if (precision < 0) {
    if (specs.type() != presentation_type::none) {
@@ -3321,7 +3311,7 @@ FMT_CONSTEXPR20 auto write_float(OutputIt out, T value, format_specs specs,
      // Use Dragonbox for the shortest format.
      using floaty = conditional_t<sizeof(T) >= sizeof(double), double, float>;
      auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
-      return write_float<Char>(out, dec, specs, s, exp_upper, loc);
+      return write_float<Char>(out, dec, specs, s, loc);
    }
  }

@@ -3349,7 +3339,7 @@ FMT_CONSTEXPR20 auto write_float(OutputIt out, T value, format_specs specs,

  specs.precision = precision;
  auto f = big_decimal_fp{buffer.data(), static_cast<int>(buffer.size()), exp};
-  return write_float<Char>(out, f, specs, s, exp_upper, loc);
+  return write_float<Char>(out, f, specs, s, loc);
 }

 template <typename Char, typename OutputIt, typename T,
@@ -3376,7 +3366,7 @@ FMT_CONSTEXPR20 auto write(OutputIt out, T value) -> OutputIt {
    return write_nonfinite<Char>(out, std::isnan(value), specs, s);

  auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
-  return write_float<Char>(out, dec, specs, s, exp_upper<T>(), {});
+  return write_float<Char>(out, dec, specs, s, {});
 }

 template <typename Char, typename OutputIt, typename T,
--- a/include/spdlog/fmt/bundled/ostream.h
+++ b/include/spdlog/fmt/bundled/ostream.h
@@ -158,8 +158,7 @@ void print(std::ostream& os, format_string<T...> fmt, T&&... args) {

 FMT_EXPORT template <typename... T>
 void println(std::ostream& os, format_string<T...> fmt, T&&... args) {
-  fmt::print(os, FMT_STRING("{}\n"),
-             fmt::format(fmt, std::forward<T>(args)...));
+  fmt::print(os, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
 }

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/ranges.h
+++ b/include/spdlog/fmt/bundled/ranges.h
@@ -774,13 +774,13 @@ struct formatter<
    : formatter<detail::all<typename T::container_type>, Char> {
  using all = detail::all<typename T::container_type>;
  template <typename FormatContext>
-  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
+  auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
    struct getter : T {
-      static auto get(const T& v) -> all {
-        return {v.*(&getter::c)};  // Access c through the derived class.
+      static auto get(const T& t) -> all {
+        return {t.*(&getter::c)};  // Access c through the derived class.
      }
    };
-    return formatter<all>::format(getter::get(value), ctx);
+    return formatter<all>::format(getter::get(t), ctx);
  }
 };

--- a/include/spdlog/fmt/bundled/std.h
+++ b/include/spdlog/fmt/bundled/std.h
@@ -113,6 +113,7 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,

 }  // namespace detail

+FMT_EXPORT
 template <typename Char> struct formatter<std::filesystem::path, Char> {
 private:
  format_specs specs_;
@@ -181,6 +182,7 @@ FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_FILESYSTEM

 FMT_BEGIN_NAMESPACE
+FMT_EXPORT
 template <std::size_t N, typename Char>
 struct formatter<std::bitset<N>, Char>
    : nested_formatter<basic_string_view<Char>, Char> {
@@ -207,12 +209,14 @@ struct formatter<std::bitset<N>, Char>
  }
 };

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

 #ifdef __cpp_lib_optional
 FMT_BEGIN_NAMESPACE
+FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<std::optional<T>, Char,
                 std::enable_if_t<is_formattable<T, Char>::value>> {
@@ -275,6 +279,7 @@ FMT_END_NAMESPACE
 #ifdef __cpp_lib_expected
 FMT_BEGIN_NAMESPACE

+FMT_EXPORT
 template <typename T, typename E, typename Char>
 struct formatter<std::expected<T, E>, Char,
                 std::enable_if_t<(std::is_void<T>::value ||
@@ -306,6 +311,7 @@ FMT_END_NAMESPACE

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

@@ -361,6 +367,7 @@ template <typename T, typename C> struct is_variant_formattable {
      detail::is_variant_formattable_<T, C>::value;
 };

+FMT_EXPORT
 template <typename Char> struct formatter<std::monostate, Char> {
  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    return ctx.begin();
@@ -373,6 +380,7 @@ template <typename Char> struct formatter<std::monostate, Char> {
  }
 };

+FMT_EXPORT
 template <typename Variant, typename Char>
 struct formatter<
    Variant, Char,
@@ -406,11 +414,11 @@ FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_VARIANT

 FMT_BEGIN_NAMESPACE
+FMT_EXPORT
 template <> struct formatter<std::error_code> {
 private:
  format_specs specs_;
  detail::arg_ref<char> width_ref_;
-  bool debug_ = false;

 public:
  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
@@ -418,19 +426,11 @@ template <> struct formatter<std::error_code> {
    if (it == end) return it;

    it = detail::parse_align(it, end, specs_);
+    if (it == end) return it;

    char c = *it;
-    if (it != end && ((c >= '0' && c <= '9') || c == '{'))
+    if ((c >= '0' && c <= '9') || c == '{')
      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
-
-    if (it != end && *it == '?') {
-      debug_ = true;
-      ++it;
-    }
-    if (it != end && *it == 's') {
-      specs_.set_type(presentation_type::string);
-      ++it;
-    }
    return it;
  }

@@ -440,21 +440,12 @@ template <> struct formatter<std::error_code> {
    auto specs = specs_;
    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
                                ctx);
-    auto buf = memory_buffer();
-    if (specs_.type() == presentation_type::string) {
-      buf.append(ec.message());
-    } else {
-      buf.append(string_view(ec.category().name()));
-      buf.push_back(':');
-      detail::write<char>(appender(buf), ec.value());
-    }
-    auto quoted = memory_buffer();
-    auto str = string_view(buf.data(), buf.size());
-    if (debug_) {
-      detail::write_escaped_string<char>(std::back_inserter(quoted), str);
-      str = string_view(quoted.data(), quoted.size());
-    }
-    return detail::write<char>(ctx.out(), str, specs);
+    memory_buffer buf;
+    buf.append(string_view(ec.category().name()));
+    buf.push_back(':');
+    detail::write<char>(appender(buf), ec.value());
+    return detail::write<char>(ctx.out(), string_view(buf.data(), buf.size()),
+                               specs);
  }
 };

@@ -529,6 +520,7 @@ auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {

 }  // namespace detail

+FMT_EXPORT
 template <typename Char>
 struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
                 > {
@@ -545,6 +537,7 @@ struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
 };
 #endif

+FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<
    T, Char,  // DEPRECATED! Mixing code unit types.
@@ -610,6 +603,7 @@ struct is_bit_reference_like<std::__bit_const_reference<C>> {
 // 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.
+FMT_EXPORT
 template <typename BitRef, typename Char>
 struct formatter<BitRef, Char,
                 enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
@@ -629,6 +623,7 @@ template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
  return p.get();
 }

+FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<std::atomic<T>, Char,
                 enable_if_t<is_formattable<T, Char>::value>>
@@ -641,6 +636,7 @@ struct formatter<std::atomic<T>, Char,
 };

 #ifdef __cpp_lib_atomic_flag_test
+FMT_EXPORT
 template <typename Char>
 struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
  template <typename FormatContext>
@@ -651,6 +647,7 @@ struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
 };
 #endif  // __cpp_lib_atomic_flag_test

+FMT_EXPORT
 template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
 private:
  detail::dynamic_format_specs<Char> specs_;
@@ -713,6 +710,7 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
  }
 };

+FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<std::reference_wrapper<T>, Char,
                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value>>
--- a/include/spdlog/fmt/bundled/xchar.h
+++ b/include/spdlog/fmt/bundled/xchar.h
@@ -112,6 +112,10 @@ inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
  return {{s}};
 }

+template <> struct is_char<wchar_t> : std::true_type {};
+template <> struct is_char<char16_t> : std::true_type {};
+template <> struct is_char<char32_t> : std::true_type {};
+
 #ifdef __cpp_char8_t
 template <> struct is_char<char8_t> : bool_constant<detail::is_utf8_enabled> {};
 #endif
@@ -318,7 +322,7 @@ template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
  return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
 }

-inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
+inline auto vformat(const text_style& ts, wstring_view fmt, wformat_args args)
    -> std::wstring {
  auto buf = wmemory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
@@ -326,19 +330,19 @@ inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
 }

 template <typename... T>
-inline auto format(text_style ts, wformat_string<T...> fmt, T&&... args)
+inline auto format(const text_style& ts, wformat_string<T...> fmt, T&&... args)
    -> std::wstring {
  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) {
+FMT_DEPRECATED void print(std::FILE* f, const 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,
+FMT_DEPRECATED void print(const text_style& ts, wformat_string<T...> fmt,
                          const T&... args) {
  return print(stdout, ts, fmt, args...);
 }
--- a/include/spdlog/fmt/fmt.h
+++ b/include/spdlog/fmt/fmt.h
@@ -21,10 +21,10 @@
        #define FMT_USE_WINDOWS_H 0
    #endif

-    #include <spdlog/fmt/bundled/base.h>
+    #include <spdlog/fmt/bundled/core.h>
    #include <spdlog/fmt/bundled/format.h>

 #else  // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
-    #include <fmt/base.h>
+    #include <fmt/core.h>
    #include <fmt/format.h>
 #endif
--- a/include/spdlog/mdc.h
+++ b/include/spdlog/mdc.h
@@ -12,14 +12,12 @@

 #include <spdlog/common.h>

-// MDC is a simple map of key->string values stored in thread local storage whose content will be
-// printed by the loggers. Note: Not supported in async mode (thread local storage - so the async
-// thread pool have different copy).
+// MDC is a simple map of key->string values stored in thread local storage whose content will be printed by the loggers.
+// Note: Not supported in async mode (thread local storage - so the async thread pool have different copy).
 //
 // Usage example:
 // spdlog::mdc::put("mdc_key_1", "mdc_value_1");
-// spdlog::info("Hello, {}", "World!");  // => [2024-04-26 02:08:05.040] [info]
-// [mdc_key_1:mdc_value_1] Hello, World!
+// spdlog::info("Hello, {}", "World!");  // => [2024-04-26 02:08:05.040] [info] [mdc_key_1:mdc_value_1] Hello, World!

 namespace spdlog {
 class SPDLOG_API mdc {
--- a/include/spdlog/sinks/ansicolor_sink-inl.h
+++ b/include/spdlog/sinks/ansicolor_sink-inl.h
@@ -111,8 +111,7 @@ SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::set_color_mode_(color_mode mode
 }

 template <typename ConsoleMutex>
-SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::print_ccode_(
-    const string_view_t &color_code) const {
+SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::print_ccode_(const string_view_t &color_code) const {
    details::os::fwrite_bytes(color_code.data(), color_code.size(), target_file_);
 }

--- a/include/spdlog/sinks/callback_sink.h
+++ b/include/spdlog/sinks/callback_sink.h
@@ -27,7 +27,7 @@ public:

 protected:
    void sink_it_(const details::log_msg &msg) override { callback_(msg); }
-    void flush_() override {}
+    void flush_() override{}

 private:
    custom_log_callback callback_;
--- a/include/spdlog/sinks/dup_filter_sink.h
+++ b/include/spdlog/sinks/dup_filter_sink.h
@@ -40,21 +40,22 @@ template <typename Mutex>
 class dup_filter_sink : public dist_sink<Mutex> {
 public:
    template <class Rep, class Period>
-    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration)
-        : max_skip_duration_{max_skip_duration} {}
+    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration,
+                             level::level_enum notification_level = level::info)
+        : max_skip_duration_{max_skip_duration},
+          log_level_{notification_level} {}

 protected:
    std::chrono::microseconds max_skip_duration_;
    log_clock::time_point last_msg_time_;
    std::string last_msg_payload_;
    size_t skip_counter_ = 0;
-    level::level_enum skipped_msg_log_level_ = spdlog::level::level_enum::off;
+    level::level_enum log_level_;

    void sink_it_(const details::log_msg &msg) override {
        bool filtered = filter_(msg);
        if (!filtered) {
            skip_counter_ += 1;
-            skipped_msg_log_level_ = msg.level;
            return;
        }

@@ -64,7 +65,7 @@ protected:
            auto msg_size = ::snprintf(buf, sizeof(buf), "Skipped %u duplicate messages..",
                                       static_cast<unsigned>(skip_counter_));
            if (msg_size > 0 && static_cast<size_t>(msg_size) < sizeof(buf)) {
-                details::log_msg skipped_msg{msg.source, msg.logger_name, skipped_msg_log_level_,
+                details::log_msg skipped_msg{msg.source, msg.logger_name, log_level_,
                                             string_view_t{buf, static_cast<size_t>(msg_size)}};
                dist_sink<Mutex>::sink_it_(skipped_msg);
            }
--- a/include/spdlog/sinks/rotating_file_sink-inl.h
+++ b/include/spdlog/sinks/rotating_file_sink-inl.h
@@ -14,6 +14,7 @@
 #include <spdlog/fmt/fmt.h>

 #include <cerrno>
+#include <chrono>
 #include <ctime>
 #include <mutex>
 #include <string>
@@ -37,8 +38,8 @@ SPDLOG_INLINE rotating_file_sink<Mutex>::rotating_file_sink(
        throw_spdlog_ex("rotating sink constructor: max_size arg cannot be zero");
    }

-    if (max_files > MaxFiles) {
-        throw_spdlog_ex("rotating sink constructor: max_files arg cannot exceed MaxFiles");
+    if (max_files > 200000) {
+        throw_spdlog_ex("rotating sink constructor: max_files arg cannot exceed 200000");
    }
    file_helper_.open(calc_filename(base_filename_, 0));
    current_size_ = file_helper_.size();  // expensive. called only once
@@ -53,12 +54,11 @@ SPDLOG_INLINE rotating_file_sink<Mutex>::rotating_file_sink(
 template <typename Mutex>
 SPDLOG_INLINE filename_t rotating_file_sink<Mutex>::calc_filename(const filename_t &filename,
                                                                  std::size_t index) {
-    if (index == 0U) {
+    if (index == 0u) {
        return filename;
    }

-    filename_t basename;
-    filename_t ext;
+    filename_t basename, ext;
    std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
    return fmt_lib::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{}.{}{}")), basename, index, ext);
 }
@@ -74,35 +74,6 @@ SPDLOG_INLINE void rotating_file_sink<Mutex>::rotate_now() {
    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
    rotate_();
 }
-template <typename Mutex>
-SPDLOG_INLINE void rotating_file_sink<Mutex>::set_max_size(std::size_t max_size) {
-    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
-    if (max_size == 0) {
-        throw_spdlog_ex("rotating sink set_max_size: max_size arg cannot be zero");
-    }
-    max_size_ = max_size;
-}
-
-template <typename Mutex>
-SPDLOG_INLINE std::size_t rotating_file_sink<Mutex>::get_max_size() {
-    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
-    return max_size_;
-}
-
-template <typename Mutex>
-SPDLOG_INLINE void rotating_file_sink<Mutex>::set_max_files(std::size_t max_files) {
-    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
-    if (max_files > MaxFiles) {
-        throw_spdlog_ex("rotating sink set_max_files: max_files arg cannot exceed 200000");
-    }
-    max_files_ = max_files;
-}
-
-template <typename Mutex>
-std::size_t rotating_file_sink<Mutex>::get_max_files() {
-    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
-    return max_files_;
-}

 template <typename Mutex>
 SPDLOG_INLINE void rotating_file_sink<Mutex>::sink_it_(const details::log_msg &msg) {
--- a/include/spdlog/sinks/rotating_file_sink.h
+++ b/include/spdlog/sinks/rotating_file_sink.h
@@ -8,6 +8,7 @@
 #include <spdlog/details/synchronous_factory.h>
 #include <spdlog/sinks/base_sink.h>

+#include <chrono>
 #include <mutex>
 #include <string>

@@ -20,7 +21,6 @@ namespace sinks {
 template <typename Mutex>
 class rotating_file_sink final : public base_sink<Mutex> {
 public:
-    static constexpr size_t MaxFiles = 200000;
    rotating_file_sink(filename_t base_filename,
                       std::size_t max_size,
                       std::size_t max_files,
@@ -29,10 +29,6 @@ public:
    static filename_t calc_filename(const filename_t &filename, std::size_t index);
    filename_t filename();
    void rotate_now();
-    void set_max_size(std::size_t max_size);
-    std::size_t get_max_size();
-    void set_max_files(std::size_t max_files);
-    std::size_t get_max_files();

 protected:
    void sink_it_(const details::log_msg &msg) override;
@@ -46,7 +42,7 @@ private:
    // log.3.txt -> delete
    void rotate_();

-    // delete the target if exists, and rename the src file to target
+    // delete the target if exists, and rename the src file  to target
    // return true on success, false otherwise.
    bool rename_file_(const filename_t &src_filename, const filename_t &target_filename);

@@ -65,24 +61,25 @@ using rotating_file_sink_st = rotating_file_sink<details::null_mutex>;
 //
 // factory functions
 //
+
 template <typename Factory = spdlog::synchronous_factory>
-std::shared_ptr<logger> rotating_logger_mt(const std::string &logger_name,
-                                           const filename_t &filename,
-                                           size_t max_file_size,
-                                           size_t max_files,
-                                           bool rotate_on_open = false,
-                                           const file_event_handlers &event_handlers = {}) {
+inline std::shared_ptr<logger> rotating_logger_mt(const std::string &logger_name,
+                                                  const filename_t &filename,
+                                                  size_t max_file_size,
+                                                  size_t max_files,
+                                                  bool rotate_on_open = false,
+                                                  const file_event_handlers &event_handlers = {}) {
    return Factory::template create<sinks::rotating_file_sink_mt>(
        logger_name, filename, max_file_size, max_files, rotate_on_open, event_handlers);
 }

 template <typename Factory = spdlog::synchronous_factory>
-std::shared_ptr<logger> rotating_logger_st(const std::string &logger_name,
-                                           const filename_t &filename,
-                                           size_t max_file_size,
-                                           size_t max_files,
-                                           bool rotate_on_open = false,
-                                           const file_event_handlers &event_handlers = {}) {
+inline std::shared_ptr<logger> rotating_logger_st(const std::string &logger_name,
+                                                  const filename_t &filename,
+                                                  size_t max_file_size,
+                                                  size_t max_files,
+                                                  bool rotate_on_open = false,
+                                                  const file_event_handlers &event_handlers = {}) {
    return Factory::template create<sinks::rotating_file_sink_st>(
        logger_name, filename, max_file_size, max_files, rotate_on_open, event_handlers);
 }
--- a/include/spdlog/sinks/wincolor_sink-inl.h
+++ b/include/spdlog/sinks/wincolor_sink-inl.h
@@ -137,10 +137,10 @@ void SPDLOG_INLINE wincolor_sink<ConsoleMutex>::print_range_(const memory_buf_t
 #if defined(SPDLOG_UTF8_TO_WCHAR_CONSOLE)
        wmemory_buf_t wformatted;
        details::os::utf8_to_wstrbuf(string_view_t(formatted.data() + start, end - start),
-                                     wformatted);
+            wformatted);
        auto size = static_cast<DWORD>(wformatted.size());
        auto ignored = ::WriteConsoleW(static_cast<HANDLE>(out_handle_), wformatted.data(), size,
-                                       nullptr, nullptr);
+            nullptr, nullptr);
 #else
        auto size = static_cast<DWORD>(end - start);
        auto ignored = ::WriteConsoleA(static_cast<HANDLE>(out_handle_), formatted.data() + start,
--- a/include/spdlog/spdlog-inl.h
+++ b/include/spdlog/spdlog-inl.h
@@ -59,10 +59,6 @@ SPDLOG_INLINE void register_logger(std::shared_ptr<logger> logger) {
    details::registry::instance().register_logger(std::move(logger));
 }

-SPDLOG_INLINE void register_or_replace(std::shared_ptr<logger> logger) {
-    details::registry::instance().register_or_replace(std::move(logger));
-}
-
 SPDLOG_INLINE void apply_all(const std::function<void(std::shared_ptr<logger>)> &fun) {
    details::registry::instance().apply_all(fun);
 }
--- a/include/spdlog/spdlog.h
+++ b/include/spdlog/spdlog.h
@@ -25,7 +25,7 @@ namespace spdlog {
 using default_factory = synchronous_factory;

 // Create and register a logger with a templated sink type
-// The logger's level, formatter and flush level will be set according to the
+// The logger's level, formatter and flush level will be set according the
 // global settings.
 //
 // Example:
@@ -46,7 +46,7 @@ inline std::shared_ptr<spdlog::logger> create(std::string logger_name, SinkArgs
 //   spdlog::initialize_logger(mylogger);
 SPDLOG_API void initialize_logger(std::shared_ptr<logger> logger);

-// Return an existing logger or nullptr if a logger with such a name doesn't
+// Return an existing logger or nullptr if a logger with such name doesn't
 // exist.
 // example: spdlog::get("my_logger")->info("hello {}", "world");
 SPDLOG_API std::shared_ptr<logger> get(const std::string &name);
@@ -71,13 +71,13 @@ SPDLOG_API void dump_backtrace();
 // Get global logging level
 SPDLOG_API level::level_enum get_level();

-// Set the global logging level
+// Set global logging level
 SPDLOG_API void set_level(level::level_enum log_level);

 // Determine whether the default logger should log messages with a certain level
 SPDLOG_API bool should_log(level::level_enum lvl);

-// Set a global flush level
+// Set global flush level
 SPDLOG_API void flush_on(level::level_enum log_level);

 // Start/Restart a periodic flusher thread
@@ -91,14 +91,9 @@ inline void flush_every(std::chrono::duration<Rep, Period> interval) {
 SPDLOG_API void set_error_handler(void (*handler)(const std::string &msg));

 // Register the given logger with the given name
-// Will throw if a logger with the same name already exists.
 SPDLOG_API void register_logger(std::shared_ptr<logger> logger);

-// Register the given logger with the given name
-// Will replace any existing logger with the same name.
-SPDLOG_API void register_or_replace(std::shared_ptr<logger> logger);
-
-// Apply a user-defined function on all registered loggers
+// Apply a user defined function on all registered loggers
 // Example:
 // spdlog::apply_all([&](std::shared_ptr<spdlog::logger> l) {l->flush();});
 SPDLOG_API void apply_all(const std::function<void(std::shared_ptr<logger>)> &fun);
@@ -116,19 +111,19 @@ SPDLOG_API void shutdown();
 SPDLOG_API void set_automatic_registration(bool automatic_registration);

 // API for using default logger (stdout_color_mt),
-// e.g.: spdlog::info("Message {}", 1);
+// e.g: spdlog::info("Message {}", 1);
 //
 // The default logger object can be accessed using the spdlog::default_logger():
 // For example, to add another sink to it:
 // spdlog::default_logger()->sinks().push_back(some_sink);
 //
-// The default logger can be replaced using spdlog::set_default_logger(new_logger).
+// The default logger can replaced using spdlog::set_default_logger(new_logger).
 // For example, to replace it with a file logger.
 //
 // IMPORTANT:
 // The default API is thread safe (for _mt loggers), but:
 // set_default_logger() *should not* be used concurrently with the default API.
-// e.g., do not call set_default_logger() from one thread while calling spdlog::info() from another.
+// e.g do not call set_default_logger() from one thread while calling spdlog::info() from another.

 SPDLOG_API std::shared_ptr<spdlog::logger> default_logger();

--- a/include/spdlog/tweakme.h
+++ b/include/spdlog/tweakme.h
@@ -109,8 +109,8 @@
 //
 // #include <string_view>
 // using namespace std::string_view_literals;
-// #define SPDLOG_LEVEL_NAMES { "MY TRACE"sv, "MY DEBUG"sv, "MY INFO"sv, "MY WARNING"sv, "MY
-// ERROR"sv, "MY CRITICAL"sv, "OFF"sv }
+// #define SPDLOG_LEVEL_NAMES { "MY TRACE"sv, "MY DEBUG"sv, "MY INFO"sv, "MY WARNING"sv, "MY ERROR"sv, "MY
+// CRITICAL"sv, "OFF"sv }
 ///////////////////////////////////////////////////////////////////////////////

 ///////////////////////////////////////////////////////////////////////////////
--- a/include/spdlog/version.h
+++ b/include/spdlog/version.h
@@ -5,7 +5,7 @@

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

 #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
@@ -13,32 +13,34 @@
 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>;
+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
+#if FMT_USE_LOCALE
 // DEPRECATED! locale_ref in the detail namespace
 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

 // 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);
+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;

 template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);
@@ -46,4 +48,5 @@ template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);
 }  // namespace detail
 FMT_END_NAMESPACE

+
 #endif  // !SPDLOG_FMT_EXTERNAL
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -19,9 +19,9 @@ if(Catch2_FOUND)
 else()
    message(STATUS "Bundled version of Catch will be downloaded and used.")
    include(FetchContent)
-    FetchContent_Declare(
-        Catch2 GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-        GIT_TAG 53d0d913a422d356b23dd927547febdf69ee9081 # v3.5.0
+    FetchContent_Declare(Catch2
+            GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+            GIT_TAG 53d0d913a422d356b23dd927547febdf69ee9081 # v3.5.0
    )
    FetchContent_MakeAvailable(Catch2)
 endif()
@@ -71,9 +71,9 @@ function(spdlog_prepare_test test_target spdlog_lib)
    target_link_libraries(${test_target} PRIVATE Catch2::Catch2WithMain)
    if(SPDLOG_SANITIZE_ADDRESS)
        spdlog_enable_addr_sanitizer(${test_target})
-    elseif(SPDLOG_SANITIZE_THREAD)
+    elseif (SPDLOG_SANITIZE_THREAD)
        spdlog_enable_thread_sanitizer(${test_target})
-    endif()
+    endif ()
    add_test(NAME ${test_target} COMMAND ${test_target})
    set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()
--- a/tests/test_custom_callbacks.cpp
+++ b/tests/test_custom_callbacks.cpp
@@ -16,8 +16,7 @@ TEST_CASE("custom_callback_logger", "[custom_callback_logger]") {
            spdlog::memory_buf_t formatted;
            formatter.format(msg, formatted);
            auto eol_len = strlen(spdlog::details::os::default_eol);
-            using diff_t =
-                typename std::iterator_traits<decltype(formatted.end())>::difference_type;
+            using diff_t = typename std::iterator_traits<decltype(formatted.end())>::difference_type; 
            lines.emplace_back(formatted.begin(), formatted.end() - static_cast<diff_t>(eol_len));
        });
    std::shared_ptr<spdlog::sinks::test_sink_st> test_sink(new spdlog::sinks::test_sink_st);
--- a/tests/test_daily_logger.cpp
+++ b/tests/test_daily_logger.cpp
@@ -46,8 +46,10 @@ TEST_CASE("daily_logger with dateonly calculator", "[daily_logger]") {

 struct custom_daily_file_name_calculator {
    static spdlog::filename_t calc_filename(const spdlog::filename_t &basename, const tm &now_tm) {
-        return spdlog::fmt_lib::format(SPDLOG_FILENAME_T("{}{:04d}{:02d}{:02d}"), basename,
-                                       now_tm.tm_year + 1900, now_tm.tm_mon + 1, now_tm.tm_mday);
+        
+        return spdlog::fmt_lib::format(SPDLOG_FILENAME_T("{}{:04d}{:02d}{:02d}"),
+                                   basename, now_tm.tm_year + 1900, now_tm.tm_mon + 1,
+                                   now_tm.tm_mday);        
    }
 };

--- a/tests/test_file_logging.cpp
+++ b/tests/test_file_logging.cpp
@@ -56,7 +56,7 @@ TEST_CASE("simple_file_logger", "[truncate]") {
    logger->info("Test message {}", 2.71);
    logger->flush();
    REQUIRE(count_lines(SIMPLE_LOG) == 2);
-
+    
    sink->truncate();
    REQUIRE(count_lines(SIMPLE_LOG) == 0);

@@ -94,11 +94,14 @@ TEST_CASE("rotating_file_logger2", "[rotating_logger]") {
        // next logger can rename the first output file.
        spdlog::drop(logger->name());
    }
+
    auto logger = spdlog::rotating_logger_mt("logger", basename, max_size, 2, true);
    for (int i = 0; i < 10; ++i) {
        logger->info("Test message {}", i);
    }
+
    logger->flush();
+
    require_message_count(ROTATING_LOG, 10);

    for (int i = 0; i < 1000; i++) {
@@ -138,50 +141,3 @@ TEST_CASE("rotating_file_logger4", "[rotating_logger]") {
    REQUIRE(get_filesize(ROTATING_LOG) > 0);
    REQUIRE(get_filesize(ROTATING_LOG ".1") > 0);
 }
-
-// test changing the max size of the rotating file sink
-TEST_CASE("rotating_file_logger5", "[rotating_logger]") {
-    prepare_logdir();
-    size_t max_size = 5 * 1024;
-    size_t max_files = 2;
-    spdlog::filename_t basename = SPDLOG_FILENAME_T(ROTATING_LOG);
-    auto sink =
-        std::make_shared<spdlog::sinks::rotating_file_sink_st>(basename, max_size, max_files);
-    auto logger = std::make_shared<spdlog::logger>("rotating_sink_logger", sink);
-    logger->set_pattern("%v");
-
-    REQUIRE(sink->get_max_size() == max_size);
-    REQUIRE(sink->get_max_files() == max_files);
-    max_size = 7 * 1024;
-    max_files = 3;
-
-    sink->set_max_size(max_size);
-    sink->set_max_files(max_files);
-    REQUIRE(sink->get_max_size() == max_size);
-    REQUIRE(sink->get_max_files() == max_files);
-
-    const auto message = std::string(200, 'x');
-    assert(message.size() < max_size);
-    const auto n_messages = max_files * max_size / message.size();
-    for (size_t i = 0; i < n_messages; ++i) {
-        logger->info(message);
-    }
-    logger.reset();  // force flush and close the file
-
-    // validate that the files were rotated correctly with the new max size and max files
-    for (size_t i = 0; i <= max_files; i++) {
-        // calc filenames
-        // e.g. rotating_log, rotating_log.0 rotating_log.1, rotating_log.2, etc.
-        std::ostringstream oss;
-        oss << ROTATING_LOG;
-        if (i > 0) {
-            oss << '.' << i;
-        }
-        const auto filename = oss.str();
-        const auto filesize = get_filesize(filename);
-        REQUIRE(filesize <= max_size);
-        if (i > 0) {
-            REQUIRE(filesize >= max_size - message.size() - 2);
-        }
-    }
-}
--- a/tests/test_misc.cpp
+++ b/tests/test_misc.cpp
@@ -1,12 +1,12 @@
-#ifdef _WIN32  // to prevent fopen warning on windows
-    #define _CRT_SECURE_NO_WARNINGS
+#ifdef _WIN32 // to prevent fopen warning on windows
+#define _CRT_SECURE_NO_WARNINGS
 #endif

 #include "includes.h"
 #include "test_sink.h"

 template <class T>
-std::string log_info(const T& what, spdlog::level::level_enum logger_level = spdlog::level::info) {
+std::string log_info(const T &what, spdlog::level::level_enum logger_level = spdlog::level::info) {
    std::ostringstream oss;
    auto oss_sink = std::make_shared<spdlog::sinks::ostream_sink_mt>(oss);

@@ -182,19 +182,17 @@ TEST_CASE("utf8 to utf16 conversion using windows api", "[windows utf]") {
    spdlog::details::os::utf8_to_wstrbuf("abc", buffer);
    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L"abc"));

-    spdlog::details::os::utf8_to_wstrbuf("\xc3\x28", buffer);  // Invalid UTF-8 sequence.
+    spdlog::details::os::utf8_to_wstrbuf("\xc3\x28", buffer); // Invalid UTF-8 sequence.
    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L"\xfffd("));

-    spdlog::details::os::utf8_to_wstrbuf("\xe3\x81\xad\xe3\x81\x93",
-                                         buffer);  // "Neko" in hiragana.
+    spdlog::details::os::utf8_to_wstrbuf("\xe3\x81\xad\xe3\x81\x93", buffer); // "Neko" in hiragana.
    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L"\x306d\x3053"));
 }
 #endif

 struct auto_closer {
    FILE* fp = nullptr;
-    explicit auto_closer(FILE* f)
-        : fp(f) {}
+    explicit auto_closer(FILE* f) : fp(f) {}
    auto_closer(const auto_closer&) = delete;
    auto_closer& operator=(const auto_closer&) = delete;
    ~auto_closer() {
@@ -203,10 +201,10 @@ struct auto_closer {
 };

 TEST_CASE("os::fwrite_bytes", "[os]") {
-    using spdlog::details::os::create_dir;
    using spdlog::details::os::fwrite_bytes;
+    using spdlog::details::os::create_dir;
    const char* filename = "log_tests/test_fwrite_bytes.txt";
-    const char* msg = "hello";
+    const char *msg = "hello";
    prepare_logdir();
    REQUIRE(create_dir(SPDLOG_FILENAME_T("log_tests")) == true);
    {
--- a/tests/test_pattern_formatter.cpp
+++ b/tests/test_pattern_formatter.cpp
@@ -1,8 +1,6 @@
 #include "includes.h"
 #include "test_sink.h"

-#include <chrono>
-
 using spdlog::memory_buf_t;
 using spdlog::details::to_string_view;

@@ -21,23 +19,6 @@ static std::string log_to_str(const std::string &msg, const Args &...args) {
    return oss.str();
 }

-// log to str and return it with time
-template <typename... Args>
-static std::string log_to_str_with_time(spdlog::log_clock::time_point log_time,
-                                        const std::string &msg,
-                                        const Args &...args) {
-    std::ostringstream oss;
-    auto oss_sink = std::make_shared<spdlog::sinks::ostream_sink_mt>(oss);
-    spdlog::logger oss_logger("pattern_tester", oss_sink);
-    oss_logger.set_level(spdlog::level::info);
-
-    oss_logger.set_formatter(
-        std::unique_ptr<spdlog::formatter>(new spdlog::pattern_formatter(args...)));
-
-    oss_logger.log(log_time, {}, spdlog::level::info, msg);
-    return oss.str();
-}
-
 TEST_CASE("custom eol", "[pattern_formatter]") {
    std::string msg = "Hello custom eol test";
    std::string eol = ";)";
@@ -77,15 +58,6 @@ TEST_CASE("date MM/DD/YY ", "[pattern_formatter]") {
            oss.str());
 }

-TEST_CASE("GMT offset ", "[pattern_formatter]") {
-    using namespace std::chrono_literals;
-    const auto now = std::chrono::system_clock::now();
-    const auto yesterday = now - 24h;
-
-    REQUIRE(log_to_str_with_time(yesterday, "Some message", "%z", spdlog::pattern_time_type::utc,
-                                 "\n") == "+00:00\n");
-}
-
 TEST_CASE("color range test1", "[pattern_formatter]") {
    auto formatter = std::make_shared<spdlog::pattern_formatter>(
        "%^%v%$", spdlog::pattern_time_type::local, "\n");
--- a/tests/test_registry.cpp
+++ b/tests/test_registry.cpp
@@ -25,19 +25,6 @@ TEST_CASE("explicit register", "[registry]") {
 }
 #endif

-TEST_CASE("register_or_replace", "[registry]") {
-    spdlog::drop_all();
-    auto logger1 = std::make_shared<spdlog::logger>(
-        tested_logger_name, std::make_shared<spdlog::sinks::null_sink_st>());
-    spdlog::register_logger(logger1);
-    REQUIRE(spdlog::get(tested_logger_name) == logger1);
-
-    auto logger2 = std::make_shared<spdlog::logger>(
-        tested_logger_name, std::make_shared<spdlog::sinks::null_sink_st>());
-    spdlog::register_or_replace(logger2);
-    REQUIRE(spdlog::get(tested_logger_name) == logger2);
-}
-
 TEST_CASE("apply_all", "[registry]") {
    spdlog::drop_all();
    auto logger = std::make_shared<spdlog::logger>(tested_logger_name,
--- a/tests/test_sink.h
+++ b/tests/test_sink.h
@@ -47,7 +47,7 @@ protected:
        base_sink<Mutex>::formatter_->format(msg, formatted);
        // save the line without the eol
        auto eol_len = strlen(details::os::default_eol);
-        using diff_t = typename std::iterator_traits<decltype(formatted.end())>::difference_type;
+        using diff_t = typename std::iterator_traits<decltype(formatted.end())>::difference_type; 
        if (lines_.size() < lines_to_save) {
            lines_.emplace_back(formatted.begin(), formatted.end() - static_cast<diff_t>(eol_len));
        }
--- a/tests/utils.cpp
+++ b/tests/utils.cpp
@@ -50,8 +50,9 @@ void require_message_count(const std::string &filename, const std::size_t messag
 std::size_t get_filesize(const std::string &filename) {
    std::ifstream ifs(filename, std::ifstream::ate | std::ifstream::binary);
    if (!ifs) {
-        throw std::runtime_error("Failed open file " + filename);
+        throw std::runtime_error("Failed open file ");
    }
+
    return static_cast<std::size_t>(ifs.tellg());
 }