Version 1.16.0

* Replaced fileapi.h include with windows.h, as instructed in https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-flushfilebuffers
Otherwise this causes compilation error on older sdks.

* Removed the fileapi.h include entirely, since windows.h is already included before

---------

Co-authored-by: MasonAngelio <MasonAngelio>

.github/workflows/coverity_scan.yml

@@ -0,0 +1,52 @@
+name: coverity-linux
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  coverity_scan:
+    runs-on: ubuntu-latest
+    name: Coverity Scan
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y curl build-essential cmake pkg-config libsystemd-dev
+
+      - name: Download Coverity Tool
+        run: |
+          curl -s -L --output coverity_tool.tgz "https://scan.coverity.com/download/linux64?token=${{ secrets.COVERITY_TOKEN }}&project=gabime%2Fspdlog"
+          mkdir coverity_tool
+          tar -C coverity_tool --strip-components=1 -xf coverity_tool.tgz
+          echo "$PWD/coverity_tool/bin" >> $GITHUB_PATH
+
+      - name: Build with Coverity
+        run: |
+          mkdir build && cd build
+          cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=17
+          cd ..
+          cov-build --dir cov-int make -C build -j4
+
+      - name: Submit results to Coverity
+        run: |
+          tar czf cov-int.tgz cov-int
+          response=$(curl --silent --show-error --fail \
+            --form email="${{ secrets.EMAIL }}" \
+            --form token="${{ secrets.COVERITY_TOKEN }}" \
+            --form file=@cov-int.tgz \
+            --form version="GitHub PR #${{ github.event.pull_request.number }}" \
+            --form description="CI run for PR" \
+            https://scan.coverity.com/builds?project=gabime%2Fspdlog)
+
+          echo "$response"
+
+          if echo "$response" | grep -qi "Build successfully submitted"; then
+            echo "Coverity upload succeeded"
+          else
+            echo "Coverity upload failed or was rejected"
+            exit 1
+          fi

.github/workflows/linux.yml

@@ -18,9 +18,8 @@ jobs:
       fail-fast: false
       matrix:
         config:
-          - { compiler: gcc, version: 7, build_type: Release, cppstd: 11 }
-          - { compiler: gcc, version: 9, build_type: Release, cppstd: 17 }
-          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 20 }
+          - { compiler: gcc, version: 9, build_type: Release, cppstd: 11 }
+          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 17 }
           - { compiler: gcc, version: 12, build_type: Release, cppstd: 20 }
           - { compiler: gcc, version: 12, build_type: Debug, cppstd: 20, asan: ON }
           - { compiler: clang, version: 12, build_type: Debug, cppstd: 17 }

.github/workflows/windows.yml

@@ -75,74 +75,5 @@ jobs:
         run: |
           build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe
 
-  # -----------------------------------------------------------------------
-  # MSVC 2019 build matrix
-  # -----------------------------------------------------------------------
-  build_2019:
-    runs-on: windows-2019
-    strategy:
-      fail-fast: true
-      matrix:
-        config:
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 17
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 14
-          - GENERATOR: "Visual Studio 16 2019"
-            BUILD_TYPE: Release
-            BUILD_SHARED: 'ON'
-            FATAL_ERRORS: 'ON'
-            WCHAR: 'OFF'
-            WCHAR_FILES: 'OFF'
-            BUILD_EXAMPLE: 'ON'
-            USE_STD_FORMAT: 'OFF'
-            CXX_STANDARD: 11
 
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: CMake ${{ matrix.config.GENERATOR }} CXX=${{matrix.config.CXX_STANDARD}} WCHAR=${{matrix.config.WCHAR_FILES}} STD_FORMAT=${{matrix.config.USE_STD_FORMAT}}
-        shell: pwsh
-        run: |
-          mkdir build
-          cd build
-          cmake -G "${{ matrix.config.GENERATOR }}"  -A x64 `
-            -D CMAKE_BUILD_TYPE=${{ matrix.config.BUILD_TYPE }} `
-            -D BUILD_SHARED_LIBS=${{ matrix.config.BUILD_SHARED }} `
-            -D SPDLOG_WCHAR_SUPPORT=${{ matrix.config.WCHAR }} `
-            -D SPDLOG_WCHAR_FILENAMES=${{ matrix.config.WCHAR_FILES }} `
-            -D SPDLOG_BUILD_EXAMPLE=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_EXAMPLE_HO=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_TESTS=ON `
-            -D SPDLOG_BUILD_TESTS_HO=OFF `
-            -D SPDLOG_BUILD_WARNINGS=${{ matrix.config.FATAL_ERRORS }} `
-            -D SPDLOG_USE_STD_FORMAT=${{ matrix.config.USE_STD_FORMAT }} `
-            -D CMAKE_CXX_STANDARD=${{ matrix.config.CXX_STANDARD }} ..
-
-      - name: Build
-        shell: pwsh
-        run: |
-          cd build
-          cmake --build  . --parallel --config ${{ matrix.config.BUILD_TYPE }}
-
-      - name: Run Tests
-        shell: pwsh
-        env:
-          PATH: ${{ env.PATH }};${{ github.workspace }}\build\_deps\catch2-build\src\${{ matrix.config.BUILD_TYPE }};${{ github.workspace }}\build\${{ matrix.config.BUILD_TYPE }}
-        run: |
-          build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe
+  

CMakeLists.txt

@@ -18,39 +18,38 @@ 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)
 
@@ -63,6 +62,9 @@ option(SPDLOG_ENABLE_PCH "Build static or shared library using precompiled heade
 # build position independent code
 option(SPDLOG_BUILD_PIC "Build position independent code (-fPIC)" OFF)
 
+# debug build postfix
+set(SPDLOG_DEBUG_POSTFIX "d" CACHE STRING "Filename postfix for libraries in debug builds")
+
 # example options
 option(SPDLOG_BUILD_EXAMPLE "Build example" ${SPDLOG_MASTER_PROJECT})
 option(SPDLOG_BUILD_EXAMPLE_HO "Build header only example" OFF)
@@ -77,9 +79,9 @@ 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)
@@ -92,61 +94,61 @@ 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})
@@ -155,56 +157,56 @@ 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})
-set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX d)
+                                                                  ${SPDLOG_VERSION_MAJOR}.${SPDLOG_VERSION_MINOR})
+set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX ${SPDLOG_DEBUG_POSTFIX})
 
-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
@@ -213,132 +215,134 @@ 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_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_USE_EXCEPTIONS=0)
+    endif()
+    if(NOT MSVC)
         target_compile_options(spdlog PRIVATE -fno-exceptions)
-    else ()
+    else()
         target_compile_options(spdlog PRIVATE /EHs-c-)
-    endif ()
-endif ()
+        target_compile_definitions(spdlog PRIVATE _HAS_EXCEPTIONS=0)
+    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")
@@ -353,30 +357,30 @@ 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}")
@@ -387,7 +391,7 @@ 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)
@@ -400,4 +404,4 @@ if (SPDLOG_INSTALL)
     # Support creation of installable packages
     # ---------------------------------------------------------------------------------------
     include(cmake/spdlogCPack.cmake)
-endif ()
+endif()

README.md

@@ -11,7 +11,7 @@ Fast C++ logging library
 
 ## Install
 #### Header-only version
-Copy the include [folder](https://github.com/gabime/spdlog/tree/v1.x/include/spdlog) to your build tree and use a C++11 compiler.
+Copy the include [folder](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](https://github.com/gabime/spdlog/blob/v1.x/example/CMakeLists.txt) on how to use.
+see example [CMakeLists.txt](example/CMakeLists.txt) on how to use.
 
 ## Platforms
 * Linux, FreeBSD, OpenBSD, Solaris, AIX
@@ -48,7 +48,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
 * 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/3.-Custom-formatting) formatting.
+* [Custom](https://github.com/gabime/spdlog/wiki/Custom-formatting) formatting.
 * Multi/Single threaded loggers.
 * Various log targets:
   * Rotating log files.
@@ -58,7 +58,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
   * 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/4.-Sinks#implementing-your-own-sink) with custom log targets.
+  * Easily [extendable](https://github.com/gabime/spdlog/wiki/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.
@@ -80,7 +80,7 @@ int main()
     spdlog::info("Positional args are {1} {0}..", "too", "supported");
     spdlog::info("{:<30}", "left aligned");
     
-    spdlog::set_level(spdlog::level::debug); // Set global log level to debug
+    spdlog::set_level(spdlog::level::debug); // Set *global* log level to debug
     spdlog::debug("This message should be displayed..");    
     
     // change log pattern
@@ -224,7 +224,7 @@ void binary_example()
 ```c++
 
 // create a logger with 2 targets, with different log levels and formats.
-// The console will show only warnings or errors, while the file will log all.
+// The console will show only warnings or errors, while the file will log all. 
 void multi_sink_example()
 {
     auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
@@ -241,6 +241,29 @@ void multi_sink_example()
 }
 ```
 
+---
+#### Register several loggers - change global level
+```c++
+
+// Creation of loggers. Set levels to all registered loggers. 
+void set_level_example()
+{
+    auto logger1 = spdlog::basic_logger_mt("logger1", "logs/logger1.txt");
+    auto logger2 = spdlog::basic_logger_mt("logger2", "logs/logger2.txt");
+
+    spdlog::set_default_logger(logger2);
+    spdlog::default_logger()->set_level(spdlog::level::trace); // set level for the default logger (logger2) to trace
+
+    spdlog::trace("trace message to the logger2 (specified as default)");
+
+    spdlog::set_level(spdlog::level::off) // (sic!) set level for *all* registered loggers to off (disable)
+  
+    logger1.warn("warn message will not appear because the level set to off");
+    logger2.warn("warn message will not appear because the level set to off");
+    spdlog::warn("warn message will not appear because the level set to off");
+}
+```
+
 ---
 #### User-defined callbacks about log events
 ```c++
@@ -467,7 +490,7 @@ void mdc_example()
 ---
 ## Benchmarks
 
-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
+Below are some [benchmarks](bench/bench.cpp) done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
 
 #### Synchronous mode
 ```
@@ -519,10 +542,12 @@ Below are some [benchmarks](https://github.com/gabime/spdlog/blob/v1.x/bench/ben
 ```
 
 ## Documentation
-Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.
+
+Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki) pages.
 
 ---
 
-Thanks to [JetBrains](https://www.jetbrains.com/?from=spdlog) for donating product licenses to help develop **spdlog** <a href="https://www.jetbrains.com/?from=spdlog"><img src="logos/jetbrains-variant-4.svg" width="94" align="center" /></a>
-
-
+### Powered by
+<a href="https://jb.gg/OpenSource">
+  <img src="https://resources.jetbrains.com/storage/products/company/brand/logos/jetbrains.svg" alt="JetBrains logo" width="200">
+</a>

cmake/pch.h.in

@@ -10,7 +10,6 @@
 
 // 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
@@ -23,7 +22,6 @@
 
 // details/os-inl.h
 // details/pattern_formatter-inl.h
-// fmt/bundled/core.h
 // fmt/bundled/format-inl.h
 #include <cstring>
 
@@ -73,7 +71,6 @@
 // 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
@@ -150,7 +147,6 @@
 
 // common.h
 // details/fmt_helper.h
-// fmt/bundled/core.h
 // fmt/bundled/ranges.h
 #include <type_traits>
 
@@ -255,4 +251,4 @@
 #include <mutex>
 
 // spdlog
-#include <spdlog/common.h>
+#include <spdlog/common.h>

example/example.cpp

@@ -33,41 +33,41 @@ void mdc_example();
 #include "spdlog/fmt/ostr.h"  // support for user defined types
 
 int main(int, char *[]) {
-    // Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
-    load_levels_example();
-
-    spdlog::info("Welcome to spdlog version {}.{}.{}  !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR,
-                 SPDLOG_VER_PATCH);
-
-    spdlog::warn("Easy padding in numbers like {:08d}", 12);
-    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
-    spdlog::info("Support for floats {:03.2f}", 1.23456);
-    spdlog::info("Positional args are {1} {0}..", "too", "supported");
-    spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");
-
-    // Runtime log levels
-    spdlog::set_level(spdlog::level::info);  // Set global log level to info
-    spdlog::debug("This message should not be displayed!");
-    spdlog::set_level(spdlog::level::trace);  // Set specific logger's log level
-    spdlog::debug("This message should be displayed..");
-
-    // Customize msg format for all loggers
-    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
-    spdlog::info("This an info message with custom format");
-    spdlog::set_pattern("%+");  // back to default format
-    spdlog::set_level(spdlog::level::info);
-
-    // Backtrace support
-    // Loggers can store in a ring buffer all messages (including debug/trace) for later inspection.
-    // When needed, call dump_backtrace() to see what happened:
-    spdlog::enable_backtrace(10);  // create ring buffer with capacity of 10  messages
-    for (int i = 0; i < 100; i++) {
-        spdlog::debug("Backtrace message {}", i);  // not logged..
-    }
-    // e.g. if some error happened:
-    spdlog::dump_backtrace();  // log them now!
-
     try {
+        // Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
+        load_levels_example();
+
+        spdlog::info("Welcome to spdlog version {}.{}.{}  !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR,
+                     SPDLOG_VER_PATCH);
+
+        spdlog::warn("Easy padding in numbers like {:08d}", 12);
+        spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
+        spdlog::info("Support for floats {:03.2f}", 1.23456);
+        spdlog::info("Positional args are {1} {0}..", "too", "supported");
+        spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");
+
+        // Runtime log levels
+        spdlog::set_level(spdlog::level::info);  // Set global log level to info
+        spdlog::debug("This message should not be displayed!");
+        spdlog::set_level(spdlog::level::trace);  // Set specific logger's log level
+        spdlog::debug("This message should be displayed..");
+
+        // Customize msg format for all loggers
+        spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
+        spdlog::info("This an info message with custom format");
+        spdlog::set_pattern("%+");  // back to default format
+        spdlog::set_level(spdlog::level::info);
+
+        // Backtrace support
+        // Loggers can store in a ring buffer all messages (including debug/trace) for later
+        // inspection. When needed, call dump_backtrace() to see what happened:
+        spdlog::enable_backtrace(10);  // create ring buffer with capacity of 10  messages
+        for (int i = 0; i < 100; i++) {
+            spdlog::debug("Backtrace message {}", i);  // not logged..
+        }
+        // e.g. if some error happened:
+        spdlog::dump_backtrace();  // log them now!
+
         stdout_logger_example();
         basic_example();
         rotating_example();
@@ -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
@@ -371,25 +371,23 @@ void replace_default_logger_example() {
     // store the old logger so we don't break other examples.
     auto old_logger = spdlog::default_logger();
 
-    auto new_logger =
-        spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
-    spdlog::set_default_logger(new_logger);
+    auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/somelog.txt", true);
+    spdlog::set_default_logger(std::move(new_logger));
     spdlog::set_level(spdlog::level::info);
     spdlog::debug("This message should not be displayed!");
     spdlog::set_level(spdlog::level::trace);
     spdlog::debug("This message should be displayed..");
-
-    spdlog::set_default_logger(old_logger);
+    spdlog::set_default_logger(std::move(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

include/spdlog/async.h

@@ -89,8 +89,7 @@ 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.

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");

include/spdlog/cfg/helpers-inl.h

@@ -9,7 +9,6 @@
 
 #include <spdlog/details/os.h>
 #include <spdlog/details/registry.h>
-#include <spdlog/spdlog.h>
 
 #include <algorithm>
 #include <sstream>
@@ -36,7 +35,7 @@ inline std::string &trim_(std::string &str) {
     return str;
 }
 
-// return (name,value) trimmed pair from given "name=value" string.
+// return (name,value) trimmed pair from the given "name = value" string.
 // return empty string on missing parts
 // "key=val" => ("key", "val")
 // " key  =  val " => ("key", "val")
@@ -55,7 +54,7 @@ inline std::pair<std::string, std::string> extract_kv_(char sep, const std::stri
     return std::make_pair(trim_(k), trim_(v));
 }
 
-// return vector of key/value pairs from sequence of "K1=V1,K2=V2,.."
+// return vector of key/value pairs from a sequence of "K1=V1,K2=V2,.."
 // "a=AAA,b=BBB,c=CCC,.." => {("a","AAA"),("b","BBB"),("c", "CCC"),...}
 inline std::unordered_map<std::string, std::string> extract_key_vals_(const std::string &str) {
     std::string token;
@@ -72,7 +71,7 @@ inline std::unordered_map<std::string, std::string> extract_key_vals_(const std:
 }
 
 SPDLOG_INLINE void load_levels(const std::string &input) {
-    if (input.empty() || input.size() > 512) {
+    if (input.empty() || input.size() >= 32768) {
         return;
     }
 
@@ -82,14 +81,14 @@ SPDLOG_INLINE void load_levels(const std::string &input) {
     bool global_level_found = false;
 
     for (auto &name_level : key_vals) {
-        auto &logger_name = name_level.first;
-        auto level_name = to_lower_(name_level.second);
+        const auto &logger_name = name_level.first;
+        const auto &level_name = to_lower_(name_level.second);
         auto level = level::from_str(level_name);
         // ignore unrecognized level names
         if (level == level::off && level_name != "off") {
             continue;
         }
-        if (logger_name.empty())  // no logger name indicate global level
+        if (logger_name.empty())  // no logger name indicates global level
         {
             global_level_found = true;
             global_level = level;

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 {

include/spdlog/details/file_helper-inl.h

@@ -11,10 +11,8 @@
 #include <spdlog/details/os.h>
 
 #include <cerrno>
-#include <chrono>
 #include <cstdio>
 #include <string>
-#include <thread>
 #include <tuple>
 
 namespace spdlog {

include/spdlog/details/os-inl.h

@@ -23,7 +23,6 @@
 
 #ifdef _WIN32
     #include <spdlog/details/windows_include.h>
-    #include <fileapi.h>  // for FlushFileBuffers
     #include <io.h>       // for _get_osfhandle, _isatty, _fileno
     #include <process.h>  // for _get_pid
 
@@ -265,10 +264,10 @@ 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)) ||  \
+    #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)))
+         (!defined(_POSIX_VERSION) || (_POSIX_VERSION < 202405L)))
     // '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(),
@@ -483,13 +482,12 @@ 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;
@@ -564,21 +562,21 @@ SPDLOG_INLINE filename_t dir_name(const filename_t &path) {
     return pos != filename_t::npos ? path.substr(0, pos) : filename_t{};
 }
 
+#ifdef _MSC_VER
+    #pragma warning(push)
+    #pragma warning(disable : 4996)
+#endif  // _MSC_VER
 std::string SPDLOG_INLINE getenv(const char *field) {
-#if defined(_MSC_VER)
-    #if defined(__cplusplus_winrt)
+#if defined(_MSC_VER) && defined(__cplusplus_winrt)
     return std::string{};  // not supported under uwp
-    #else
-    size_t len = 0;
-    char buf[128];
-    bool ok = ::getenv_s(&len, buf, sizeof(buf), field) == 0;
-    return ok ? buf : std::string{};
-    #endif
-#else  // revert to getenv
-    char *buf = ::getenv(field);
+#else
+    char *buf = std::getenv(field);
     return buf ? buf : std::string{};
 #endif
 }
+#ifdef _MSC_VER
+    #pragma warning(pop)
+#endif  // _MSC_VER
 
 // Do fsync by FILE handlerpointer
 // Return true on success
@@ -593,13 +591,13 @@ 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

include/spdlog/details/registry-inl.h

@@ -54,6 +54,11 @@ 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());
@@ -96,7 +101,7 @@ SPDLOG_INLINE std::shared_ptr<logger> registry::default_logger() {
 SPDLOG_INLINE logger *registry::get_default_raw() { return default_logger_.get(); }
 
 // set default logger.
-// default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
+// the default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
 SPDLOG_INLINE void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);
     if (new_default_logger != nullptr) {
@@ -252,10 +257,14 @@ 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

include/spdlog/details/registry.h

@@ -31,6 +31,7 @@ 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();
@@ -105,6 +106,7 @@ 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_;

include/spdlog/details/tcp_client-windows.h

@@ -58,8 +58,81 @@ public:
 
     SOCKET fd() const { return socket_; }
 
+    int connect_socket_with_timeout(SOCKET sockfd,
+                                    const struct sockaddr *addr,
+                                    int addrlen,
+                                    const timeval &tv) {
+        // If no timeout requested, do a normal blocking connect.
+        if (tv.tv_sec == 0 && tv.tv_usec == 0) {
+            int rv = ::connect(sockfd, addr, addrlen);
+            if (rv == SOCKET_ERROR && WSAGetLastError() == WSAEISCONN) {
+                return 0;
+            }
+            return rv;
+        }
+
+        // Switch to non‐blocking mode
+        u_long mode = 1UL;
+        if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        int rv = ::connect(sockfd, addr, addrlen);
+        int last_error = WSAGetLastError();
+        if (rv == 0 || last_error == WSAEISCONN) {
+            mode = 0UL;
+            if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+                return SOCKET_ERROR;
+            }
+            return 0;
+        }
+        if (last_error != WSAEWOULDBLOCK) {
+            // Real error
+            mode = 0UL;
+            if (::ioctlsocket(sockfd, FIONBIO, &mode)) {
+                return SOCKET_ERROR;
+            }
+            return SOCKET_ERROR;
+        }
+
+        // Wait until socket is writable or timeout expires
+        fd_set wfds;
+        FD_ZERO(&wfds);
+        FD_SET(sockfd, &wfds);
+
+        rv = ::select(0, nullptr, &wfds, nullptr, const_cast<timeval *>(&tv));
+
+        // Restore blocking mode regardless of select result
+        mode = 0UL;
+        if (::ioctlsocket(sockfd, FIONBIO, &mode) == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        if (rv == 0) {
+            WSASetLastError(WSAETIMEDOUT);
+            return SOCKET_ERROR;
+        }
+        if (rv == SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+
+        int so_error = 0;
+        int len = sizeof(so_error);
+        if (::getsockopt(sockfd, SOL_SOCKET, SO_ERROR, reinterpret_cast<char *>(&so_error), &len) ==
+            SOCKET_ERROR) {
+            return SOCKET_ERROR;
+        }
+        if (so_error != 0 && so_error != WSAEISCONN) {
+            // connection failed
+            WSASetLastError(so_error);
+            return SOCKET_ERROR;
+        }
+
+        return 0;  // success
+    }
+
     // try to connect or throw on failure
-    void connect(const std::string &host, int port) {
+    void connect(const std::string &host, int port, int timeout_ms = 0) {
         if (is_connected()) {
             close();
         }
@@ -71,6 +144,10 @@ public:
         hints.ai_flags = AI_NUMERICSERV;  // port passed as as numeric value
         hints.ai_protocol = 0;
 
+        timeval tv;
+        tv.tv_sec = timeout_ms / 1000;
+        tv.tv_usec = (timeout_ms % 1000) * 1000;
+
         auto port_str = std::to_string(port);
         struct addrinfo *addrinfo_result;
         auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
@@ -82,7 +159,6 @@ public:
         }
 
         // Try each address until we successfully connect(2).
-
         for (auto *rp = addrinfo_result; rp != nullptr; rp = rp->ai_next) {
             socket_ = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
             if (socket_ == INVALID_SOCKET) {
@@ -90,18 +166,24 @@ public:
                 WSACleanup();
                 continue;
             }
-            if (::connect(socket_, rp->ai_addr, (int)rp->ai_addrlen) == 0) {
+            if (connect_socket_with_timeout(socket_, rp->ai_addr, (int)rp->ai_addrlen, tv) == 0) {
+                last_error = 0;
                 break;
-            } else {
-                last_error = ::WSAGetLastError();
-                close();
             }
+            last_error = WSAGetLastError();
+            ::closesocket(socket_);
+            socket_ = INVALID_SOCKET;
         }
         ::freeaddrinfo(addrinfo_result);
         if (socket_ == INVALID_SOCKET) {
             WSACleanup();
             throw_winsock_error_("connect failed", last_error);
         }
+        if (timeout_ms > 0) {
+            DWORD tv = static_cast<DWORD>(timeout_ms);
+            ::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, (const char *)&tv, sizeof(tv));
+            ::setsockopt(socket_, SOL_SOCKET, SO_SNDTIMEO, (const char *)&tv, sizeof(tv));
+        }
 
         // set TCP_NODELAY
         int enable_flag = 1;

include/spdlog/details/tcp_client.h

@@ -39,8 +39,72 @@ public:
 
     ~tcp_client() { close(); }
 
+    int connect_socket_with_timeout(int sockfd,
+                                    const struct sockaddr *addr,
+                                    socklen_t addrlen,
+                                    const timeval &tv) {
+        // Blocking connect if timeout is zero
+        if (tv.tv_sec == 0 && tv.tv_usec == 0) {
+            int rv = ::connect(sockfd, addr, addrlen);
+            if (rv < 0 && errno == EISCONN) {
+                // already connected, treat as success
+                return 0;
+            }
+            return rv;
+        }
+
+        // Non-blocking path
+        int orig_flags = ::fcntl(sockfd, F_GETFL, 0);
+        if (orig_flags < 0) {
+            return -1;
+        }
+        if (::fcntl(sockfd, F_SETFL, orig_flags | O_NONBLOCK) < 0) {
+            return -1;
+        }
+
+        int rv = ::connect(sockfd, addr, addrlen);
+        if (rv == 0 || (rv < 0 && errno == EISCONN)) {
+            // immediate connect or already connected
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return 0;
+        }
+        if (errno != EINPROGRESS) {
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return -1;
+        }
+
+        // wait for writability
+        fd_set wfds;
+        FD_ZERO(&wfds);
+        FD_SET(sockfd, &wfds);
+
+        struct timeval tv_copy = tv;
+        rv = ::select(sockfd + 1, nullptr, &wfds, nullptr, &tv_copy);
+        if (rv <= 0) {
+            // timeout or error
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            if (rv == 0) errno = ETIMEDOUT;
+            return -1;
+        }
+
+        // check socket error
+        int so_error = 0;
+        socklen_t len = sizeof(so_error);
+        if (::getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &so_error, &len) < 0) {
+            ::fcntl(sockfd, F_SETFL, orig_flags);
+            return -1;
+        }
+        ::fcntl(sockfd, F_SETFL, orig_flags);
+        if (so_error != 0 && so_error != EISCONN) {
+            errno = so_error;
+            return -1;
+        }
+
+        return 0;
+    }
+
     // try to connect or throw on failure
-    void connect(const std::string &host, int port) {
+    void connect(const std::string &host, int port, int timeout_ms = 0) {
         close();
         struct addrinfo hints {};
         memset(&hints, 0, sizeof(struct addrinfo));
@@ -49,6 +113,10 @@ public:
         hints.ai_flags = AI_NUMERICSERV;  // port passed as as numeric value
         hints.ai_protocol = 0;
 
+        struct timeval tv;
+        tv.tv_sec = timeout_ms / 1000;
+        tv.tv_usec = (timeout_ms % 1000) * 1000;
+
         auto port_str = std::to_string(port);
         struct addrinfo *addrinfo_result;
         auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
@@ -69,8 +137,9 @@ public:
                 last_errno = errno;
                 continue;
             }
-            rv = ::connect(socket_, rp->ai_addr, rp->ai_addrlen);
-            if (rv == 0) {
+            ::fcntl(socket_, F_SETFD, FD_CLOEXEC);
+            if (connect_socket_with_timeout(socket_, rp->ai_addr, rp->ai_addrlen, tv) == 0) {
+                last_errno = 0;
                 break;
             }
             last_errno = errno;
@@ -82,6 +151,12 @@ public:
             throw_spdlog_ex("::connect failed", last_errno);
         }
 
+        if (timeout_ms > 0) {
+            // Set timeouts for send and recv
+            ::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, (const char *)&tv, sizeof(tv));
+            ::setsockopt(socket_, SOL_SOCKET, SO_SNDTIMEO, (const char *)&tv, sizeof(tv));
+        }
+
         // set TCP_NODELAY
         int enable_flag = 1;
         ::setsockopt(socket_, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char *>(&enable_flag),

include/spdlog/details/thread_pool-inl.h

@@ -35,11 +35,10 @@ SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
 SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
                                        size_t threads_n,
                                        std::function<void()> on_thread_start)
-    : thread_pool(q_max_items, threads_n, on_thread_start, [] {}) {}
+    : thread_pool(q_max_items, threads_n, std::move(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() {
@@ -95,8 +94,7 @@ void SPDLOG_INLINE thread_pool::worker_loop_() {
 }
 
 // process next message in the queue
-// return true if this thread should still be active (while no terminate msg
-// was received)
+// returns true if this thread should still be active (while no terminated msg was received)
 bool SPDLOG_INLINE thread_pool::process_next_msg_() {
     async_msg incoming_async_msg;
     q_.dequeue(incoming_async_msg);

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;

include/spdlog/fmt/bundled/args.h

@@ -71,7 +71,7 @@ class dynamic_arg_list {
  * It can be implicitly converted into `fmt::basic_format_args` for passing
  * into type-erased formatting functions such as `fmt::vformat`.
  */
-template <typename Context> class dynamic_format_arg_store {
+FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
  private:
   using char_type = typename Context::char_type;
 
@@ -212,7 +212,7 @@ template <typename Context> class dynamic_format_arg_store {
   }
 
   /// Returns the number of elements in the store.
-  size_t size() const noexcept { return data_.size(); }
+  auto size() const noexcept -> size_t { return data_.size(); }
 };
 
 FMT_END_NAMESPACE

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 110104
+#define FMT_VERSION 120000
 
 // Detect compiler versions.
 #if defined(__clang__) && !defined(__ibmxl__)
@@ -201,28 +201,6 @@
 #  define FMT_NODISCARD
 #endif
 
-#ifdef FMT_DEPRECATED
-// Use the provided definition.
-#elif FMT_HAS_CPP14_ATTRIBUTE(deprecated)
-#  define FMT_DEPRECATED [[deprecated]]
-#else
-#  define FMT_DEPRECATED /* deprecated */
-#endif
-
-#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
@@ -249,10 +227,32 @@
 #  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 {           \
-    inline namespace v11 {
+    inline namespace v12 {
 #  define FMT_END_NAMESPACE \
     }                       \
     }
@@ -297,13 +297,6 @@
   using unused = int[];          \
   (void)unused { 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
 
 // Implementations of enable_if_t and other metafunctions for older systems.
@@ -325,8 +318,8 @@ 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
-// A workaround for gcc 4.9 to make void_t work in a SFINAE context.
+#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.
 template <typename...> struct void_t_impl {
   using type = void;
 };
@@ -355,6 +348,9 @@ template <typename T> constexpr auto max_of(T a, T b) -> T {
   return a > b ? a : b;
 }
 
+FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
+                                      const char* message);
+
 namespace detail {
 // Suppresses "unused variable" warnings with the method described in
 // https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
@@ -395,7 +391,7 @@ FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
 #  define FMT_ASSERT(condition, message)                                    \
     ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
          ? (void)0                                                          \
-         : fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
+         : ::fmt::assert_fail(__FILE__, __LINE__, (message)))
 #endif
 
 #ifdef FMT_USE_INT128
@@ -462,12 +458,13 @@ enum { use_utf8 = !FMT_WIN32 || is_utf8_enabled };
 static_assert(!FMT_UNICODE || use_utf8,
               "Unicode support requires compiling with /utf-8");
 
-template <typename T> constexpr const char* narrow(const T*) { return nullptr; }
-constexpr FMT_ALWAYS_INLINE const char* narrow(const char* s) { return s; }
+template <typename T> constexpr auto narrow(T*) -> char* { return nullptr; }
+constexpr FMT_ALWAYS_INLINE auto narrow(const char* s) -> const char* {
+  return s;
+}
 
 template <typename Char>
-FMT_CONSTEXPR auto compare(const Char* s1, const Char* s2, std::size_t n)
-    -> int {
+FMT_CONSTEXPR auto compare(const Char* s1, const Char* s2, size_t n) -> int {
   if (!is_constant_evaluated() && sizeof(Char) == 1) return memcmp(s1, s2, n);
   for (; n != 0; ++s1, ++s2, --n) {
     if (*s1 < *s2) return -1;
@@ -526,20 +523,20 @@ template <typename Char> class basic_string_view {
 
   constexpr basic_string_view() noexcept : data_(nullptr), size_(0) {}
 
-  /// Constructs a string reference object from a C string and a size.
+  /// Constructs a string view 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 reference object from a C string.
+  /// Constructs a string view 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) {
-      size_ = __builtin_strlen(detail::narrow(s));
+    if (std::is_same<Char, char>::value && !detail::is_constant_evaluated()) {
+      size_ = __builtin_strlen(detail::narrow(s));  // strlen is not constexpr.
       return;
     }
 #endif
@@ -548,7 +545,7 @@ template <typename Char> class basic_string_view {
     size_ = len;
   }
 
-  /// Constructs a string reference from a `std::basic_string` or a
+  /// Constructs a string view 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<
@@ -585,7 +582,6 @@ 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_));
@@ -616,19 +612,6 @@ template <typename Char> class basic_string_view {
 
 using string_view = basic_string_view<char>;
 
-/// 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 {};
-template <> struct is_xchar<char32_t> : std::true_type {};
-#ifdef __cpp_char8_t
-template <> struct is_xchar<char8_t> : std::true_type {};
-#endif
-
-// 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 {};
-
 template <typename T> class basic_appender;
 using appender = basic_appender<char>;
 
@@ -781,7 +764,7 @@ class basic_specs {
             (static_cast<unsigned>(p) << precision_shift);
   }
 
-  constexpr bool dynamic() const {
+  constexpr auto dynamic() const -> bool {
     return (data_ & (width_mask | precision_mask)) != 0;
   }
 
@@ -921,14 +904,47 @@ template <typename Char = char> class parse_context {
   FMT_CONSTEXPR void check_dynamic_spec(int arg_id);
 };
 
+#ifndef FMT_USE_LOCALE
+#  define FMT_USE_LOCALE (FMT_OPTIMIZE_SIZE <= 1)
+#endif
+
+// A type-erased reference to std::locale to avoid the heavy <locale> include.
+class locale_ref {
+#if FMT_USE_LOCALE
+ private:
+  const void* locale_;  // A type-erased pointer to std::locale.
+
+ public:
+  constexpr locale_ref() : locale_(nullptr) {}
+
+  template <typename Locale, FMT_ENABLE_IF(sizeof(Locale::collate) != 0)>
+  locale_ref(const Locale& loc);
+
+  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
+#endif  // FMT_USE_LOCALE
+
+ public:
+  template <typename Locale> auto get() const -> Locale;
+};
+
 FMT_END_EXPORT
 
 namespace detail {
 
+// Specifies if `T` is a code unit type.
+template <typename T> struct is_code_unit : std::false_type {};
+template <> struct is_code_unit<char> : std::true_type {};
+template <> struct is_code_unit<wchar_t> : std::true_type {};
+template <> struct is_code_unit<char16_t> : std::true_type {};
+template <> struct is_code_unit<char32_t> : std::true_type {};
+#ifdef __cpp_char8_t
+template <> struct is_code_unit<char8_t> : bool_constant<is_utf8_enabled> {};
+#endif
+
 // Constructs fmt::basic_string_view<Char> from types implicitly convertible
 // to it, deducing Char. Explicitly convertible types such as the ones returned
 // from FMT_STRING are intentionally excluded.
-template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
+template <typename Char, FMT_ENABLE_IF(is_code_unit<Char>::value)>
 constexpr auto to_string_view(const Char* s) -> basic_string_view<Char> {
   return s;
 }
@@ -1032,6 +1048,11 @@ 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 {};
@@ -1052,11 +1073,11 @@ template <bool B1, bool B2, bool... Tail> constexpr auto count() -> int {
   return (B1 ? 1 : 0) + count<B2, Tail...>();
 }
 
-template <typename... Args> constexpr auto count_named_args() -> int {
-  return count<is_named_arg<Args>::value...>();
+template <typename... T> constexpr auto count_named_args() -> int {
+  return count<is_named_arg<T>::value...>();
 }
-template <typename... Args> constexpr auto count_static_named_args() -> int {
-  return count<is_static_named_arg<Args>::value...>();
+template <typename... T> constexpr auto count_static_named_args() -> int {
+  return count<is_static_named_arg<T>::value...>();
 }
 
 template <typename Char> struct named_arg_info {
@@ -1064,6 +1085,16 @@ template <typename Char> struct named_arg_info {
   int id;
 };
 
+// named_args is non-const to suppress a bogus -Wmaybe-uninitialized in gcc 13.
+template <typename Char>
+FMT_CONSTEXPR void check_for_duplicate(named_arg_info<Char>* named_args,
+                                       int named_arg_index,
+                                       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;
@@ -1071,6 +1102,7 @@ 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++};
 }
 
@@ -1084,12 +1116,13 @@ 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) };
+enum { long_short = sizeof(long) == sizeof(int) && FMT_BUILTIN_TYPES };
 using long_type = conditional_t<long_short, int, long long>;
 using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
 
@@ -1156,7 +1189,7 @@ template <typename Char> struct type_mapper {
   static auto map(ubitint<N>)
       -> conditional_t<N <= 64, unsigned long long, void>;
 
-  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  template <typename T, FMT_ENABLE_IF(is_code_unit<T>::value)>
   static auto map(T) -> conditional_t<
       std::is_same<T, char>::value || std::is_same<T, Char>::value, Char, void>;
 
@@ -1662,12 +1695,12 @@ template <typename... T> struct arg_pack {};
 template <typename Char, int NUM_ARGS, int NUM_NAMED_ARGS, bool DYNAMIC_NAMES>
 class format_string_checker {
  private:
-  type types_[max_of(1, NUM_ARGS)];
-  named_arg_info<Char> named_args_[max_of(1, NUM_NAMED_ARGS)];
+  type types_[max_of<size_t>(1, NUM_ARGS)];
+  named_arg_info<Char> named_args_[max_of<size_t>(1, NUM_NAMED_ARGS)];
   compile_parse_context<Char> context_;
 
   using parse_func = auto (*)(parse_context<Char>&) -> const Char*;
-  parse_func parse_funcs_[max_of(1, NUM_ARGS)];
+  parse_func parse_funcs_[max_of<size_t>(1, NUM_ARGS)];
 
  public:
   template <typename... T>
@@ -1706,7 +1739,17 @@ class format_string_checker {
       -> const Char* {
     context_.advance_to(begin);
     if (id >= 0 && id < NUM_ARGS) return parse_funcs_[id](context_);
-    while (begin != end && *begin != '}') ++begin;
+
+    // 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;
+    }
     return begin;
   }
 
@@ -2006,6 +2049,17 @@ struct has_back_insert_iterator_container_append<
                         .append(std::declval<InputIt>(),
                                 std::declval<InputIt>()))>> : std::true_type {};
 
+template <typename OutputIt, typename InputIt, typename = void>
+struct has_back_insert_iterator_container_insert_at_end : std::false_type {};
+
+template <typename OutputIt, typename InputIt>
+struct has_back_insert_iterator_container_insert_at_end<
+    OutputIt, InputIt,
+    void_t<decltype(get_container(std::declval<OutputIt>())
+                        .insert(get_container(std::declval<OutputIt>()).end(),
+                                std::declval<InputIt>(),
+                                std::declval<InputIt>()))>> : std::true_type {};
+
 // An optimized version of std::copy with the output value type (T).
 template <typename T, typename InputIt, typename OutputIt,
           FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
@@ -2020,6 +2074,8 @@ FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
 template <typename T, typename InputIt, typename OutputIt,
           FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value &&
                         !has_back_insert_iterator_container_append<
+                            OutputIt, InputIt>::value &&
+                        has_back_insert_iterator_container_insert_at_end<
                             OutputIt, InputIt>::value)>
 FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
     -> OutputIt {
@@ -2029,7 +2085,11 @@ FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
 }
 
 template <typename T, typename InputIt, typename OutputIt,
-          FMT_ENABLE_IF(!is_back_insert_iterator<OutputIt>::value)>
+          FMT_ENABLE_IF(!(is_back_insert_iterator<OutputIt>::value &&
+                          (has_back_insert_iterator_container_append<
+                               OutputIt, InputIt>::value ||
+                           has_back_insert_iterator_container_insert_at_end<
+                               OutputIt, InputIt>::value)))>
 FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
   while (begin != end) *out++ = static_cast<T>(*begin++);
   return out;
@@ -2149,7 +2209,7 @@ template <typename Context> class value {
     static_assert(N <= 64, "unsupported _BitInt");
   }
 
-  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  template <typename T, FMT_ENABLE_IF(is_code_unit<T>::value)>
   constexpr FMT_INLINE value(T x FMT_BUILTIN) : char_value(x) {
     static_assert(
         std::is_same<T, char>::value || std::is_same<T, char_type>::value,
@@ -2225,7 +2285,7 @@ template <typename Context> class value {
         custom.value = const_cast<value_type*>(&x);
 #endif
     }
-    custom.format = format_custom<value_type, formatter<value_type, char_type>>;
+    custom.format = format_custom<value_type>;
   }
 
   template <typename T, FMT_ENABLE_IF(!has_formatter<T, char_type>())>
@@ -2236,10 +2296,10 @@ template <typename Context> class value {
   }
 
   // Formats an argument of a custom type, such as a user-defined class.
-  template <typename T, typename Formatter>
+  template <typename T>
   static void format_custom(void* arg, parse_context<char_type>& parse_ctx,
                             Context& ctx) {
-    auto f = Formatter();
+    auto f = formatter<T, char_type>();
     parse_ctx.advance_to(f.parse(parse_ctx));
     using qualified_type =
         conditional_t<has_formatter<const T, char_type>(), const T, T>;
@@ -2266,35 +2326,14 @@ struct is_output_iterator<
     enable_if_t<std::is_assignable<decltype(*std::declval<decay_t<It>&>()++),
                                    T>::value>> : std::true_type {};
 
-#ifndef FMT_USE_LOCALE
-#  define FMT_USE_LOCALE (FMT_OPTIMIZE_SIZE <= 1)
-#endif
-
-// A type-erased reference to an std::locale to avoid a heavy <locale> include.
-class locale_ref {
-#if FMT_USE_LOCALE
- private:
-  const void* locale_;  // A type-erased pointer to std::locale.
-
- public:
-  constexpr locale_ref() : locale_(nullptr) {}
-  template <typename Locale> locale_ref(const Locale& loc);
-
-  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
-#endif  // FMT_USE_LOCALE
-
- public:
-  template <typename Locale> auto get() const -> Locale;
-};
-
 template <typename> constexpr auto encode_types() -> unsigned long long {
   return 0;
 }
 
-template <typename Context, typename Arg, typename... Args>
+template <typename Context, typename First, typename... T>
 constexpr auto encode_types() -> unsigned long long {
-  return static_cast<unsigned>(stored_type_constant<Arg, Context>::value) |
-         (encode_types<Context, Args...>() << packed_arg_bits);
+  return static_cast<unsigned>(stored_type_constant<First, Context>::value) |
+         (encode_types<Context, T...>() << packed_arg_bits);
 }
 
 template <typename Context, typename... T, size_t NUM_ARGS = sizeof...(T)>
@@ -2311,8 +2350,9 @@ template <typename Context, int NUM_ARGS, int NUM_NAMED_ARGS,
           unsigned long long DESC>
 struct named_arg_store {
   // args_[0].named_args points to named_args to avoid bloating format_args.
-  arg_t<Context, NUM_ARGS> args[1 + NUM_ARGS];
-  named_arg_info<typename Context::char_type> named_args[NUM_NAMED_ARGS];
+  arg_t<Context, NUM_ARGS> args[1u + NUM_ARGS];
+  named_arg_info<typename Context::char_type>
+      named_args[static_cast<size_t>(NUM_NAMED_ARGS)];
 
   template <typename... T>
   FMT_CONSTEXPR FMT_ALWAYS_INLINE named_arg_store(T&... values)
@@ -2331,8 +2371,8 @@ struct named_arg_store {
   }
 
   named_arg_store(const named_arg_store& rhs) = delete;
-  named_arg_store& operator=(const named_arg_store& rhs) = delete;
-  named_arg_store& operator=(named_arg_store&& rhs) = delete;
+  auto operator=(const named_arg_store& rhs) -> named_arg_store& = delete;
+  auto operator=(named_arg_store&& rhs) -> named_arg_store& = delete;
   operator const arg_t<Context, NUM_ARGS>*() const { return args + 1; }
 };
 
@@ -2345,7 +2385,7 @@ struct format_arg_store {
   // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
   using type =
       conditional_t<NUM_NAMED_ARGS == 0,
-                    arg_t<Context, NUM_ARGS>[max_of(1, NUM_ARGS)],
+                    arg_t<Context, NUM_ARGS>[max_of<size_t>(1, NUM_ARGS)],
                     named_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>>;
   type args;
 };
@@ -2629,22 +2669,17 @@ class context {
  private:
   appender out_;
   format_args args_;
-  FMT_NO_UNIQUE_ADDRESS detail::locale_ref loc_;
+  FMT_NO_UNIQUE_ADDRESS locale_ref loc_;
 
  public:
-  /// The character type for the output.
-  using char_type = char;
-
+  using char_type = char;  ///< The character type for the output.
   using iterator = appender;
   using format_arg = basic_format_arg<context>;
-  using parse_context_type FMT_DEPRECATED = parse_context<>;
-  template <typename T> using formatter_type FMT_DEPRECATED = formatter<T>;
   enum { builtin_types = FMT_BUILTIN_TYPES };
 
   /// Constructs a `context` object. References to the arguments are stored
   /// in the object so make sure they have appropriate lifetimes.
-  FMT_CONSTEXPR context(iterator out, format_args args,
-                        detail::locale_ref loc = {})
+  FMT_CONSTEXPR context(iterator out, format_args args, locale_ref loc = {})
       : out_(out), args_(args), loc_(loc) {}
   context(context&&) = default;
   context(const context&) = delete;
@@ -2665,7 +2700,7 @@ class context {
   // Advances the begin iterator to `it`.
   FMT_CONSTEXPR void advance_to(iterator) {}
 
-  FMT_CONSTEXPR auto locale() const -> detail::locale_ref { return loc_; }
+  FMT_CONSTEXPR auto locale() const -> locale_ref { return loc_; }
 };
 
 template <typename Char = char> struct runtime_format_string {
@@ -2703,7 +2738,7 @@ 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<(std::is_base_of<view, remove_reference_t<T>>::value &&
+    static_assert(count<(is_view<remove_cvref_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()));
@@ -2752,9 +2787,6 @@ template <typename T, typename Char = char>
 concept formattable = is_formattable<remove_reference_t<T>, Char>::value;
 #endif
 
-template <typename T, typename Char>
-using has_formatter FMT_DEPRECATED = std::is_constructible<formatter<T, Char>>;
-
 // A formatter specialization for natively supported types.
 template <typename T, typename Char>
 struct formatter<T, Char,
@@ -2951,9 +2983,9 @@ FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
   return fmt::println(stdout, fmt, static_cast<T&&>(args)...);
 }
 
-FMT_END_EXPORT
 FMT_PRAGMA_CLANG(diagnostic pop)
 FMT_PRAGMA_GCC(pop_options)
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 
 #ifdef FMT_HEADER_ONLY

include/spdlog/fmt/bundled/chrono.h

@@ -22,21 +22,6 @@
 
 #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.
@@ -53,6 +38,7 @@ FMT_BEGIN_NAMESPACE
 // Copyright Paul Dreik 2019
 namespace safe_duration_cast {
 
+// DEPRECATED!
 template <typename To, typename From,
           FMT_ENABLE_IF(!std::is_same<From, To>::value &&
                         std::numeric_limits<From>::is_signed ==
@@ -176,17 +162,6 @@ auto safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
                         int& ec) -> To {
   using From = std::chrono::duration<FromRep, FromPeriod>;
   ec = 0;
-  if (std::isnan(from.count())) {
-    // nan in, gives nan out. easy.
-    return To{std::numeric_limits<typename To::rep>::quiet_NaN()};
-  }
-  // maybe we should also check if from is denormal, and decide what to do about
-  // it.
-
-  // +-inf should be preserved.
-  if (std::isinf(from.count())) {
-    return To{from.count()};
-  }
 
   // the basic idea is that we need to convert from count() in the from type
   // to count() in the To type, by multiplying it with this:
@@ -297,8 +272,6 @@ namespace detail {
 #define FMT_NOMACRO
 
 template <typename T = void> struct null {};
-inline auto localtime_r FMT_NOMACRO(...) -> null<> { return null<>(); }
-inline auto localtime_s(...) -> null<> { return null<>(); }
 inline auto gmtime_r(...) -> null<> { return null<>(); }
 inline auto gmtime_s(...) -> null<> { return null<>(); }
 
@@ -341,7 +314,7 @@ inline auto get_classic_locale() -> const std::locale& {
 }
 
 template <typename CodeUnit> struct codecvt_result {
-  static constexpr const size_t max_size = 32;
+  static constexpr size_t max_size = 32;
   CodeUnit buf[max_size];
   CodeUnit* end;
 };
@@ -435,14 +408,11 @@ 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 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)> {
-};
+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)>;
 
 FMT_NORETURN inline void throw_duration_error() {
   FMT_THROW(format_error("cannot format duration"));
@@ -461,11 +431,7 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
 
   using common_rep = typename std::common_type<FromRep, typename To::rep,
                                                decltype(factor::num)>::type;
-
-  int ec = 0;
-  auto count = safe_duration_cast::lossless_integral_conversion<common_rep>(
-      from.count(), ec);
-  if (ec) throw_duration_error();
+  common_rep count = from.count();  // This conversion is lossless.
 
   // Multiply from.count() by factor and check for overflow.
   if (const_check(factor::num != 1)) {
@@ -476,6 +442,7 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
     count *= factor::num;
   }
   if (const_check(factor::den != 1)) count /= factor::den;
+  int ec = 0;
   auto to =
       To(safe_duration_cast::lossless_integral_conversion<typename To::rep>(
           count, ec));
@@ -489,6 +456,8 @@ template <typename To, typename FromRep, typename FromPeriod,
                             std::is_floating_point<typename To::rep>::value)>
 auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
 #if FMT_SAFE_DURATION_CAST
+  // Preserve infinity and NaN.
+  if (!isfinite(from.count())) return static_cast<To>(from.count());
   // Throwing version of safe_duration_cast is only available for
   // integer to integer or float to float casts.
   int ec;
@@ -501,11 +470,11 @@ auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
 #endif
 }
 
-template <
-    typename To, typename FromRep, typename FromPeriod,
-    FMT_ENABLE_IF(!is_same_arithmetic_type<FromRep, typename To::rep>::value)>
+template <typename To, typename FromRep, typename FromPeriod,
+          FMT_ENABLE_IF(
+              !is_similar_arithmetic_type<FromRep, typename To::rep>::value)>
 auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
-  // Mixed integer <-> float cast is not supported by safe_duration_cast.
+  // Mixed integer <-> float cast is not supported by safe duration_cast.
   return std::chrono::duration_cast<To>(from);
 }
 
@@ -519,68 +488,10 @@ auto to_time_t(sys_time<Duration> time_point) -> std::time_t {
       .count();
 }
 
-// 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
 
 FMT_BEGIN_EXPORT
 
-/**
- * Converts given time since epoch as `std::time_t` value into calendar time,
- * expressed in local time. Unlike `std::localtime`, this function is
- * thread-safe on most platforms.
- */
-inline auto localtime(std::time_t time) -> std::tm {
-  struct dispatcher {
-    std::time_t time_;
-    std::tm tm_;
-
-    inline dispatcher(std::time_t t) : time_(t) {}
-
-    inline auto run() -> bool {
-      using namespace fmt::detail;
-      return handle(localtime_r(&time_, &tm_));
-    }
-
-    inline auto handle(std::tm* tm) -> bool { return tm != nullptr; }
-
-    inline auto handle(detail::null<>) -> bool {
-      using namespace fmt::detail;
-      return fallback(localtime_s(&tm_, &time_));
-    }
-
-    inline auto fallback(int res) -> bool { return res == 0; }
-
-#if !FMT_MSC_VERSION
-    inline auto fallback(detail::null<>) -> bool {
-      using namespace fmt::detail;
-      std::tm* tm = std::localtime(&time_);
-      if (tm) tm_ = *tm;
-      return tm != nullptr;
-    }
-#endif
-  };
-  dispatcher lt(time);
-  // Too big time values may be unsupported.
-  if (!lt.run()) FMT_THROW(format_error("time_t value out of range"));
-  return lt.tm_;
-}
-
-#if FMT_USE_LOCAL_TIME
-template <typename Duration,
-          FMT_ENABLE_IF(detail::has_current_zone<Duration>())>
-inline auto localtime(std::chrono::local_time<Duration> time) -> std::tm {
-  using namespace std::chrono;
-  using namespace fmt_detail;
-  return localtime(detail::to_time_t(current_zone()->to_sys<Duration>(time)));
-}
-#endif
-
 /**
  * Converts given time since epoch as `std::time_t` value into calendar time,
  * expressed in Coordinated Universal Time (UTC). Unlike `std::gmtime`, this
@@ -652,7 +563,7 @@ inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
   // Add ASCII '0' to each digit byte and insert separators.
   digits |= 0x3030003030003030 | (usep << 16) | (usep << 40);
 
-  constexpr const size_t len = 8;
+  constexpr size_t len = 8;
   if (const_check(is_big_endian())) {
     char tmp[len];
     std::memcpy(tmp, &digits, len);
@@ -911,7 +822,14 @@ template <typename Derived> struct null_chrono_spec_handler {
   FMT_CONSTEXPR void on_tz_name() { unsupported(); }
 };
 
-struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
+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) {}
+
   FMT_NORETURN inline void unsupported() {
     FMT_THROW(format_error("no format"));
   }
@@ -949,8 +867,12 @@ struct tm_format_checker : 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) {}
-  FMT_CONSTEXPR void on_tz_name() {}
+  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"));
+  }
 };
 
 inline auto tm_wday_full_name(int wday) -> const char* {
@@ -980,24 +902,27 @@ inline auto tm_mon_short_name(int mon) -> const char* {
 }
 
 template <typename T, typename = void>
-struct has_member_data_tm_gmtoff : std::false_type {};
+struct has_tm_gmtoff : std::false_type {};
 template <typename T>
-struct has_member_data_tm_gmtoff<T, void_t<decltype(T::tm_gmtoff)>>
-    : std::true_type {};
+struct has_tm_gmtoff<T, void_t<decltype(T::tm_gmtoff)>> : std::true_type {};
 
-template <typename T, typename = void>
-struct has_member_data_tm_zone : std::false_type {};
+template <typename T, typename = void> struct has_tm_zone : std::false_type {};
 template <typename T>
-struct has_member_data_tm_zone<T, void_t<decltype(T::tm_zone)>>
-    : std::true_type {};
+struct has_tm_zone<T, void_t<decltype(T::tm_zone)>> : std::true_type {};
 
-inline void tzset_once() {
-  static bool init = []() {
-    using namespace fmt_detail;
-    _tzset();
-    return false;
-  }();
-  ignore_unused(init);
+template <typename T, FMT_ENABLE_IF(has_tm_zone<T>::value)>
+auto set_tm_zone(T& time, char* tz) -> bool {
+  time.tm_zone = tz;
+  return true;
+}
+template <typename T, FMT_ENABLE_IF(!has_tm_zone<T>::value)>
+auto set_tm_zone(T&, char*) -> bool {
+  return false;
+}
+
+inline auto utc() -> char* {
+  static char tz[] = "UTC";
+  return tz;
 }
 
 // Converts value to Int and checks that it's in the range [0, upper).
@@ -1005,7 +930,7 @@ 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(fmt::format_error("chrono value is out of range"));
+    FMT_THROW(format_error("chrono value is out of range"));
   }
   return static_cast<Int>(value);
 }
@@ -1090,7 +1015,7 @@ 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 chrono_formatter.
+// explicitly need to pass the Rep value in the duration_formatter.
 template <typename Duration>
 void write_floating_seconds(memory_buffer& buf, Duration duration,
                             int num_fractional_digits = -1) {
@@ -1124,7 +1049,7 @@ class tm_writer {
   static constexpr int days_per_week = 7;
 
   const std::locale& loc_;
-  const bool is_classic_;
+  bool is_classic_;
   OutputIt out_;
   const Duration* subsecs_;
   const std::tm& tm_;
@@ -1160,8 +1085,8 @@ class tm_writer {
   }
 
   auto tm_hour12() const noexcept -> int {
-    const auto h = tm_hour();
-    const auto z = h < 12 ? h : h - 12;
+    auto h = tm_hour();
+    auto z = h < 12 ? h : h - 12;
     return z == 0 ? 12 : z;
   }
 
@@ -1177,11 +1102,11 @@ class tm_writer {
 
   // Algorithm: https://en.wikipedia.org/wiki/ISO_week_date.
   auto iso_year_weeks(long long curr_year) const noexcept -> int {
-    const auto prev_year = curr_year - 1;
-    const auto curr_p =
+    auto prev_year = curr_year - 1;
+    auto curr_p =
         (curr_year + curr_year / 4 - curr_year / 100 + curr_year / 400) %
         days_per_week;
-    const auto prev_p =
+    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);
@@ -1191,15 +1116,15 @@ class tm_writer {
            days_per_week;
   }
   auto tm_iso_week_year() const noexcept -> long long {
-    const auto year = tm_year();
-    const auto w = iso_week_num(tm_yday(), tm_wday());
+    auto year = tm_year();
+    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 {
-    const auto year = tm_year();
-    const auto w = iso_week_num(tm_yday(), tm_wday());
+    auto year = tm_year();
+    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;
@@ -1236,9 +1161,8 @@ 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);
   }
@@ -1259,45 +1183,22 @@ class tm_writer {
     write2(static_cast<int>(offset % 60));
   }
 
-  template <typename T, FMT_ENABLE_IF(has_member_data_tm_gmtoff<T>::value)>
-  void format_utc_offset_impl(const T& tm, numeric_system ns) {
+  template <typename T, FMT_ENABLE_IF(has_tm_gmtoff<T>::value)>
+  void format_utc_offset(const T& tm, numeric_system ns) {
     write_utc_offset(tm.tm_gmtoff, 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_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_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& 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&) {
-    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_);
   }
 
   void format_localized(char format, char modifier = 0) {
@@ -1408,8 +1309,8 @@ class tm_writer {
     out_ = copy<Char>(std::begin(buf) + offset, std::end(buf), out_);
   }
 
-  void on_utc_offset(numeric_system ns) { format_utc_offset_impl(tm_, ns); }
-  void on_tz_name() { format_tz_name_impl(tm_); }
+  void on_utc_offset(numeric_system ns) { format_utc_offset(tm_, ns); }
+  void on_tz_name() { format_tz_name(tm_); }
 
   void on_year(numeric_system ns, pad_type pad) {
     if (is_classic_ || ns == numeric_system::standard)
@@ -1483,11 +1384,10 @@ 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);
   }
 
@@ -1624,18 +1524,16 @@ 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 CommonSecondsType =
+  using common_seconds_type =
       typename std::common_type<decltype(d), std::chrono::seconds>::type;
-  const auto d_as_common = detail::duration_cast<CommonSecondsType>(d);
-  const auto d_as_whole_seconds =
+  auto d_as_common = detail::duration_cast<common_seconds_type>(d);
+  auto d_as_whole_seconds =
       detail::duration_cast<std::chrono::seconds>(d_as_common);
-  // 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);
+  // 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);
   return ms;
 #else
   auto s = detail::duration_cast<std::chrono::seconds>(d);
@@ -1707,32 +1605,28 @@ class get_locale {
   }
 };
 
-template <typename FormatContext, typename OutputIt, typename Rep,
-          typename Period>
-struct chrono_formatter {
-  FormatContext& context;
-  OutputIt out;
-  int precision;
-  bool localized = false;
+template <typename Char, typename Rep, typename Period>
+struct duration_formatter {
+  using iterator = basic_appender<Char>;
+  iterator out;
   // 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 char_type = typename FormatContext::char_type;
-  using tm_writer_type = tm_writer<OutputIt, char_type>;
+  using tm_writer_type = tm_writer<iterator, Char>;
 
-  chrono_formatter(FormatContext& ctx, OutputIt o,
-                   std::chrono::duration<Rep, Period> d)
-      : context(ctx),
-        out(o),
-        val(static_cast<rep>(d.count())),
-        negative(false) {
+  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) {
     if (d.count() < 0) {
       val = 0 - val;
       negative = true;
@@ -1746,19 +1640,16 @@ struct chrono_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) {
-      write_pinf();
-    } else {
-      write_ninf();
-    }
+    if (val > 0)
+      std::copy_n("inf", 3, out);
+    else
+      std::copy_n("-inf", 4, out);
     return true;
   }
 
@@ -1786,10 +1677,9 @@ struct chrono_formatter {
   }
 
   void write_sign() {
-    if (negative) {
-      *out++ = '-';
-      negative = false;
-    }
+    if (!negative) return;
+    *out++ = '-';
+    negative = false;
   }
 
   void write(Rep value, int width, pad_type pad = pad_type::zero) {
@@ -1801,24 +1691,22 @@ struct chrono_formatter {
     if (width > num_digits) {
       out = detail::write_padding(out, pad, width - num_digits);
     }
-    out = format_decimal<char_type>(out, n, num_digits);
+    out = format_decimal<Char>(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, context.locale());
+    get_locale loc(localized, locale);
     auto w = tm_writer_type(loc, out, time);
     (w.*cb)(args...);
     out = w.out();
   }
 
-  void on_text(const char_type* begin, const char_type* end) {
-    copy<char_type>(begin, end, out);
+  void on_text(const Char* begin, const Char* end) {
+    copy<Char>(begin, end, out);
   }
 
   // These are not implemented because durations don't have date information.
@@ -1888,13 +1776,12 @@ struct chrono_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_type>(buf.begin(), buf.end(), out);
+        out = copy<Char>(buf.begin(), buf.end(), out);
       } else {
         write(second(), 2, pad);
-        write_fractional_seconds<char_type>(
+        write_fractional_seconds<Char>(
             out, std::chrono::duration<rep, Period>(val), precision);
       }
       return;
@@ -1936,12 +1823,10 @@ struct chrono_formatter {
   void on_duration_value() {
     if (handle_nan_inf()) return;
     write_sign();
-    out = format_duration_value<char_type>(out, val, precision);
+    out = format_duration_value<Char>(out, val, precision);
   }
 
-  void on_duration_unit() {
-    out = format_duration_unit<char_type, Period>(out);
-  }
+  void on_duration_unit() { out = format_duration_unit<Char, Period>(out); }
 };
 
 }  // namespace detail
@@ -2011,12 +1896,11 @@ class year_month_day {
   constexpr auto month() const noexcept -> fmt::month { return month_; }
   constexpr auto day() const noexcept -> fmt::day { return day_; }
 };
-#endif
+#endif  // __cpp_lib_chrono >= 201907
 
 template <typename Char>
 struct formatter<weekday, Char> : private formatter<std::tm, Char> {
  private:
-  bool localized_ = false;
   bool use_tm_formatter_ = false;
 
  public:
@@ -2024,8 +1908,7 @@ struct formatter<weekday, Char> : private formatter<std::tm, Char> {
     auto it = ctx.begin(), end = ctx.end();
     if (it != end && *it == 'L') {
       ++it;
-      localized_ = true;
-      return it;
+      this->set_localized();
     }
     use_tm_formatter_ = it != end && *it != '}';
     return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2036,7 +1919,7 @@ 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(localized_, ctx.locale());
+    detail::get_locale loc(this->localized(), ctx.locale());
     auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
     w.on_abbr_weekday();
     return w.out();
@@ -2070,7 +1953,6 @@ 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:
@@ -2078,8 +1960,7 @@ struct formatter<month, Char> : private formatter<std::tm, Char> {
     auto it = ctx.begin(), end = ctx.end();
     if (it != end && *it == 'L') {
       ++it;
-      localized_ = true;
-      return it;
+      this->set_localized();
     }
     use_tm_formatter_ = it != end && *it != '}';
     return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2090,7 +1971,7 @@ 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(localized_, ctx.locale());
+    detail::get_locale loc(this->localized(), ctx.locale());
     auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
     w.on_abbr_month();
     return w.out();
@@ -2154,7 +2035,6 @@ 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:
@@ -2177,7 +2057,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
       it = detail::parse_precision(it, end, specs_, precision_ref_, ctx);
     }
     if (it != end && *it == 'L') {
-      localized_ = true;
+      specs_.set_localized();
       ++it;
     }
     end = detail::parse_chrono_format(it, end, checker);
@@ -2204,11 +2084,10 @@ 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 {
-      using chrono_formatter =
-          detail::chrono_formatter<FormatContext, decltype(out), Rep, Period>;
-      auto f = chrono_formatter(ctx, out, d);
+      auto f =
+          detail::duration_formatter<Char, Rep, Period>(out, d, ctx.locale());
       f.precision = precision;
-      f.localized = localized_;
+      f.localized = specs_.localized();
       detail::parse_chrono_format(begin, end, f);
     }
     return detail::write(
@@ -2220,30 +2099,15 @@ 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:
-  basic_string_view<Char> fmt_;
+  auto localized() const -> bool { return specs_.localized(); }
+  FMT_CONSTEXPR void set_localized() { specs_.set_localized(); }
 
-  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* {
+  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx, bool has_timezone)
+      -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end || *it == '}') return it;
 
@@ -2256,12 +2120,41 @@ template <typename Char> struct formatter<std::tm, Char> {
       if (it == end) return it;
     }
 
-    end = detail::parse_chrono_format(it, end, detail::tm_format_checker());
+    if (*it == 'L') {
+      specs_.set_localized();
+      ++it;
+    }
+
+    end = detail::parse_chrono_format(it, end,
+                                      detail::tm_format_checker(has_timezone));
     // 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() : 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()) {
@@ -2269,10 +2162,11 @@ 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> : formatter<std::tm, Char> {
-  FMT_CONSTEXPR formatter() {
-    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
+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);
   }
 
   template <typename FormatContext>
@@ -2283,6 +2177,7 @@ struct formatter<sys_time<Duration>, Char> : 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();
@@ -2290,11 +2185,13 @@ struct formatter<sys_time<Duration>, Char> : 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);
-      subsecs += detail::duration_cast<Duration>(std::chrono::seconds(1));
+        detail::set_tm_zone(tm, detail::utc());
+      }
+      subsecs += second;
     }
     return formatter<std::tm, Char>::do_format(tm, ctx, &subsecs);
   }
@@ -2312,23 +2209,29 @@ struct formatter<utc_time<Duration>, Char>
 };
 
 template <typename Duration, typename Char>
-struct formatter<local_time<Duration>, Char> : formatter<std::tm, Char> {
-  FMT_CONSTEXPR formatter() {
-    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
+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);
   }
 
   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(localtime(val), ctx);
+      return formatter<std::tm, Char>::format(t, ctx);
     }
-    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);
+    auto subsecs =
+        detail::duration_cast<Duration>(time_since_epoch - seconds_since_epoch);
+    return formatter<std::tm, Char>::do_format(t, ctx, &subsecs);
   }
 };
 

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 {
-  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)
+  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)
       : r((hex >> 16) & 0xFF), g((hex >> 8) & 0xFF), b(hex & 0xFF) {}
-  FMT_CONSTEXPR rgb(color hex)
+  constexpr rgb(color hex)
       : r((uint32_t(hex) >> 16) & 0xFF),
         g((uint32_t(hex) >> 8) & 0xFF),
         b(uint32_t(hex) & 0xFF) {}
@@ -205,97 +205,135 @@ struct rgb {
 
 namespace detail {
 
-// color is a struct of either a rgb color or a terminal color.
+// A bit-packed variant of an RGB color, a terminal color, or unset color.
+// see text_style for the bit-packing scheme.
 struct color_type {
-  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 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(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 auto value() const noexcept -> uint32_t {
+    return value_ & 0xFFFFFF;
   }
-  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;
+
+  constexpr color_type(uint32_t value) noexcept : value_(value) {}
+
+  uint32_t value_ = 0;
 };
 }  // 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
-      : set_foreground_color(), set_background_color(), ems(em) {}
+      : style_(static_cast<uint64_t>(em) << 54) {}
 
-  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));
+  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_;
     return *this;
   }
 
-  friend FMT_CONSTEXPR auto operator|(text_style lhs, const text_style& rhs)
+  friend FMT_CONSTEXPR auto operator|(text_style lhs, 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 set_foreground_color;
+    return (style_ & (1 << 24)) != 0;
   }
   FMT_CONSTEXPR auto has_background() const noexcept -> bool {
-    return set_background_color;
+    return (style_ & (1ULL << 51)) != 0;
   }
   FMT_CONSTEXPR auto has_emphasis() const noexcept -> bool {
-    return static_cast<uint8_t>(ems) != 0;
+    return (style_ >> 54) != 0;
   }
   FMT_CONSTEXPR auto get_foreground() const noexcept -> detail::color_type {
     FMT_ASSERT(has_foreground(), "no foreground specified for this style");
-    return foreground_color;
+    return style_ & 0x3FFFFFF;
   }
   FMT_CONSTEXPR auto get_background() const noexcept -> detail::color_type {
     FMT_ASSERT(has_background(), "no background specified for this style");
-    return background_color;
+    return (style_ >> 27) & 0x3FFFFFF;
   }
   FMT_CONSTEXPR auto get_emphasis() const noexcept -> emphasis {
     FMT_ASSERT(has_emphasis(), "no emphasis specified for this style");
-    return ems;
+    return static_cast<emphasis>(style_ >> 54);
   }
 
  private:
-  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;
-    }
-  }
+  FMT_CONSTEXPR text_style(uint64_t style) noexcept : style_(style) {}
 
   friend FMT_CONSTEXPR auto fg(detail::color_type foreground) noexcept
       -> text_style;
@@ -303,23 +341,19 @@ class text_style {
   friend FMT_CONSTEXPR auto bg(detail::color_type background) noexcept
       -> text_style;
 
-  detail::color_type foreground_color;
-  detail::color_type background_color;
-  bool set_foreground_color;
-  bool set_background_color;
-  emphasis ems;
+  uint64_t style_ = 0;
 };
 
 /// Creates a text style from the foreground (text) color.
 FMT_CONSTEXPR inline auto fg(detail::color_type foreground) noexcept
     -> text_style {
-  return text_style(true, foreground);
+  return foreground.value_;
 }
 
 /// Creates a text style from the background color.
 FMT_CONSTEXPR inline auto bg(detail::color_type background) noexcept
     -> text_style {
-  return text_style(false, background);
+  return static_cast<uint64_t>(background.value_) << 27;
 }
 
 FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept
@@ -334,37 +368,35 @@ 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_rgb) {
+    if (text_color.is_terminal_color()) {
       bool is_background = esc == string_view("\x1b[48;2;");
-      uint32_t value = text_color.value.term_color;
+      uint32_t value = text_color.value();
       // Background ASCII codes are the same as the foreground ones but with
       // 10 more.
       if (is_background) value += 10u;
 
-      size_t index = 0;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
+      buffer[size++] = static_cast<Char>('\x1b');
+      buffer[size++] = static_cast<Char>('[');
 
       if (value >= 100u) {
-        buffer[index++] = static_cast<Char>('1');
+        buffer[size++] = static_cast<Char>('1');
         value %= 100u;
       }
-      buffer[index++] = static_cast<Char>('0' + value / 10u);
-      buffer[index++] = static_cast<Char>('0' + value % 10u);
+      buffer[size++] = static_cast<Char>('0' + value / 10u);
+      buffer[size++] = static_cast<Char>('0' + value % 10u);
 
-      buffer[index++] = static_cast<Char>('m');
-      buffer[index++] = static_cast<Char>('\0');
+      buffer[size++] = static_cast<Char>('m');
       return;
     }
 
     for (int i = 0; i < 7; i++) {
       buffer[i] = static_cast<Char>(esc[i]);
     }
-    rgb color(text_color.value.rgb_color);
+    rgb color(text_color.value());
     to_esc(color.r, buffer + 7, ';');
     to_esc(color.g, buffer + 11, ';');
     to_esc(color.b, buffer + 15, 'm');
-    buffer[19] = static_cast<Char>(0);
+    size = 19;
   }
   FMT_CONSTEXPR ansi_color_escape(emphasis em) noexcept {
     uint8_t em_codes[num_emphases] = {};
@@ -377,26 +409,28 @@ template <typename Char> struct ansi_color_escape {
     if (has_emphasis(em, emphasis::conceal)) em_codes[6] = 8;
     if (has_emphasis(em, emphasis::strikethrough)) em_codes[7] = 9;
 
-    size_t index = 0;
+    buffer[size++] = static_cast<Char>('\x1b');
+    buffer[size++] = static_cast<Char>('[');
+
     for (size_t i = 0; i < num_emphases; ++i) {
       if (!em_codes[i]) continue;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
-      buffer[index++] = static_cast<Char>('0' + em_codes[i]);
-      buffer[index++] = static_cast<Char>('m');
+      buffer[size++] = static_cast<Char>('0' + em_codes[i]);
+      buffer[size++] = static_cast<Char>(';');
     }
-    buffer[index++] = static_cast<Char>(0);
+
+    buffer[size - 1] = static_cast<Char>('m');
   }
   FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }
 
   FMT_CONSTEXPR auto begin() const noexcept -> const Char* { return buffer; }
-  FMT_CONSTEXPR20 auto end() const noexcept -> const Char* {
-    return buffer + basic_string_view<Char>(buffer).size();
+  FMT_CONSTEXPR auto end() const noexcept -> const Char* {
+    return buffer + size;
   }
 
  private:
   static constexpr size_t num_emphases = 8;
-  Char buffer[7u + 3u * num_emphases + 1u];
+  Char buffer[7u + 4u * num_emphases];
+  size_t size = 0;
 
   static FMT_CONSTEXPR void to_esc(uint8_t c, Char* out,
                                    char delimiter) noexcept {
@@ -441,32 +475,26 @@ template <typename T> struct styled_arg : view {
 };
 
 template <typename Char>
-void vformat_to(buffer<Char>& buf, const text_style& ts,
-                basic_string_view<Char> fmt,
+void vformat_to(buffer<Char>& buf, 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 (has_style) reset_color<Char>(buf);
+  if (ts != text_style()) reset_color<Char>(buf);
 }
 }  // namespace detail
 
-inline void vprint(FILE* f, const text_style& ts, string_view fmt,
-                   format_args args) {
+inline void vprint(FILE* f, 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()));
@@ -482,8 +510,7 @@ inline void vprint(FILE* f, const text_style& ts, string_view fmt,
  *                "Elapsed time: {0:.2f} seconds", 1.23);
  */
 template <typename... T>
-void print(FILE* f, const text_style& ts, format_string<T...> fmt,
-           T&&... args) {
+void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) {
   vprint(f, ts, fmt.str, vargs<T...>{{args...}});
 }
 
@@ -497,11 +524,11 @@ void print(FILE* f, const text_style& ts, format_string<T...> fmt,
  *                "Elapsed time: {0:.2f} seconds", 1.23);
  */
 template <typename... T>
-void print(const text_style& ts, format_string<T...> fmt, T&&... args) {
+void print(text_style ts, format_string<T...> fmt, T&&... args) {
   return print(stdout, ts, fmt, std::forward<T>(args)...);
 }
 
-inline auto vformat(const text_style& ts, string_view fmt, format_args args)
+inline auto vformat(text_style ts, string_view fmt, format_args args)
     -> std::string {
   auto buf = memory_buffer();
   detail::vformat_to(buf, ts, fmt, args);
@@ -521,7 +548,7 @@ inline auto vformat(const text_style& ts, string_view fmt, format_args args)
  * ```
  */
 template <typename... T>
-inline auto format(const text_style& ts, format_string<T...> fmt, T&&... args)
+inline auto format(text_style ts, format_string<T...> fmt, T&&... args)
     -> std::string {
   return fmt::vformat(ts, fmt.str, vargs<T...>{{args...}});
 }
@@ -529,8 +556,8 @@ inline auto format(const 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, const text_style& ts, string_view fmt,
-                format_args args) -> OutputIt {
+auto vformat_to(OutputIt out, 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);
@@ -548,8 +575,8 @@ auto vformat_to(OutputIt out, const text_style& ts, string_view fmt,
  */
 template <typename OutputIt, typename... T,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-inline auto format_to(OutputIt out, const text_style& ts,
-                      format_string<T...> fmt, T&&... args) -> OutputIt {
+inline auto format_to(OutputIt out, text_style ts, format_string<T...> fmt,
+                      T&&... args) -> OutputIt {
   return vformat_to(out, ts, fmt.str, vargs<T...>{{args...}});
 }
 

include/spdlog/fmt/bundled/compile.h

@@ -22,8 +22,6 @@ FMT_EXPORT class compiled_string {};
 template <typename S>
 struct is_compiled_string : std::is_base_of<compiled_string, S> {};
 
-namespace detail {
-
 /**
  * Converts a string literal `s` into a format string that will be parsed at
  * compile time and converted into efficient formatting code. Requires C++17
@@ -41,18 +39,40 @@ namespace detail {
 #  define FMT_COMPILE(s) FMT_STRING(s)
 #endif
 
+/**
+ * Converts a string literal into a format string that will be parsed at
+ * compile time and converted into efficient formatting code. Requires support
+ * for class types in constant template parameters (a C++20 feature).
+ *
+ *  **Example**:
+ *
+ *     // Converts 42 into std::string using the most efficient method and no
+ *     // runtime format string processing.
+ *     using namespace fmt::literals;
+ *     std::string s = fmt::format("{}"_cf, 42);
+ */
+#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+inline namespace literals {
+template <detail::fixed_string Str> constexpr auto operator""_cf() {
+  return FMT_COMPILE(Str.data);
+}
+}  // namespace literals
+#endif
+
+namespace detail {
+
 template <typename T, typename... Tail>
-auto first(const T& value, const Tail&...) -> const T& {
+constexpr auto first(const T& value, const Tail&...) -> const T& {
   return value;
 }
 
 #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-template <typename... Args> struct type_list {};
+template <typename... T> struct type_list {};
 
 // Returns a reference to the argument at index N from [first, rest...].
 template <int N, typename T, typename... Args>
-constexpr const auto& get([[maybe_unused]] const T& first,
-                          [[maybe_unused]] const Args&... rest) {
+constexpr auto get([[maybe_unused]] const T& first,
+                   [[maybe_unused]] const Args&... rest) -> const auto& {
   static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
   if constexpr (N == 0)
     return first;
@@ -84,8 +104,8 @@ FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
 }
 
 template <typename Char, typename... Args>
-constexpr int get_arg_index_by_name(basic_string_view<Char> name,
-                                    type_list<Args...>) {
+constexpr auto get_arg_index_by_name(basic_string_view<Char> name,
+                                     type_list<Args...>) -> int {
   return get_arg_index_by_name<Args...>(name);
 }
 
@@ -105,8 +125,8 @@ template <typename Char> struct text {
   basic_string_view<Char> data;
   using char_type = Char;
 
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
     return write<Char>(out, data);
   }
 };
@@ -115,8 +135,8 @@ template <typename Char>
 struct is_compiled_format<text<Char>> : std::true_type {};
 
 template <typename Char>
-constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
-                               size_t size) {
+constexpr auto make_text(basic_string_view<Char> s, size_t pos, size_t size)
+    -> text<Char> {
   return {{&s[pos], size}};
 }
 
@@ -124,8 +144,8 @@ template <typename Char> struct code_unit {
   Char value;
   using char_type = Char;
 
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
     *out++ = value;
     return out;
   }
@@ -133,7 +153,7 @@ template <typename Char> struct code_unit {
 
 // This ensures that the argument type is convertible to `const T&`.
 template <typename T, int N, typename... Args>
-constexpr const T& get_arg_checked(const Args&... args) {
+constexpr auto get_arg_checked(const Args&... args) -> const T& {
   const auto& arg = detail::get<N>(args...);
   if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>()) {
     return arg.value;
@@ -146,13 +166,13 @@ template <typename Char>
 struct is_compiled_format<code_unit<Char>> : std::true_type {};
 
 // A replacement field that refers to argument N.
-template <typename Char, typename T, int N> struct field {
+template <typename Char, typename V, int N> struct field {
   using char_type = Char;
 
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    const T& arg = get_arg_checked<T, N>(args...);
-    if constexpr (std::is_convertible<T, basic_string_view<Char>>::value) {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
+    const V& arg = get_arg_checked<V, N>(args...);
+    if constexpr (std::is_convertible<V, basic_string_view<Char>>::value) {
       auto s = basic_string_view<Char>(arg);
       return copy<Char>(s.begin(), s.end(), out);
     } else {
@@ -170,10 +190,10 @@ template <typename Char> struct runtime_named_field {
   basic_string_view<Char> name;
 
   template <typename OutputIt, typename T>
-  constexpr static bool try_format_argument(
+  constexpr static auto try_format_argument(
       OutputIt& out,
       // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
-      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) {
+      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) -> bool {
     if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
       if (arg_name == arg.name) {
         out = write<Char>(out, arg.value);
@@ -183,8 +203,8 @@ template <typename Char> struct runtime_named_field {
     return false;
   }
 
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
     bool found = (try_format_argument(out, name, args) || ...);
     if (!found) {
       FMT_THROW(format_error("argument with specified name is not found"));
@@ -197,17 +217,17 @@ template <typename Char>
 struct is_compiled_format<runtime_named_field<Char>> : std::true_type {};
 
 // A replacement field that refers to argument N and has format specifiers.
-template <typename Char, typename T, int N> struct spec_field {
+template <typename Char, typename V, int N> struct spec_field {
   using char_type = Char;
-  formatter<T, Char> fmt;
+  formatter<V, Char> fmt;
 
-  template <typename OutputIt, typename... Args>
-  constexpr FMT_INLINE OutputIt format(OutputIt out,
-                                       const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr FMT_INLINE auto format(OutputIt out, const T&... args) const
+      -> OutputIt {
     const auto& vargs =
         fmt::make_format_args<basic_format_context<OutputIt, Char>>(args...);
     basic_format_context<OutputIt, Char> ctx(out, vargs);
-    return fmt.format(get_arg_checked<T, N>(args...), ctx);
+    return fmt.format(get_arg_checked<V, N>(args...), ctx);
   }
 };
 
@@ -219,8 +239,8 @@ template <typename L, typename R> struct concat {
   R rhs;
   using char_type = typename L::char_type;
 
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
     out = lhs.format(out, args...);
     return rhs.format(out, args...);
   }
@@ -230,14 +250,14 @@ template <typename L, typename R>
 struct is_compiled_format<concat<L, R>> : std::true_type {};
 
 template <typename L, typename R>
-constexpr concat<L, R> make_concat(L lhs, R rhs) {
+constexpr auto make_concat(L lhs, R rhs) -> concat<L, R> {
   return {lhs, rhs};
 }
 
 struct unknown_format {};
 
 template <typename Char>
-constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
+constexpr auto parse_text(basic_string_view<Char> str, size_t pos) -> size_t {
   for (size_t size = str.size(); pos != size; ++pos) {
     if (str[pos] == '{' || str[pos] == '}') break;
   }
@@ -270,8 +290,8 @@ template <typename T, typename Char> struct parse_specs_result {
 enum { manual_indexing_id = -1 };
 
 template <typename T, typename Char>
-constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
-                                                  size_t pos, int next_arg_id) {
+constexpr auto parse_specs(basic_string_view<Char> str, size_t pos,
+                           int next_arg_id) -> parse_specs_result<T, Char> {
   str.remove_prefix(pos);
   auto ctx =
       compile_parse_context<Char>(str, max_value<int>(), nullptr, next_arg_id);
@@ -285,16 +305,16 @@ template <typename Char> struct arg_id_handler {
   arg_id_kind kind;
   arg_ref<Char> arg_id;
 
-  constexpr int on_auto() {
+  constexpr auto on_auto() -> int {
     FMT_ASSERT(false, "handler cannot be used with automatic indexing");
     return 0;
   }
-  constexpr int on_index(int id) {
+  constexpr auto on_index(int id) -> int {
     kind = arg_id_kind::index;
     arg_id = arg_ref<Char>(id);
     return 0;
   }
-  constexpr int on_name(basic_string_view<Char> id) {
+  constexpr auto on_name(basic_string_view<Char> id) -> int {
     kind = arg_id_kind::name;
     arg_id = arg_ref<Char>(id);
     return 0;
@@ -433,27 +453,28 @@ FMT_BEGIN_EXPORT
 
 #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
 
-template <typename CompiledFormat, typename... Args,
+template <typename CompiledFormat, typename... T,
           typename Char = typename CompiledFormat::char_type,
           FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
-                                          const Args&... args) {
+FMT_INLINE FMT_CONSTEXPR_STRING auto format(const CompiledFormat& cf,
+                                            const T&... args)
+    -> std::basic_string<Char> {
   auto s = std::basic_string<Char>();
   cf.format(std::back_inserter(s), args...);
   return s;
 }
 
-template <typename OutputIt, typename CompiledFormat, typename... Args,
+template <typename OutputIt, typename CompiledFormat, typename... T,
           FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
-                                        const Args&... args) {
+constexpr FMT_INLINE auto format_to(OutputIt out, const CompiledFormat& cf,
+                                    const T&... args) -> OutputIt {
   return cf.format(out, args...);
 }
 
-template <typename S, typename... Args,
+template <typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
-                                                           Args&&... args) {
+FMT_INLINE FMT_CONSTEXPR_STRING auto format(const S&, T&&... args)
+    -> std::basic_string<typename S::char_type> {
   if constexpr (std::is_same<typename S::char_type, char>::value) {
     constexpr auto str = basic_string_view<typename S::char_type>(S());
     if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
@@ -466,72 +487,97 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
       }
     }
   }
-  constexpr auto compiled = detail::compile<Args...>(S());
+  constexpr auto compiled = detail::compile<T...>(S());
   if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
                              detail::unknown_format>()) {
     return fmt::format(
         static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
+        std::forward<T>(args)...);
   } else {
-    return fmt::format(compiled, std::forward<Args>(args)...);
+    return fmt::format(compiled, std::forward<T>(args)...);
   }
 }
 
-template <typename OutputIt, typename S, typename... Args,
+template <typename OutputIt, typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
-  constexpr auto compiled = detail::compile<Args...>(S());
+FMT_CONSTEXPR auto format_to(OutputIt out, const S&, T&&... args) -> OutputIt {
+  constexpr auto compiled = detail::compile<T...>(S());
   if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
                              detail::unknown_format>()) {
     return fmt::format_to(
         out, static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
+        std::forward<T>(args)...);
   } else {
-    return fmt::format_to(out, compiled, std::forward<Args>(args)...);
+    return fmt::format_to(out, compiled, std::forward<T>(args)...);
   }
 }
 #endif
 
-template <typename OutputIt, typename S, typename... Args,
+template <typename OutputIt, typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
+auto format_to_n(OutputIt out, size_t n, const S& fmt, T&&... args)
     -> format_to_n_result<OutputIt> {
   using traits = detail::fixed_buffer_traits;
   auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
-  fmt::format_to(std::back_inserter(buf), fmt, std::forward<Args>(args)...);
+  fmt::format_to(std::back_inserter(buf), fmt, std::forward<T>(args)...);
   return {buf.out(), buf.count()};
 }
 
-template <typename S, typename... Args,
+template <typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
-    -> size_t {
+FMT_CONSTEXPR20 auto formatted_size(const S& fmt, T&&... args) -> size_t {
   auto buf = detail::counting_buffer<>();
-  fmt::format_to(appender(buf), fmt, args...);
+  fmt::format_to(appender(buf), fmt, std::forward<T>(args)...);
   return buf.count();
 }
 
-template <typename S, typename... Args,
+template <typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-void print(std::FILE* f, const S& fmt, const Args&... args) {
+void print(std::FILE* f, const S& fmt, T&&... args) {
   auto buf = memory_buffer();
-  fmt::format_to(appender(buf), fmt, args...);
+  fmt::format_to(appender(buf), fmt, std::forward<T>(args)...);
   detail::print(f, {buf.data(), buf.size()});
 }
 
-template <typename S, typename... Args,
+template <typename S, typename... T,
           FMT_ENABLE_IF(is_compiled_string<S>::value)>
-void print(const S& fmt, const Args&... args) {
-  print(stdout, fmt, args...);
+void print(const S& fmt, T&&... args) {
+  print(stdout, fmt, std::forward<T>(args)...);
 }
 
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-inline namespace literals {
-template <detail::fixed_string Str> constexpr auto operator""_cf() {
-  return FMT_COMPILE(Str.data);
-}
-}  // namespace literals
-#endif
+template <size_t N> class static_format_result {
+ private:
+  char data[N];
+
+ public:
+  template <typename S, typename... T,
+            FMT_ENABLE_IF(is_compiled_string<S>::value)>
+  explicit FMT_CONSTEXPR static_format_result(const S& fmt, T&&... args) {
+    *fmt::format_to(data, fmt, std::forward<T>(args)...) = '\0';
+  }
+
+  auto str() const -> fmt::string_view { return {data, N - 1}; }
+  auto c_str() const -> const char* { return data; }
+};
+
+/**
+ * Formats arguments according to the format string `fmt_str` and produces
+ * a string of the exact required size at compile time. Both the format string
+ * and the arguments must be compile-time expressions.
+ *
+ * The resulting string can be accessed as a C string via `c_str()` or as
+ * a `fmt::string_view` via `str()`.
+ *
+ * **Example**:
+ *
+ *     // Produces the static string "42" at compile time.
+ *     static constexpr auto result = FMT_STATIC_FORMAT("{}", 42);
+ *     const char* s = result.c_str();
+ */
+#define FMT_STATIC_FORMAT(fmt_str, ...)                            \
+  fmt::static_format_result<                                       \
+      fmt::formatted_size(FMT_COMPILE(fmt_str), __VA_ARGS__) + 1>( \
+      FMT_COMPILE(fmt_str), __VA_ARGS__)
 
 FMT_END_EXPORT
 FMT_END_NAMESPACE

include/spdlog/fmt/bundled/fmt.license.rst

@@ -1,4 +1,4 @@
-Copyright (c) 2012 - present, Victor Zverovich
+Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the

include/spdlog/fmt/bundled/format-inl.h

@@ -22,7 +22,7 @@
 
 #include "format.h"
 
-#if FMT_USE_LOCALE
+#if FMT_USE_LOCALE && !defined(FMT_MODULE)
 #  include <locale>
 #endif
 
@@ -31,14 +31,49 @@
 #endif
 
 FMT_BEGIN_NAMESPACE
-namespace detail {
 
+#ifndef FMT_CUSTOM_ASSERT_FAIL
 FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
   // Use unchecked std::fprintf to avoid triggering another assertion when
   // writing to stderr fails.
   fprintf(stderr, "%s:%d: assertion failed: %s", file, line, message);
   abort();
 }
+#endif
+
+#if FMT_USE_LOCALE
+namespace detail {
+using std::locale;
+using std::numpunct;
+using std::use_facet;
+}  // namespace detail
+
+template <typename Locale, enable_if_t<(sizeof(Locale::collate) != 0), int>>
+locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
+  static_assert(std::is_same<Locale, std::locale>::value, "");
+}
+#else
+namespace detail {
+struct locale {};
+template <typename Char> struct numpunct {
+  auto grouping() const -> std::string { return "\03"; }
+  auto thousands_sep() const -> Char { return ','; }
+  auto decimal_point() const -> Char { return '.'; }
+};
+template <typename Facet> Facet use_facet(locale) { return {}; }
+}  // namespace detail
+#endif  // FMT_USE_LOCALE
+
+template <typename Locale> auto locale_ref::get() const -> Locale {
+  using namespace detail;
+  static_assert(std::is_same<Locale, locale>::value, "");
+#if FMT_USE_LOCALE
+  if (locale_) return *static_cast<const locale*>(locale_);
+#endif
+  return locale();
+}
+
+namespace detail {
 
 FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
                                 string_view message) noexcept {
@@ -79,33 +114,6 @@ inline void fwrite_all(const void* ptr, size_t count, FILE* stream) {
     FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
 }
 
-#if FMT_USE_LOCALE
-using std::locale;
-using std::numpunct;
-using std::use_facet;
-
-template <typename Locale>
-locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
-  static_assert(std::is_same<Locale, locale>::value, "");
-}
-#else
-struct locale {};
-template <typename Char> struct numpunct {
-  auto grouping() const -> std::string { return "\03"; }
-  auto thousands_sep() const -> Char { return ','; }
-  auto decimal_point() const -> Char { return '.'; }
-};
-template <typename Facet> Facet use_facet(locale) { return {}; }
-#endif  // FMT_USE_LOCALE
-
-template <typename Locale> auto locale_ref::get() const -> Locale {
-  static_assert(std::is_same<Locale, locale>::value, "");
-#if FMT_USE_LOCALE
-  if (locale_) return *static_cast<const locale*>(locale_);
-#endif
-  return locale();
-}
-
 template <typename Char>
 FMT_FUNC auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char> {
   auto&& facet = use_facet<numpunct<Char>>(loc.get<locale>());
@@ -133,14 +141,13 @@ FMT_FUNC auto write_loc(appender out, loc_value value,
 }  // namespace detail
 
 FMT_FUNC void report_error(const char* message) {
-#if FMT_USE_EXCEPTIONS
-  // Use FMT_THROW instead of throw to avoid bogus unreachable code warnings
-  // from MSVC.
-  FMT_THROW(format_error(message));
-#else
-  fputs(message, stderr);
-  abort();
+#if FMT_MSC_VERSION || defined(__NVCC__)
+  // Silence unreachable code warnings in MSVC and NVCC because these
+  // are nearly impossible to fix in a generic code.
+  volatile bool b = true;
+  if (!b) return;
 #endif
+  FMT_THROW(format_error(message));
 }
 
 template <typename Locale> typename Locale::id format_facet<Locale>::id;
@@ -174,11 +181,11 @@ inline auto operator==(basic_fp<F> x, basic_fp<F> y) -> bool {
 }
 
 // Compilers should be able to optimize this into the ror instruction.
-FMT_CONSTEXPR inline auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
+FMT_INLINE auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
   r &= 31;
   return (n >> r) | (n << (32 - r));
 }
-FMT_CONSTEXPR inline auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
+FMT_INLINE auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
   r &= 63;
   return (n >> r) | (n << (64 - r));
 }
@@ -212,7 +219,7 @@ inline auto floor_log10_pow2_minus_log10_4_over_3(int e) noexcept -> int {
   return (e * 631305 - 261663) >> 21;
 }
 
-FMT_INLINE_VARIABLE constexpr struct {
+FMT_INLINE_VARIABLE constexpr struct div_small_pow10_infos_struct {
   uint32_t divisor;
   int shift_amount;
 } div_small_pow10_infos[] = {{10, 16}, {100, 16}};
@@ -275,7 +282,7 @@ template <> struct cache_accessor<float> {
   static auto get_cached_power(int k) noexcept -> uint64_t {
     FMT_ASSERT(k >= float_info<float>::min_k && k <= float_info<float>::max_k,
                "k is out of range");
-    static constexpr const uint64_t pow10_significands[] = {
+    static constexpr uint64_t pow10_significands[] = {
         0x81ceb32c4b43fcf5, 0xa2425ff75e14fc32, 0xcad2f7f5359a3b3f,
         0xfd87b5f28300ca0e, 0x9e74d1b791e07e49, 0xc612062576589ddb,
         0xf79687aed3eec552, 0x9abe14cd44753b53, 0xc16d9a0095928a28,
@@ -370,7 +377,7 @@ template <> struct cache_accessor<double> {
     FMT_ASSERT(k >= float_info<double>::min_k && k <= float_info<double>::max_k,
                "k is out of range");
 
-    static constexpr const uint128_fallback pow10_significands[] = {
+    static constexpr uint128_fallback pow10_significands[] = {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
       {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
       {0x9faacf3df73609b1, 0x77b191618c54e9ad},
@@ -1037,7 +1044,7 @@ template <> struct cache_accessor<double> {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
     return pow10_significands[k - float_info<double>::min_k];
 #else
-    static constexpr const uint64_t powers_of_5_64[] = {
+    static constexpr uint64_t powers_of_5_64[] = {
         0x0000000000000001, 0x0000000000000005, 0x0000000000000019,
         0x000000000000007d, 0x0000000000000271, 0x0000000000000c35,
         0x0000000000003d09, 0x000000000001312d, 0x000000000005f5e1,
@@ -1097,7 +1104,7 @@ template <> struct cache_accessor<double> {
     return {r.high(), r.low() == 0};
   }
 
-  static auto compute_delta(cache_entry_type const& cache, int beta) noexcept
+  static auto compute_delta(const cache_entry_type& cache, int beta) noexcept
       -> uint32_t {
     return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta));
   }
@@ -1149,8 +1156,8 @@ auto is_left_endpoint_integer_shorter_interval(int exponent) noexcept -> bool {
          exponent <= case_shorter_interval_left_endpoint_upper_threshold;
 }
 
-// Remove trailing zeros from n and return the number of zeros removed (float)
-FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
+// Remove trailing zeros from n and return the number of zeros removed (float).
+FMT_INLINE auto remove_trailing_zeros(uint32_t& n, int s = 0) noexcept -> int {
   FMT_ASSERT(n != 0, "");
   // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
   constexpr uint32_t mod_inv_5 = 0xcccccccd;
@@ -1170,22 +1177,19 @@ FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
   return s;
 }
 
-// Removes trailing zeros and returns the number of zeros removed (double)
-FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
+// Removes trailing zeros and returns the number of zeros removed (double).
+FMT_INLINE auto remove_trailing_zeros(uint64_t& n) noexcept -> int {
   FMT_ASSERT(n != 0, "");
 
-  // This magic number is ceil(2^90 / 10^8).
-  constexpr uint64_t magic_number = 12379400392853802749ull;
-  auto nm = umul128(n, magic_number);
-
   // Is n is divisible by 10^8?
-  if ((nm.high() & ((1ull << (90 - 64)) - 1)) == 0 && nm.low() < magic_number) {
+  constexpr uint32_t ten_pow_8 = 100000000u;
+  if ((n % ten_pow_8) == 0) {
     // If yes, work with the quotient...
-    auto n32 = static_cast<uint32_t>(nm.high() >> (90 - 64));
+    auto n32 = static_cast<uint32_t>(n / ten_pow_8);
     // ... and use the 32 bit variant of the function
-    int s = remove_trailing_zeros(n32, 8);
+    int num_zeros = remove_trailing_zeros(n32, 8);
     n = n32;
-    return s;
+    return num_zeros;
   }
 
   // If n is not divisible by 10^8, work with n itself.
@@ -1210,7 +1214,7 @@ FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
 
 // The main algorithm for shorter interval case
 template <typename T>
-FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
+FMT_INLINE auto shorter_interval_case(int exponent) noexcept -> decimal_fp<T> {
   decimal_fp<T> ret_value;
   // Compute k and beta
   const int minus_k = floor_log10_pow2_minus_log10_4_over_3(exponent);
@@ -1454,8 +1458,8 @@ FMT_FUNC void vformat_to(buffer<char>& buf, string_view fmt, format_args args,
   auto out = appender(buf);
   if (fmt.size() == 2 && equal2(fmt.data(), "{}"))
     return args.get(0).visit(default_arg_formatter<char>{out});
-  parse_format_string(
-      fmt, format_handler<char>{parse_context<char>(fmt), {out, args, loc}});
+  parse_format_string(fmt,
+                      format_handler<>{parse_context<>(fmt), {out, args, loc}});
 }
 
 template <typename T> struct span {
@@ -1526,9 +1530,8 @@ template <typename F> class glibc_file : public file_base<F> {
   }
 
   void init_buffer() {
-    if (this->file_->_IO_write_ptr) return;
+    if (this->file_->_IO_write_ptr < this->file_->_IO_write_end) 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;
   }
@@ -1547,10 +1550,11 @@ template <typename F> class glibc_file : public file_base<F> {
 
   void advance_write_buffer(size_t size) { this->file_->_IO_write_ptr += size; }
 
-  bool needs_flush() const {
+  auto needs_flush() const -> bool {
     if ((this->file_->_flags & line_buffered) == 0) return false;
     char* end = this->file_->_IO_write_end;
-    return memchr(end, '\n', to_unsigned(this->file_->_IO_write_ptr - end));
+    auto size = max_of<ptrdiff_t>(this->file_->_IO_write_ptr - end, 0);
+    return memchr(end, '\n', static_cast<size_t>(size));
   }
 
   void flush() { fflush_unlocked(this->file_); }
@@ -1574,7 +1578,7 @@ template <typename F> class apple_file : public file_base<F> {
   void init_buffer() {
     if (this->file_->_p) return;
     // Force buffer initialization by placing and removing a char in a buffer.
-    putc_unlocked(0, this->file_);
+    if (!FMT_CLANG_ANALYZER) putc_unlocked(0, this->file_);
     --this->file_->_p;
     ++this->file_->_w;
   }
@@ -1595,7 +1599,7 @@ template <typename F> class apple_file : public file_base<F> {
     this->file_->_w -= size;
   }
 
-  bool needs_flush() const {
+  auto needs_flush() const -> bool {
     if ((this->file_->_flags & line_buffered) == 0) return false;
     return memchr(this->file_->_p + this->file_->_w, '\n',
                   to_unsigned(-this->file_->_w));

include/spdlog/fmt/bundled/os.h

@@ -29,7 +29,8 @@
 #  if (FMT_HAS_INCLUDE(<fcntl.h>) || defined(__APPLE__) || \
        defined(__linux__)) &&                              \
       (!defined(WINAPI_FAMILY) ||                          \
-       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)) &&    \
+      !defined(__wasm__)
 #    include <fcntl.h>  // for O_RDONLY
 #    define FMT_USE_FCNTL 1
 #  else

include/spdlog/fmt/bundled/ostream.h

@@ -33,8 +33,8 @@
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
-// Generate a unique explicit instantion in every translation unit using a tag
-// type in an anonymous namespace.
+// Generate a unique explicit instantiation in every translation unit using a
+// tag type in an anonymous namespace.
 namespace {
 struct file_access_tag {};
 }  // namespace
@@ -158,7 +158,8 @@ 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, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
+  fmt::print(os, FMT_STRING("{}\n"),
+             fmt::format(fmt, std::forward<T>(args)...));
 }
 
 FMT_END_NAMESPACE

include/spdlog/fmt/bundled/printf.h

@@ -9,7 +9,7 @@
 #define FMT_PRINTF_H_
 
 #ifndef FMT_MODULE
-#  include <algorithm>  // std::max
+#  include <algorithm>  // std::find
 #  include <limits>     // std::numeric_limits
 #endif
 
@@ -18,10 +18,6 @@
 FMT_BEGIN_NAMESPACE
 FMT_BEGIN_EXPORT
 
-template <typename T> struct printf_formatter {
-  printf_formatter() = delete;
-};
-
 template <typename Char> class basic_printf_context {
  private:
   basic_appender<Char> out_;
@@ -33,8 +29,6 @@ template <typename Char> class basic_printf_context {
 
  public:
   using char_type = Char;
-  using parse_context_type = parse_context<Char>;
-  template <typename T> using formatter_type = printf_formatter<T>;
   enum { builtin_types = 1 };
 
   /// Constructs a `printf_context` object. References to the arguments are
@@ -46,7 +40,7 @@ template <typename Char> class basic_printf_context {
   auto out() -> basic_appender<Char> { return out_; }
   void advance_to(basic_appender<Char>) {}
 
-  auto locale() -> detail::locale_ref { return {}; }
+  auto locale() -> locale_ref { return {}; }
 
   auto arg(int id) const -> basic_format_arg<basic_printf_context> {
     return args_.get(id);
@@ -74,10 +68,9 @@ inline auto find<false, char>(const char* first, const char* last, char value,
 
 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
-template <bool IsSigned> struct int_checker {
+template <bool IS_SIGNED> struct int_checker {
   template <typename T> static auto fits_in_int(T value) -> bool {
-    unsigned max = to_unsigned(max_value<int>());
-    return value <= max;
+    return value <= to_unsigned(max_value<int>());
   }
   inline static auto fits_in_int(bool) -> bool { return true; }
 };
@@ -95,7 +88,7 @@ struct printf_precision_handler {
   auto operator()(T value) -> int {
     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
       report_error("number is too big");
-    return (std::max)(static_cast<int>(value), 0);
+    return max_of(static_cast<int>(value), 0);
   }
 
   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
@@ -410,7 +403,9 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
       arg_index = parse_ctx.next_arg_id();
     else
       parse_ctx.check_arg_id(--arg_index);
-    return detail::get_arg(context, arg_index);
+    auto arg = context.arg(arg_index);
+    if (!arg) report_error("argument not found");
+    return arg;
   };
 
   const Char* start = parse_ctx.begin();
@@ -571,15 +566,19 @@ inline auto vsprintf(basic_string_view<Char> fmt,
  *
  *     std::string message = fmt::sprintf("The answer is %d", 42);
  */
-template <typename S, typename... T, typename Char = detail::char_t<S>>
-inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
-  return vsprintf(detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
+template <typename... T>
+inline auto sprintf(string_view fmt, const T&... args) -> std::string {
+  return vsprintf(fmt, make_printf_args(args...));
+}
+template <typename... T>
+FMT_DEPRECATED auto sprintf(basic_string_view<wchar_t> fmt, const T&... args)
+    -> std::wstring {
+  return vsprintf(fmt, make_printf_args<wchar_t>(args...));
 }
 
 template <typename Char>
-inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
-                     typename vprintf_args<Char>::type args) -> int {
+auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
+              typename vprintf_args<Char>::type args) -> int {
   auto buf = basic_memory_buffer<Char>();
   detail::vprintf(buf, fmt, args);
   size_t size = buf.size();
@@ -596,17 +595,14 @@ inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
  *
  *     fmt::fprintf(stderr, "Don't %s!", "panic");
  */
-template <typename S, typename... T, typename Char = detail::char_t<S>>
-inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
-  return vfprintf(f, detail::to_string_view(fmt),
-                  make_printf_args<Char>(args...));
+template <typename... T>
+inline auto fprintf(std::FILE* f, string_view fmt, const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args(args...));
 }
-
-template <typename Char>
-FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
-                                   typename vprintf_args<Char>::type args)
-    -> int {
-  return vfprintf(stdout, fmt, args);
+template <typename... T>
+FMT_DEPRECATED auto fprintf(std::FILE* f, basic_string_view<wchar_t> fmt,
+                            const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args<wchar_t>(args...));
 }
 
 /**
@@ -621,11 +617,6 @@ template <typename... T>
 inline auto printf(string_view fmt, const T&... args) -> int {
   return vfprintf(stdout, fmt, make_printf_args(args...));
 }
-template <typename... T>
-FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
-                                  const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
-}
 
 FMT_END_EXPORT
 FMT_END_NAMESPACE

include/spdlog/fmt/bundled/ranges.h

@@ -11,7 +11,6 @@
 #ifndef FMT_MODULE
 #  include <initializer_list>
 #  include <iterator>
-#  include <string>
 #  include <tuple>
 #  include <type_traits>
 #  include <utility>
@@ -31,7 +30,7 @@ template <typename T> class is_map {
   template <typename> static void check(...);
 
  public:
-  static constexpr const bool value =
+  static constexpr bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value;
 };
 
@@ -40,17 +39,16 @@ template <typename T> class is_set {
   template <typename> static void check(...);
 
  public:
-  static constexpr const bool value =
+  static constexpr bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
 };
 
 // C array overload
-template <typename T, std::size_t N>
+template <typename T, size_t N>
 auto range_begin(const T (&arr)[N]) -> const T* {
   return arr;
 }
-template <typename T, std::size_t N>
-auto range_end(const T (&arr)[N]) -> const T* {
+template <typename T, size_t N> auto range_end(const T (&arr)[N]) -> const T* {
   return arr + N;
 }
 
@@ -120,7 +118,7 @@ template <typename T> class is_tuple_like_ {
   template <typename> static void check(...);
 
  public:
-  static constexpr const bool value =
+  static constexpr bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value;
 };
 
@@ -154,7 +152,7 @@ using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 class is_tuple_formattable_ {
  public:
-  static constexpr const bool value = false;
+  static constexpr bool value = false;
 };
 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
   template <size_t... Is>
@@ -170,7 +168,7 @@ template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
                                        C>::value)...>{}));
 
  public:
-  static constexpr const bool value =
+  static constexpr bool value =
       decltype(check(tuple_index_sequence<T>{}))::value;
 };
 
@@ -208,7 +206,7 @@ template <typename Char, typename... T>
 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;
 
 using std::get;
-template <typename Tuple, typename Char, std::size_t... Is>
+template <typename Tuple, typename Char, size_t... Is>
 auto get_formatters(index_sequence<Is...>)
     -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 }  // namespace tuple
@@ -219,7 +217,7 @@ template <typename R> struct range_reference_type_impl {
   using type = decltype(*detail::range_begin(std::declval<R&>()));
 };
 
-template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
+template <typename T, size_t N> struct range_reference_type_impl<T[N]> {
   using type = T&;
 };
 
@@ -281,14 +279,15 @@ template <typename FormatContext> struct format_tuple_element {
 
 }  // namespace detail
 
+FMT_EXPORT
 template <typename T> struct is_tuple_like {
-  static constexpr const bool value =
+  static constexpr bool value =
       detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 };
 
+FMT_EXPORT
 template <typename T, typename C> struct is_tuple_formattable {
-  static constexpr const bool value =
-      detail::is_tuple_formattable_<T, C>::value;
+  static constexpr bool value = detail::is_tuple_formattable_<T, C>::value;
 };
 
 template <typename Tuple, typename Char>
@@ -343,8 +342,9 @@ struct formatter<Tuple, Char,
   }
 };
 
+FMT_EXPORT
 template <typename T, typename Char> struct is_range {
-  static constexpr const bool value =
+  static constexpr bool value =
       detail::is_range_<T>::value && !detail::has_to_string_view<T>::value;
 };
 
@@ -368,6 +368,7 @@ template <typename P1, typename... Pn>
 struct conjunction<P1, Pn...>
     : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
 
+FMT_EXPORT
 template <typename T, typename Char, typename Enable = void>
 struct range_formatter;
 
@@ -670,7 +671,8 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
   }
 };
 
-template <typename Char, typename Tuple> struct tuple_join_view : detail::view {
+FMT_EXPORT
+template <typename Tuple, typename Char> struct tuple_join_view : detail::view {
   const Tuple& tuple;
   basic_string_view<Char> sep;
 
@@ -685,15 +687,15 @@ template <typename Char, typename Tuple> struct tuple_join_view : detail::view {
 #  define FMT_TUPLE_JOIN_SPECIFIERS 0
 #endif
 
-template <typename Char, typename Tuple>
-struct formatter<tuple_join_view<Char, Tuple>, Char,
+template <typename Tuple, typename Char>
+struct formatter<tuple_join_view<Tuple, Char>, Char,
                  enable_if_t<is_tuple_like<Tuple>::value>> {
   FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return do_parse(ctx, std::tuple_size<Tuple>());
   }
 
   template <typename FormatContext>
-  auto format(const tuple_join_view<Char, Tuple>& value,
+  auto format(const tuple_join_view<Tuple, Char>& value,
               FormatContext& ctx) const -> typename FormatContext::iterator {
     return do_format(value, ctx, std::tuple_size<Tuple>());
   }
@@ -725,14 +727,14 @@ struct formatter<tuple_join_view<Char, Tuple>, Char,
   }
 
   template <typename FormatContext>
-  auto do_format(const tuple_join_view<Char, Tuple>&, FormatContext& ctx,
+  auto do_format(const tuple_join_view<Tuple, Char>&, FormatContext& ctx,
                  std::integral_constant<size_t, 0>) const ->
       typename FormatContext::iterator {
     return ctx.out();
   }
 
   template <typename FormatContext, size_t N>
-  auto do_format(const tuple_join_view<Char, Tuple>& value, FormatContext& ctx,
+  auto do_format(const tuple_join_view<Tuple, Char>& value, FormatContext& ctx,
                  std::integral_constant<size_t, N>) const ->
       typename FormatContext::iterator {
     using std::get;
@@ -754,7 +756,7 @@ template <typename T> class is_container_adaptor_like {
   template <typename> static void check(...);
 
  public:
-  static constexpr const bool value =
+  static constexpr bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value;
 };
 
@@ -774,13 +776,13 @@ 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& t, FormatContext& ctx) const -> decltype(ctx.out()) {
+  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
     struct getter : T {
-      static auto get(const T& t) -> all {
-        return {t.*(&getter::c)};  // Access c through the derived class.
+      static auto get(const T& v) -> all {
+        return {v.*(&getter::c)};  // Access c through the derived class.
       }
     };
-    return formatter<all>::format(getter::get(t), ctx);
+    return formatter<all>::format(getter::get(value), ctx);
   }
 };
 
@@ -825,7 +827,7 @@ auto join(Range&& r, string_view sep)
  */
 template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
 FMT_CONSTEXPR auto join(const Tuple& tuple, string_view sep)
-    -> tuple_join_view<char, Tuple> {
+    -> tuple_join_view<Tuple, char> {
   return {tuple, sep};
 }
 

include/spdlog/fmt/bundled/std.h

@@ -15,15 +15,13 @@
 #  include <atomic>
 #  include <bitset>
 #  include <complex>
-#  include <cstdlib>
 #  include <exception>
-#  include <functional>
+#  include <functional>  // std::reference_wrapper
 #  include <memory>
 #  include <thread>
 #  include <type_traits>
-#  include <typeinfo>
-#  include <utility>
-#  include <vector>
+#  include <typeinfo>  // std::type_info
+#  include <utility>   // std::make_index_sequence
 
 // Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
@@ -62,27 +60,26 @@
 #  endif
 #endif
 
-// For older Xcode versions, __cpp_lib_xxx flags are inaccurately defined.
-#ifndef FMT_CPP_LIB_FILESYSTEM
-#  ifdef __cpp_lib_filesystem
-#    define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
-#  else
-#    define FMT_CPP_LIB_FILESYSTEM 0
-#  endif
+#ifdef FMT_CPP_LIB_FILESYSTEM
+// Use the provided definition.
+#elif defined(__cpp_lib_filesystem)
+#  define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
+#else
+#  define FMT_CPP_LIB_FILESYSTEM 0
 #endif
 
-#ifndef FMT_CPP_LIB_VARIANT
-#  ifdef __cpp_lib_variant
-#    define FMT_CPP_LIB_VARIANT __cpp_lib_variant
-#  else
-#    define FMT_CPP_LIB_VARIANT 0
-#  endif
+#ifdef FMT_CPP_LIB_VARIANT
+// Use the provided definition.
+#elif defined(__cpp_lib_variant)
+#  define FMT_CPP_LIB_VARIANT __cpp_lib_variant
+#else
+#  define FMT_CPP_LIB_VARIANT 0
 #endif
 
+FMT_BEGIN_NAMESPACE
+namespace detail {
+
 #if FMT_CPP_LIB_FILESYSTEM
-FMT_BEGIN_NAMESPACE
-
-namespace detail {
 
 template <typename Char, typename PathChar>
 auto get_path_string(const std::filesystem::path& p,
@@ -111,9 +108,168 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
   }
 }
 
+#endif  // FMT_CPP_LIB_FILESYSTEM
+
+#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
+template <typename Char, typename OutputIt, typename T>
+auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
+  if constexpr (has_to_string_view<T>::value)
+    return write_escaped_string<Char>(out, detail::to_string_view(v));
+  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
+  return write<Char>(out, v);
+}
+#endif
+
+#if FMT_CPP_LIB_VARIANT
+
+template <typename> struct is_variant_like_ : std::false_type {};
+template <typename... Types>
+struct is_variant_like_<std::variant<Types...>> : std::true_type {};
+
+template <typename Variant, typename Char> class is_variant_formattable {
+  template <size_t... Is>
+  static auto check(std::index_sequence<Is...>) -> std::conjunction<
+      is_formattable<std::variant_alternative_t<Is, Variant>, Char>...>;
+
+ public:
+  static constexpr bool value = decltype(check(
+      std::make_index_sequence<std::variant_size<Variant>::value>()))::value;
+};
+
+#endif  // FMT_CPP_LIB_VARIANT
+
+#if FMT_USE_RTTI
+
+template <typename OutputIt>
+auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
+#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
+  int status = 0;
+  size_t size = 0;
+  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
+      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
+
+  string_view demangled_name_view;
+  if (demangled_name_ptr) {
+    demangled_name_view = demangled_name_ptr.get();
+
+    // Normalization of stdlib inline namespace names.
+    // libc++ inline namespaces.
+    //  std::__1::*       -> std::*
+    //  std::__1::__fs::* -> std::*
+    // libstdc++ inline namespaces.
+    //  std::__cxx11::*             -> std::*
+    //  std::filesystem::__cxx11::* -> std::filesystem::*
+    if (demangled_name_view.starts_with("std::")) {
+      char* begin = demangled_name_ptr.get();
+      char* to = begin + 5;  // std::
+      for (char *from = to, *end = begin + demangled_name_view.size();
+           from < end;) {
+        // This is safe, because demangled_name is NUL-terminated.
+        if (from[0] == '_' && from[1] == '_') {
+          char* next = from + 1;
+          while (next < end && *next != ':') next++;
+          if (next[0] == ':' && next[1] == ':') {
+            from = next + 2;
+            continue;
+          }
+        }
+        *to++ = *from++;
+      }
+      demangled_name_view = {begin, detail::to_unsigned(to - begin)};
+    }
+  } else {
+    demangled_name_view = string_view(ti.name());
+  }
+  return detail::write_bytes<char>(out, demangled_name_view);
+#  elif FMT_MSC_VERSION
+  const string_view demangled_name(ti.name());
+  for (size_t i = 0; i < demangled_name.size(); ++i) {
+    auto sub = demangled_name;
+    sub.remove_prefix(i);
+    if (sub.starts_with("enum ")) {
+      i += 4;
+      continue;
+    }
+    if (sub.starts_with("class ") || sub.starts_with("union ")) {
+      i += 5;
+      continue;
+    }
+    if (sub.starts_with("struct ")) {
+      i += 6;
+      continue;
+    }
+    if (*sub.begin() != ' ') *out++ = *sub.begin();
+  }
+  return out;
+#  else
+  return detail::write_bytes<char>(out, string_view(ti.name()));
+#  endif
+}
+
+#endif  // FMT_USE_RTTI
+
+template <typename T, typename Enable = void>
+struct has_flip : std::false_type {};
+
+template <typename T>
+struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
+    : std::true_type {};
+
+template <typename T> struct is_bit_reference_like {
+  static constexpr bool value = std::is_convertible<T, bool>::value &&
+                                std::is_nothrow_assignable<T, bool>::value &&
+                                has_flip<T>::value;
+};
+
+// Workaround for libc++ incompatibility with C++ standard.
+// According to the Standard, `bitset::operator[] const` returns bool.
+#if defined(_LIBCPP_VERSION) && !defined(FMT_IMPORT_STD)
+template <typename C>
+struct is_bit_reference_like<std::__bit_const_reference<C>> {
+  static constexpr bool value = true;
+};
+#endif
+
+template <typename T, typename Enable = void>
+struct has_format_as : std::false_type {};
+template <typename T>
+struct has_format_as<T, void_t<decltype(format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
+template <typename T, typename Enable = void>
+struct has_format_as_member : std::false_type {};
+template <typename T>
+struct has_format_as_member<
+    T, void_t<decltype(formatter<T>::format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
 }  // namespace detail
 
-FMT_EXPORT
+template <typename T, typename Deleter>
+auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
+  return p.get();
+}
+template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
+  return p.get();
+}
+
+#if FMT_CPP_LIB_FILESYSTEM
+
+class path : public std::filesystem::path {
+ public:
+  auto display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{}"), base);
+  }
+  auto system_string() const -> std::string { return string(); }
+
+  auto generic_display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{:g}"), base);
+  }
+  auto generic_system_string() const -> std::string { return generic_string(); }
+};
+
 template <typename Char> struct formatter<std::filesystem::path, Char> {
  private:
   format_specs specs_;
@@ -163,40 +319,20 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
   }
 };
 
-class path : public std::filesystem::path {
- public:
-  auto display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{}"), base);
-  }
-  auto system_string() const -> std::string { return string(); }
-
-  auto generic_display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{:g}"), base);
-  }
-  auto generic_system_string() const -> std::string { return generic_string(); }
-};
-
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_FILESYSTEM
 
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <std::size_t N, typename Char>
+template <size_t N, typename Char>
 struct formatter<std::bitset<N>, Char>
     : nested_formatter<basic_string_view<Char>, Char> {
  private:
-  // Functor because C++11 doesn't support generic lambdas.
+  // This is a functor because C++11 doesn't support generic lambdas.
   struct writer {
     const std::bitset<N>& bs;
 
     template <typename OutputIt>
     FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
-      for (auto pos = N; pos > 0; --pos) {
+      for (auto pos = N; pos > 0; --pos)
         out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
-      }
-
       return out;
     }
   };
@@ -209,14 +345,10 @@ 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>> {
@@ -255,31 +387,9 @@ struct formatter<std::optional<T>, Char,
     return detail::write(out, ')');
   }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_optional
 
-#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename Char, typename OutputIt, typename T>
-auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
-  if constexpr (has_to_string_view<T>::value)
-    return write_escaped_string<Char>(out, detail::to_string_view(v));
-  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
-  return write<Char>(out, v);
-}
-
-}  // namespace detail
-
-FMT_END_NAMESPACE
-#endif
-
 #ifdef __cpp_lib_expected
-FMT_BEGIN_NAMESPACE
-
-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 ||
@@ -306,12 +416,9 @@ struct formatter<std::expected<T, E>, Char,
     return out;
   }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_expected
 
 #ifdef __cpp_lib_source_location
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
 template <> struct formatter<std::source_location> {
   FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
 
@@ -329,45 +436,14 @@ template <> struct formatter<std::source_location> {
     return out;
   }
 };
-FMT_END_NAMESPACE
 #endif
 
 #if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using variant_index_sequence =
-    std::make_index_sequence<std::variant_size<T>::value>;
-
-template <typename> struct is_variant_like_ : std::false_type {};
-template <typename... Types>
-struct is_variant_like_<std::variant<Types...>> : std::true_type {};
-
-// formattable element check.
-template <typename T, typename C> class is_variant_formattable_ {
-  template <std::size_t... Is>
-  static std::conjunction<
-      is_formattable<std::variant_alternative_t<Is, T>, C>...>
-      check(std::index_sequence<Is...>);
-
- public:
-  static constexpr const bool value =
-      decltype(check(variant_index_sequence<T>{}))::value;
-};
-
-}  // namespace detail
 
 template <typename T> struct is_variant_like {
-  static constexpr const bool value = detail::is_variant_like_<T>::value;
+  static constexpr bool value = detail::is_variant_like_<T>::value;
 };
 
-template <typename T, typename C> struct is_variant_formattable {
-  static constexpr const bool value =
-      detail::is_variant_formattable_<T, C>::value;
-};
-
-FMT_EXPORT
 template <typename Char> struct formatter<std::monostate, Char> {
   FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
@@ -380,12 +456,11 @@ template <typename Char> struct formatter<std::monostate, Char> {
   }
 };
 
-FMT_EXPORT
 template <typename Variant, typename Char>
-struct formatter<
-    Variant, Char,
-    std::enable_if_t<std::conjunction_v<
-        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
+struct formatter<Variant, Char,
+                 std::enable_if_t<std::conjunction_v<
+                     is_variant_like<Variant>,
+                     detail::is_variant_formattable<Variant, Char>>>> {
   FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
@@ -410,15 +485,14 @@ struct formatter<
     return out;
   }
 };
-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* {
@@ -426,11 +500,19 @@ 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 ((c >= '0' && c <= '9') || c == '{')
+    if (it != end && ((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;
   }
 
@@ -440,113 +522,48 @@ template <> struct formatter<std::error_code> {
     auto specs = specs_;
     detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
                                 ctx);
-    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);
+    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);
   }
 };
 
 #if FMT_USE_RTTI
-namespace detail {
-
-template <typename Char, typename OutputIt>
-auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
-#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
-  int status = 0;
-  std::size_t size = 0;
-  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
-      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
-
-  string_view demangled_name_view;
-  if (demangled_name_ptr) {
-    demangled_name_view = demangled_name_ptr.get();
-
-    // Normalization of stdlib inline namespace names.
-    // libc++ inline namespaces.
-    //  std::__1::*       -> std::*
-    //  std::__1::__fs::* -> std::*
-    // libstdc++ inline namespaces.
-    //  std::__cxx11::*             -> std::*
-    //  std::filesystem::__cxx11::* -> std::filesystem::*
-    if (demangled_name_view.starts_with("std::")) {
-      char* begin = demangled_name_ptr.get();
-      char* to = begin + 5;  // std::
-      for (char *from = to, *end = begin + demangled_name_view.size();
-           from < end;) {
-        // This is safe, because demangled_name is NUL-terminated.
-        if (from[0] == '_' && from[1] == '_') {
-          char* next = from + 1;
-          while (next < end && *next != ':') next++;
-          if (next[0] == ':' && next[1] == ':') {
-            from = next + 2;
-            continue;
-          }
-        }
-        *to++ = *from++;
-      }
-      demangled_name_view = {begin, detail::to_unsigned(to - begin)};
-    }
-  } else {
-    demangled_name_view = string_view(ti.name());
-  }
-  return detail::write_bytes<Char>(out, demangled_name_view);
-#  elif FMT_MSC_VERSION
-  const string_view demangled_name(ti.name());
-  for (std::size_t i = 0; i < demangled_name.size(); ++i) {
-    auto sub = demangled_name;
-    sub.remove_prefix(i);
-    if (sub.starts_with("enum ")) {
-      i += 4;
-      continue;
-    }
-    if (sub.starts_with("class ") || sub.starts_with("union ")) {
-      i += 5;
-      continue;
-    }
-    if (sub.starts_with("struct ")) {
-      i += 6;
-      continue;
-    }
-    if (*sub.begin() != ' ') *out++ = *sub.begin();
-  }
-  return out;
-#  else
-  return detail::write_bytes<Char>(out, string_view(ti.name()));
-#  endif
-}
-
-}  // namespace detail
-
-FMT_EXPORT
-template <typename Char>
-struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
-                 > {
+template <> struct formatter<std::type_info> {
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
     return ctx.begin();
   }
 
   template <typename Context>
   auto format(const std::type_info& ti, Context& ctx) const
       -> decltype(ctx.out()) {
-    return detail::write_demangled_name<Char>(ctx.out(), ti);
+    return detail::write_demangled_name(ctx.out(), ti);
   }
 };
-#endif
+#endif  // FMT_USE_RTTI
 
-FMT_EXPORT
-template <typename T, typename Char>
+template <typename T>
 struct formatter<
-    T, Char,  // DEPRECATED! Mixing code unit types.
+    T, char,
     typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
  private:
   bool with_typename_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
     auto it = ctx.begin();
     auto end = ctx.end();
     if (it == end || *it == '}') return it;
@@ -563,47 +580,18 @@ struct formatter<
     auto out = ctx.out();
 #if FMT_USE_RTTI
     if (with_typename_) {
-      out = detail::write_demangled_name<Char>(out, typeid(ex));
+      out = detail::write_demangled_name(out, typeid(ex));
       *out++ = ':';
       *out++ = ' ';
     }
 #endif
-    return detail::write_bytes<Char>(out, string_view(ex.what()));
+    return detail::write_bytes<char>(out, string_view(ex.what()));
   }
 };
 
-namespace detail {
-
-template <typename T, typename Enable = void>
-struct has_flip : std::false_type {};
-
-template <typename T>
-struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
-    : std::true_type {};
-
-template <typename T> struct is_bit_reference_like {
-  static constexpr const bool value =
-      std::is_convertible<T, bool>::value &&
-      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
-};
-
-#ifdef _LIBCPP_VERSION
-
-// Workaround for libc++ incompatibility with C++ standard.
-// According to the Standard, `bitset::operator[] const` returns bool.
-template <typename C>
-struct is_bit_reference_like<std::__bit_const_reference<C>> {
-  static constexpr const bool value = true;
-};
-
-#endif
-
-}  // namespace detail
-
 // We can't use std::vector<bool, Allocator>::reference and
 // std::bitset<N>::reference because the compiler can't deduce Allocator and N
 // in partial specialization.
-FMT_EXPORT
 template <typename BitRef, typename Char>
 struct formatter<BitRef, Char,
                  enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
@@ -615,15 +603,6 @@ struct formatter<BitRef, Char,
   }
 };
 
-template <typename T, typename Deleter>
-auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
-  return p.get();
-}
-template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
-  return p.get();
-}
-
-FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<std::atomic<T>, Char,
                  enable_if_t<is_formattable<T, Char>::value>>
@@ -636,7 +615,6 @@ 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>
@@ -647,7 +625,6 @@ 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_;
@@ -710,10 +687,13 @@ 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>>
+                 // Guard against format_as because reference_wrapper is
+                 // implicitly convertible to T&.
+                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value &&
+                             !detail::has_format_as<T>::value &&
+                             !detail::has_format_as_member<T>::value>>
     : formatter<remove_cvref_t<T>, Char> {
   template <typename FormatContext>
   auto format(std::reference_wrapper<T> ref, FormatContext& ctx) const
@@ -723,4 +703,5 @@ struct formatter<std::reference_wrapper<T>, Char,
 };
 
 FMT_END_NAMESPACE
+
 #endif  // FMT_STD_H_

include/spdlog/fmt/bundled/xchar.h

@@ -55,6 +55,16 @@ inline auto write_loc(basic_appender<wchar_t> out, loc_value value,
 #endif
   return false;
 }
+
+template <typename Char>
+void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
+                basic_format_args<buffered_context<Char>> args,
+                locale_ref loc = {}) {
+  static_assert(!std::is_same<Char, char>::value, "");
+  auto out = basic_appender<Char>(buf);
+  parse_format_string(
+      fmt, format_handler<Char>{parse_context<Char>(fmt), {out, args, loc}});
+}
 }  // namespace detail
 
 FMT_BEGIN_EXPORT
@@ -112,14 +122,6 @@ 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
-
 template <typename... T>
 constexpr auto make_wformat_args(T&... args)
     -> decltype(fmt::make_format_args<wformat_context>(args...)) {
@@ -155,13 +157,13 @@ auto join(std::initializer_list<T> list, wstring_view sep)
 
 template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
 auto join(const Tuple& tuple, basic_string_view<wchar_t> sep)
-    -> tuple_join_view<wchar_t, Tuple> {
+    -> tuple_join_view<Tuple, wchar_t> {
   return {tuple, sep};
 }
 
 template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
 auto vformat(basic_string_view<Char> fmt,
-             typename detail::vformat_args<Char>::type args)
+             basic_format_args<buffered_context<Char>> args)
     -> std::basic_string<Char> {
   auto buf = basic_memory_buffer<Char>();
   detail::vformat_to(buf, fmt, args);
@@ -191,24 +193,20 @@ auto format(const S& fmt, T&&... args) -> std::basic_string<Char> {
                  fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
-template <typename Locale, typename S,
-          typename Char = detail::format_string_char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto vformat(const Locale& loc, const S& fmt,
-                    typename detail::vformat_args<Char>::type args)
+template <typename S, typename Char = detail::format_string_char_t<S>,
+          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+inline auto vformat(locale_ref loc, const S& fmt,
+                    basic_format_args<buffered_context<Char>> args)
     -> std::basic_string<Char> {
   auto buf = basic_memory_buffer<Char>();
-  detail::vformat_to(buf, detail::to_string_view(fmt), args,
-                     detail::locale_ref(loc));
+  detail::vformat_to(buf, detail::to_string_view(fmt), args, loc);
   return {buf.data(), buf.size()};
 }
 
-template <typename Locale, typename S, typename... T,
+template <typename S, typename... T,
           typename Char = detail::format_string_char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format(const Locale& loc, const S& fmt, T&&... args)
+          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+inline auto format(locale_ref loc, const S& fmt, T&&... args)
     -> std::basic_string<Char> {
   return vformat(loc, detail::to_string_view(fmt),
                  fmt::make_format_args<buffered_context<Char>>(args...));
@@ -219,7 +217,7 @@ template <typename OutputIt, typename S,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                             detail::is_exotic_char<Char>::value)>
 auto vformat_to(OutputIt out, const S& fmt,
-                typename detail::vformat_args<Char>::type args) -> OutputIt {
+                basic_format_args<buffered_context<Char>> args) -> OutputIt {
   auto&& buf = detail::get_buffer<Char>(out);
   detail::vformat_to(buf, detail::to_string_view(fmt), args);
   return detail::get_iterator(buf, out);
@@ -235,27 +233,24 @@ inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
                     fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
-template <typename Locale, typename S, typename OutputIt, typename... Args,
+template <typename S, typename OutputIt, typename... Args,
           typename Char = detail::format_string_char_t<S>,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_locale<Locale>::value&&
-                                detail::is_exotic_char<Char>::value)>
-inline auto vformat_to(OutputIt out, const Locale& loc, const S& fmt,
-                       typename detail::vformat_args<Char>::type args)
+                            detail::is_exotic_char<Char>::value)>
+inline auto vformat_to(OutputIt out, locale_ref loc, const S& fmt,
+                       basic_format_args<buffered_context<Char>> args)
     -> OutputIt {
   auto&& buf = detail::get_buffer<Char>(out);
-  vformat_to(buf, detail::to_string_view(fmt), args, detail::locale_ref(loc));
+  vformat_to(buf, detail::to_string_view(fmt), args, loc);
   return detail::get_iterator(buf, out);
 }
 
-template <typename Locale, typename OutputIt, typename S, typename... T,
+template <typename OutputIt, typename S, typename... T,
           typename Char = detail::format_string_char_t<S>,
           bool enable = detail::is_output_iterator<OutputIt, Char>::value &&
-                        detail::is_locale<Locale>::value &&
                         detail::is_exotic_char<Char>::value>
-inline auto format_to(OutputIt out, const Locale& loc, const S& fmt,
-                      T&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
+inline auto format_to(OutputIt out, locale_ref loc, const S& fmt, T&&... args)
+    -> typename std::enable_if<enable, OutputIt>::type {
   return vformat_to(out, loc, detail::to_string_view(fmt),
                     fmt::make_format_args<buffered_context<Char>>(args...));
 }
@@ -264,7 +259,7 @@ template <typename OutputIt, typename Char, typename... Args,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                             detail::is_exotic_char<Char>::value)>
 inline auto vformat_to_n(OutputIt out, size_t n, basic_string_view<Char> fmt,
-                         typename detail::vformat_args<Char>::type args)
+                         basic_format_args<buffered_context<Char>> args)
     -> format_to_n_result<OutputIt> {
   using traits = detail::fixed_buffer_traits;
   auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
@@ -322,7 +317,7 @@ 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(const text_style& ts, wstring_view fmt, wformat_args args)
+inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
     -> std::wstring {
   auto buf = wmemory_buffer();
   detail::vformat_to(buf, ts, fmt, args);
@@ -330,23 +325,11 @@ inline auto vformat(const text_style& ts, wstring_view fmt, wformat_args args)
 }
 
 template <typename... T>
-inline auto format(const text_style& ts, wformat_string<T...> fmt, T&&... args)
+inline auto format(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, 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(const text_style& ts, wformat_string<T...> fmt,
-                          const T&... args) {
-  return print(stdout, ts, fmt, args...);
-}
-
 inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
   auto buffer = basic_memory_buffer<wchar_t>();
   detail::vformat_to(buffer, fmt, args);

include/spdlog/fmt/fmt.h

@@ -20,11 +20,7 @@
     #ifndef FMT_USE_WINDOWS_H
         #define FMT_USE_WINDOWS_H 0
     #endif
-
-    #include <spdlog/fmt/bundled/core.h>
     #include <spdlog/fmt/bundled/format.h>
-
 #else  // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
-    #include <fmt/core.h>
     #include <fmt/format.h>
 #endif

include/spdlog/logger-inl.h

@@ -57,7 +57,7 @@ SPDLOG_INLINE void logger::swap(spdlog::logger &other) SPDLOG_NOEXCEPT {
     std::swap(tracer_, other.tracer_);
 }
 
-SPDLOG_INLINE void swap(logger &a, logger &b) { a.swap(b); }
+SPDLOG_INLINE void swap(logger &a, logger &b) noexcept { a.swap(b); }
 
 SPDLOG_INLINE void logger::set_level(level::level_enum log_level) { level_.store(log_level); }
 
@@ -163,12 +163,12 @@ SPDLOG_INLINE void logger::dump_backtrace_() {
     }
 }
 
-SPDLOG_INLINE bool logger::should_flush_(const details::log_msg &msg) {
+SPDLOG_INLINE bool logger::should_flush_(const details::log_msg &msg) const {
     auto flush_level = flush_level_.load(std::memory_order_relaxed);
     return (msg.level >= flush_level) && (msg.level != level::off);
 }
 
-SPDLOG_INLINE void logger::err_handler_(const std::string &msg) {
+SPDLOG_INLINE void logger::err_handler_(const std::string &msg) const {
     if (custom_err_handler_) {
         custom_err_handler_(msg);
     } else {

include/spdlog/logger.h

@@ -363,14 +363,14 @@ protected:
     virtual void sink_it_(const details::log_msg &msg);
     virtual void flush_();
     void dump_backtrace_();
-    bool should_flush_(const details::log_msg &msg);
+    bool should_flush_(const details::log_msg &msg) const;
 
     // handle errors during logging.
     // default handler prints the error to stderr at max rate of 1 message/sec.
-    void err_handler_(const std::string &msg);
+    void err_handler_(const std::string &msg) const;
 };
 
-void swap(logger &a, logger &b);
+void swap(logger &a, logger &b) noexcept;
 
 }  // namespace spdlog
 

include/spdlog/mdc.h

@@ -12,12 +12,14 @@
 
 #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 {

include/spdlog/sinks/ansicolor_sink-inl.h

@@ -111,7 +111,8 @@ 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_);
 }
 

include/spdlog/sinks/ansicolor_sink.h

@@ -40,7 +40,7 @@ public:
 
     void log(const details::log_msg &msg) override;
     void flush() override;
-    void set_pattern(const std::string &pattern) final override;
+    void set_pattern(const std::string &pattern) override;
     void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) override;
 
     // Formatting codes

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_;

include/spdlog/sinks/dup_filter_sink.h

@@ -40,22 +40,21 @@ 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,
-                             level::level_enum notification_level = level::info)
-        : max_skip_duration_{max_skip_duration},
-          log_level_{notification_level} {}
+    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration)
+        : max_skip_duration_{max_skip_duration} {}
 
 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 log_level_;
+    level::level_enum skipped_msg_log_level_ = spdlog::level::level_enum::off;
 
     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;
         }
 
@@ -65,7 +64,7 @@ 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, log_level_,
+                details::log_msg skipped_msg{msg.source, msg.logger_name, skipped_msg_log_level_,
                                              string_view_t{buf, static_cast<size_t>(msg_size)}};
                 dist_sink<Mutex>::sink_it_(skipped_msg);
             }

include/spdlog/sinks/ringbuffer_sink.h

@@ -21,7 +21,11 @@ template <typename Mutex>
 class ringbuffer_sink final : public base_sink<Mutex> {
 public:
     explicit ringbuffer_sink(size_t n_items)
-        : q_{n_items} {}
+        : q_{n_items} {
+        if (n_items == 0) {
+            throw_spdlog_ex("ringbuffer_sink: n_items cannot be zero");
+        }
+    }
 
     std::vector<details::log_msg_buffer> last_raw(size_t lim = 0) {
         std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);

include/spdlog/sinks/rotating_file_sink-inl.h

@@ -14,7 +14,6 @@
 #include <spdlog/fmt/fmt.h>
 
 #include <cerrno>
-#include <chrono>
 #include <ctime>
 #include <mutex>
 #include <string>
@@ -38,8 +37,8 @@ SPDLOG_INLINE rotating_file_sink<Mutex>::rotating_file_sink(
         throw_spdlog_ex("rotating sink constructor: max_size arg cannot be zero");
     }
 
-    if (max_files > 200000) {
-        throw_spdlog_ex("rotating sink constructor: max_files arg cannot exceed 200000");
+    if (max_files > MaxFiles) {
+        throw_spdlog_ex("rotating sink constructor: max_files arg cannot exceed MaxFiles");
     }
     file_helper_.open(calc_filename(base_filename_, 0));
     current_size_ = file_helper_.size();  // expensive. called only once
@@ -54,11 +53,12 @@ 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, ext;
+    filename_t basename;
+    filename_t 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);
 }
@@ -74,6 +74,35 @@ 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) {

include/spdlog/sinks/rotating_file_sink.h

@@ -8,7 +8,6 @@
 #include <spdlog/details/synchronous_factory.h>
 #include <spdlog/sinks/base_sink.h>
 
-#include <chrono>
 #include <mutex>
 #include <string>
 
@@ -21,6 +20,7 @@ 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,
@@ -29,6 +29,10 @@ 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;
@@ -42,7 +46,7 @@ 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);
 
@@ -61,25 +65,24 @@ using rotating_file_sink_st = rotating_file_sink<details::null_mutex>;
 //
 // factory functions
 //
-
 template <typename Factory = spdlog::synchronous_factory>
-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 = {}) {
+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>
-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 = {}) {
+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);
 }

include/spdlog/sinks/tcp_sink.h

@@ -31,6 +31,8 @@ namespace sinks {
 struct tcp_sink_config {
     std::string server_host;
     int server_port;
+    int timeout_ms =
+        0;  // The timeout for all 3 major socket operations that is connect, send, and recv
     bool lazy_connect = false;  // if true connect on first log call instead of on construction
 
     tcp_sink_config(std::string host, int port)
@@ -44,10 +46,22 @@ public:
     // connect to tcp host/port or throw if failed
     // host can be hostname or ip address
 
+    explicit tcp_sink(const std::string &host,
+                      int port,
+                      int timeout_ms = 0,
+                      bool lazy_connect = false)
+        : config_{host, port} {
+        config_.timeout_ms = timeout_ms;
+        config_.lazy_connect = lazy_connect;
+        if (!config_.lazy_connect) {
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
+        }
+    }
+
     explicit tcp_sink(tcp_sink_config sink_config)
         : config_{std::move(sink_config)} {
         if (!config_.lazy_connect) {
-            this->client_.connect(config_.server_host, config_.server_port);
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
         }
     }
 
@@ -58,7 +72,7 @@ protected:
         spdlog::memory_buf_t formatted;
         spdlog::sinks::base_sink<Mutex>::formatter_->format(msg, formatted);
         if (!client_.is_connected()) {
-            client_.connect(config_.server_host, config_.server_port);
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
         }
         client_.send(formatted.data(), formatted.size());
     }

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,

include/spdlog/sinks/wincolor_sink.h

@@ -31,10 +31,10 @@ public:
 
     // change the color for the given level
     void set_color(level::level_enum level, std::uint16_t color);
-    void log(const details::log_msg &msg) final override;
-    void flush() final override;
-    void set_pattern(const std::string &pattern) override final;
-    void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) override final;
+    void log(const details::log_msg &msg) override;
+    void flush() override;
+    void set_pattern(const std::string &pattern) override;
+    void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) override;
     void set_color_mode(color_mode mode);
 
 protected:

include/spdlog/spdlog-inl.h

@@ -59,6 +59,10 @@ 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);
 }

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 the
+// The logger's level, formatter and flush level will be set according to 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 name doesn't
+// Return an existing logger or nullptr if a logger with such a 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 global logging level
+// Set the 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 global flush level
+// Set a global flush level
 SPDLOG_API void flush_on(level::level_enum log_level);
 
 // Start/Restart a periodic flusher thread
@@ -91,9 +91,14 @@ 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);
 
-// Apply a user defined function on all registered loggers
+// 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
 // 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);
@@ -111,19 +116,19 @@ 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 replaced using spdlog::set_default_logger(new_logger).
+// The default logger can be 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();
 

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 }
 ///////////////////////////////////////////////////////////////////////////////
 
 ///////////////////////////////////////////////////////////////////////////////

include/spdlog/version.h

@@ -4,8 +4,8 @@
 #pragma once
 
 #define SPDLOG_VER_MAJOR 1
-#define SPDLOG_VER_MINOR 15
-#define SPDLOG_VER_PATCH 1
+#define SPDLOG_VER_MINOR 16
+#define SPDLOG_VER_PATCH 0
 
 #define SPDLOG_TO_VERSION(major, minor, patch) (major * 10000 + minor * 100 + patch)
 #define SPDLOG_VERSION SPDLOG_TO_VERSION(SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR, SPDLOG_VER_PATCH)

src/bundled_fmtlib_format.cpp

@@ -11,6 +11,12 @@
     #include <spdlog/fmt/bundled/format-inl.h>
 
 FMT_BEGIN_NAMESPACE
+
+#if FMT_USE_LOCALE
+template FMT_API locale_ref::locale_ref(const std::locale& loc);
+template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
+#endif
+
 namespace detail {
 
 template FMT_API auto dragonbox::to_decimal(float x) noexcept
@@ -18,12 +24,6 @@ template FMT_API auto dragonbox::to_decimal(float x) noexcept
 template FMT_API auto dragonbox::to_decimal(double x) noexcept
     -> dragonbox::decimal_fp<double>;
 
-#if FMT_USE_LOCALE
-// DEPRECATED! locale_ref in the detail namespace
-template FMT_API locale_ref::locale_ref(const std::locale& loc);
-template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
-#endif
-
 // Explicit instantiations for char.
 
 template FMT_API auto thousands_sep_impl(locale_ref)
@@ -33,20 +33,16 @@ template FMT_API auto decimal_point_impl(locale_ref) -> char;
 // DEPRECATED!
 template FMT_API void buffer<char>::append(const char*, const char*);
 
-// DEPRECATED!
-template FMT_API void vformat_to(buffer<char>&, string_view,
-                                 typename vformat_args<>::type, locale_ref);
-
 // Explicit instantiations for wchar_t.
 
 template FMT_API auto thousands_sep_impl(locale_ref)
     -> thousands_sep_result<wchar_t>;
 template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
 
+// DEPRECATED!
 template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);
 
 }  // namespace detail
 FMT_END_NAMESPACE
 
-
 #endif  // !SPDLOG_FMT_EXTERNAL

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()
@@ -49,7 +49,8 @@ set(SPDLOG_UTESTS_SOURCES
     test_time_point.cpp
     test_stopwatch.cpp
     test_circular_q.cpp
-    test_bin_to_hex.cpp)
+    test_bin_to_hex.cpp
+    test_ringbuffer.cpp)
 
 if(NOT SPDLOG_NO_EXCEPTIONS)
     list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
@@ -71,10 +72,10 @@ 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 ()
-    add_test(NAME ${test_target} COMMAND ${test_target})
+    endif()
+    add_test(NAME ${test_target} COMMAND ${test_target} --order decl)
     set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()
 

tests/test_custom_callbacks.cpp

@@ -16,7 +16,8 @@ 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);

tests/test_daily_logger.cpp

@@ -46,10 +46,8 @@ 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);
     }
 };
 

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);
 
@@ -94,14 +94,11 @@ 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++) {
@@ -141,3 +138,50 @@ 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);
+        }
+    }
+}

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);
 
@@ -182,17 +182,19 @@ 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() {
@@ -201,10 +203,10 @@ struct auto_closer {
 };
 
 TEST_CASE("os::fwrite_bytes", "[os]") {
-    using spdlog::details::os::fwrite_bytes;
     using spdlog::details::os::create_dir;
+    using spdlog::details::os::fwrite_bytes;
     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);
     {

tests/test_pattern_formatter.cpp

@@ -23,7 +23,9 @@ static std::string log_to_str(const std::string &msg, const Args &...args) {
 
 // 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) {
+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);
@@ -80,8 +82,8 @@ TEST_CASE("GMT offset ", "[pattern_formatter]") {
     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");
+    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]") {

tests/test_registry.cpp

@@ -25,6 +25,19 @@ 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,

tests/test_ringbuffer.cpp

@@ -0,0 +1,52 @@
+#include "includes.h"
+#include "spdlog/sinks/ringbuffer_sink.h"
+
+TEST_CASE("ringbuffer invalid size", "[ringbuffer]") {
+    REQUIRE_THROWS_AS(spdlog::sinks::ringbuffer_sink_mt(0), spdlog::spdlog_ex);
+}
+
+TEST_CASE("ringbuffer stores formatted messages", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg1"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg2"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg3"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 3);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("msg1{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("msg2{}", default_eol));
+    REQUIRE(formatted[2] == spdlog::fmt_lib::format("msg3{}", default_eol));
+}
+
+TEST_CASE("ringbuffer overrun keeps last items", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(2);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "first"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "second"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "third"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("second{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("third{}", default_eol));
+}
+
+TEST_CASE("ringbuffer retrieval limit", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "A"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "B"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "C"});
+
+    auto formatted = sink.last_formatted(2);
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("B{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("C{}", default_eol));
+}

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));
         }

tests/test_stopwatch.cpp

@@ -5,7 +5,7 @@
 TEST_CASE("stopwatch1", "[stopwatch]") {
     using std::chrono::milliseconds;
     using clock = std::chrono::steady_clock;
-    milliseconds wait_ms(200);
+    milliseconds wait_ms(500);
     milliseconds tolerance_ms(250);
     auto start = clock::now();
     spdlog::stopwatch sw;
@@ -22,7 +22,7 @@ TEST_CASE("stopwatch2", "[stopwatch]") {
     using std::chrono::milliseconds;
     using clock = std::chrono::steady_clock;
 
-    clock::duration wait_duration(milliseconds(200));
+    clock::duration wait_duration(milliseconds(500));
     clock::duration tolerance_duration(milliseconds(250));
 
     auto test_sink = std::make_shared<test_sink_st>();

tests/utils.cpp

@@ -50,9 +50,8 @@ 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 ");
+        throw std::runtime_error("Failed open file " + filename);
     }
-
     return static_cast<std::size_t>(ifs.tellg());
 }