Added const qualifiers to some ansicolor_sink functions

* Added SPDLOG_FWRITE_UNLOCKED option to CMakeLists.txt

* Update CMakeLists.txt

.github/workflows/linux.yml

@@ -1,9 +1,15 @@
-name: ci
+name: linux
 
 on: [push, pull_request]
 
+permissions:
+  contents: read
+
 jobs:
-  build_linux:
+  # -----------------------------------------------------------------------
+  # Linux build matrix
+  # -----------------------------------------------------------------------
+  build:
     runs-on: ubuntu-latest
     defaults:
       run:
@@ -16,16 +22,17 @@ jobs:
           - { compiler: gcc, version: 9, build_type: Release, cppstd: 17 }
           - { compiler: gcc, version: 11, build_type: Debug, cppstd: 20 }
           - { compiler: gcc, version: 12, build_type: Release, cppstd: 20 }
-          - { compiler: clang, version: 12, build_type: Debug, cppstd: 17, asan: OFF }
-          - { compiler: clang, version: 15, build_type: Release, cppstd: 20, asan: OFF }
+          - { compiler: gcc, version: 12, build_type: Debug, cppstd: 20, asan: ON }
+          - { compiler: clang, version: 12, build_type: Debug, cppstd: 17 }
+          - { compiler: clang, version: 15, build_type: Release, cppstd: 20, tsan: ON }
     container:
       image: ${{ matrix.config.compiler == 'clang' && 'teeks99/clang-ubuntu' || matrix.config.compiler }}:${{ matrix.config.version }}
-    name: "${{ matrix.config.compiler}} ${{ matrix.config.version }} (C++${{ matrix.config.cppstd }}, ${{ matrix.config.build_type }})"
+    name: "${{ matrix.config.compiler}} ${{ matrix.config.version }} (C++${{ matrix.config.cppstd }} ${{ matrix.config.build_type }} ${{ matrix.config.asan == 'ON' && 'ASAN' || '' }}${{ matrix.config.tsan == 'ON' && 'TSAN' || '' }})"
     steps:
-      - uses: actions/checkout@main
+      - uses: actions/checkout@v4
       - name: Setup
         run: |
-          apt-get update          
+          apt-get update
           apt-get install -y curl git pkg-config libsystemd-dev
           CMAKE_VERSION="3.24.2"
           curl -sSL https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/cmake-${CMAKE_VERSION}-linux-x86_64.sh -o install-cmake.sh
@@ -34,10 +41,8 @@ jobs:
       - name: Setup Compiler
         if: matrix.config.compiler == 'clang'
         run: |
-          if [[ "${{ matrix.config.version }}" -ge 4 ]]; then
-            scripts/ci_setup_clang.sh "${{ matrix.config.version }}"
-            echo "CXXFLAGS=-stdlib=libc++" >> $GITHUB_ENV
-          fi
+          scripts/ci_setup_clang.sh "${{ matrix.config.version }}"
+          echo "CXXFLAGS=-stdlib=libc++" >> $GITHUB_ENV          
           echo "CC=clang-${{ matrix.config.version }}" >> $GITHUB_ENV
           echo "CXX=clang++-${{ matrix.config.version }}" >> $GITHUB_ENV
       - name: Build
@@ -52,15 +57,19 @@ jobs:
             -DSPDLOG_BUILD_BENCH=OFF \
             -DSPDLOG_BUILD_TESTS=ON \
             -DSPDLOG_BUILD_TESTS_HO=OFF \
-            -DSPDLOG_SANITIZE_ADDRESS=${{ matrix.config.asan || 'ON' }}
-          make -j2
-          ctest -j2 --output-on-failure
+            -DSPDLOG_SANITIZE_ADDRESS=${{ matrix.config.asan || 'OFF' }} \
+            -DSPDLOG_SANITIZE_THREAD=${{ matrix.config.tsan || 'OFF' }}
+          make -j 4
+          ctest -j 4 --output-on-failure
 
+  # -----------------------------------------------------------------------
+  # OS X build matrix
+  # -----------------------------------------------------------------------
   build_osx:
     runs-on: macOS-latest
     name: "OS X Clang (C++11, Release)"
     steps:
-      - uses: actions/checkout@main
+      - uses: actions/checkout@v4
       - name: Build
         run: |
           mkdir -p build && cd build
@@ -74,6 +83,5 @@ jobs:
             -DSPDLOG_BUILD_TESTS=ON \
             -DSPDLOG_BUILD_TESTS_HO=OFF \
             -DSPDLOG_SANITIZE_ADDRESS=OFF
-          make -j2
-          ctest -j2 --output-on-failure
-
+          make -j 4
+          ctest -j 4 --output-on-failure

.github/workflows/macos.yml

@@ -0,0 +1,38 @@
+name: macos
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: macOS-latest
+    name: "macOS Clang (C++11, Release)"
+    strategy:
+      fail-fast: true
+      matrix:
+        config:
+            - USE_STD_FORMAT: 'ON'
+              BUILD_EXAMPLE: 'OFF'
+            - USE_STD_FORMAT: 'OFF'
+              BUILD_EXAMPLE: 'ON'
+              
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build
+        run: |
+          mkdir -p build && cd build
+          cmake .. \
+            -DCMAKE_BUILD_TYPE=Release \
+            -DCMAKE_CXX_STANDARD=11 \
+            -DSPDLOG_BUILD_EXAMPLE=${{ matrix.config.BUILD_EXAMPLE }} \
+            -DSPDLOG_BUILD_EXAMPLE_HO=${{ matrix.config.BUILD_EXAMPLE }} \
+            -DSPDLOG_BUILD_WARNINGS=ON \
+            -DSPDLOG_BUILD_BENCH=OFF \
+            -DSPDLOG_BUILD_TESTS=ON \
+            -DSPDLOG_BUILD_TESTS_HO=OFF \
+            -DSPDLOG_USE_STD_FORMAT=${{ matrix.config.USE_STD_FORMAT }} \
+            -DSPDLOG_SANITIZE_ADDRESS=OFF
+          make -j 4
+          ctest -j 4 --output-on-failure

.github/workflows/windows.yml

@@ -0,0 +1,148 @@
+name: windows
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: windows-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        config:
+          - GENERATOR: "Visual Studio 17 2022"
+            BUILD_TYPE: Release
+            BUILD_SHARED: 'ON'
+            FATAL_ERRORS: 'ON'
+            WCHAR: 'OFF'
+            WCHAR_FILES: 'OFF'
+            BUILD_EXAMPLE: 'OFF'
+            USE_STD_FORMAT: 'ON'
+            CXX_STANDARD: 20
+          - GENERATOR: "Visual Studio 17 2022"
+            BUILD_TYPE: Release
+            BUILD_SHARED: 'ON'
+            FATAL_ERRORS: 'ON'
+            WCHAR: 'ON'
+            WCHAR_FILES: 'ON'
+            BUILD_EXAMPLE: 'OFF'
+            USE_STD_FORMAT: 'ON'
+            CXX_STANDARD: 20
+          - GENERATOR: "Visual Studio 17 2022"
+            BUILD_TYPE: Release
+            BUILD_SHARED: 'ON'
+            FATAL_ERRORS: 'ON'
+            WCHAR: 'OFF'
+            WCHAR_FILES: 'OFF'
+            BUILD_EXAMPLE: 'ON'
+            USE_STD_FORMAT: 'OFF'
+            CXX_STANDARD: 17
+
+    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
+
+  # -----------------------------------------------------------------------
+  # 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

@@ -18,43 +18,39 @@ include(GNUInstallDirs)
 # ---------------------------------------------------------------------------------------
 # Set default build to release
 # ---------------------------------------------------------------------------------------
-if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
     set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
-endif()
+endif ()
 
 # ---------------------------------------------------------------------------------------
 # Compiler config
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_USE_STD_FORMAT)
+if (SPDLOG_USE_STD_FORMAT)
     set(CMAKE_CXX_STANDARD 20)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
-elseif(NOT CMAKE_CXX_STANDARD)
+elseif (NOT CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 11)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
-endif()
+endif ()
 
-# make sure __cplusplus is defined when using msvc and enable parallel build
-if(MSVC)
-    string(APPEND CMAKE_CXX_FLAGS " /Zc:__cplusplus /MP")
-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)
 
@@ -80,6 +76,10 @@ 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)
+    message(FATAL_ERROR "SPDLOG_SANITIZE_ADDRESS and SPDLOG_SANITIZE_THREAD are mutually exclusive")
+endif ()
 
 # warning options
 option(SPDLOG_BUILD_WARNINGS "Enable compiler warnings" OFF)
@@ -92,54 +92,61 @@ option(SPDLOG_FMT_EXTERNAL "Use external fmt library instead of bundled" OFF)
 option(SPDLOG_FMT_EXTERNAL_HO "Use external fmt header-only library instead of bundled" OFF)
 option(SPDLOG_NO_EXCEPTIONS "Compile with -fno-exceptions. Call abort() on any spdlog exceptions" OFF)
 
-if(SPDLOG_FMT_EXTERNAL AND SPDLOG_FMT_EXTERNAL_HO)
+if (SPDLOG_FMT_EXTERNAL AND SPDLOG_FMT_EXTERNAL_HO)
     message(FATAL_ERROR "SPDLOG_FMT_EXTERNAL and SPDLOG_FMT_EXTERNAL_HO are mutually exclusive")
-endif()
+endif ()
 
-if(SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL_HO)
+if (SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL_HO)
     message(FATAL_ERROR "SPDLOG_USE_STD_FORMAT and SPDLOG_FMT_EXTERNAL_HO are mutually exclusive")
-endif()
+endif ()
 
-if(SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL)
+if (SPDLOG_USE_STD_FORMAT AND SPDLOG_FMT_EXTERNAL)
     message(FATAL_ERROR "SPDLOG_USE_STD_FORMAT and SPDLOG_FMT_EXTERNAL are mutually exclusive")
-endif()
+endif ()
 
 # misc tweakme options
-if(WIN32)
+if (WIN32)
     option(SPDLOG_WCHAR_SUPPORT "Support wchar api" OFF)
     option(SPDLOG_WCHAR_FILENAMES "Support wchar filenames" OFF)
-else()
+    option(SPDLOG_WCHAR_CONSOLE "Support wchar output to console" OFF)
+else ()
     set(SPDLOG_WCHAR_SUPPORT OFF CACHE BOOL "non supported option" FORCE)
     set(SPDLOG_WCHAR_FILENAMES OFF CACHE BOOL "non supported option" FORCE)
-endif()
+    set(SPDLOG_WCHAR_CONSOLE OFF CACHE BOOL "non supported option" FORCE)
+endif ()
 
-if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+if (MSVC)
+    option(SPDLOG_MSVC_UTF8 "Enable/disable msvc /utf-8 flag required by fmt lib" ON)
+endif ()
+
+if (${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})
@@ -148,49 +155,56 @@ message(STATUS "Build type: " ${CMAKE_BUILD_TYPE})
 # ---------------------------------------------------------------------------------------
 set(SPDLOG_SRCS src/spdlog.cpp src/stdout_sinks.cpp src/color_sinks.cpp src/file_sinks.cpp src/async.cpp src/cfg.cpp)
 
-if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
     list(APPEND SPDLOG_SRCS src/bundled_fmtlib_format.cpp)
-endif()
+endif ()
 
-if(SPDLOG_BUILD_SHARED OR BUILD_SHARED_LIBS)
-    if(WIN32)
+if (SPDLOG_BUILD_SHARED OR BUILD_SHARED_LIBS)
+    if (WIN32)
         configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/version.rc.in ${CMAKE_CURRENT_BINARY_DIR}/version.rc @ONLY)
         list(APPEND SPDLOG_SRCS ${CMAKE_CURRENT_BINARY_DIR}/version.rc)
-    endif()
+    endif ()
     add_library(spdlog SHARED ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
     target_compile_definitions(spdlog PUBLIC SPDLOG_SHARED_LIB)
-    if(MSVC)
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
         target_compile_options(spdlog PUBLIC $<$<AND:$<CXX_COMPILER_ID:MSVC>,$<NOT:$<COMPILE_LANGUAGE:CUDA>>>:/wd4251
-                                             /wd4275>)
-    endif()
-    if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+                /wd4275>)
+    endif ()
+    if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
         target_compile_definitions(spdlog PRIVATE FMT_LIB_EXPORT PUBLIC FMT_SHARED)
-    endif()
-else()
+    endif ()
+else ()
     add_library(spdlog STATIC ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
-endif()
+endif ()
 
 add_library(spdlog::spdlog ALIAS spdlog)
 
 set(SPDLOG_INCLUDES_LEVEL "")
-if(SPDLOG_SYSTEM_INCLUDES)
+if (SPDLOG_SYSTEM_INCLUDES)
     set(SPDLOG_INCLUDES_LEVEL "SYSTEM")
-endif()
+endif ()
 
 target_compile_definitions(spdlog PUBLIC SPDLOG_COMPILED_LIB)
 target_include_directories(spdlog ${SPDLOG_INCLUDES_LEVEL} PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
-                                                                  "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
+        "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
 target_link_libraries(spdlog PUBLIC Threads::Threads)
 spdlog_enable_warnings(spdlog)
 
 set_target_properties(spdlog PROPERTIES VERSION ${SPDLOG_VERSION} SOVERSION
-                                                                  ${SPDLOG_VERSION_MAJOR}.${SPDLOG_VERSION_MINOR})
+        ${SPDLOG_VERSION_MAJOR}.${SPDLOG_VERSION_MINOR})
 set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX d)
 
-if(COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
+if (COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
     configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/pch.h.in ${PROJECT_BINARY_DIR}/spdlog_pch.h @ONLY)
     target_precompile_headers(spdlog PRIVATE ${PROJECT_BINARY_DIR}/spdlog_pch.h)
-endif()
+endif ()
+
+# sanitizer support
+if (SPDLOG_SANITIZE_ADDRESS)
+    spdlog_enable_addr_sanitizer(spdlog)
+elseif (SPDLOG_SANITIZE_THREAD)
+    spdlog_enable_thread_sanitizer(spdlog)
+endif ()
 
 # ---------------------------------------------------------------------------------------
 # Header only version
@@ -199,102 +213,132 @@ add_library(spdlog_header_only INTERFACE)
 add_library(spdlog::spdlog_header_only ALIAS spdlog_header_only)
 
 target_include_directories(
-    spdlog_header_only ${SPDLOG_INCLUDES_LEVEL} INTERFACE "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
-                                                          "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
+        spdlog_header_only ${SPDLOG_INCLUDES_LEVEL} INTERFACE "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+        "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
 target_link_libraries(spdlog_header_only INTERFACE Threads::Threads)
 
 # ---------------------------------------------------------------------------------------
 # Use fmt package if using external fmt
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_FMT_EXTERNAL OR SPDLOG_FMT_EXTERNAL_HO)
-    if(NOT TARGET fmt::fmt)
+if (SPDLOG_FMT_EXTERNAL OR SPDLOG_FMT_EXTERNAL_HO)
+    if (NOT TARGET fmt::fmt)
         find_package(fmt CONFIG REQUIRED)
-    endif()
+    endif ()
     target_compile_definitions(spdlog PUBLIC SPDLOG_FMT_EXTERNAL)
     target_compile_definitions(spdlog_header_only INTERFACE SPDLOG_FMT_EXTERNAL)
 
-    # use external fmt-header-nly
-    if(SPDLOG_FMT_EXTERNAL_HO)
+    # use external fmt-header-only
+    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)
+    include(CheckSymbolExists)
+    if (WIN32)
+        check_symbol_exists(_fwrite_nolock "stdio.h" HAVE_FWRITE_UNLOCKED)
+    else ()
+        check_symbol_exists(fwrite_unlocked "stdio.h" 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 ()
 
 # ---------------------------------------------------------------------------------------
 # 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 ${SPDLOG_WCHAR_SUPPORT})
-foreach(
-    SPDLOG_OPTION
-    SPDLOG_WCHAR_TO_UTF8_SUPPORT
-    SPDLOG_WCHAR_FILENAMES
-    SPDLOG_NO_EXCEPTIONS
-    SPDLOG_CLOCK_COARSE
-    SPDLOG_PREVENT_CHILD_FD
-    SPDLOG_NO_THREAD_ID
-    SPDLOG_NO_TLS
-    SPDLOG_NO_ATOMIC_LEVELS
-    SPDLOG_DISABLE_DEFAULT_LOGGER
-    SPDLOG_USE_STD_FORMAT)
-    if(${SPDLOG_OPTION})
+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})
         target_compile_definitions(spdlog PUBLIC ${SPDLOG_OPTION})
         target_compile_definitions(spdlog_header_only INTERFACE ${SPDLOG_OPTION})
-    endif()
-endforeach()
+    endif ()
+endforeach ()
+
+if (MSVC)
+    target_compile_options(spdlog PRIVATE "/Zc:__cplusplus")
+    target_compile_options(spdlog_header_only INTERFACE "/Zc:__cplusplus")
+    if (SPDLOG_MSVC_UTF8)
+        # fmtlib requires the /utf-8 flag when building with msvc.
+        # see https://github.com/fmtlib/fmt/pull/4159 on the purpose of the additional
+        # "$<$<AND:$<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 ()
 
 # ---------------------------------------------------------------------------------------
 # 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)
+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)
+    endif ()
+    if (NOT MSVC)
         target_compile_options(spdlog PRIVATE -fno-exceptions)
-    else()
+    else ()
         target_compile_options(spdlog PRIVATE /EHs-c-)
-    endif()
-endif()
+    endif ()
+endif ()
 # ---------------------------------------------------------------------------------------
 # Build binaries
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_BUILD_EXAMPLE OR SPDLOG_BUILD_EXAMPLE_HO OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_EXAMPLE OR SPDLOG_BUILD_EXAMPLE_HO OR SPDLOG_BUILD_ALL)
     message(STATUS "Generating example(s)")
     add_subdirectory(example)
     spdlog_enable_warnings(example)
-    if(SPDLOG_BUILD_EXAMPLE_HO)
+    if (SPDLOG_BUILD_EXAMPLE_HO)
         spdlog_enable_warnings(example_header_only)
-    endif()
-endif()
+    endif ()
+endif ()
 
-if(SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
     message(STATUS "Generating tests")
     enable_testing()
     add_subdirectory(tests)
-endif()
+endif ()
 
-if(SPDLOG_BUILD_BENCH OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_BENCH OR SPDLOG_BUILD_ALL)
     message(STATUS "Generating benchmarks")
     add_subdirectory(bench)
-endif()
+endif ()
 
 # ---------------------------------------------------------------------------------------
 # Install
 # ---------------------------------------------------------------------------------------
-if(SPDLOG_INSTALL)
+if (SPDLOG_INSTALL)
     message(STATUS "Generating install")
     set(project_config_in "${CMAKE_CURRENT_LIST_DIR}/cmake/spdlogConfig.cmake.in")
     set(project_config_out "${CMAKE_CURRENT_BINARY_DIR}/spdlogConfig.cmake")
@@ -309,30 +353,30 @@ if(SPDLOG_INSTALL)
     # ---------------------------------------------------------------------------------------
     install(DIRECTORY include/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}" PATTERN "fmt/bundled" EXCLUDE)
     install(
-        TARGETS spdlog spdlog_header_only
-        EXPORT spdlog
-        LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+            TARGETS spdlog spdlog_header_only
+            EXPORT spdlog
+            LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 
-    if(NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+    if (NOT SPDLOG_USE_STD_FORMAT AND NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
         install(DIRECTORY include/${PROJECT_NAME}/fmt/bundled/
                 DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}/fmt/bundled/")
-    endif()
+    endif ()
 
     # ---------------------------------------------------------------------------------------
     # Install pkg-config file
     # ---------------------------------------------------------------------------------------
-    if(IS_ABSOLUTE "${CMAKE_INSTALL_INCLUDEDIR}")
+    if (IS_ABSOLUTE "${CMAKE_INSTALL_INCLUDEDIR}")
         set(PKG_CONFIG_INCLUDEDIR "${CMAKE_INSTALL_INCLUDEDIR}")
-    else()
+    else ()
         set(PKG_CONFIG_INCLUDEDIR "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
-    endif()
-    if(IS_ABSOLUTE "${CMAKE_INSTALL_LIBDIR}")
+    endif ()
+    if (IS_ABSOLUTE "${CMAKE_INSTALL_LIBDIR}")
         set(PKG_CONFIG_LIBDIR "${CMAKE_INSTALL_LIBDIR}")
-    else()
+    else ()
         set(PKG_CONFIG_LIBDIR "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
-    endif()
+    endif ()
     get_target_property(PKG_CONFIG_DEFINES spdlog INTERFACE_COMPILE_DEFINITIONS)
     string(REPLACE ";" " -D" PKG_CONFIG_DEFINES "${PKG_CONFIG_DEFINES}")
     string(CONCAT PKG_CONFIG_DEFINES "-D" "${PKG_CONFIG_DEFINES}")
@@ -343,7 +387,7 @@ if(SPDLOG_INSTALL)
     # Install CMake config files
     # ---------------------------------------------------------------------------------------
     export(TARGETS spdlog spdlog_header_only NAMESPACE spdlog::
-           FILE "${CMAKE_CURRENT_BINARY_DIR}/${config_targets_file}")
+            FILE "${CMAKE_CURRENT_BINARY_DIR}/${config_targets_file}")
     install(EXPORT spdlog DESTINATION ${export_dest_dir} NAMESPACE spdlog:: FILE ${config_targets_file})
 
     include(CMakePackageConfigHelpers)
@@ -356,4 +400,4 @@ if(SPDLOG_INSTALL)
     # Support creation of installable packages
     # ---------------------------------------------------------------------------------------
     include(cmake/spdlogCPack.cmake)
-endif()
+endif ()

README.md

@@ -1,6 +1,13 @@
 # spdlog
 
-Very fast, header-only/compiled, C++ logging library. [![ci](https://github.com/gabime/spdlog/actions/workflows/ci.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/ci.yml)  [![Build status](https://ci.appveyor.com/api/projects/status/d2jnxclg20vd0o50?svg=true&branch=v1.x)](https://ci.appveyor.com/project/gabime/spdlog) [![Release](https://img.shields.io/github/release/gabime/spdlog.svg)](https://github.com/gabime/spdlog/releases/latest)
+ 
+[![ci](https://github.com/gabime/spdlog/actions/workflows/linux.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/linux.yml) 
+[![ci](https://github.com/gabime/spdlog/actions/workflows/windows.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/windows.yml) 
+[![ci](https://github.com/gabime/spdlog/actions/workflows/macos.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/macos.yml) 
+[![Build status](https://ci.appveyor.com/api/projects/status/d2jnxclg20vd0o50?svg=true&branch=v1.x)](https://ci.appveyor.com/project/gabime/spdlog) [![Release](https://img.shields.io/github/release/gabime/spdlog.svg)](https://github.com/gabime/spdlog/releases/latest)
+
+Fast C++ logging library
+
 
 ## Install
 #### Header-only version
@@ -10,7 +17,7 @@ Copy the include [folder](https://github.com/gabime/spdlog/tree/v1.x/include/spd
 ```console
 $ git clone https://github.com/gabime/spdlog.git
 $ cd spdlog && mkdir build && cd build
-$ cmake .. && make -j
+$ cmake .. && cmake --build .
 ```
 see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/CMakeLists.txt) on how to use.
 
@@ -30,7 +37,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
 * Arch Linux: `pacman -S spdlog`
 * openSUSE: `sudo zypper in spdlog-devel`
 * vcpkg: `vcpkg install spdlog`
-* conan: `spdlog/[>=1.4.1]`
+* conan: `conan install --requires=spdlog/[*]`
 * conda: `conda install -c conda-forge spdlog`
 * build2: ```depends: spdlog ^1.8.2```
 
@@ -296,7 +303,7 @@ struct fmt::formatter<my_type> : fmt::formatter<std::string>
 {
     auto format(my_type my, format_context &ctx) const -> decltype(ctx.out())
     {
-        return format_to(ctx.out(), "[my_type i={}]", my.i);
+        return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
     }
 };
 
@@ -437,7 +444,22 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
     logger->info("Some info message");
 }
 ```
+---
 
+#### Mapped Diagnostic Context
+```c++
+// 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.
+#include "spdlog/mdc.h"
+void mdc_example()
+{
+    spdlog::mdc::put("key1", "value1");
+    spdlog::mdc::put("key2", "value2");
+    // if not using the default format, use the %& formatter to print mdc data
+    // spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
+}
+```
 ---
 ## Benchmarks
 

bench/async_bench.cpp

@@ -160,7 +160,7 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> logger, int thread_co
 
     for (auto &t : threads) {
         t.join();
-    };
+    }
 
     auto delta = high_resolution_clock::now() - start;
     auto delta_d = duration_cast<duration<double>>(delta).count();

bench/bench.cpp

@@ -181,7 +181,7 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> log, size_t thread_co
 
     for (auto &t : threads) {
         t.join();
-    };
+    }
 
     auto delta = high_resolution_clock::now() - start;
     auto delta_d = duration_cast<duration<double>>(delta).count();
@@ -243,4 +243,4 @@ odio. Maecenas malesuada quam ex, posuere congue nibh turpis duis.";
 delta_d));
 }
 
-*/
+*/

cmake/utils.cmake

@@ -49,7 +49,7 @@ function(spdlog_enable_warnings target_name)
 endfunction()
 
 # Enable address sanitizer (gcc/clang only)
-function(spdlog_enable_sanitizer target_name)
+function(spdlog_enable_addr_sanitizer target_name)
     if(NOT CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
         message(FATAL_ERROR "Sanitizer supported only for gcc/clang")
     endif()
@@ -58,5 +58,16 @@ function(spdlog_enable_sanitizer target_name)
     target_compile_options(${target_name} PRIVATE -fno-sanitize=signed-integer-overflow)
     target_compile_options(${target_name} PRIVATE -fno-sanitize-recover=all)
     target_compile_options(${target_name} PRIVATE -fno-omit-frame-pointer)
-    target_link_libraries(${target_name} PRIVATE -fsanitize=address,undefined -fuse-ld=gold)
+    target_link_libraries(${target_name} PRIVATE -fsanitize=address,undefined)
+endfunction()
+
+# Enable thread sanitizer (gcc/clang only)
+function(spdlog_enable_thread_sanitizer target_name)
+    if(NOT CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+        message(FATAL_ERROR "Sanitizer supported only for gcc/clang")
+    endif()
+    message(STATUS "Thread sanitizer enabled")
+    target_compile_options(${target_name} PRIVATE -fsanitize=thread)
+    target_compile_options(${target_name} PRIVATE -fno-omit-frame-pointer)
+    target_link_libraries(${target_name} PRIVATE -fsanitize=thread)
 endfunction()

example/example.cpp

@@ -26,6 +26,7 @@ void udp_example();
 void custom_flags_example();
 void file_events_example();
 void replace_default_logger_example();
+void mdc_example();
 
 #include "spdlog/spdlog.h"
 #include "spdlog/cfg/env.h"   // support for loading levels from the environment variable
@@ -84,6 +85,7 @@ int main(int, char *[]) {
         custom_flags_example();
         file_events_example();
         replace_default_logger_example();
+        mdc_example();
 
         // Flush all *registered* loggers using a worker thread every 3 seconds.
         // note: registered loggers *must* be thread safe for this to work correctly!
@@ -264,13 +266,13 @@ 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
 template <>
 struct fmt::formatter<my_type> : fmt::formatter<std::string> {
-    auto format(my_type my, format_context &ctx) -> decltype(ctx.out()) {
+    auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
         return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
     }
 };
@@ -279,7 +281,7 @@ struct fmt::formatter<my_type> : fmt::formatter<std::string> {
 template <>
 struct std::formatter<my_type> : std::formatter<std::string> {
     auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
-        return format_to(ctx.out(), "[my_type i={}]", my.i);
+        return std::format_to(ctx.out(), "[my_type i={}]", my.i);
     }
 };
 #endif
@@ -376,3 +378,23 @@ void replace_default_logger_example() {
 
     spdlog::set_default_logger(old_logger);
 }
+
+// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
+// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
+// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
+
+#ifndef SPDLOG_NO_TLS
+    #include "spdlog/mdc.h"
+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
+    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
+    spdlog::info("Some log message with context");
+}
+#else
+void mdc_example() {
+    // if TLS feature is disabled
+}
+#endif

include/spdlog/async_logger-inl.h

@@ -43,15 +43,13 @@ SPDLOG_LOGGER_CATCH(msg.source)
 }
 
 // send flush request to the thread pool
-SPDLOG_INLINE void spdlog::async_logger::flush_(){SPDLOG_TRY{auto pool_ptr = thread_pool_.lock();
-if (!pool_ptr) {
+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_);
+}
+else {
     throw_spdlog_ex("async flush: thread pool doesn't exist anymore");
 }
-
-std::future<void> future = pool_ptr->post_flush(shared_from_this(), overflow_policy_);
-// Wait for the flush operation to complete.
-// This might throw exception if the flush message get dropped because of overflow.
-future.get();
 }
 SPDLOG_LOGGER_CATCH(source_loc())
 }

include/spdlog/common.h

@@ -81,7 +81,7 @@
     #if FMT_USE_CONSTEXPR
         #define SPDLOG_CONSTEXPR_FUNC FMT_CONSTEXPR
     #else
-	#define SPDLOG_CONSTEXPR_FUNC inline
+        #define SPDLOG_CONSTEXPR_FUNC inline
     #endif
 #endif
 
@@ -364,12 +364,7 @@ SPDLOG_CONSTEXPR_FUNC spdlog::wstring_view_t to_string_view(spdlog::wstring_view
 }
 #endif
 
-#ifndef SPDLOG_USE_STD_FORMAT
-template <typename T, typename... Args>
-inline fmt::basic_string_view<T> to_string_view(fmt::basic_format_string<T, Args...> fmt) {
-    return fmt;
-}
-#elif __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

@@ -98,10 +98,11 @@ SPDLOG_INLINE void file_helper::close() {
 }
 
 SPDLOG_INLINE void file_helper::write(const memory_buf_t &buf) {
-    if(fd_ == nullptr) return;
+    if (fd_ == nullptr) return;
     size_t msg_size = buf.size();
     auto data = buf.data();
-    if (std::fwrite(data, 1, msg_size, fd_) != msg_size) {
+
+    if (!details::os::fwrite_bytes(data, msg_size, fd_)) {
         throw_spdlog_ex("Failed writing to file " + os::filename_to_str(filename_), errno);
     }
 }

include/spdlog/details/mpmc_blocking_q.h

@@ -148,19 +148,19 @@ public:
 #endif
 
     size_t overrun_counter() {
-        std::unique_lock<std::mutex> lock(queue_mutex_);
+        std::lock_guard<std::mutex> lock(queue_mutex_);
         return q_.overrun_counter();
     }
 
     size_t discard_counter() { return discard_counter_.load(std::memory_order_relaxed); }
 
     size_t size() {
-        std::unique_lock<std::mutex> lock(queue_mutex_);
+        std::lock_guard<std::mutex> lock(queue_mutex_);
         return q_.size();
     }
 
     void reset_overrun_counter() {
-        std::unique_lock<std::mutex> lock(queue_mutex_);
+        std::lock_guard<std::mutex> lock(queue_mutex_);
         q_.reset_overrun_counter();
     }
 

include/spdlog/details/os-inl.h

@@ -483,12 +483,12 @@ 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, MB_ERR_INVALID_CHARS, str.data(), str_size, NULL, 0);
+        ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, NULL, 0);
 
     if (result_size > 0) {
         target.resize(result_size);
-        result_size = ::MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, 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;
@@ -534,6 +534,15 @@ SPDLOG_INLINE bool create_dir(const filename_t &path) {
         }
 
         auto subdir = path.substr(0, token_pos);
+#ifdef _WIN32
+        // if subdir is just a drive letter, add a slash e.g. "c:"=>"c:\",
+        // otherwise path_exists(subdir) returns false (issue #3079)
+        const bool is_drive = subdir.length() == 2 && subdir[1] == ':';
+        if (is_drive) {
+            subdir += '\\';
+            token_pos++;
+        }
+#endif
 
         if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir)) {
             return false;  // return error if failed creating dir
@@ -580,6 +589,18 @@ SPDLOG_INLINE bool fsync(FILE *fp) {
 #endif
 }
 
+// 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)
+    return _fwrite_nolock(ptr, 1, n_bytes, fp) == n_bytes;
+    #elif defined(SPDLOG_FWRITE_UNLOCKED)
+    return ::fwrite_unlocked(ptr, 1, n_bytes, fp) == n_bytes;
+    #else
+    return std::fwrite(ptr, 1, n_bytes, fp) == n_bytes;
+    #endif
+}
+
 }  // namespace os
 }  // namespace details
 }  // namespace spdlog

include/spdlog/details/os.h

@@ -114,6 +114,10 @@ SPDLOG_API std::string getenv(const char *field);
 // Return true on success.
 SPDLOG_API bool fsync(FILE *fp);
 
+// Do non-locking fwrite if possible by the os or use the regular locking fwrite
+// Return true on success.
+SPDLOG_API bool fwrite_bytes(const void *ptr, const size_t n_bytes, FILE *fp);
+
 }  // namespace os
 }  // namespace details
 }  // namespace spdlog

include/spdlog/details/registry-inl.h

@@ -84,31 +84,6 @@ SPDLOG_INLINE std::shared_ptr<logger> registry::get(const std::string &logger_na
     return found == loggers_.end() ? nullptr : found->second;
 }
 
-#if __cplusplus >= 201703L  // C++17
-// if the map is small do a sequential search and avoid creating string for find(logger_name)
-// otherwise use the standard find()
-SPDLOG_INLINE std::shared_ptr<logger> registry::get(std::string_view logger_name) {
-    std::lock_guard<std::mutex> lock(logger_map_mutex_);
-    if (loggers_.size() <= 10) {
-        for (const auto &[key, val]: loggers_) {
-            if (logger_name == key) {
-                return val;
-            }
-        }
-        return nullptr;
-    }
-    // otherwise use the normal map lookup
-    else {
-        auto found = loggers_.find(std::string(logger_name));
-        return found == loggers_.end() ? nullptr : found->second;
-    }
-}
-
-SPDLOG_INLINE std::shared_ptr<logger> registry::get(const char *logger_name) {
-    return get(std::string_view(logger_name));
-}
-#endif
-
 SPDLOG_INLINE std::shared_ptr<logger> registry::default_logger() {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);
     return default_logger_;
@@ -123,7 +98,7 @@ 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.
 SPDLOG_INLINE void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
-    std::lock_guard<std::mutex> lock(logger_map_mutex_);    
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
     if (new_default_logger != nullptr) {
         loggers_[new_default_logger->name()] = new_default_logger;
     }

include/spdlog/details/registry.h

@@ -18,10 +18,6 @@
 #include <string>
 #include <unordered_map>
 
-#if __cplusplus >= 201703L  // C++17
-    #include <string_view>
-#endif
-
 namespace spdlog {
 class logger;
 
@@ -37,10 +33,6 @@ public:
     void register_logger(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);
-#if __cplusplus >= 201703L  // C++17
-    std::shared_ptr<logger> get(std::string_view logger_name);
-    std::shared_ptr<logger> get(const char *logger_name);
-#endif
     std::shared_ptr<logger> default_logger();
 
     // Return raw ptr to the default logger.
@@ -52,7 +44,8 @@ public:
 
     // set default logger and add it to the registry if not registered already.
     // default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
-    // Note: Make sure to unregister it when no longer needed or before calling again with a new logger.
+    // Note: Make sure to unregister it when no longer needed or before calling again with a new
+    // logger.
     void set_default_logger(std::shared_ptr<logger> new_default_logger);
 
     void set_tp(std::shared_ptr<thread_pool> tp);
@@ -78,8 +71,8 @@ public:
     }
 
     std::unique_ptr<periodic_worker> &get_flusher() {
-        std::lock_guard<std::mutex> lock(flusher_mutex_); 
-        return periodic_flusher_; 
+        std::lock_guard<std::mutex> lock(flusher_mutex_);
+        return periodic_flusher_;
     }
 
     void set_error_handler(err_handler handler);

include/spdlog/details/thread_pool-inl.h

@@ -62,13 +62,9 @@ void SPDLOG_INLINE thread_pool::post_log(async_logger_ptr &&worker_ptr,
     post_async_msg_(std::move(async_m), overflow_policy);
 }
 
-std::future<void> SPDLOG_INLINE thread_pool::post_flush(async_logger_ptr &&worker_ptr,
-                                                        async_overflow_policy overflow_policy) {
-    std::promise<void> promise;
-    std::future<void> future = promise.get_future();
-    post_async_msg_(async_msg(std::move(worker_ptr), async_msg_type::flush, std::move(promise)),
-                    overflow_policy);
-    return future;
+void SPDLOG_INLINE thread_pool::post_flush(async_logger_ptr &&worker_ptr,
+                                           async_overflow_policy overflow_policy) {
+    post_async_msg_(async_msg(std::move(worker_ptr), async_msg_type::flush), overflow_policy);
 }
 
 size_t SPDLOG_INLINE thread_pool::overrun_counter() { return q_.overrun_counter(); }
@@ -112,7 +108,6 @@ bool SPDLOG_INLINE thread_pool::process_next_msg_() {
         }
         case async_msg_type::flush: {
             incoming_async_msg.worker_ptr->backend_flush_();
-            incoming_async_msg.flush_promise.set_value();
             return true;
         }
 

include/spdlog/details/thread_pool.h

@@ -9,7 +9,6 @@
 
 #include <chrono>
 #include <functional>
-#include <future>
 #include <memory>
 #include <thread>
 #include <vector>
@@ -28,7 +27,6 @@ enum class async_msg_type { log, flush, terminate };
 struct async_msg : log_msg_buffer {
     async_msg_type msg_type{async_msg_type::log};
     async_logger_ptr worker_ptr;
-    std::promise<void> flush_promise;
 
     async_msg() = default;
     ~async_msg() = default;
@@ -58,22 +56,12 @@ struct async_msg : log_msg_buffer {
     async_msg(async_logger_ptr &&worker, async_msg_type the_type, const details::log_msg &m)
         : log_msg_buffer{m},
           msg_type{the_type},
-          worker_ptr{std::move(worker)},
-          flush_promise{} {}
+          worker_ptr{std::move(worker)} {}
 
     async_msg(async_logger_ptr &&worker, async_msg_type the_type)
         : log_msg_buffer{},
           msg_type{the_type},
-          worker_ptr{std::move(worker)},
-          flush_promise{} {}
-
-    async_msg(async_logger_ptr &&worker,
-              async_msg_type the_type,
-              std::promise<void> &&promise)
-        : log_msg_buffer{},
-          msg_type{the_type},
-          worker_ptr{std::move(worker)},
-          flush_promise{std::move(promise)} {}
+          worker_ptr{std::move(worker)} {}
 
     explicit async_msg(async_msg_type the_type)
         : async_msg{nullptr, the_type} {}
@@ -100,8 +88,7 @@ public:
     void post_log(async_logger_ptr &&worker_ptr,
                   const details::log_msg &msg,
                   async_overflow_policy overflow_policy);
-    std::future<void> post_flush(async_logger_ptr &&worker_ptr,
-                                 async_overflow_policy overflow_policy);
+    void post_flush(async_logger_ptr &&worker_ptr, async_overflow_policy overflow_policy);
     size_t overrun_counter();
     void reset_overrun_counter();
     size_t discard_counter();

include/spdlog/fmt/bin_to_hex.h

@@ -102,7 +102,7 @@ namespace
 
 template <typename T>
 struct formatter<spdlog::details::dump_info<T>, char> {
-    const char delimiter = ' ';
+    char delimiter = ' ';
     bool put_newlines = true;
     bool put_delimiters = true;
     bool use_uppercase = false;

include/spdlog/fmt/bundled/args.h

@@ -8,11 +8,13 @@
 #ifndef FMT_ARGS_H_
 #define FMT_ARGS_H_
 
-#include <functional>  // std::reference_wrapper
-#include <memory>      // std::unique_ptr
-#include <vector>
+#ifndef FMT_MODULE
+#  include <functional>  // std::reference_wrapper
+#  include <memory>      // std::unique_ptr
+#  include <vector>
+#endif
 
-#include "core.h"
+#include "format.h"  // std_string_view
 
 FMT_BEGIN_NAMESPACE
 
@@ -28,15 +30,18 @@ auto unwrap(const std::reference_wrapper<T>& v) -> const T& {
   return static_cast<const T&>(v);
 }
 
-class dynamic_arg_list {
-  // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
-  // templates it doesn't complain about inability to deduce single translation
-  // unit for placing vtable. So storage_node_base is made a fake template.
-  template <typename = void> struct node {
-    virtual ~node() = default;
-    std::unique_ptr<node<>> next;
-  };
+// node is defined outside dynamic_arg_list to workaround a C2504 bug in MSVC
+// 2022 (v17.10.0).
+//
+// Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
+// templates it doesn't complain about inability to deduce single translation
+// unit for placing vtable. So node is made a fake template.
+template <typename = void> struct node {
+  virtual ~node() = default;
+  std::unique_ptr<node<>> next;
+};
 
+class dynamic_arg_list {
   template <typename T> struct typed_node : node<> {
     T value;
 
@@ -62,14 +67,10 @@ class dynamic_arg_list {
 }  // namespace detail
 
 /**
-  \rst
-  A dynamic version of `fmt::format_arg_store`.
-  It's equipped with a storage to potentially temporary objects which lifetimes
-  could be shorter than the format arguments object.
-
-  It can be implicitly converted into `~fmt::basic_format_args` for passing
-  into type-erased formatting functions such as `~fmt::vformat`.
-  \endrst
+ * A dynamic list of formatting arguments with storage.
+ *
+ * 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
@@ -147,22 +148,20 @@ class dynamic_format_arg_store
   constexpr dynamic_format_arg_store() = default;
 
   /**
-    \rst
-    Adds an argument into the dynamic store for later passing to a formatting
-    function.
-
-    Note that custom types and string types (but not string views) are copied
-    into the store dynamically allocating memory if necessary.
-
-    **Example**::
-
-      fmt::dynamic_format_arg_store<fmt::format_context> store;
-      store.push_back(42);
-      store.push_back("abc");
-      store.push_back(1.5f);
-      std::string result = fmt::vformat("{} and {} and {}", store);
-    \endrst
-  */
+   * Adds an argument into the dynamic store for later passing to a formatting
+   * function.
+   *
+   * Note that custom types and string types (but not string views) are copied
+   * into the store dynamically allocating memory if necessary.
+   *
+   * **Example**:
+   *
+   *     fmt::dynamic_format_arg_store<fmt::format_context> store;
+   *     store.push_back(42);
+   *     store.push_back("abc");
+   *     store.push_back(1.5f);
+   *     std::string result = fmt::vformat("{} and {} and {}", store);
+   */
   template <typename T> void push_back(const T& arg) {
     if (detail::const_check(need_copy<T>::value))
       emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
@@ -171,20 +170,18 @@ class dynamic_format_arg_store
   }
 
   /**
-    \rst
-    Adds a reference to the argument into the dynamic store for later passing to
-    a formatting function.
-
-    **Example**::
-
-      fmt::dynamic_format_arg_store<fmt::format_context> store;
-      char band[] = "Rolling Stones";
-      store.push_back(std::cref(band));
-      band[9] = 'c'; // Changing str affects the output.
-      std::string result = fmt::vformat("{}", store);
-      // result == "Rolling Scones"
-    \endrst
-  */
+   * Adds a reference to the argument into the dynamic store for later passing
+   * to a formatting function.
+   *
+   * **Example**:
+   *
+   *     fmt::dynamic_format_arg_store<fmt::format_context> store;
+   *     char band[] = "Rolling Stones";
+   *     store.push_back(std::cref(band));
+   *     band[9] = 'c'; // Changing str affects the output.
+   *     std::string result = fmt::vformat("{}", store);
+   *     // result == "Rolling Scones"
+   */
   template <typename T> void push_back(std::reference_wrapper<T> arg) {
     static_assert(
         need_copy<T>::value,
@@ -193,10 +190,10 @@ class dynamic_format_arg_store
   }
 
   /**
-    Adds named argument into the dynamic store for later passing to a formatting
-    function. ``std::reference_wrapper`` is supported to avoid copying of the
-    argument. The name is always copied into the store.
-  */
+   * Adds named argument into the dynamic store for later passing to a
+   * formatting function. `std::reference_wrapper` is supported to avoid
+   * copying of the argument. The name is always copied into the store.
+   */
   template <typename T>
   void push_back(const detail::named_arg<char_type, T>& arg) {
     const char_type* arg_name =
@@ -209,19 +206,15 @@ class dynamic_format_arg_store
     }
   }
 
-  /** Erase all elements from the store */
+  /// Erase all elements from the store.
   void clear() {
     data_.clear();
     named_info_.clear();
     dynamic_args_ = detail::dynamic_arg_list();
   }
 
-  /**
-    \rst
-    Reserves space to store at least *new_cap* arguments including
-    *new_cap_named* named arguments.
-    \endrst
-  */
+  /// Reserves space to store at least `new_cap` arguments including
+  /// `new_cap_named` named arguments.
   void reserve(size_t new_cap, size_t new_cap_named) {
     FMT_ASSERT(new_cap >= new_cap_named,
                "Set of arguments includes set of named arguments");

include/spdlog/fmt/bundled/chrono.h

@@ -8,17 +8,19 @@
 #ifndef FMT_CHRONO_H_
 #define FMT_CHRONO_H_
 
-#include <algorithm>
-#include <chrono>
-#include <cmath>    // std::isfinite
-#include <cstring>  // std::memcpy
-#include <ctime>
-#include <iterator>
-#include <locale>
-#include <ostream>
-#include <type_traits>
+#ifndef FMT_MODULE
+#  include <algorithm>
+#  include <chrono>
+#  include <cmath>    // std::isfinite
+#  include <cstring>  // std::memcpy
+#  include <ctime>
+#  include <iterator>
+#  include <locale>
+#  include <ostream>
+#  include <type_traits>
+#endif
 
-#include "ostream.h"  // formatbuf
+#include "format.h"
 
 FMT_BEGIN_NAMESPACE
 
@@ -94,10 +96,8 @@ FMT_CONSTEXPR auto lossless_integral_conversion(const From from, int& ec)
   return static_cast<To>(from);
 }
 
-/**
- * converts From to To, without loss. If the dynamic value of from
- * can't be converted to To without loss, ec is set.
- */
+/// Converts From to To, without loss. If the dynamic value of from
+/// can't be converted to To without loss, ec is set.
 template <typename To, typename From,
           FMT_ENABLE_IF(!std::is_same<From, To>::value &&
                         std::numeric_limits<From>::is_signed !=
@@ -185,9 +185,7 @@ FMT_CONSTEXPR auto safe_float_conversion(const From from, int& ec) -> To {
   return from;
 }
 
-/**
- * safe duration cast between integral durations
- */
+/// Safe duration cast between integral durations
 template <typename To, typename FromRep, typename FromPeriod,
           FMT_ENABLE_IF(std::is_integral<FromRep>::value),
           FMT_ENABLE_IF(std::is_integral<typename To::rep>::value)>
@@ -237,9 +235,7 @@ auto safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
   return ec ? To() : To(tocount);
 }
 
-/**
- * safe duration_cast between floating point durations
- */
+/// Safe duration_cast between floating point durations
 template <typename To, typename FromRep, typename FromPeriod,
           FMT_ENABLE_IF(std::is_floating_point<FromRep>::value),
           FMT_ENABLE_IF(std::is_floating_point<typename To::rep>::value)>
@@ -329,6 +325,39 @@ inline auto localtime_s(...) -> null<> { return null<>(); }
 inline auto gmtime_r(...) -> null<> { return null<>(); }
 inline auto gmtime_s(...) -> null<> { return null<>(); }
 
+// It is defined here and not in ostream.h because the latter has expensive
+// includes.
+template <typename Streambuf> class formatbuf : public Streambuf {
+ private:
+  using char_type = typename Streambuf::char_type;
+  using streamsize = decltype(std::declval<Streambuf>().sputn(nullptr, 0));
+  using int_type = typename Streambuf::int_type;
+  using traits_type = typename Streambuf::traits_type;
+
+  buffer<char_type>& buffer_;
+
+ public:
+  explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
+
+ protected:
+  // The put area is always empty. This makes the implementation simpler and has
+  // the advantage that the streambuf and the buffer are always in sync and
+  // sputc never writes into uninitialized memory. A disadvantage is that each
+  // call to sputc always results in a (virtual) call to overflow. There is no
+  // disadvantage here for sputn since this always results in a call to xsputn.
+
+  auto overflow(int_type ch) -> int_type override {
+    if (!traits_type::eq_int_type(ch, traits_type::eof()))
+      buffer_.push_back(static_cast<char_type>(ch));
+    return ch;
+  }
+
+  auto xsputn(const char_type* s, streamsize count) -> streamsize override {
+    buffer_.append(s, s + count);
+    return count;
+  }
+};
+
 inline auto get_classic_locale() -> const std::locale& {
   static const auto& locale = std::locale::classic();
   return locale;
@@ -362,11 +391,12 @@ void write_codecvt(codecvt_result<CodeUnit>& out, string_view in_buf,
 template <typename OutputIt>
 auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
     -> OutputIt {
-  if (detail::is_utf8() && loc != get_classic_locale()) {
+  if (detail::use_utf8() && loc != get_classic_locale()) {
     // char16_t and char32_t codecvts are broken in MSVC (linkage errors) and
     // gcc-4.
-#if FMT_MSC_VERSION != 0 || \
-    (defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_DUAL_ABI))
+#if FMT_MSC_VERSION != 0 ||  \
+    (defined(__GLIBCXX__) && \
+     (!defined(_GLIBCXX_USE_DUAL_ABI) || _GLIBCXX_USE_DUAL_ABI == 0))
     // The _GLIBCXX_USE_DUAL_ABI macro is always defined in libstdc++ from gcc-5
     // and newer.
     using code_unit = wchar_t;
@@ -382,9 +412,9 @@ auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
         to_utf8<code_unit, basic_memory_buffer<char, unit_t::max_size * 4>>();
     if (!u.convert({unit.buf, to_unsigned(unit.end - unit.buf)}))
       FMT_THROW(format_error("failed to format time"));
-    return copy_str<char>(u.c_str(), u.c_str() + u.size(), out);
+    return copy<char>(u.c_str(), u.c_str() + u.size(), out);
   }
-  return copy_str<char>(in.data(), in.data() + in.size(), out);
+  return copy<char>(in.data(), in.data() + in.size(), out);
 }
 
 template <typename Char, typename OutputIt,
@@ -393,7 +423,7 @@ auto write_tm_str(OutputIt out, string_view sv, const std::locale& loc)
     -> OutputIt {
   codecvt_result<Char> unit;
   write_codecvt(unit, sv, loc);
-  return copy_str<Char>(unit.buf, unit.end, out);
+  return copy<Char>(unit.buf, unit.end, out);
 }
 
 template <typename Char, typename OutputIt,
@@ -482,9 +512,9 @@ auto to_time_t(
 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.
+ * 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 {
@@ -531,9 +561,9 @@ inline auto localtime(std::chrono::local_time<Duration> time) -> std::tm {
 #endif
 
 /**
-  Converts given time since epoch as ``std::time_t`` value into calendar time,
-  expressed in Coordinated Universal Time (UTC). Unlike ``std::gmtime``, this
-  function is thread-safe on most platforms.
+ * Converts given time since epoch as `std::time_t` value into calendar time,
+ * expressed in Coordinated Universal Time (UTC). Unlike `std::gmtime`, this
+ * function is thread-safe on most platforms.
  */
 inline auto gmtime(std::time_t time) -> std::tm {
   struct dispatcher {
@@ -646,12 +676,10 @@ enum class numeric_system {
 
 // Glibc extensions for formatting numeric values.
 enum class pad_type {
-  unspecified,
+  // Pad a numeric result string with zeros (the default).
+  zero,
   // Do not pad a numeric result string.
   none,
-  // Pad a numeric result string with zeros even if the conversion specifier
-  // character uses space-padding by default.
-  zero,
   // Pad a numeric result string with spaces.
   space,
 };
@@ -659,7 +687,7 @@ enum class pad_type {
 template <typename OutputIt>
 auto write_padding(OutputIt out, pad_type pad, int width) -> OutputIt {
   if (pad == pad_type::none) return out;
-  return std::fill_n(out, width, pad == pad_type::space ? ' ' : '0');
+  return detail::fill_n(out, width, pad == pad_type::space ? ' ' : '0');
 }
 
 template <typename OutputIt>
@@ -675,8 +703,8 @@ FMT_CONSTEXPR auto parse_chrono_format(const Char* begin, const Char* end,
   if (begin == end || *begin == '}') return begin;
   if (*begin != '%') FMT_THROW(format_error("invalid format"));
   auto ptr = begin;
-  pad_type pad = pad_type::unspecified;
   while (ptr != end) {
+    pad_type pad = pad_type::zero;
     auto c = *ptr;
     if (c == '}') break;
     if (c != '%') {
@@ -696,10 +724,6 @@ FMT_CONSTEXPR auto parse_chrono_format(const Char* begin, const Char* end,
       pad = pad_type::none;
       ++ptr;
       break;
-    case '0':
-      pad = pad_type::zero;
-      ++ptr;
-      break;
     }
     if (ptr == end) FMT_THROW(format_error("invalid format"));
     c = *ptr++;
@@ -759,22 +783,22 @@ FMT_CONSTEXPR auto parse_chrono_format(const Char* begin, const Char* end,
       break;
     // Day of the year/month:
     case 'U':
-      handler.on_dec0_week_of_year(numeric_system::standard);
+      handler.on_dec0_week_of_year(numeric_system::standard, pad);
       break;
     case 'W':
-      handler.on_dec1_week_of_year(numeric_system::standard);
+      handler.on_dec1_week_of_year(numeric_system::standard, pad);
       break;
     case 'V':
-      handler.on_iso_week_of_year(numeric_system::standard);
+      handler.on_iso_week_of_year(numeric_system::standard, pad);
       break;
     case 'j':
       handler.on_day_of_year();
       break;
     case 'd':
-      handler.on_day_of_month(numeric_system::standard);
+      handler.on_day_of_month(numeric_system::standard, pad);
       break;
     case 'e':
-      handler.on_day_of_month_space(numeric_system::standard);
+      handler.on_day_of_month(numeric_system::standard, pad_type::space);
       break;
     // Hour, minute, second:
     case 'H':
@@ -871,19 +895,19 @@ FMT_CONSTEXPR auto parse_chrono_format(const Char* begin, const Char* end,
         handler.on_dec_month(numeric_system::alternative);
         break;
       case 'U':
-        handler.on_dec0_week_of_year(numeric_system::alternative);
+        handler.on_dec0_week_of_year(numeric_system::alternative, pad);
         break;
       case 'W':
-        handler.on_dec1_week_of_year(numeric_system::alternative);
+        handler.on_dec1_week_of_year(numeric_system::alternative, pad);
         break;
       case 'V':
-        handler.on_iso_week_of_year(numeric_system::alternative);
+        handler.on_iso_week_of_year(numeric_system::alternative, pad);
         break;
       case 'd':
-        handler.on_day_of_month(numeric_system::alternative);
+        handler.on_day_of_month(numeric_system::alternative, pad);
         break;
       case 'e':
-        handler.on_day_of_month_space(numeric_system::alternative);
+        handler.on_day_of_month(numeric_system::alternative, pad_type::space);
         break;
       case 'w':
         handler.on_dec0_weekday(numeric_system::alternative);
@@ -936,12 +960,19 @@ template <typename Derived> struct null_chrono_spec_handler {
   FMT_CONSTEXPR void on_abbr_month() { unsupported(); }
   FMT_CONSTEXPR void on_full_month() { unsupported(); }
   FMT_CONSTEXPR void on_dec_month(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) { unsupported(); }
+  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system, pad_type) {
+    unsupported();
+  }
+  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system, pad_type) {
+    unsupported();
+  }
+  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system, pad_type) {
+    unsupported();
+  }
   FMT_CONSTEXPR void on_day_of_year() { unsupported(); }
-  FMT_CONSTEXPR void on_day_of_month(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) { unsupported(); }
+  FMT_CONSTEXPR void on_day_of_month(numeric_system, pad_type) {
+    unsupported();
+  }
   FMT_CONSTEXPR void on_24_hour(numeric_system) { unsupported(); }
   FMT_CONSTEXPR void on_12_hour(numeric_system) { unsupported(); }
   FMT_CONSTEXPR void on_minute(numeric_system) { unsupported(); }
@@ -979,12 +1010,11 @@ struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
   FMT_CONSTEXPR void on_abbr_month() {}
   FMT_CONSTEXPR void on_full_month() {}
   FMT_CONSTEXPR void on_dec_month(numeric_system) {}
-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) {}
-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) {}
-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) {}
+  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system, pad_type) {}
+  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system, pad_type) {}
+  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system, pad_type) {}
   FMT_CONSTEXPR void on_day_of_year() {}
-  FMT_CONSTEXPR void on_day_of_month(numeric_system) {}
-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) {}
+  FMT_CONSTEXPR void on_day_of_month(numeric_system, pad_type) {}
   FMT_CONSTEXPR void on_24_hour(numeric_system, pad_type) {}
   FMT_CONSTEXPR void on_12_hour(numeric_system, pad_type) {}
   FMT_CONSTEXPR void on_minute(numeric_system, pad_type) {}
@@ -1061,9 +1091,10 @@ inline auto to_nonnegative_int(T value, Int upper) -> Int {
 }
 template <typename T, typename Int, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 inline auto to_nonnegative_int(T value, Int upper) -> Int {
-  if (value < 0 || value > static_cast<T>(upper))
+  auto int_value = static_cast<Int>(value);
+  if (int_value < 0 || value > static_cast<T>(upper))
     FMT_THROW(format_error("invalid value"));
-  return static_cast<Int>(value);
+  return int_value;
 }
 
 constexpr auto pow10(std::uint32_t n) -> long long {
@@ -1115,22 +1146,27 @@ void write_fractional_seconds(OutputIt& out, Duration d, int precision = -1) {
     if (std::ratio_less<typename subsecond_precision::period,
                         std::chrono::seconds::period>::value) {
       *out++ = '.';
-      out = std::fill_n(out, leading_zeroes, '0');
+      out = detail::fill_n(out, leading_zeroes, '0');
       out = format_decimal<Char>(out, n, num_digits).end;
     }
-  } else {
+  } else if (precision > 0) {
     *out++ = '.';
     leading_zeroes = (std::min)(leading_zeroes, precision);
-    out = std::fill_n(out, leading_zeroes, '0');
     int remaining = precision - leading_zeroes;
-    if (remaining != 0 && remaining < num_digits) {
-      n /= to_unsigned(detail::pow10(to_unsigned(num_digits - remaining)));
-      out = format_decimal<Char>(out, n, remaining).end;
+    out = detail::fill_n(out, leading_zeroes, '0');
+    if (remaining < num_digits) {
+      int num_truncated_digits = num_digits - remaining;
+      n /= to_unsigned(detail::pow10(to_unsigned(num_truncated_digits)));
+      if (n) {
+        out = format_decimal<Char>(out, n, remaining).end;
+      }
       return;
     }
-    out = format_decimal<Char>(out, n, num_digits).end;
-    remaining -= num_digits;
-    out = std::fill_n(out, remaining, '0');
+    if (n) {
+      out = format_decimal<Char>(out, n, num_digits).end;
+      remaining -= num_digits;
+    }
+    out = detail::fill_n(out, remaining, '0');
   }
 }
 
@@ -1281,7 +1317,8 @@ class tm_writer {
     }
     uint32_or_64_or_128_t<long long> n = to_unsigned(year);
     const int num_digits = count_digits(n);
-    if (width > num_digits) out_ = std::fill_n(out_, width - num_digits, '0');
+    if (width > num_digits)
+      out_ = detail::fill_n(out_, width - num_digits, '0');
     out_ = format_decimal<Char>(out_, n, num_digits).end;
   }
   void write_year(long long year) {
@@ -1364,7 +1401,7 @@ class tm_writer {
   auto out() const -> OutputIt { return out_; }
 
   FMT_CONSTEXPR void on_text(const Char* begin, const Char* end) {
-    out_ = copy_str<Char>(begin, end, out_);
+    out_ = copy<Char>(begin, end, out_);
   }
 
   void on_abbr_weekday() {
@@ -1411,7 +1448,7 @@ class tm_writer {
       *out_++ = ' ';
       on_abbr_month();
       *out_++ = ' ';
-      on_day_of_month_space(numeric_system::standard);
+      on_day_of_month(numeric_system::standard, pad_type::space);
       *out_++ = ' ';
       on_iso_time();
       *out_++ = ' ';
@@ -1437,7 +1474,7 @@ class tm_writer {
     write_digit2_separated(buf, to_unsigned(tm_mon() + 1),
                            to_unsigned(tm_mday()),
                            to_unsigned(split_year_lower(tm_year())), '/');
-    out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
+    out_ = copy<Char>(std::begin(buf), std::end(buf), out_);
   }
   void on_iso_date() {
     auto year = tm_year();
@@ -1453,7 +1490,7 @@ class tm_writer {
     write_digit2_separated(buf + 2, static_cast<unsigned>(year % 100),
                            to_unsigned(tm_mon() + 1), to_unsigned(tm_mday()),
                            '-');
-    out_ = copy_str<Char>(std::begin(buf) + offset, std::end(buf), out_);
+    out_ = copy<Char>(std::begin(buf) + offset, std::end(buf), out_);
   }
 
   void on_utc_offset(numeric_system ns) { format_utc_offset_impl(tm_, ns); }
@@ -1498,24 +1535,26 @@ class tm_writer {
     format_localized('m', 'O');
   }
 
-  void on_dec0_week_of_year(numeric_system ns) {
+  void on_dec0_week_of_year(numeric_system ns, pad_type pad) {
     if (is_classic_ || ns == numeric_system::standard)
-      return write2((tm_yday() + days_per_week - tm_wday()) / days_per_week);
+      return write2((tm_yday() + days_per_week - tm_wday()) / days_per_week,
+                    pad);
     format_localized('U', 'O');
   }
-  void on_dec1_week_of_year(numeric_system ns) {
+  void on_dec1_week_of_year(numeric_system ns, pad_type pad) {
     if (is_classic_ || ns == numeric_system::standard) {
       auto wday = tm_wday();
       write2((tm_yday() + days_per_week -
               (wday == 0 ? (days_per_week - 1) : (wday - 1))) /
-             days_per_week);
+                 days_per_week,
+             pad);
     } else {
       format_localized('W', 'O');
     }
   }
-  void on_iso_week_of_year(numeric_system ns) {
+  void on_iso_week_of_year(numeric_system ns, pad_type pad) {
     if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_iso_week_of_year());
+      return write2(tm_iso_week_of_year(), pad);
     format_localized('V', 'O');
   }
 
@@ -1529,20 +1568,11 @@ class tm_writer {
     write1(yday / 100);
     write2(yday % 100);
   }
-  void on_day_of_month(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) return write2(tm_mday());
+  void on_day_of_month(numeric_system ns, pad_type pad) {
+    if (is_classic_ || ns == numeric_system::standard)
+      return write2(tm_mday(), pad);
     format_localized('d', 'O');
   }
-  void on_day_of_month_space(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      auto mday = to_unsigned(tm_mday()) % 100;
-      const char* d2 = digits2(mday);
-      *out_++ = mday < 10 ? ' ' : d2[0];
-      *out_++ = d2[1];
-    } else {
-      format_localized('e', 'O');
-    }
-  }
 
   void on_24_hour(numeric_system ns, pad_type pad) {
     if (is_classic_ || ns == numeric_system::standard)
@@ -1586,7 +1616,7 @@ class tm_writer {
       char buf[8];
       write_digit2_separated(buf, to_unsigned(tm_hour12()),
                              to_unsigned(tm_min()), to_unsigned(tm_sec()), ':');
-      out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
+      out_ = copy<Char>(std::begin(buf), std::end(buf), out_);
       *out_++ = ' ';
       on_am_pm();
     } else {
@@ -1601,7 +1631,7 @@ class tm_writer {
   void on_iso_time() {
     on_24_hour_time();
     *out_++ = ':';
-    on_second(numeric_system::standard, pad_type::unspecified);
+    on_second(numeric_system::standard, pad_type::zero);
   }
 
   void on_am_pm() {
@@ -1700,10 +1730,10 @@ auto format_duration_value(OutputIt out, Rep val, int) -> OutputIt {
 template <typename Char, typename Rep, typename OutputIt,
           FMT_ENABLE_IF(std::is_floating_point<Rep>::value)>
 auto format_duration_value(OutputIt out, Rep val, int precision) -> OutputIt {
-  auto specs = format_specs<Char>();
+  auto specs = format_specs();
   specs.precision = precision;
-  specs.type = precision >= 0 ? presentation_type::fixed_lower
-                              : presentation_type::general_lower;
+  specs.type =
+      precision >= 0 ? presentation_type::fixed : presentation_type::general;
   return write<Char>(out, val, specs);
 }
 
@@ -1744,8 +1774,10 @@ class get_locale {
 
  public:
   get_locale(bool localized, locale_ref loc) : has_locale_(localized) {
+#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
     if (localized)
       ::new (&locale_) std::locale(loc.template get<std::locale>());
+#endif
   }
   ~get_locale() {
     if (has_locale_) locale_.~locale();
@@ -1840,7 +1872,7 @@ struct chrono_formatter {
     }
   }
 
-  void write(Rep value, int width, pad_type pad = pad_type::unspecified) {
+  void write(Rep value, int width, pad_type pad = pad_type::zero) {
     write_sign();
     if (isnan(value)) return write_nan();
     uint32_or_64_or_128_t<int> n =
@@ -1890,11 +1922,10 @@ struct chrono_formatter {
   void on_iso_week_based_year() {}
   void on_iso_week_based_short_year() {}
   void on_dec_month(numeric_system) {}
-  void on_dec0_week_of_year(numeric_system) {}
-  void on_dec1_week_of_year(numeric_system) {}
-  void on_iso_week_of_year(numeric_system) {}
-  void on_day_of_month(numeric_system) {}
-  void on_day_of_month_space(numeric_system) {}
+  void on_dec0_week_of_year(numeric_system, pad_type) {}
+  void on_dec1_week_of_year(numeric_system, pad_type) {}
+  void on_iso_week_of_year(numeric_system, pad_type) {}
+  void on_day_of_month(numeric_system, pad_type) {}
 
   void on_day_of_year() {
     if (handle_nan_inf()) return;
@@ -1974,7 +2005,7 @@ struct chrono_formatter {
     on_24_hour_time();
     *out++ = ':';
     if (handle_nan_inf()) return;
-    on_second(numeric_system::standard, pad_type::unspecified);
+    on_second(numeric_system::standard, pad_type::zero);
   }
 
   void on_am_pm() {
@@ -1997,53 +2028,215 @@ struct chrono_formatter {
 
 #if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907
 using weekday = std::chrono::weekday;
+using day = std::chrono::day;
+using month = std::chrono::month;
+using year = std::chrono::year;
+using year_month_day = std::chrono::year_month_day;
 #else
 // A fallback version of weekday.
 class weekday {
  private:
-  unsigned char value;
+  unsigned char value_;
 
  public:
   weekday() = default;
-  explicit constexpr weekday(unsigned wd) noexcept
-      : value(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
-  constexpr auto c_encoding() const noexcept -> unsigned { return value; }
+  constexpr explicit weekday(unsigned wd) noexcept
+      : value_(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
+  constexpr auto c_encoding() const noexcept -> unsigned { return value_; }
 };
 
-class year_month_day {};
+class day {
+ private:
+  unsigned char value_;
+
+ public:
+  day() = default;
+  constexpr explicit day(unsigned d) noexcept
+      : value_(static_cast<unsigned char>(d)) {}
+  constexpr explicit operator unsigned() const noexcept { return value_; }
+};
+
+class month {
+ private:
+  unsigned char value_;
+
+ public:
+  month() = default;
+  constexpr explicit month(unsigned m) noexcept
+      : value_(static_cast<unsigned char>(m)) {}
+  constexpr explicit operator unsigned() const noexcept { return value_; }
+};
+
+class year {
+ private:
+  int value_;
+
+ public:
+  year() = default;
+  constexpr explicit year(int y) noexcept : value_(y) {}
+  constexpr explicit operator int() const noexcept { return value_; }
+};
+
+class year_month_day {
+ private:
+  fmt::year year_;
+  fmt::month month_;
+  fmt::day day_;
+
+ public:
+  year_month_day() = default;
+  constexpr year_month_day(const year& y, const month& m, const day& d) noexcept
+      : year_(y), month_(m), day_(d) {}
+  constexpr auto year() const noexcept -> fmt::year { return year_; }
+  constexpr auto month() const noexcept -> fmt::month { return month_; }
+  constexpr auto day() const noexcept -> fmt::day { return day_; }
+};
 #endif
 
-// A rudimentary weekday formatter.
-template <typename Char> struct formatter<weekday, Char> {
+template <typename Char>
+struct formatter<weekday, Char> : private formatter<std::tm, Char> {
  private:
-  bool localized = false;
+  bool localized_ = false;
+  bool use_tm_formatter_ = false;
 
  public:
   FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
       -> decltype(ctx.begin()) {
-    auto begin = ctx.begin(), end = ctx.end();
-    if (begin != end && *begin == 'L') {
-      ++begin;
-      localized = true;
+    auto it = ctx.begin(), end = ctx.end();
+    if (it != end && *it == 'L') {
+      ++it;
+      localized_ = true;
+      return it;
     }
-    return begin;
+    use_tm_formatter_ = it != end && *it != '}';
+    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
   }
 
   template <typename FormatContext>
   auto format(weekday wd, FormatContext& ctx) const -> decltype(ctx.out()) {
     auto time = std::tm();
     time.tm_wday = static_cast<int>(wd.c_encoding());
-    detail::get_locale loc(localized, ctx.locale());
+    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
+    detail::get_locale loc(localized_, ctx.locale());
     auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
     w.on_abbr_weekday();
     return w.out();
   }
 };
 
+template <typename Char>
+struct formatter<day, Char> : private formatter<std::tm, Char> {
+ private:
+  bool use_tm_formatter_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    auto it = ctx.begin(), end = ctx.end();
+    use_tm_formatter_ = it != end && *it != '}';
+    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
+  }
+
+  template <typename FormatContext>
+  auto format(day d, FormatContext& ctx) const -> decltype(ctx.out()) {
+    auto time = std::tm();
+    time.tm_mday = static_cast<int>(static_cast<unsigned>(d));
+    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
+    detail::get_locale loc(false, ctx.locale());
+    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
+    w.on_day_of_month(detail::numeric_system::standard, detail::pad_type::zero);
+    return w.out();
+  }
+};
+
+template <typename Char>
+struct formatter<month, Char> : private formatter<std::tm, Char> {
+ private:
+  bool localized_ = false;
+  bool use_tm_formatter_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    auto it = ctx.begin(), end = ctx.end();
+    if (it != end && *it == 'L') {
+      ++it;
+      localized_ = true;
+      return it;
+    }
+    use_tm_formatter_ = it != end && *it != '}';
+    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
+  }
+
+  template <typename FormatContext>
+  auto format(month m, FormatContext& ctx) const -> decltype(ctx.out()) {
+    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());
+    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
+    w.on_abbr_month();
+    return w.out();
+  }
+};
+
+template <typename Char>
+struct formatter<year, Char> : private formatter<std::tm, Char> {
+ private:
+  bool use_tm_formatter_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    auto it = ctx.begin(), end = ctx.end();
+    use_tm_formatter_ = it != end && *it != '}';
+    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
+  }
+
+  template <typename FormatContext>
+  auto format(year y, FormatContext& ctx) const -> decltype(ctx.out()) {
+    auto time = std::tm();
+    time.tm_year = static_cast<int>(y) - 1900;
+    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
+    detail::get_locale loc(false, ctx.locale());
+    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
+    w.on_year(detail::numeric_system::standard);
+    return w.out();
+  }
+};
+
+template <typename Char>
+struct formatter<year_month_day, Char> : private formatter<std::tm, Char> {
+ private:
+  bool use_tm_formatter_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    auto it = ctx.begin(), end = ctx.end();
+    use_tm_formatter_ = it != end && *it != '}';
+    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
+  }
+
+  template <typename FormatContext>
+  auto format(year_month_day val, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto time = std::tm();
+    time.tm_year = static_cast<int>(val.year()) - 1900;
+    time.tm_mon = static_cast<int>(static_cast<unsigned>(val.month())) - 1;
+    time.tm_mday = static_cast<int>(static_cast<unsigned>(val.day()));
+    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
+    detail::get_locale loc(true, ctx.locale());
+    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
+    w.on_iso_date();
+    return w.out();
+  }
+};
+
 template <typename Rep, typename Period, typename Char>
 struct formatter<std::chrono::duration<Rep, Period>, Char> {
  private:
-  format_specs<Char> specs_;
+  format_specs specs_;
   detail::arg_ref<Char> width_ref_;
   detail::arg_ref<Char> precision_ref_;
   bool localized_ = false;
@@ -2117,27 +2310,26 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
   template <typename FormatContext>
   auto format(std::chrono::time_point<std::chrono::system_clock, Duration> val,
               FormatContext& ctx) const -> decltype(ctx.out()) {
+    std::tm tm = gmtime(val);
     using period = typename Duration::period;
     if (detail::const_check(
-            period::num != 1 || period::den != 1 ||
-            std::is_floating_point<typename Duration::rep>::value)) {
-      const auto epoch = val.time_since_epoch();
-      auto subsecs = detail::fmt_duration_cast<Duration>(
-          epoch - detail::fmt_duration_cast<std::chrono::seconds>(epoch));
-
-      if (subsecs.count() < 0) {
-        auto second =
-            detail::fmt_duration_cast<Duration>(std::chrono::seconds(1));
-        if (epoch.count() < ((Duration::min)() + second).count())
-          FMT_THROW(format_error("duration is too small"));
-        subsecs += second;
-        val -= second;
-      }
-
-      return formatter<std::tm, Char>::do_format(gmtime(val), ctx, &subsecs);
+            period::num == 1 && period::den == 1 &&
+            !std::is_floating_point<typename Duration::rep>::value)) {
+      return formatter<std::tm, Char>::format(tm, ctx);
     }
-
-    return formatter<std::tm, Char>::format(gmtime(val), ctx);
+    Duration epoch = val.time_since_epoch();
+    Duration subsecs = detail::fmt_duration_cast<Duration>(
+        epoch - detail::fmt_duration_cast<std::chrono::seconds>(epoch));
+    if (subsecs.count() < 0) {
+      auto second =
+          detail::fmt_duration_cast<Duration>(std::chrono::seconds(1));
+      if (tm.tm_sec != 0)
+        --tm.tm_sec;
+      else
+        tm = gmtime(val - second);
+      subsecs += detail::fmt_duration_cast<Duration>(std::chrono::seconds(1));
+    }
+    return formatter<std::tm, Char>::do_format(tm, ctx, &subsecs);
   }
 };
 
@@ -2185,7 +2377,7 @@ struct formatter<std::chrono::time_point<std::chrono::utc_clock, Duration>,
 
 template <typename Char> struct formatter<std::tm, Char> {
  private:
-  format_specs<Char> specs_;
+  format_specs specs_;
   detail::arg_ref<Char> width_ref_;
 
  protected:

include/spdlog/fmt/bundled/color.h

@@ -227,7 +227,7 @@ struct color_type {
 };
 }  // namespace detail
 
-/** A text style consisting of foreground and background colors and emphasis. */
+/// A text style consisting of foreground and background colors and emphasis.
 class text_style {
  public:
   FMT_CONSTEXPR text_style(emphasis em = emphasis()) noexcept
@@ -239,7 +239,7 @@ class text_style {
       foreground_color = rhs.foreground_color;
     } else if (rhs.set_foreground_color) {
       if (!foreground_color.is_rgb || !rhs.foreground_color.is_rgb)
-        FMT_THROW(format_error("can't OR a terminal color"));
+        report_error("can't OR a terminal color");
       foreground_color.value.rgb_color |= rhs.foreground_color.value.rgb_color;
     }
 
@@ -248,7 +248,7 @@ class text_style {
       background_color = rhs.background_color;
     } else if (rhs.set_background_color) {
       if (!background_color.is_rgb || !rhs.background_color.is_rgb)
-        FMT_THROW(format_error("can't OR a terminal color"));
+        report_error("can't OR a terminal color");
       background_color.value.rgb_color |= rhs.background_color.value.rgb_color;
     }
 
@@ -310,13 +310,13 @@ class text_style {
   emphasis ems;
 };
 
-/** Creates a text style from the foreground (text) color. */
+/// 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);
 }
 
-/** Creates a text style from the background color. */
+/// 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);
@@ -390,8 +390,8 @@ template <typename Char> struct ansi_color_escape {
   FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }
 
   FMT_CONSTEXPR auto begin() const noexcept -> const Char* { return buffer; }
-  FMT_CONSTEXPR_CHAR_TRAITS auto end() const noexcept -> const Char* {
-    return buffer + std::char_traits<Char>::length(buffer);
+  FMT_CONSTEXPR20 auto end() const noexcept -> const Char* {
+    return buffer + basic_string_view<Char>(buffer).size();
   }
 
  private:
@@ -441,9 +441,9 @@ template <typename T> struct styled_arg : detail::view {
 };
 
 template <typename Char>
-void vformat_to(buffer<Char>& buf, const text_style& ts,
-                basic_string_view<Char> format_str,
-                basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+void vformat_to(
+    buffer<Char>& buf, const text_style& ts, basic_string_view<Char> format_str,
+    basic_format_args<buffered_context<type_identity_t<Char>>> args) {
   bool has_style = false;
   if (ts.has_emphasis()) {
     has_style = true;
@@ -466,121 +466,92 @@ void vformat_to(buffer<Char>& buf, const text_style& ts,
 
 }  // namespace detail
 
-inline void vprint(std::FILE* f, const text_style& ts, string_view fmt,
+inline void vprint(FILE* f, const text_style& ts, string_view fmt,
                    format_args args) {
-  // Legacy wide streams are not supported.
   auto buf = memory_buffer();
   detail::vformat_to(buf, ts, fmt, args);
-  if (detail::is_utf8()) {
-    detail::print(f, string_view(buf.begin(), buf.size()));
-    return;
-  }
-  buf.push_back('\0');
-  int result = std::fputs(buf.data(), f);
-  if (result < 0)
-    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
+  print(f, FMT_STRING("{}"), string_view(buf.begin(), buf.size()));
 }
 
 /**
-  \rst
-  Formats a string and prints it to the specified file stream using ANSI
-  escape sequences to specify text formatting.
-
-  **Example**::
-
-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
-               "Elapsed time: {0:.2f} seconds", 1.23);
-  \endrst
+ * Formats a string and prints it to the specified file stream using ANSI
+ * escape sequences to specify text formatting.
+ *
+ * **Example**:
+ *
+ *     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
+ *                "Elapsed time: {0:.2f} seconds", 1.23);
  */
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_string<S>::value)>
-void print(std::FILE* f, const text_style& ts, const S& format_str,
-           const Args&... args) {
-  vprint(f, ts, format_str,
-         fmt::make_format_args<buffer_context<char_t<S>>>(args...));
+template <typename... T>
+void print(FILE* f, const text_style& ts, format_string<T...> fmt,
+           T&&... args) {
+  vprint(f, ts, fmt, fmt::make_format_args(args...));
 }
 
 /**
-  \rst
-  Formats a string and prints it to stdout using ANSI escape sequences to
-  specify text formatting.
-
-  **Example**::
-
-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
-               "Elapsed time: {0:.2f} seconds", 1.23);
-  \endrst
+ * Formats a string and prints it to stdout using ANSI escape sequences to
+ * specify text formatting.
+ *
+ * **Example**:
+ *
+ *     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
+ *                "Elapsed time: {0:.2f} seconds", 1.23);
  */
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_string<S>::value)>
-void print(const text_style& ts, const S& format_str, const Args&... args) {
-  return print(stdout, ts, format_str, args...);
+template <typename... T>
+void print(const text_style& ts, format_string<T...> fmt, T&&... args) {
+  return print(stdout, ts, fmt, std::forward<T>(args)...);
 }
 
-template <typename S, typename Char = char_t<S>>
-inline auto vformat(
-    const text_style& ts, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> std::basic_string<Char> {
-  basic_memory_buffer<Char> buf;
-  detail::vformat_to(buf, ts, detail::to_string_view(format_str), args);
+inline auto vformat(const text_style& ts, string_view fmt, format_args args)
+    -> std::string {
+  auto buf = memory_buffer();
+  detail::vformat_to(buf, ts, fmt, args);
   return fmt::to_string(buf);
 }
 
 /**
-  \rst
-  Formats arguments and returns the result as a string using ANSI
-  escape sequences to specify text formatting.
-
-  **Example**::
-
-    #include <fmt/color.h>
-    std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
-                                      "The answer is {}", 42);
-  \endrst
-*/
-template <typename S, typename... Args, typename Char = char_t<S>>
-inline auto format(const text_style& ts, const S& format_str,
-                   const Args&... args) -> std::basic_string<Char> {
-  return fmt::vformat(ts, detail::to_string_view(format_str),
-                      fmt::make_format_args<buffer_context<Char>>(args...));
+ * Formats arguments and returns the result as a string using ANSI escape
+ * sequences to specify text formatting.
+ *
+ * **Example**:
+ *
+ * ```
+ * #include <fmt/color.h>
+ * std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
+ *                                   "The answer is {}", 42);
+ * ```
+ */
+template <typename... T>
+inline auto format(const text_style& ts, format_string<T...> fmt, T&&... args)
+    -> std::string {
+  return fmt::vformat(ts, fmt, fmt::make_format_args(args...));
 }
 
-/**
-  Formats a string with the given text_style and writes the output to ``out``.
- */
-template <typename OutputIt, typename Char,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
-auto vformat_to(OutputIt out, const text_style& ts,
-                basic_string_view<Char> format_str,
-                basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> OutputIt {
-  auto&& buf = detail::get_buffer<Char>(out);
-  detail::vformat_to(buf, ts, format_str, 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&& buf = detail::get_buffer<char>(out);
+  detail::vformat_to(buf, ts, fmt, args);
   return detail::get_iterator(buf, out);
 }
 
 /**
-  \rst
-  Formats arguments with the given text_style, writes the result to the output
-  iterator ``out`` and returns the iterator past the end of the output range.
-
-  **Example**::
-
-    std::vector<char> out;
-    fmt::format_to(std::back_inserter(out),
-                   fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
-  \endrst
-*/
-template <
-    typename OutputIt, typename S, typename... Args,
-    bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value &&
-                  detail::is_string<S>::value>
-inline auto format_to(OutputIt out, const text_style& ts, const S& format_str,
-                      Args&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
-  return vformat_to(out, ts, detail::to_string_view(format_str),
-                    fmt::make_format_args<buffer_context<char_t<S>>>(args...));
+ * Formats arguments with the given text style, writes the result to the output
+ * iterator `out` and returns the iterator past the end of the output range.
+ *
+ * **Example**:
+ *
+ *     std::vector<char> out;
+ *     fmt::format_to(std::back_inserter(out),
+ *                    fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
+ */
+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 {
+  return vformat_to(out, ts, fmt, fmt::make_format_args(args...));
 }
 
 template <typename T, typename Char>
@@ -620,16 +591,14 @@ struct formatter<detail::styled_arg<T>, Char> : formatter<T, Char> {
 };
 
 /**
-  \rst
-  Returns an argument that will be formatted using ANSI escape sequences,
-  to be used in a formatting function.
-
-  **Example**::
-
-    fmt::print("Elapsed time: {0:.2f} seconds",
-               fmt::styled(1.23, fmt::fg(fmt::color::green) |
-                                 fmt::bg(fmt::color::blue)));
-  \endrst
+ * Returns an argument that will be formatted using ANSI escape sequences,
+ * to be used in a formatting function.
+ *
+ * **Example**:
+ *
+ *     fmt::print("Elapsed time: {0:.2f} seconds",
+ *                fmt::styled(1.23, fmt::fg(fmt::color::green) |
+ *                                  fmt::bg(fmt::color::blue)));
  */
 template <typename T>
 FMT_CONSTEXPR auto styled(const T& value, text_style ts)

include/spdlog/fmt/bundled/compile.h

@@ -8,39 +8,41 @@
 #ifndef FMT_COMPILE_H_
 #define FMT_COMPILE_H_
 
+#ifndef FMT_MODULE
+#  include <iterator>  // std::back_inserter
+#endif
+
 #include "format.h"
 
 FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename Char, typename InputIt>
-FMT_CONSTEXPR inline auto copy_str(InputIt begin, InputIt end,
-                                   counting_iterator it) -> counting_iterator {
-  return it + (end - begin);
-}
 
 // A compile-time string which is compiled into fast formatting code.
-class compiled_string {};
+FMT_EXPORT class compiled_string {};
+
+namespace detail {
+
+template <typename T, typename InputIt>
+FMT_CONSTEXPR inline auto copy(InputIt begin, InputIt end, counting_iterator it)
+    -> counting_iterator {
+  return it + (end - begin);
+}
 
 template <typename S>
 struct is_compiled_string : std::is_base_of<compiled_string, S> {};
 
 /**
-  \rst
-  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
-  ``constexpr if`` compiler support.
-
-  **Example**::
-
-    // Converts 42 into std::string using the most efficient method and no
-    // runtime format string processing.
-    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
-  \endrst
+ * 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
+ * `constexpr if` compiler support.
+ *
+ * **Example**:
+ *
+ *     // Converts 42 into std::string using the most efficient method and no
+ *     // runtime format string processing.
+ *     std::string s = fmt::format(FMT_COMPILE("{}"), 42);
  */
 #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-#  define FMT_COMPILE(s) \
-    FMT_STRING_IMPL(s, fmt::detail::compiled_string, explicit)
+#  define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::compiled_string, explicit)
 #else
 #  define FMT_COMPILE(s) FMT_STRING(s)
 #endif
@@ -144,9 +146,9 @@ template <typename Char, typename T, int N> struct field {
   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_v<T, basic_string_view<Char>>) {
+    if constexpr (std::is_convertible<T, basic_string_view<Char>>::value) {
       auto s = basic_string_view<Char>(arg);
-      return copy_str<Char>(s.begin(), s.end(), out);
+      return copy<Char>(s.begin(), s.end(), out);
     }
     return write<Char>(out, arg);
   }
@@ -236,13 +238,12 @@ constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
 }
 
 template <typename Args, size_t POS, int ID, typename S>
-constexpr auto compile_format_string(S format_str);
+constexpr auto compile_format_string(S fmt);
 
 template <typename Args, size_t POS, int ID, typename T, typename S>
-constexpr auto parse_tail(T head, S format_str) {
-  if constexpr (POS !=
-                basic_string_view<typename S::char_type>(format_str).size()) {
-    constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
+constexpr auto parse_tail(T head, S fmt) {
+  if constexpr (POS != basic_string_view<typename S::char_type>(fmt).size()) {
+    constexpr auto tail = compile_format_string<Args, POS, ID>(fmt);
     if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
                                unknown_format>())
       return tail;
@@ -313,14 +314,13 @@ struct field_type<T, enable_if_t<detail::is_named_arg<T>::value>> {
 
 template <typename T, typename Args, size_t END_POS, int ARG_INDEX, int NEXT_ID,
           typename S>
-constexpr auto parse_replacement_field_then_tail(S format_str) {
+constexpr auto parse_replacement_field_then_tail(S fmt) {
   using char_type = typename S::char_type;
-  constexpr auto str = basic_string_view<char_type>(format_str);
+  constexpr auto str = basic_string_view<char_type>(fmt);
   constexpr char_type c = END_POS != str.size() ? str[END_POS] : char_type();
   if constexpr (c == '}') {
     return parse_tail<Args, END_POS + 1, NEXT_ID>(
-        field<char_type, typename field_type<T>::type, ARG_INDEX>(),
-        format_str);
+        field<char_type, typename field_type<T>::type, ARG_INDEX>(), fmt);
   } else if constexpr (c != ':') {
     FMT_THROW(format_error("expected ':'"));
   } else {
@@ -333,7 +333,7 @@ constexpr auto parse_replacement_field_then_tail(S format_str) {
       return parse_tail<Args, result.end + 1, result.next_arg_id>(
           spec_field<char_type, typename field_type<T>::type, ARG_INDEX>{
               result.fmt},
-          format_str);
+          fmt);
     }
   }
 }
@@ -341,22 +341,21 @@ constexpr auto parse_replacement_field_then_tail(S format_str) {
 // Compiles a non-empty format string and returns the compiled representation
 // or unknown_format() on unrecognized input.
 template <typename Args, size_t POS, int ID, typename S>
-constexpr auto compile_format_string(S format_str) {
+constexpr auto compile_format_string(S fmt) {
   using char_type = typename S::char_type;
-  constexpr auto str = basic_string_view<char_type>(format_str);
+  constexpr auto str = basic_string_view<char_type>(fmt);
   if constexpr (str[POS] == '{') {
     if constexpr (POS + 1 == str.size())
       FMT_THROW(format_error("unmatched '{' in format string"));
     if constexpr (str[POS + 1] == '{') {
-      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
+      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), fmt);
     } else if constexpr (str[POS + 1] == '}' || str[POS + 1] == ':') {
       static_assert(ID != manual_indexing_id,
                     "cannot switch from manual to automatic argument indexing");
       constexpr auto next_id =
           ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
       return parse_replacement_field_then_tail<get_type<ID, Args>, Args,
-                                               POS + 1, ID, next_id>(
-          format_str);
+                                               POS + 1, ID, next_id>(fmt);
     } else {
       constexpr auto arg_id_result =
           parse_arg_id<ID>(str.data() + POS + 1, str.data() + str.size());
@@ -372,7 +371,7 @@ constexpr auto compile_format_string(S format_str) {
         return parse_replacement_field_then_tail<get_type<arg_index, Args>,
                                                  Args, arg_id_end_pos,
                                                  arg_index, manual_indexing_id>(
-            format_str);
+            fmt);
       } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
         constexpr auto arg_index =
             get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
@@ -381,11 +380,11 @@ constexpr auto compile_format_string(S format_str) {
               ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
           return parse_replacement_field_then_tail<
               decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos,
-              arg_index, next_id>(format_str);
+              arg_index, next_id>(fmt);
         } else if constexpr (c == '}') {
           return parse_tail<Args, arg_id_end_pos + 1, ID>(
               runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
-              format_str);
+              fmt);
         } else if constexpr (c == ':') {
           return unknown_format();  // no type info for specs parsing
         }
@@ -394,29 +393,26 @@ constexpr auto compile_format_string(S format_str) {
   } else if constexpr (str[POS] == '}') {
     if constexpr (POS + 1 == str.size())
       FMT_THROW(format_error("unmatched '}' in format string"));
-    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
+    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), fmt);
   } else {
     constexpr auto end = parse_text(str, POS + 1);
     if constexpr (end - POS > 1) {
-      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
-                                       format_str);
+      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS), fmt);
     } else {
-      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
-                                       format_str);
+      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]}, fmt);
     }
   }
 }
 
 template <typename... Args, typename S,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-constexpr auto compile(S format_str) {
-  constexpr auto str = basic_string_view<typename S::char_type>(format_str);
+constexpr auto compile(S fmt) {
+  constexpr auto str = basic_string_view<typename S::char_type>(fmt);
   if constexpr (str.size() == 0) {
     return detail::make_text(str, 0, 0);
   } else {
     constexpr auto result =
-        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
-            format_str);
+        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(fmt);
     return result;
   }
 }
@@ -488,35 +484,33 @@ FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
 
 template <typename OutputIt, typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-auto format_to_n(OutputIt out, size_t n, const S& format_str, Args&&... args)
+auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
     -> format_to_n_result<OutputIt> {
   using traits = detail::fixed_buffer_traits;
   auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
-  fmt::format_to(std::back_inserter(buf), format_str,
-                 std::forward<Args>(args)...);
+  fmt::format_to(std::back_inserter(buf), fmt, std::forward<Args>(args)...);
   return {buf.out(), buf.count()};
 }
 
 template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_CONSTEXPR20 auto formatted_size(const S& format_str, const Args&... args)
+FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
     -> size_t {
-  return fmt::format_to(detail::counting_iterator(), format_str, args...)
-      .count();
+  return fmt::format_to(detail::counting_iterator(), fmt, args...).count();
 }
 
 template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-void print(std::FILE* f, const S& format_str, const Args&... args) {
+void print(std::FILE* f, const S& fmt, const Args&... args) {
   memory_buffer buffer;
-  fmt::format_to(std::back_inserter(buffer), format_str, args...);
+  fmt::format_to(std::back_inserter(buffer), fmt, args...);
   detail::print(f, {buffer.data(), buffer.size()});
 }
 
 template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-void print(const S& format_str, const Args&... args) {
-  print(stdout, format_str, args...);
+void print(const S& fmt, const Args&... args) {
+  print(stdout, fmt, args...);
 }
 
 #if FMT_USE_NONTYPE_TEMPLATE_ARGS

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

@@ -8,17 +8,19 @@
 #ifndef FMT_FORMAT_INL_H_
 #define FMT_FORMAT_INL_H_
 
-#include <algorithm>
-#include <cerrno>  // errno
-#include <climits>
-#include <cmath>
-#include <exception>
+#ifndef FMT_MODULE
+#  include <algorithm>
+#  include <cerrno>  // errno
+#  include <climits>
+#  include <cmath>
+#  include <exception>
 
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-#  include <locale>
+#  if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
+#    include <locale>
+#  endif
 #endif
 
-#if defined(_WIN32) && !defined(FMT_WINDOWS_NO_WCHAR)
+#if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
 #  include <io.h>  // _isatty
 #endif
 
@@ -36,10 +38,6 @@ FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
   std::terminate();
 }
 
-FMT_FUNC void throw_format_error(const char* message) {
-  FMT_THROW(format_error(message));
-}
-
 FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
                                 string_view message) noexcept {
   // Report error code making sure that the output fits into
@@ -56,7 +54,7 @@ FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
     ++error_code_size;
   }
   error_code_size += detail::to_unsigned(detail::count_digits(abs_value));
-  auto it = buffer_appender<char>(out);
+  auto it = appender(out);
   if (message.size() <= inline_buffer_size - error_code_size)
     fmt::format_to(it, FMT_STRING("{}{}"), message, SEP);
   fmt::format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
@@ -113,8 +111,12 @@ template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref) {
 #endif
 
 FMT_FUNC auto write_loc(appender out, loc_value value,
-                        const format_specs<>& specs, locale_ref loc) -> bool {
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+                        const format_specs& specs, locale_ref loc) -> bool {
+#ifdef FMT_STATIC_THOUSANDS_SEPARATOR
+  value.visit(loc_writer<>{
+      out, specs, std::string(1, FMT_STATIC_THOUSANDS_SEPARATOR), "\3", "."});
+  return true;
+#else
   auto locale = loc.get<std::locale>();
   // We cannot use the num_put<char> facet because it may produce output in
   // a wrong encoding.
@@ -123,10 +125,13 @@ FMT_FUNC auto write_loc(appender out, loc_value value,
     return std::use_facet<facet>(locale).put(out, value, specs);
   return facet(locale).put(out, value, specs);
 #endif
-  return false;
 }
 }  // namespace detail
 
+FMT_FUNC void report_error(const char* message) {
+  FMT_THROW(format_error(message));
+}
+
 template <typename Locale> typename Locale::id format_facet<Locale>::id;
 
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
@@ -138,7 +143,7 @@ template <typename Locale> format_facet<Locale>::format_facet(Locale& loc) {
 
 template <>
 FMT_API FMT_FUNC auto format_facet<std::locale>::do_put(
-    appender out, loc_value val, const format_specs<>& specs) const -> bool {
+    appender out, loc_value val, const format_specs& specs) const -> bool {
   return val.visit(
       detail::loc_writer<>{out, specs, separator_, grouping_, decimal_point_});
 }
@@ -1411,7 +1416,7 @@ FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,
                                   const char* message) noexcept {
   FMT_TRY {
     auto ec = std::error_code(error_code, std::generic_category());
-    write(std::back_inserter(out), std::system_error(ec, message).what());
+    detail::write(appender(out), std::system_error(ec, message).what());
     return;
   }
   FMT_CATCH(...) {}
@@ -1432,9 +1437,242 @@ FMT_FUNC auto vformat(string_view fmt, format_args args) -> std::string {
 }
 
 namespace detail {
-#if !defined(_WIN32) || defined(FMT_WINDOWS_NO_WCHAR)
+
+template <typename T> struct span {
+  T* data;
+  size_t size;
+};
+
+template <typename F> auto flockfile(F* f) -> decltype(_lock_file(f)) {
+  _lock_file(f);
+}
+template <typename F> auto funlockfile(F* f) -> decltype(_unlock_file(f)) {
+  _unlock_file(f);
+}
+
+#ifndef getc_unlocked
+template <typename F> auto getc_unlocked(F* f) -> decltype(_fgetc_nolock(f)) {
+  return _fgetc_nolock(f);
+}
+#endif
+
+template <typename F = FILE, typename Enable = void>
+struct has_flockfile : std::false_type {};
+
+template <typename F>
+struct has_flockfile<F, void_t<decltype(flockfile(&std::declval<F&>()))>>
+    : std::true_type {};
+
+// A FILE wrapper. F is FILE defined as a template parameter to make system API
+// detection work.
+template <typename F> class file_base {
+ public:
+  F* file_;
+
+ public:
+  file_base(F* file) : file_(file) {}
+  operator F*() const { return file_; }
+
+  // Reads a code unit from the stream.
+  auto get() -> int {
+    int result = getc_unlocked(file_);
+    if (result == EOF && ferror(file_) != 0)
+      FMT_THROW(system_error(errno, FMT_STRING("getc failed")));
+    return result;
+  }
+
+  // Puts the code unit back into the stream buffer.
+  void unget(char c) {
+    if (ungetc(c, file_) == EOF)
+      FMT_THROW(system_error(errno, FMT_STRING("ungetc failed")));
+  }
+
+  void flush() { fflush(this->file_); }
+};
+
+// A FILE wrapper for glibc.
+template <typename F> class glibc_file : public file_base<F> {
+ private:
+  enum {
+    line_buffered = 0x200,  // _IO_LINE_BUF
+    unbuffered = 2          // _IO_UNBUFFERED
+  };
+
+ public:
+  using file_base<F>::file_base;
+
+  auto is_buffered() const -> bool {
+    return (this->file_->_flags & unbuffered) == 0;
+  }
+
+  void init_buffer() {
+    if (this->file_->_IO_write_ptr) return;
+    // Force buffer initialization by placing and removing a char in a buffer.
+    putc_unlocked(0, this->file_);
+    --this->file_->_IO_write_ptr;
+  }
+
+  // Returns the file's read buffer.
+  auto get_read_buffer() const -> span<const char> {
+    auto ptr = this->file_->_IO_read_ptr;
+    return {ptr, to_unsigned(this->file_->_IO_read_end - ptr)};
+  }
+
+  // Returns the file's write buffer.
+  auto get_write_buffer() const -> span<char> {
+    auto ptr = this->file_->_IO_write_ptr;
+    return {ptr, to_unsigned(this->file_->_IO_buf_end - ptr)};
+  }
+
+  void advance_write_buffer(size_t size) { this->file_->_IO_write_ptr += size; }
+
+  bool needs_flush() const {
+    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));
+  }
+
+  void flush() { fflush_unlocked(this->file_); }
+};
+
+// A FILE wrapper for Apple's libc.
+template <typename F> class apple_file : public file_base<F> {
+ private:
+  enum {
+    line_buffered = 1,  // __SNBF
+    unbuffered = 2      // __SLBF
+  };
+
+ public:
+  using file_base<F>::file_base;
+
+  auto is_buffered() const -> bool {
+    return (this->file_->_flags & unbuffered) == 0;
+  }
+
+  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_);
+    --this->file_->_p;
+    ++this->file_->_w;
+  }
+
+  auto get_read_buffer() const -> span<const char> {
+    return {reinterpret_cast<char*>(this->file_->_p),
+            to_unsigned(this->file_->_r)};
+  }
+
+  auto get_write_buffer() const -> span<char> {
+    return {reinterpret_cast<char*>(this->file_->_p),
+            to_unsigned(this->file_->_bf._base + this->file_->_bf._size -
+                        this->file_->_p)};
+  }
+
+  void advance_write_buffer(size_t size) {
+    this->file_->_p += size;
+    this->file_->_w -= size;
+  }
+
+  bool needs_flush() const {
+    if ((this->file_->_flags & line_buffered) == 0) return false;
+    return memchr(this->file_->_p + this->file_->_w, '\n',
+                  to_unsigned(-this->file_->_w));
+  }
+};
+
+// A fallback FILE wrapper.
+template <typename F> class fallback_file : public file_base<F> {
+ private:
+  char next_;  // The next unconsumed character in the buffer.
+  bool has_next_ = false;
+
+ public:
+  using file_base<F>::file_base;
+
+  auto is_buffered() const -> bool { return false; }
+  auto needs_flush() const -> bool { return false; }
+  void init_buffer() {}
+
+  auto get_read_buffer() const -> span<const char> {
+    return {&next_, has_next_ ? 1u : 0u};
+  }
+
+  auto get_write_buffer() const -> span<char> { return {nullptr, 0}; }
+
+  void advance_write_buffer(size_t) {}
+
+  auto get() -> int {
+    has_next_ = false;
+    return file_base<F>::get();
+  }
+
+  void unget(char c) {
+    file_base<F>::unget(c);
+    next_ = c;
+    has_next_ = true;
+  }
+};
+
+#ifndef FMT_USE_FALLBACK_FILE
+#  define FMT_USE_FALLBACK_FILE 1
+#endif
+
+template <typename F,
+          FMT_ENABLE_IF(sizeof(F::_p) != 0 && !FMT_USE_FALLBACK_FILE)>
+auto get_file(F* f, int) -> apple_file<F> {
+  return f;
+}
+template <typename F,
+          FMT_ENABLE_IF(sizeof(F::_IO_read_ptr) != 0 && !FMT_USE_FALLBACK_FILE)>
+inline auto get_file(F* f, int) -> glibc_file<F> {
+  return f;
+}
+
+inline auto get_file(FILE* f, ...) -> fallback_file<FILE> { return f; }
+
+using file_ref = decltype(get_file(static_cast<FILE*>(nullptr), 0));
+
+template <typename F = FILE, typename Enable = void>
+class file_print_buffer : public buffer<char> {
+ public:
+  explicit file_print_buffer(F*) : buffer(nullptr, size_t()) {}
+};
+
+template <typename F>
+class file_print_buffer<F, enable_if_t<has_flockfile<F>::value>>
+    : public buffer<char> {
+ private:
+  file_ref file_;
+
+  static void grow(buffer<char>& base, size_t) {
+    auto& self = static_cast<file_print_buffer&>(base);
+    self.file_.advance_write_buffer(self.size());
+    if (self.file_.get_write_buffer().size == 0) self.file_.flush();
+    auto buf = self.file_.get_write_buffer();
+    FMT_ASSERT(buf.size > 0, "");
+    self.set(buf.data, buf.size);
+    self.clear();
+  }
+
+ public:
+  explicit file_print_buffer(F* f) : buffer(grow, size_t()), file_(f) {
+    flockfile(f);
+    file_.init_buffer();
+    auto buf = file_.get_write_buffer();
+    set(buf.data, buf.size);
+  }
+  ~file_print_buffer() {
+    file_.advance_write_buffer(size());
+    bool flush = file_.needs_flush();
+    F* f = file_;    // Make funlockfile depend on the template parameter F
+    funlockfile(f);  // for the system API detection to work.
+    if (flush) fflush(file_);
+  }
+};
+
+#if !defined(_WIN32) || defined(FMT_USE_WRITE_CONSOLE)
 FMT_FUNC auto write_console(int, string_view) -> bool { return false; }
-FMT_FUNC auto write_console(std::FILE*, string_view) -> bool { return false; }
 #else
 using dword = conditional_t<sizeof(long) == 4, unsigned long, unsigned>;
 extern "C" __declspec(dllimport) int __stdcall WriteConsoleW(  //
@@ -1445,23 +1683,21 @@ FMT_FUNC bool write_console(int fd, string_view text) {
   return WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)), u16.c_str(),
                        static_cast<dword>(u16.size()), nullptr, nullptr) != 0;
 }
-
-FMT_FUNC auto write_console(std::FILE* f, string_view text) -> bool {
-  return write_console(_fileno(f), text);
-}
 #endif
 
 #ifdef _WIN32
 // Print assuming legacy (non-Unicode) encoding.
-FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args) {
+FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args,
+                              bool newline) {
   auto buffer = memory_buffer();
   detail::vformat_to(buffer, fmt, args);
+  if (newline) buffer.push_back('\n');
   fwrite_fully(buffer.data(), buffer.size(), f);
 }
 #endif
 
 FMT_FUNC void print(std::FILE* f, string_view text) {
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
   int fd = _fileno(f);
   if (_isatty(fd)) {
     std::fflush(f);
@@ -1472,12 +1708,26 @@ FMT_FUNC void print(std::FILE* f, string_view text) {
 }
 }  // namespace detail
 
-FMT_FUNC void vprint(std::FILE* f, string_view fmt, format_args args) {
+FMT_FUNC void vprint_buffered(std::FILE* f, string_view fmt, format_args args) {
   auto buffer = memory_buffer();
   detail::vformat_to(buffer, fmt, args);
   detail::print(f, {buffer.data(), buffer.size()});
 }
 
+FMT_FUNC void vprint(std::FILE* f, string_view fmt, format_args args) {
+  if (!detail::file_ref(f).is_buffered() || !detail::has_flockfile<>())
+    return vprint_buffered(f, fmt, args);
+  auto&& buffer = detail::file_print_buffer<>(f);
+  return detail::vformat_to(buffer, fmt, args);
+}
+
+FMT_FUNC void vprintln(std::FILE* f, string_view fmt, format_args args) {
+  auto buffer = memory_buffer();
+  detail::vformat_to(buffer, fmt, args);
+  buffer.push_back('\n');
+  detail::print(f, {buffer.data(), buffer.size()});
+}
+
 FMT_FUNC void vprint(string_view fmt, format_args args) {
   vprint(stdout, fmt, args);
 }

include/spdlog/fmt/bundled/os.h

@@ -8,18 +8,18 @@
 #ifndef FMT_OS_H_
 #define FMT_OS_H_
 
-#include <cerrno>
-#include <cstddef>
-#include <cstdio>
-#include <system_error>  // std::system_error
-
 #include "format.h"
 
-#if defined __APPLE__ || defined(__FreeBSD__)
+#ifndef FMT_MODULE
+#  include <cerrno>
+#  include <cstddef>
+#  include <cstdio>
+#  include <system_error>  // std::system_error
+
 #  if FMT_HAS_INCLUDE(<xlocale.h>)
-#    include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+#    include <xlocale.h>  // LC_NUMERIC_MASK on macOS
 #  endif
-#endif
+#endif  // FMT_MODULE
 
 #ifndef FMT_USE_FCNTL
 // UWP doesn't provide _pipe.
@@ -77,46 +77,33 @@ FMT_BEGIN_NAMESPACE
 FMT_BEGIN_EXPORT
 
 /**
-  \rst
-  A reference to a null-terminated string. It can be constructed from a C
-  string or ``std::string``.
-
-  You can use one of the following type aliases for common character types:
-
-  +---------------+-----------------------------+
-  | Type          | Definition                  |
-  +===============+=============================+
-  | cstring_view  | basic_cstring_view<char>    |
-  +---------------+-----------------------------+
-  | wcstring_view | basic_cstring_view<wchar_t> |
-  +---------------+-----------------------------+
-
-  This class is most useful as a parameter type to allow passing
-  different types of strings to a function, for example::
-
-    template <typename... Args>
-    std::string format(cstring_view format_str, const Args & ... args);
-
-    format("{}", 42);
-    format(std::string("{}"), 42);
-  \endrst
+ * A reference to a null-terminated string. It can be constructed from a C
+ * string or `std::string`.
+ *
+ * You can use one of the following type aliases for common character types:
+ *
+ * +---------------+-----------------------------+
+ * | Type          | Definition                  |
+ * +===============+=============================+
+ * | cstring_view  | basic_cstring_view<char>    |
+ * +---------------+-----------------------------+
+ * | wcstring_view | basic_cstring_view<wchar_t> |
+ * +---------------+-----------------------------+
+ *
+ * This class is most useful as a parameter type for functions that wrap C APIs.
  */
 template <typename Char> class basic_cstring_view {
  private:
   const Char* data_;
 
  public:
-  /** Constructs a string reference object from a C string. */
+  /// Constructs a string reference object from a C string.
   basic_cstring_view(const Char* s) : data_(s) {}
 
-  /**
-    \rst
-    Constructs a string reference from an ``std::string`` object.
-    \endrst
-   */
+  /// Constructs a string reference from an `std::string` object.
   basic_cstring_view(const std::basic_string<Char>& s) : data_(s.c_str()) {}
 
-  /** Returns the pointer to a C string. */
+  /// Returns the pointer to a C string.
   auto c_str() const -> const Char* { return data_; }
 };
 
@@ -135,33 +122,30 @@ FMT_API std::system_error vwindows_error(int error_code, string_view format_str,
                                          format_args args);
 
 /**
- \rst
- Constructs a :class:`std::system_error` object with the description
- of the form
-
- .. parsed-literal::
-   *<message>*: *<system-message>*
-
- where *<message>* is the formatted message and *<system-message>* is the
- system message corresponding to the error code.
- *error_code* is a Windows error code as given by ``GetLastError``.
- If *error_code* is not a valid error code such as -1, the system message
- will look like "error -1".
-
- **Example**::
-
-   // This throws a system_error with the description
-   //   cannot open file 'madeup': The system cannot find the file specified.
-   // or similar (system message may vary).
-   const char *filename = "madeup";
-   LPOFSTRUCT of = LPOFSTRUCT();
-   HFILE file = OpenFile(filename, &of, OF_READ);
-   if (file == HFILE_ERROR) {
-     throw fmt::windows_error(GetLastError(),
-                              "cannot open file '{}'", filename);
-   }
- \endrst
-*/
+ * Constructs a `std::system_error` object with the description of the form
+ *
+ *     <message>: <system-message>
+ *
+ * where `<message>` is the formatted message and `<system-message>` is the
+ * system message corresponding to the error code.
+ * `error_code` is a Windows error code as given by `GetLastError`.
+ * If `error_code` is not a valid error code such as -1, the system message
+ * will look like "error -1".
+ *
+ * **Example**:
+ *
+ *     // This throws a system_error with the description
+ *     //   cannot open file 'madeup': The system cannot find the file
+ * specified.
+ *     // or similar (system message may vary).
+ *     const char *filename = "madeup";
+ *     LPOFSTRUCT of = LPOFSTRUCT();
+ *     HFILE file = OpenFile(filename, &of, OF_READ);
+ *     if (file == HFILE_ERROR) {
+ *       throw fmt::windows_error(GetLastError(),
+ *                                "cannot open file '{}'", filename);
+ *     }
+ */
 template <typename... Args>
 std::system_error windows_error(int error_code, string_view message,
                                 const Args&... args) {
@@ -227,17 +211,16 @@ class buffered_file {
 
   FMT_API auto descriptor() const -> int;
 
-  void vprint(string_view format_str, format_args args) {
-    fmt::vprint(file_, format_str, args);
-  }
-
-  template <typename... Args>
-  inline void print(string_view format_str, const Args&... args) {
-    vprint(format_str, fmt::make_format_args(args...));
+  template <typename... T>
+  inline void print(string_view fmt, const T&... args) {
+    const auto& vargs = fmt::make_format_args(args...);
+    detail::is_locking<T...>() ? fmt::vprint_buffered(file_, fmt, vargs)
+                               : fmt::vprint(file_, fmt, vargs);
   }
 };
 
 #if FMT_USE_FCNTL
+
 // A file. Closed file is represented by a file object with descriptor -1.
 // Methods that are not declared with noexcept may throw
 // fmt::system_error in case of failure. Note that some errors such as
@@ -251,6 +234,8 @@ class FMT_API file {
   // Constructs a file object with a given descriptor.
   explicit file(int fd) : fd_(fd) {}
 
+  friend struct pipe;
+
  public:
   // Possible values for the oflag argument to the constructor.
   enum {
@@ -313,11 +298,6 @@ class FMT_API file {
   // necessary.
   void dup2(int fd, std::error_code& ec) noexcept;
 
-  // Creates a pipe setting up read_end and write_end file objects for reading
-  // and writing respectively.
-  // DEPRECATED! Taking files as out parameters is deprecated.
-  static void pipe(file& read_end, file& write_end);
-
   // Creates a buffered_file object associated with this file and detaches
   // this file object from the file.
   auto fdopen(const char* mode) -> buffered_file;
@@ -329,6 +309,15 @@ class FMT_API file {
 #  endif
 };
 
+struct FMT_API pipe {
+  file read_end;
+  file write_end;
+
+  // Creates a pipe setting up read_end and write_end file objects for reading
+  // and writing respectively.
+  pipe();
+};
+
 // Returns the memory page size.
 auto getpagesize() -> long;
 
@@ -370,13 +359,14 @@ struct ostream_params {
 };
 
 class file_buffer final : public buffer<char> {
+ private:
   file file_;
 
-  FMT_API void grow(size_t) override;
+  FMT_API static void grow(buffer<char>& buf, size_t);
 
  public:
   FMT_API file_buffer(cstring_view path, const ostream_params& params);
-  FMT_API file_buffer(file_buffer&& other);
+  FMT_API file_buffer(file_buffer&& other) noexcept;
   FMT_API ~file_buffer();
 
   void flush() {
@@ -393,11 +383,10 @@ class file_buffer final : public buffer<char> {
 
 }  // namespace detail
 
-// Added {} below to work around default constructor error known to
-// occur in Xcode versions 7.2.1 and 8.2.1.
-constexpr detail::buffer_size buffer_size{};
+constexpr auto buffer_size = detail::buffer_size();
 
-/** A fast output stream which is not thread-safe. */
+/// A fast output stream for writing from a single thread. Writing from
+/// multiple threads without external synchronization may result in a data race.
 class FMT_API ostream {
  private:
   FMT_MSC_WARNING(suppress : 4251)
@@ -418,30 +407,25 @@ class FMT_API ostream {
 
   void close() { buffer_.close(); }
 
-  /**
-    Formats ``args`` according to specifications in ``fmt`` and writes the
-    output to the file.
-   */
+  /// Formats `args` according to specifications in `fmt` and writes the
+  /// output to the file.
   template <typename... T> void print(format_string<T...> fmt, T&&... args) {
-    vformat_to(std::back_inserter(buffer_), fmt,
-               fmt::make_format_args(args...));
+    vformat_to(appender(buffer_), fmt, fmt::make_format_args(args...));
   }
 };
 
 /**
-  \rst
-  Opens a file for writing. Supported parameters passed in *params*:
-
-  * ``<integer>``: Flags passed to `open
-    <https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html>`_
-    (``file::WRONLY | file::CREATE | file::TRUNC`` by default)
-  * ``buffer_size=<integer>``: Output buffer size
-
-  **Example**::
-
-    auto out = fmt::output_file("guide.txt");
-    out.print("Don't {}", "Panic");
-  \endrst
+ * Opens a file for writing. Supported parameters passed in `params`:
+ *
+ * - `<integer>`: Flags passed to [open](
+ *   https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html)
+ *   (`file::WRONLY | file::CREATE | file::TRUNC` by default)
+ * - `buffer_size=<integer>`: Output buffer size
+ *
+ * **Example**:
+ *
+ *     auto out = fmt::output_file("guide.txt");
+ *     out.print("Don't {}", "Panic");
  */
 template <typename... T>
 inline auto output_file(cstring_view path, T... params) -> ostream {

include/spdlog/fmt/bundled/ostream.h

@@ -8,7 +8,9 @@
 #ifndef FMT_OSTREAM_H_
 #define FMT_OSTREAM_H_
 
-#include <fstream>  // std::filebuf
+#ifndef FMT_MODULE
+#  include <fstream>  // std::filebuf
+#endif
 
 #ifdef _WIN32
 #  ifdef __GLIBCXX__
@@ -18,42 +20,11 @@
 #  include <io.h>
 #endif
 
-#include "format.h"
+#include "chrono.h"  // formatbuf
 
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
-template <typename Streambuf> class formatbuf : public Streambuf {
- private:
-  using char_type = typename Streambuf::char_type;
-  using streamsize = decltype(std::declval<Streambuf>().sputn(nullptr, 0));
-  using int_type = typename Streambuf::int_type;
-  using traits_type = typename Streambuf::traits_type;
-
-  buffer<char_type>& buffer_;
-
- public:
-  explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
-
- protected:
-  // The put area is always empty. This makes the implementation simpler and has
-  // the advantage that the streambuf and the buffer are always in sync and
-  // sputc never writes into uninitialized memory. A disadvantage is that each
-  // call to sputc always results in a (virtual) call to overflow. There is no
-  // disadvantage here for sputn since this always results in a call to xsputn.
-
-  auto overflow(int_type ch) -> int_type override {
-    if (!traits_type::eq_int_type(ch, traits_type::eof()))
-      buffer_.push_back(static_cast<char_type>(ch));
-    return ch;
-  }
-
-  auto xsputn(const char_type* s, streamsize count) -> streamsize override {
-    buffer_.append(s, s + count);
-    return count;
-  }
-};
-
 // Generate a unique explicit instantion in every translation unit using a tag
 // type in an anonymous namespace.
 namespace {
@@ -73,12 +44,12 @@ auto get_file(std::filebuf&) -> FILE*;
 inline auto write_ostream_unicode(std::ostream& os, fmt::string_view data)
     -> bool {
   FILE* f = nullptr;
-#if FMT_MSC_VERSION
+#if FMT_MSC_VERSION && FMT_USE_RTTI
   if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
     f = get_file(*buf);
   else
     return false;
-#elif defined(_WIN32) && defined(__GLIBCXX__)
+#elif defined(_WIN32) && defined(__GLIBCXX__) && FMT_USE_RTTI
   auto* rdbuf = os.rdbuf();
   if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
     f = sfbuf->file();
@@ -143,9 +114,8 @@ template <typename Char>
 struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
   void set_debug_format() = delete;
 
-  template <typename T, typename OutputIt>
-  auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
-      -> OutputIt {
+  template <typename T, typename Context>
+  auto format(const T& value, Context& ctx) const -> decltype(ctx.out()) {
     auto buffer = basic_memory_buffer<Char>();
     detail::format_value(buffer, value);
     return formatter<basic_string_view<Char>, Char>::format(
@@ -158,22 +128,20 @@ using ostream_formatter = basic_ostream_formatter<char>;
 template <typename T, typename Char>
 struct formatter<detail::streamed_view<T>, Char>
     : basic_ostream_formatter<Char> {
-  template <typename OutputIt>
-  auto format(detail::streamed_view<T> view,
-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
+  template <typename Context>
+  auto format(detail::streamed_view<T> view, Context& ctx) const
+      -> decltype(ctx.out()) {
     return basic_ostream_formatter<Char>::format(view.value, ctx);
   }
 };
 
 /**
-  \rst
-  Returns a view that formats `value` via an ostream ``operator<<``.
-
-  **Example**::
-
-    fmt::print("Current thread id: {}\n",
-               fmt::streamed(std::this_thread::get_id()));
-  \endrst
+ * Returns a view that formats `value` via an ostream `operator<<`.
+ *
+ * **Example**:
+ *
+ *     fmt::print("Current thread id: {}\n",
+ *                fmt::streamed(std::this_thread::get_id()));
  */
 template <typename T>
 constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
@@ -194,7 +162,7 @@ inline void vprint_directly(std::ostream& os, string_view format_str,
 FMT_EXPORT template <typename Char>
 void vprint(std::basic_ostream<Char>& os,
             basic_string_view<type_identity_t<Char>> format_str,
-            basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+            typename detail::vformat_args<Char>::type args) {
   auto buffer = basic_memory_buffer<Char>();
   detail::vformat_to(buffer, format_str, args);
   if (detail::write_ostream_unicode(os, {buffer.data(), buffer.size()})) return;
@@ -202,18 +170,16 @@ void vprint(std::basic_ostream<Char>& os,
 }
 
 /**
-  \rst
-  Prints formatted data to the stream *os*.
-
-  **Example**::
-
-    fmt::print(cerr, "Don't {}!", "panic");
-  \endrst
+ * Prints formatted data to the stream `os`.
+ *
+ * **Example**:
+ *
+ *     fmt::print(cerr, "Don't {}!", "panic");
  */
 FMT_EXPORT template <typename... T>
 void print(std::ostream& os, format_string<T...> fmt, T&&... args) {
   const auto& vargs = fmt::make_format_args(args...);
-  if (detail::is_utf8())
+  if (detail::use_utf8())
     vprint(os, fmt, vargs);
   else
     detail::vprint_directly(os, fmt, vargs);
@@ -224,7 +190,7 @@ template <typename... Args>
 void print(std::wostream& os,
            basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
            Args&&... args) {
-  vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
+  vprint(os, fmt, fmt::make_format_args<buffered_context<wchar_t>>(args...));
 }
 
 FMT_EXPORT template <typename... T>

include/spdlog/fmt/bundled/printf.h

@@ -8,8 +8,10 @@
 #ifndef FMT_PRINTF_H_
 #define FMT_PRINTF_H_
 
-#include <algorithm>  // std::max
-#include <limits>     // std::numeric_limits
+#ifndef FMT_MODULE
+#  include <algorithm>  // std::max
+#  include <limits>     // std::numeric_limits
+#endif
 
 #include "format.h"
 
@@ -22,7 +24,7 @@ template <typename T> struct printf_formatter {
 
 template <typename Char> class basic_printf_context {
  private:
-  detail::buffer_appender<Char> out_;
+  basic_appender<Char> out_;
   basic_format_args<basic_printf_context> args_;
 
   static_assert(std::is_same<Char, char>::value ||
@@ -34,28 +36,20 @@ template <typename Char> class basic_printf_context {
   using parse_context_type = basic_format_parse_context<Char>;
   template <typename T> using formatter_type = printf_formatter<T>;
 
-  /**
-    \rst
-    Constructs a ``printf_context`` object. References to the arguments are
-    stored in the context object so make sure they have appropriate lifetimes.
-    \endrst
-   */
-  basic_printf_context(detail::buffer_appender<Char> out,
+  /// Constructs a `printf_context` object. References to the arguments are
+  /// stored in the context object so make sure they have appropriate lifetimes.
+  basic_printf_context(basic_appender<Char> out,
                        basic_format_args<basic_printf_context> args)
       : out_(out), args_(args) {}
 
-  auto out() -> detail::buffer_appender<Char> { return out_; }
-  void advance_to(detail::buffer_appender<Char>) {}
+  auto out() -> basic_appender<Char> { return out_; }
+  void advance_to(basic_appender<Char>) {}
 
   auto locale() -> detail::locale_ref { return {}; }
 
   auto arg(int id) const -> basic_format_arg<basic_printf_context> {
     return args_.get(id);
   }
-
-  FMT_CONSTEXPR void on_error(const char* message) {
-    detail::error_handler().on_error(message);
-  }
 };
 
 namespace detail {
@@ -64,7 +58,7 @@ namespace detail {
 // signed and unsigned integers.
 template <bool IsSigned> struct int_checker {
   template <typename T> static auto fits_in_int(T value) -> bool {
-    unsigned max = max_value<int>();
+    unsigned max = to_unsigned(max_value<int>());
     return value <= max;
   }
   static auto fits_in_int(bool) -> bool { return true; }
@@ -82,13 +76,13 @@ struct printf_precision_handler {
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
   auto operator()(T value) -> int {
     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
-      throw_format_error("number is too big");
+      report_error("number is too big");
     return (std::max)(static_cast<int>(value), 0);
   }
 
   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
   auto operator()(T) -> int {
-    throw_format_error("precision is not integer");
+    report_error("precision is not integer");
     return 0;
   }
 };
@@ -165,7 +159,7 @@ template <typename T, typename Context> class arg_converter {
 // unsigned).
 template <typename T, typename Context, typename Char>
 void convert_arg(basic_format_arg<Context>& arg, Char type) {
-  visit_format_arg(arg_converter<T, Context>(arg, type), arg);
+  arg.visit(arg_converter<T, Context>(arg, type));
 }
 
 // Converts an integer argument to char for printf.
@@ -195,12 +189,12 @@ template <typename Char> struct get_cstring {
 
 // Checks if an argument is a valid printf width specifier and sets
 // left alignment if it is negative.
-template <typename Char> class printf_width_handler {
+class printf_width_handler {
  private:
-  format_specs<Char>& specs_;
+  format_specs& specs_;
 
  public:
-  explicit printf_width_handler(format_specs<Char>& specs) : specs_(specs) {}
+  explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
 
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
   auto operator()(T value) -> unsigned {
@@ -209,14 +203,14 @@ template <typename Char> class printf_width_handler {
       specs_.align = align::left;
       width = 0 - width;
     }
-    unsigned int_max = max_value<int>();
-    if (width > int_max) throw_format_error("number is too big");
+    unsigned int_max = to_unsigned(max_value<int>());
+    if (width > int_max) report_error("number is too big");
     return static_cast<unsigned>(width);
   }
 
   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
   auto operator()(T) -> unsigned {
-    throw_format_error("width is not integer");
+    report_error("width is not integer");
     return 0;
   }
 };
@@ -224,12 +218,12 @@ template <typename Char> class printf_width_handler {
 // Workaround for a bug with the XL compiler when initializing
 // printf_arg_formatter's base class.
 template <typename Char>
-auto make_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s)
+auto make_arg_formatter(basic_appender<Char> iter, format_specs& s)
     -> arg_formatter<Char> {
   return {iter, s, locale_ref()};
 }
 
-// The ``printf`` argument formatter.
+// The `printf` argument formatter.
 template <typename Char>
 class printf_arg_formatter : public arg_formatter<Char> {
  private:
@@ -241,11 +235,11 @@ class printf_arg_formatter : public arg_formatter<Char> {
   void write_null_pointer(bool is_string = false) {
     auto s = this->specs;
     s.type = presentation_type::none;
-    write_bytes(this->out, is_string ? "(null)" : "(nil)", s);
+    write_bytes<Char>(this->out, is_string ? "(null)" : "(nil)", s);
   }
 
  public:
-  printf_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s,
+  printf_arg_formatter(basic_appender<Char> iter, format_specs& s,
                        context_type& ctx)
       : base(make_arg_formatter(iter, s)), context_(ctx) {}
 
@@ -259,19 +253,18 @@ class printf_arg_formatter : public arg_formatter<Char> {
       base::operator()(value);
       return;
     }
-    format_specs<Char> fmt_specs = this->specs;
-    if (fmt_specs.type != presentation_type::none &&
-        fmt_specs.type != presentation_type::chr) {
+    format_specs s = this->specs;
+    if (s.type != presentation_type::none && s.type != presentation_type::chr) {
       return (*this)(static_cast<int>(value));
     }
-    fmt_specs.sign = sign::none;
-    fmt_specs.alt = false;
-    fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
+    s.sign = sign::none;
+    s.alt = false;
+    s.fill = ' ';  // Ignore '0' flag for char types.
     // align::numeric needs to be overwritten here since the '0' flag is
     // ignored for non-numeric types
-    if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
-      fmt_specs.align = align::right;
-    write<Char>(this->out, static_cast<Char>(value), fmt_specs);
+    if (s.align == align::none || s.align == align::numeric)
+      s.align = align::right;
+    write<Char>(this->out, static_cast<Char>(value), s);
   }
 
   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
@@ -279,7 +272,6 @@ class printf_arg_formatter : public arg_formatter<Char> {
     base::operator()(value);
   }
 
-  /** Formats a null-terminated C string. */
   void operator()(const char* value) {
     if (value)
       base::operator()(value);
@@ -287,7 +279,6 @@ class printf_arg_formatter : public arg_formatter<Char> {
       write_null_pointer(this->specs.type != presentation_type::pointer);
   }
 
-  /** Formats a null-terminated wide C string. */
   void operator()(const wchar_t* value) {
     if (value)
       base::operator()(value);
@@ -297,7 +288,6 @@ class printf_arg_formatter : public arg_formatter<Char> {
 
   void operator()(basic_string_view<Char> value) { base::operator()(value); }
 
-  /** Formats a pointer. */
   void operator()(const void* value) {
     if (value)
       base::operator()(value);
@@ -305,7 +295,6 @@ class printf_arg_formatter : public arg_formatter<Char> {
       write_null_pointer();
   }
 
-  /** Formats an argument of a custom (user-defined) type. */
   void operator()(typename basic_format_arg<context_type>::handle handle) {
     auto parse_ctx = basic_format_parse_context<Char>({});
     handle.format(parse_ctx, context_);
@@ -313,7 +302,7 @@ class printf_arg_formatter : public arg_formatter<Char> {
 };
 
 template <typename Char>
-void parse_flags(format_specs<Char>& specs, const Char*& it, const Char* end) {
+void parse_flags(format_specs& specs, const Char*& it, const Char* end) {
   for (; it != end; ++it) {
     switch (*it) {
     case '-':
@@ -323,7 +312,7 @@ void parse_flags(format_specs<Char>& specs, const Char*& it, const Char* end) {
       specs.sign = sign::plus;
       break;
     case '0':
-      specs.fill[0] = '0';
+      specs.fill = '0';
       break;
     case ' ':
       if (specs.sign != sign::plus) specs.sign = sign::space;
@@ -338,7 +327,7 @@ void parse_flags(format_specs<Char>& specs, const Char*& it, const Char* end) {
 }
 
 template <typename Char, typename GetArg>
-auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
+auto parse_header(const Char*& it, const Char* end, format_specs& specs,
                   GetArg get_arg) -> int {
   int arg_index = -1;
   Char c = *it;
@@ -350,11 +339,11 @@ auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
       ++it;
       arg_index = value != -1 ? value : max_value<int>();
     } else {
-      if (c == '0') specs.fill[0] = '0';
+      if (c == '0') specs.fill = '0';
       if (value != 0) {
         // Nonzero value means that we parsed width and don't need to
         // parse it or flags again, so return now.
-        if (value == -1) throw_format_error("number is too big");
+        if (value == -1) report_error("number is too big");
         specs.width = value;
         return arg_index;
       }
@@ -365,17 +354,17 @@ auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
   if (it != end) {
     if (*it >= '0' && *it <= '9') {
       specs.width = parse_nonnegative_int(it, end, -1);
-      if (specs.width == -1) throw_format_error("number is too big");
+      if (specs.width == -1) report_error("number is too big");
     } else if (*it == '*') {
       ++it;
-      specs.width = static_cast<int>(visit_format_arg(
-          detail::printf_width_handler<Char>(specs), get_arg(-1)));
+      specs.width = static_cast<int>(
+          get_arg(-1).visit(detail::printf_width_handler(specs)));
     }
   }
   return arg_index;
 }
 
-inline auto parse_printf_presentation_type(char c, type t)
+inline auto parse_printf_presentation_type(char c, type t, bool& upper)
     -> presentation_type {
   using pt = presentation_type;
   constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
@@ -384,26 +373,31 @@ inline auto parse_printf_presentation_type(char c, type t)
     return in(t, integral_set) ? pt::dec : pt::none;
   case 'o':
     return in(t, integral_set) ? pt::oct : pt::none;
-  case 'x':
-    return in(t, integral_set) ? pt::hex_lower : pt::none;
   case 'X':
-    return in(t, integral_set) ? pt::hex_upper : pt::none;
-  case 'a':
-    return in(t, float_set) ? pt::hexfloat_lower : pt::none;
-  case 'A':
-    return in(t, float_set) ? pt::hexfloat_upper : pt::none;
-  case 'e':
-    return in(t, float_set) ? pt::exp_lower : pt::none;
+    upper = true;
+    FMT_FALLTHROUGH;
+  case 'x':
+    return in(t, integral_set) ? pt::hex : pt::none;
   case 'E':
-    return in(t, float_set) ? pt::exp_upper : pt::none;
-  case 'f':
-    return in(t, float_set) ? pt::fixed_lower : pt::none;
+    upper = true;
+    FMT_FALLTHROUGH;
+  case 'e':
+    return in(t, float_set) ? pt::exp : pt::none;
   case 'F':
-    return in(t, float_set) ? pt::fixed_upper : pt::none;
-  case 'g':
-    return in(t, float_set) ? pt::general_lower : pt::none;
+    upper = true;
+    FMT_FALLTHROUGH;
+  case 'f':
+    return in(t, float_set) ? pt::fixed : pt::none;
   case 'G':
-    return in(t, float_set) ? pt::general_upper : pt::none;
+    upper = true;
+    FMT_FALLTHROUGH;
+  case 'g':
+    return in(t, float_set) ? pt::general : pt::none;
+  case 'A':
+    upper = true;
+    FMT_FALLTHROUGH;
+  case 'a':
+    return in(t, float_set) ? pt::hexfloat : pt::none;
   case 'c':
     return in(t, integral_set) ? pt::chr : pt::none;
   case 's':
@@ -418,7 +412,7 @@ inline auto parse_printf_presentation_type(char c, type t)
 template <typename Char, typename Context>
 void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
              basic_format_args<Context> args) {
-  using iterator = buffer_appender<Char>;
+  using iterator = basic_appender<Char>;
   auto out = iterator(buf);
   auto context = basic_printf_context<Char>(out, args);
   auto parse_ctx = basic_format_parse_context<Char>(format);
@@ -449,12 +443,12 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
     }
     write(out, basic_string_view<Char>(start, to_unsigned(it - 1 - start)));
 
-    auto specs = format_specs<Char>();
+    auto specs = format_specs();
     specs.align = align::right;
 
     // Parse argument index, flags and width.
     int arg_index = parse_header(it, end, specs, get_arg);
-    if (arg_index == 0) throw_format_error("argument not found");
+    if (arg_index == 0) report_error("argument not found");
 
     // Parse precision.
     if (it != end && *it == '.') {
@@ -464,8 +458,8 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
         specs.precision = parse_nonnegative_int(it, end, 0);
       } else if (c == '*') {
         ++it;
-        specs.precision = static_cast<int>(
-            visit_format_arg(printf_precision_handler(), get_arg(-1)));
+        specs.precision =
+            static_cast<int>(get_arg(-1).visit(printf_precision_handler()));
       } else {
         specs.precision = 0;
       }
@@ -476,23 +470,23 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
     // specified, the '0' flag is ignored
     if (specs.precision >= 0 && arg.is_integral()) {
       // Ignore '0' for non-numeric types or if '-' present.
-      specs.fill[0] = ' ';
+      specs.fill = ' ';
     }
     if (specs.precision >= 0 && arg.type() == type::cstring_type) {
-      auto str = visit_format_arg(get_cstring<Char>(), arg);
+      auto str = arg.visit(get_cstring<Char>());
       auto str_end = str + specs.precision;
       auto nul = std::find(str, str_end, Char());
       auto sv = basic_string_view<Char>(
           str, to_unsigned(nul != str_end ? nul - str : specs.precision));
       arg = make_arg<basic_printf_context<Char>>(sv);
     }
-    if (specs.alt && visit_format_arg(is_zero_int(), arg)) specs.alt = false;
-    if (specs.fill[0] == '0') {
+    if (specs.alt && arg.visit(is_zero_int())) specs.alt = false;
+    if (specs.fill.template get<Char>() == '0') {
       if (arg.is_arithmetic() && specs.align != align::left)
         specs.align = align::numeric;
       else
-        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
-                              // flag is also present.
+        specs.fill = ' ';  // Ignore '0' flag for non-numeric types or if '-'
+                           // flag is also present.
     }
 
     // Parse length and convert the argument to the required type.
@@ -536,7 +530,7 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
     }
 
     // Parse type.
-    if (it == end) throw_format_error("invalid format string");
+    if (it == end) report_error("invalid format string");
     char type = static_cast<char>(*it++);
     if (arg.is_integral()) {
       // Normalize type.
@@ -546,18 +540,20 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
         type = 'd';
         break;
       case 'c':
-        visit_format_arg(char_converter<basic_printf_context<Char>>(arg), arg);
+        arg.visit(char_converter<basic_printf_context<Char>>(arg));
         break;
       }
     }
-    specs.type = parse_printf_presentation_type(type, arg.type());
+    bool upper = false;
+    specs.type = parse_printf_presentation_type(type, arg.type(), upper);
     if (specs.type == presentation_type::none)
-      throw_format_error("invalid format specifier");
+      report_error("invalid format specifier");
+    specs.upper = upper;
 
     start = it;
 
     // Format argument.
-    visit_format_arg(printf_arg_formatter<Char>(out, specs, context), arg);
+    arg.visit(printf_arg_formatter<Char>(out, specs, context));
   }
   write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 }
@@ -569,29 +565,21 @@ using wprintf_context = basic_printf_context<wchar_t>;
 using printf_args = basic_format_args<printf_context>;
 using wprintf_args = basic_format_args<wprintf_context>;
 
-/**
-  \rst
-  Constructs an `~fmt::format_arg_store` object that contains references to
-  arguments and can be implicitly converted to `~fmt::printf_args`.
-  \endrst
- */
-template <typename... T>
-inline auto make_printf_args(const T&... args)
-    -> format_arg_store<printf_context, T...> {
-  return {args...};
+/// Constructs an `format_arg_store` object that contains references to
+/// arguments and can be implicitly converted to `printf_args`.
+template <typename Char = char, typename... T>
+inline auto make_printf_args(T&... args)
+    -> decltype(fmt::make_format_args<basic_printf_context<Char>>(args...)) {
+  return fmt::make_format_args<basic_printf_context<Char>>(args...);
 }
 
-// DEPRECATED!
-template <typename... T>
-inline auto make_wprintf_args(const T&... args)
-    -> format_arg_store<wprintf_context, T...> {
-  return {args...};
-}
+template <typename Char> struct vprintf_args {
+  using type = basic_format_args<basic_printf_context<Char>>;
+};
 
 template <typename Char>
-inline auto vsprintf(
-    basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
+inline auto vsprintf(basic_string_view<Char> fmt,
+                     typename vprintf_args<Char>::type args)
     -> std::basic_string<Char> {
   auto buf = basic_memory_buffer<Char>();
   detail::vprintf(buf, fmt, args);
@@ -599,26 +587,22 @@ inline auto vsprintf(
 }
 
 /**
-  \rst
-  Formats arguments and returns the result as a string.
-
-  **Example**::
-
-    std::string message = fmt::sprintf("The answer is %d", 42);
-  \endrst
-*/
-template <typename S, typename... T,
-          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
+ * Formats `args` according to specifications in `fmt` and returns the result
+ * as as string.
+ *
+ * **Example**:
+ *
+ *     std::string message = fmt::sprintf("The answer is %d", 42);
+ */
+template <typename S, typename... T, typename Char = 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 Char>
-inline auto vfprintf(
-    std::FILE* f, basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
-    -> int {
+inline 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();
@@ -628,36 +612,33 @@ inline auto vfprintf(
 }
 
 /**
-  \rst
-  Prints formatted data to the file *f*.
-
-  **Example**::
-
-    fmt::fprintf(stderr, "Don't %s!", "panic");
-  \endrst
+ * Formats `args` according to specifications in `fmt` and writes the output
+ * to `f`.
+ *
+ * **Example**:
+ *
+ *     fmt::fprintf(stderr, "Don't %s!", "panic");
  */
 template <typename S, typename... T, typename Char = char_t<S>>
 inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
   return vfprintf(f, detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
+                  make_printf_args<Char>(args...));
 }
 
 template <typename Char>
-FMT_DEPRECATED inline auto vprintf(
-    basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
+FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
+                                   typename vprintf_args<Char>::type args)
     -> int {
   return vfprintf(stdout, fmt, args);
 }
 
 /**
-  \rst
-  Prints formatted data to ``stdout``.
-
-  **Example**::
-
-    fmt::printf("Elapsed time: %.2f seconds", 1.23);
-  \endrst
+ * Formats `args` according to specifications in `fmt` and writes the output
+ * to `stdout`.
+ *
+ * **Example**:
+ *
+ *   fmt::printf("Elapsed time: %.2f seconds", 1.23);
  */
 template <typename... T>
 inline auto printf(string_view fmt, const T&... args) -> int {
@@ -666,7 +647,7 @@ inline auto printf(string_view fmt, const T&... args) -> int {
 template <typename... T>
 FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
                                   const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_wprintf_args(args...));
+  return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
 }
 
 FMT_END_EXPORT

include/spdlog/fmt/bundled/ranges.h

@@ -8,67 +8,31 @@
 #ifndef FMT_RANGES_H_
 #define FMT_RANGES_H_
 
-#include <initializer_list>
-#include <tuple>
-#include <type_traits>
+#ifndef FMT_MODULE
+#  include <initializer_list>
+#  include <iterator>
+#  include <string>
+#  include <tuple>
+#  include <type_traits>
+#  include <utility>
+#endif
 
 #include "format.h"
 
 FMT_BEGIN_NAMESPACE
 
+FMT_EXPORT
+enum class range_format { disabled, map, set, sequence, string, debug_string };
+
 namespace detail {
 
-template <typename Range, typename OutputIt>
-auto copy(const Range& range, OutputIt out) -> OutputIt {
-  for (auto it = range.begin(), end = range.end(); it != end; ++it)
-    *out++ = *it;
-  return out;
-}
-
-template <typename OutputIt>
-auto copy(const char* str, OutputIt out) -> OutputIt {
-  while (*str) *out++ = *str++;
-  return out;
-}
-
-template <typename OutputIt> auto copy(char ch, OutputIt out) -> OutputIt {
-  *out++ = ch;
-  return out;
-}
-
-template <typename OutputIt> auto copy(wchar_t ch, OutputIt out) -> OutputIt {
-  *out++ = ch;
-  return out;
-}
-
-// Returns true if T has a std::string-like interface, like std::string_view.
-template <typename T> class is_std_string_like {
-  template <typename U>
-  static auto check(U* p)
-      -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
-  template <typename> static void check(...);
-
- public:
-  static constexpr const bool value =
-      is_string<T>::value ||
-      std::is_convertible<T, std_string_view<char>>::value ||
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-};
-
-template <typename Char>
-struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
-
 template <typename T> class is_map {
   template <typename U> static auto check(U*) -> typename U::mapped_type;
   template <typename> static void check(...);
 
  public:
-#ifdef FMT_FORMAT_MAP_AS_LIST  // DEPRECATED!
-  static constexpr const bool value = false;
-#else
   static constexpr const bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value;
-#endif
 };
 
 template <typename T> class is_set {
@@ -76,12 +40,8 @@ template <typename T> class is_set {
   template <typename> static void check(...);
 
  public:
-#ifdef FMT_FORMAT_SET_AS_LIST  // DEPRECATED!
-  static constexpr const bool value = false;
-#else
   static constexpr const bool value =
       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
-#endif
 };
 
 template <typename... Ts> struct conditional_helper {};
@@ -110,17 +70,17 @@ template <typename T, typename Enable = void>
 struct has_member_fn_begin_end_t : std::false_type {};
 
 template <typename T>
-struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
+struct has_member_fn_begin_end_t<T, void_t<decltype(*std::declval<T>().begin()),
                                            decltype(std::declval<T>().end())>>
     : std::true_type {};
 
-// Member function overload
+// Member function overloads.
 template <typename T>
 auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
 template <typename T>
 auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
 
-// ADL overload. Only participates in overload resolution if member functions
+// ADL overloads. Only participate in overload resolution if member functions
 // are not found.
 template <typename T>
 auto range_begin(T&& rng)
@@ -141,16 +101,16 @@ struct has_mutable_begin_end : std::false_type {};
 
 template <typename T>
 struct has_const_begin_end<
-    T,
-    void_t<
-        decltype(detail::range_begin(std::declval<const remove_cvref_t<T>&>())),
-        decltype(detail::range_end(std::declval<const remove_cvref_t<T>&>()))>>
+    T, void_t<decltype(*detail::range_begin(
+                  std::declval<const remove_cvref_t<T>&>())),
+              decltype(detail::range_end(
+                  std::declval<const remove_cvref_t<T>&>()))>>
     : std::true_type {};
 
 template <typename T>
 struct has_mutable_begin_end<
-    T, void_t<decltype(detail::range_begin(std::declval<T>())),
-              decltype(detail::range_end(std::declval<T>())),
+    T, void_t<decltype(*detail::range_begin(std::declval<T&>())),
+              decltype(detail::range_end(std::declval<T&>())),
               // the extra int here is because older versions of MSVC don't
               // SFINAE properly unless there are distinct types
               int>> : std::true_type {};
@@ -206,12 +166,13 @@ class is_tuple_formattable_ {
   static constexpr const bool value = false;
 };
 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
-  template <std::size_t... Is>
-  static auto check2(index_sequence<Is...>,
-                     integer_sequence<bool, (Is == Is)...>) -> std::true_type;
-  static auto check2(...) -> std::false_type;
-  template <std::size_t... Is>
-  static auto check(index_sequence<Is...>) -> decltype(check2(
+  template <size_t... Is>
+  static auto all_true(index_sequence<Is...>,
+                       integer_sequence<bool, (Is >= 0)...>) -> std::true_type;
+  static auto all_true(...) -> std::false_type;
+
+  template <size_t... Is>
+  static auto check(index_sequence<Is...>) -> decltype(all_true(
       index_sequence<Is...>{},
       integer_sequence<bool,
                        (is_formattable<typename std::tuple_element<Is, T>::type,
@@ -292,6 +253,18 @@ FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
 template <typename Formatter>
 FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
 
+template <typename T>
+struct range_format_kind_
+    : std::integral_constant<range_format,
+                             std::is_same<uncvref_type<T>, T>::value
+                                 ? range_format::disabled
+                             : is_map<T>::value ? range_format::map
+                             : is_set<T>::value ? range_format::set
+                                                : range_format::sequence> {};
+
+template <range_format K>
+using range_format_constant = std::integral_constant<range_format, K>;
+
 // These are not generic lambdas for compatibility with C++11.
 template <typename ParseContext> struct parse_empty_specs {
   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
@@ -305,8 +278,7 @@ template <typename FormatContext> struct format_tuple_element {
 
   template <typename T>
   void operator()(const formatter<T, char_type>& f, const T& v) {
-    if (i > 0)
-      ctx.advance_to(detail::copy_str<char_type>(separator, ctx.out()));
+    if (i > 0) ctx.advance_to(detail::copy<char_type>(separator, ctx.out()));
     ctx.advance_to(f.format(v, ctx));
     ++i;
   }
@@ -358,8 +330,7 @@ struct formatter<Tuple, Char,
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     auto it = ctx.begin();
-    if (it != ctx.end() && *it != '}')
-      FMT_THROW(format_error("invalid format specifier"));
+    if (it != ctx.end() && *it != '}') report_error("invalid format specifier");
     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
     return it;
   }
@@ -367,19 +338,17 @@ struct formatter<Tuple, Char,
   template <typename FormatContext>
   auto format(const Tuple& value, FormatContext& ctx) const
       -> decltype(ctx.out()) {
-    ctx.advance_to(detail::copy_str<Char>(opening_bracket_, ctx.out()));
+    ctx.advance_to(detail::copy<Char>(opening_bracket_, ctx.out()));
     detail::for_each2(
         formatters_, value,
         detail::format_tuple_element<FormatContext>{0, ctx, separator_});
-    return detail::copy_str<Char>(closing_bracket_, ctx.out());
+    return detail::copy<Char>(closing_bracket_, ctx.out());
   }
 };
 
 template <typename T, typename Char> struct is_range {
   static constexpr const bool value =
-      detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
-      !std::is_convertible<T, std::basic_string<Char>>::value &&
-      !std::is_convertible<T, detail::std_string_view<Char>>::value;
+      detail::is_range_<T>::value && !detail::has_to_string_view<T>::value;
 };
 
 namespace detail {
@@ -401,8 +370,8 @@ template <typename Context> struct range_mapper {
 
 template <typename Char, typename Element>
 using range_formatter_type =
-    formatter<remove_cvref_t<decltype(range_mapper<buffer_context<Char>>{}.map(
-                  std::declval<Element>()))>,
+    formatter<remove_cvref_t<decltype(range_mapper<buffered_context<Char>>{}
+                                          .map(std::declval<Element>()))>,
               Char>;
 
 template <typename R>
@@ -438,6 +407,24 @@ struct range_formatter<
       detail::string_literal<Char, '['>{};
   basic_string_view<Char> closing_bracket_ =
       detail::string_literal<Char, ']'>{};
+  bool is_debug = false;
+
+  template <typename Output, typename It, typename Sentinel, typename U = T,
+            FMT_ENABLE_IF(std::is_same<U, Char>::value)>
+  auto write_debug_string(Output& out, It it, Sentinel end) const -> Output {
+    auto buf = basic_memory_buffer<Char>();
+    for (; it != end; ++it) buf.push_back(*it);
+    auto specs = format_specs();
+    specs.type = presentation_type::debug;
+    return detail::write<Char>(
+        out, basic_string_view<Char>(buf.data(), buf.size()), specs);
+  }
+
+  template <typename Output, typename It, typename Sentinel, typename U = T,
+            FMT_ENABLE_IF(!std::is_same<U, Char>::value)>
+  auto write_debug_string(Output& out, It, Sentinel) const -> Output {
+    return out;
+  }
 
  public:
   FMT_CONSTEXPR range_formatter() {}
@@ -460,17 +447,37 @@ struct range_formatter<
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     auto it = ctx.begin();
     auto end = ctx.end();
+    detail::maybe_set_debug_format(underlying_, true);
+    if (it == end) return underlying_.parse(ctx);
 
-    if (it != end && *it == 'n') {
+    switch (detail::to_ascii(*it)) {
+    case 'n':
       set_brackets({}, {});
       ++it;
+      break;
+    case '?':
+      is_debug = true;
+      set_brackets({}, {});
+      ++it;
+      if (it == end || *it != 's') report_error("invalid format specifier");
+      FMT_FALLTHROUGH;
+    case 's':
+      if (!std::is_same<T, Char>::value)
+        report_error("invalid format specifier");
+      if (!is_debug) {
+        set_brackets(detail::string_literal<Char, '"'>{},
+                     detail::string_literal<Char, '"'>{});
+        set_separator({});
+        detail::maybe_set_debug_format(underlying_, false);
+      }
+      ++it;
+      return it;
     }
 
     if (it != end && *it != '}') {
-      if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
+      if (*it != ':') report_error("invalid format specifier");
+      detail::maybe_set_debug_format(underlying_, false);
       ++it;
-    } else {
-      detail::maybe_set_debug_format(underlying_, true);
     }
 
     ctx.advance_to(it);
@@ -479,80 +486,27 @@ struct range_formatter<
 
   template <typename R, typename FormatContext>
   auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
-    detail::range_mapper<buffer_context<Char>> mapper;
+    auto mapper = detail::range_mapper<buffered_context<Char>>();
     auto out = ctx.out();
-    out = detail::copy_str<Char>(opening_bracket_, out);
-    int i = 0;
     auto it = detail::range_begin(range);
     auto end = detail::range_end(range);
+    if (is_debug) return write_debug_string(out, std::move(it), end);
+
+    out = detail::copy<Char>(opening_bracket_, out);
+    int i = 0;
     for (; it != end; ++it) {
-      if (i > 0) out = detail::copy_str<Char>(separator_, out);
+      if (i > 0) out = detail::copy<Char>(separator_, out);
       ctx.advance_to(out);
-      auto&& item = *it;
+      auto&& item = *it;  // Need an lvalue
       out = underlying_.format(mapper.map(item), ctx);
       ++i;
     }
-    out = detail::copy_str<Char>(closing_bracket_, out);
+    out = detail::copy<Char>(closing_bracket_, out);
     return out;
   }
 };
 
-enum class range_format { disabled, map, set, sequence, string, debug_string };
-
-namespace detail {
-template <typename T>
-struct range_format_kind_
-    : std::integral_constant<range_format,
-                             std::is_same<uncvref_type<T>, T>::value
-                                 ? range_format::disabled
-                             : is_map<T>::value ? range_format::map
-                             : is_set<T>::value ? range_format::set
-                                                : range_format::sequence> {};
-
-template <range_format K, typename R, typename Char, typename Enable = void>
-struct range_default_formatter;
-
-template <range_format K>
-using range_format_constant = std::integral_constant<range_format, K>;
-
-template <range_format K, typename R, typename Char>
-struct range_default_formatter<
-    K, R, Char,
-    enable_if_t<(K == range_format::sequence || K == range_format::map ||
-                 K == range_format::set)>> {
-  using range_type = detail::maybe_const_range<R>;
-  range_formatter<detail::uncvref_type<range_type>, Char> underlying_;
-
-  FMT_CONSTEXPR range_default_formatter() { init(range_format_constant<K>()); }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::set>) {
-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
-                             detail::string_literal<Char, '}'>{});
-  }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::map>) {
-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
-                             detail::string_literal<Char, '}'>{});
-    underlying_.underlying().set_brackets({}, {});
-    underlying_.underlying().set_separator(
-        detail::string_literal<Char, ':', ' '>{});
-  }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::sequence>) {}
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return underlying_.parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(range_type& range, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return underlying_.format(range, ctx);
-  }
-};
-}  // namespace detail
-
+FMT_EXPORT
 template <typename T, typename Char, typename Enable = void>
 struct range_format_kind
     : conditional_t<
@@ -562,18 +516,221 @@ struct range_format_kind
 template <typename R, typename Char>
 struct formatter<
     R, Char,
-    enable_if_t<conjunction<bool_constant<range_format_kind<R, Char>::value !=
-                                          range_format::disabled>
+    enable_if_t<conjunction<
+        bool_constant<
+            range_format_kind<R, Char>::value != range_format::disabled &&
+            range_format_kind<R, Char>::value != range_format::map &&
+            range_format_kind<R, Char>::value != range_format::string &&
+            range_format_kind<R, Char>::value != range_format::debug_string>
 // Workaround a bug in MSVC 2015 and earlier.
 #if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
-                            ,
-                            detail::is_formattable_delayed<R, Char>
+        ,
+        detail::is_formattable_delayed<R, Char>
 #endif
-                            >::value>>
-    : detail::range_default_formatter<range_format_kind<R, Char>::value, R,
-                                      Char> {
+        >::value>> {
+ private:
+  using range_type = detail::maybe_const_range<R>;
+  range_formatter<detail::uncvref_type<range_type>, Char> range_formatter_;
+
+ public:
+  using nonlocking = void;
+
+  FMT_CONSTEXPR formatter() {
+    if (detail::const_check(range_format_kind<R, Char>::value !=
+                            range_format::set))
+      return;
+    range_formatter_.set_brackets(detail::string_literal<Char, '{'>{},
+                                  detail::string_literal<Char, '}'>{});
+  }
+
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    return range_formatter_.parse(ctx);
+  }
+
+  template <typename FormatContext>
+  auto format(range_type& range, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return range_formatter_.format(range, ctx);
+  }
 };
 
+// A map formatter.
+template <typename R, typename Char>
+struct formatter<
+    R, Char,
+    enable_if_t<range_format_kind<R, Char>::value == range_format::map>> {
+ private:
+  using map_type = detail::maybe_const_range<R>;
+  using element_type = detail::uncvref_type<map_type>;
+
+  decltype(detail::tuple::get_formatters<element_type, Char>(
+      detail::tuple_index_sequence<element_type>())) formatters_;
+  bool no_delimiters_ = false;
+
+ public:
+  FMT_CONSTEXPR formatter() {}
+
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    auto it = ctx.begin();
+    auto end = ctx.end();
+    if (it != end) {
+      if (detail::to_ascii(*it) == 'n') {
+        no_delimiters_ = true;
+        ++it;
+      }
+      if (it != end && *it != '}') {
+        if (*it != ':') report_error("invalid format specifier");
+        ++it;
+      }
+      ctx.advance_to(it);
+    }
+    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
+    return it;
+  }
+
+  template <typename FormatContext>
+  auto format(map_type& map, FormatContext& ctx) const -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    basic_string_view<Char> open = detail::string_literal<Char, '{'>{};
+    if (!no_delimiters_) out = detail::copy<Char>(open, out);
+    int i = 0;
+    auto mapper = detail::range_mapper<buffered_context<Char>>();
+    basic_string_view<Char> sep = detail::string_literal<Char, ',', ' '>{};
+    for (auto&& value : map) {
+      if (i > 0) out = detail::copy<Char>(sep, out);
+      ctx.advance_to(out);
+      detail::for_each2(formatters_, mapper.map(value),
+                        detail::format_tuple_element<FormatContext>{
+                            0, ctx, detail::string_literal<Char, ':', ' '>{}});
+      ++i;
+    }
+    basic_string_view<Char> close = detail::string_literal<Char, '}'>{};
+    if (!no_delimiters_) out = detail::copy<Char>(close, out);
+    return out;
+  }
+};
+
+// A (debug_)string formatter.
+template <typename R, typename Char>
+struct formatter<
+    R, Char,
+    enable_if_t<range_format_kind<R, Char>::value == range_format::string ||
+                range_format_kind<R, Char>::value ==
+                    range_format::debug_string>> {
+ private:
+  using range_type = detail::maybe_const_range<R>;
+  using string_type =
+      conditional_t<std::is_constructible<
+                        detail::std_string_view<Char>,
+                        decltype(detail::range_begin(std::declval<R>())),
+                        decltype(detail::range_end(std::declval<R>()))>::value,
+                    detail::std_string_view<Char>, std::basic_string<Char>>;
+
+  formatter<string_type, Char> underlying_;
+
+ public:
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    return underlying_.parse(ctx);
+  }
+
+  template <typename FormatContext>
+  auto format(range_type& range, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    if (detail::const_check(range_format_kind<R, Char>::value ==
+                            range_format::debug_string))
+      *out++ = '"';
+    out = underlying_.format(
+        string_type{detail::range_begin(range), detail::range_end(range)}, ctx);
+    if (detail::const_check(range_format_kind<R, Char>::value ==
+                            range_format::debug_string))
+      *out++ = '"';
+    return out;
+  }
+};
+
+template <typename It, typename Sentinel, typename Char = char>
+struct join_view : detail::view {
+  It begin;
+  Sentinel end;
+  basic_string_view<Char> sep;
+
+  join_view(It b, Sentinel e, basic_string_view<Char> s)
+      : begin(std::move(b)), end(e), sep(s) {}
+};
+
+template <typename It, typename Sentinel, typename Char>
+struct formatter<join_view<It, Sentinel, Char>, Char> {
+ private:
+  using value_type =
+#ifdef __cpp_lib_ranges
+      std::iter_value_t<It>;
+#else
+      typename std::iterator_traits<It>::value_type;
+#endif
+  formatter<remove_cvref_t<value_type>, Char> value_formatter_;
+
+  using view_ref = conditional_t<std::is_copy_constructible<It>::value,
+                                 const join_view<It, Sentinel, Char>&,
+                                 join_view<It, Sentinel, Char>&&>;
+
+ public:
+  using nonlocking = void;
+
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
+    return value_formatter_.parse(ctx);
+  }
+
+  template <typename FormatContext>
+  auto format(view_ref& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto it = std::forward<view_ref>(value).begin;
+    auto out = ctx.out();
+    if (it == value.end) return out;
+    out = value_formatter_.format(*it, ctx);
+    ++it;
+    while (it != value.end) {
+      out = detail::copy<Char>(value.sep.begin(), value.sep.end(), out);
+      ctx.advance_to(out);
+      out = value_formatter_.format(*it, ctx);
+      ++it;
+    }
+    return out;
+  }
+};
+
+/// Returns a view that formats the iterator range `[begin, end)` with elements
+/// separated by `sep`.
+template <typename It, typename Sentinel>
+auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
+  return {std::move(begin), end, sep};
+}
+
+/**
+ * Returns a view that formats `range` with elements separated by `sep`.
+ *
+ * **Example**:
+ *
+ *     auto v = std::vector<int>{1, 2, 3};
+ *     fmt::print("{}", fmt::join(v, ", "));
+ *     // Output: 1, 2, 3
+ *
+ * `fmt::join` applies passed format specifiers to the range elements:
+ *
+ *     fmt::print("{:02}", fmt::join(v, ", "));
+ *     // Output: 01, 02, 03
+ */
+template <typename Range>
+auto join(Range&& r, string_view sep)
+    -> join_view<decltype(detail::range_begin(r)),
+                 decltype(detail::range_end(r))> {
+  return {detail::range_begin(r), detail::range_end(r), sep};
+}
+
 template <typename Char, typename... T> struct tuple_join_view : detail::view {
   const std::tuple<T...>& tuple;
   basic_string_view<Char> sep;
@@ -623,7 +780,7 @@ struct formatter<tuple_join_view<Char, T...>, Char> {
     if (N > 1) {
       auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
       if (end != end1)
-        FMT_THROW(format_error("incompatible format specs for tuple elements"));
+        report_error("incompatible format specs for tuple elements");
     }
 #endif
     return end;
@@ -642,12 +799,10 @@ struct formatter<tuple_join_view<Char, T...>, Char> {
       typename FormatContext::iterator {
     auto out = std::get<sizeof...(T) - N>(formatters_)
                    .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
-    if (N > 1) {
-      out = std::copy(value.sep.begin(), value.sep.end(), out);
-      ctx.advance_to(out);
-      return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
-    }
-    return out;
+    if (N <= 1) return out;
+    out = detail::copy<Char>(value.sep, out);
+    ctx.advance_to(out);
+    return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
   }
 };
 
@@ -692,15 +847,13 @@ struct formatter<
 FMT_BEGIN_EXPORT
 
 /**
-  \rst
-  Returns an object that formats `tuple` with elements separated by `sep`.
-
-  **Example**::
-
-    std::tuple<int, char> t = {1, 'a'};
-    fmt::print("{}", fmt::join(t, ", "));
-    // Output: "1, a"
-  \endrst
+ * Returns an object that formats `std::tuple` with elements separated by `sep`.
+ *
+ * **Example**:
+ *
+ *     auto t = std::tuple<int, char>{1, 'a'};
+ *     fmt::print("{}", fmt::join(t, ", "));
+ *     // Output: 1, a
  */
 template <typename... T>
 FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
@@ -708,23 +861,14 @@ FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
   return {tuple, sep};
 }
 
-template <typename... T>
-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
-                        basic_string_view<wchar_t> sep)
-    -> tuple_join_view<wchar_t, T...> {
-  return {tuple, sep};
-}
-
 /**
-  \rst
-  Returns an object that formats `initializer_list` with elements separated by
-  `sep`.
-
-  **Example**::
-
-    fmt::print("{}", fmt::join({1, 2, 3}, ", "));
-    // Output: "1, 2, 3"
-  \endrst
+ * Returns an object that formats `std::initializer_list` with elements
+ * separated by `sep`.
+ *
+ * **Example**:
+ *
+ *     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
+ *     // Output: "1, 2, 3"
  */
 template <typename T>
 auto join(std::initializer_list<T> list, string_view sep)

include/spdlog/fmt/bundled/std.h

@@ -8,39 +8,47 @@
 #ifndef FMT_STD_H_
 #define FMT_STD_H_
 
-#include <atomic>
-#include <bitset>
-#include <cstdlib>
-#include <exception>
-#include <memory>
-#include <thread>
-#include <type_traits>
-#include <typeinfo>
-#include <utility>
-#include <vector>
-
 #include "format.h"
 #include "ostream.h"
 
+#ifndef FMT_MODULE
+#  include <atomic>
+#  include <bitset>
+#  include <complex>
+#  include <cstdlib>
+#  include <exception>
+#  include <memory>
+#  include <thread>
+#  include <type_traits>
+#  include <typeinfo>
+#  include <utility>
+#  include <vector>
+
+// Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
+#  if FMT_CPLUSPLUS >= 201703L
+#    if FMT_HAS_INCLUDE(<filesystem>)
+#      include <filesystem>
+#    endif
+#    if FMT_HAS_INCLUDE(<variant>)
+#      include <variant>
+#    endif
+#    if FMT_HAS_INCLUDE(<optional>)
+#      include <optional>
+#    endif
+#  endif
+// Use > instead of >= in the version check because <source_location> may be
+// available after C++17 but before C++20 is marked as implemented.
+#  if FMT_CPLUSPLUS > 201703L && FMT_HAS_INCLUDE(<source_location>)
+#    include <source_location>
+#  endif
+#  if FMT_CPLUSPLUS > 202002L && FMT_HAS_INCLUDE(<expected>)
+#    include <expected>
+#  endif
+#endif  // FMT_MODULE
+
 #if FMT_HAS_INCLUDE(<version>)
 #  include <version>
 #endif
-// Checking FMT_CPLUSPLUS for warning suppression in MSVC.
-#if FMT_CPLUSPLUS >= 201703L
-#  if FMT_HAS_INCLUDE(<filesystem>)
-#    include <filesystem>
-#  endif
-#  if FMT_HAS_INCLUDE(<variant>)
-#    include <variant>
-#  endif
-#  if FMT_HAS_INCLUDE(<optional>)
-#    include <optional>
-#  endif
-#endif
-
-#if FMT_CPLUSPLUS > 201703L && FMT_HAS_INCLUDE(<source_location>)
-#  include <source_location>
-#endif
 
 // GCC 4 does not support FMT_HAS_INCLUDE.
 #if FMT_HAS_INCLUDE(<cxxabi.h>) || defined(__GLIBCXX__)
@@ -52,17 +60,6 @@
 #  endif
 #endif
 
-// Check if typeid is available.
-#ifndef FMT_USE_TYPEID
-// __RTTI is for EDG compilers. In MSVC typeid is available without RTTI.
-#  if defined(__GXX_RTTI) || FMT_HAS_FEATURE(cxx_rtti) || FMT_MSC_VERSION || \
-      defined(__INTEL_RTTI__) || defined(__RTTI)
-#    define FMT_USE_TYPEID 1
-#  else
-#    define FMT_USE_TYPEID 0
-#  endif
-#endif
-
 // For older Xcode versions, __cpp_lib_xxx flags are inaccurately defined.
 #ifndef FMT_CPP_LIB_FILESYSTEM
 #  ifdef __cpp_lib_filesystem
@@ -117,7 +114,7 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
 FMT_EXPORT
 template <typename Char> struct formatter<std::filesystem::path, Char> {
  private:
-  format_specs<Char> specs_;
+  format_specs specs_;
   detail::arg_ref<Char> width_ref_;
   bool debug_ = false;
   char path_type_ = 0;
@@ -137,18 +134,16 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
       debug_ = true;
       ++it;
     }
-    if (it != end && (*it == 'g')) path_type_ = *it++;
+    if (it != end && (*it == 'g')) path_type_ = detail::to_ascii(*it++);
     return it;
   }
 
   template <typename FormatContext>
   auto format(const std::filesystem::path& p, FormatContext& ctx) const {
     auto specs = specs_;
-#  ifdef _WIN32
-    auto path_string = !path_type_ ? p.native() : p.generic_wstring();
-#  else
-    auto path_string = !path_type_ ? p.native() : p.generic_string();
-#  endif
+    auto path_string =
+        !path_type_ ? p.native()
+                    : p.generic_string<std::filesystem::path::value_type>();
 
     detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
                                                        ctx);
@@ -163,6 +158,22 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
                          specs);
   }
 };
+
+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
 
@@ -242,6 +253,56 @@ struct formatter<std::optional<T>, Char,
 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<is_formattable<T, Char>::value &&
+                                  is_formattable<E, Char>::value>> {
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const std::expected<T, E>& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+
+    if (value.has_value()) {
+      out = detail::write<Char>(out, "expected(");
+      out = detail::write_escaped_alternative<Char>(out, *value);
+    } else {
+      out = detail::write<Char>(out, "unexpected(");
+      out = detail::write_escaped_alternative<Char>(out, value.error());
+    }
+    *out++ = ')';
+    return out;
+  }
+};
+FMT_END_NAMESPACE
+#endif  // __cpp_lib_expected
+
 #ifdef __cpp_lib_source_location
 FMT_BEGIN_NAMESPACE
 FMT_EXPORT
@@ -291,16 +352,6 @@ template <typename T, typename C> class is_variant_formattable_ {
       decltype(check(variant_index_sequence<T>{}))::value;
 };
 
-template <typename Char, typename OutputIt, typename T>
-auto write_variant_alternative(OutputIt out, const T& v) -> OutputIt {
-  if constexpr (is_string<T>::value)
-    return write_escaped_string<Char>(out, detail::to_string_view(v));
-  else if constexpr (std::is_same_v<T, Char>)
-    return write_escaped_char(out, v);
-  else
-    return write<Char>(out, v);
-}
-
 }  // namespace detail
 
 template <typename T> struct is_variant_like {
@@ -346,7 +397,7 @@ struct formatter<
     FMT_TRY {
       std::visit(
           [&](const auto& v) {
-            out = detail::write_variant_alternative<Char>(out, v);
+            out = detail::write_escaped_alternative<Char>(out, v);
           },
           value);
     }
@@ -372,13 +423,102 @@ template <typename Char> struct formatter<std::error_code, Char> {
   FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
       -> decltype(ctx.out()) {
     auto out = ctx.out();
-    out = detail::write_bytes(out, ec.category().name(), format_specs<Char>());
+    out = detail::write_bytes<Char>(out, ec.category().name(), format_specs());
     out = detail::write<Char>(out, Char(':'));
     out = detail::write<Char>(out, ec.value());
     return out;
   }
 };
 
+#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.
+                 > {
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    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);
+  }
+};
+#endif
+
 FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<
@@ -395,74 +535,23 @@ struct formatter<
     if (it == end || *it == '}') return it;
     if (*it == 't') {
       ++it;
-      with_typename_ = FMT_USE_TYPEID != 0;
+      with_typename_ = FMT_USE_RTTI != 0;
     }
     return it;
   }
 
-  template <typename OutputIt>
-  auto format(const std::exception& ex,
-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
-    format_specs<Char> spec;
+  template <typename Context>
+  auto format(const std::exception& ex, Context& ctx) const
+      -> decltype(ctx.out()) {
     auto out = ctx.out();
-    if (!with_typename_)
-      return detail::write_bytes(out, string_view(ex.what()), spec);
-
-#if FMT_USE_TYPEID
-    const std::type_info& ti = typeid(ex);
-#  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());
+#if FMT_USE_RTTI
+    if (with_typename_) {
+      out = detail::write_demangled_name<Char>(out, typeid(ex));
+      *out++ = ':';
+      *out++ = ' ';
     }
-    out = detail::write_bytes(out, demangled_name_view, spec);
-#  elif FMT_MSC_VERSION
-    string_view demangled_name_view(ti.name());
-    if (demangled_name_view.starts_with("class "))
-      demangled_name_view.remove_prefix(6);
-    else if (demangled_name_view.starts_with("struct "))
-      demangled_name_view.remove_prefix(7);
-    out = detail::write_bytes(out, demangled_name_view, spec);
-#  else
-    out = detail::write_bytes(out, string_view(ti.name()), spec);
-#  endif
-    *out++ = ':';
-    *out++ = ' ';
-    return detail::write_bytes(out, string_view(ex.what()), spec);
 #endif
+    return detail::write_bytes<Char>(out, string_view(ex.what()));
   }
 };
 
@@ -509,6 +598,14 @@ 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,
@@ -533,5 +630,70 @@ 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_;
+
+  template <typename FormatContext, typename OutputIt>
+  FMT_CONSTEXPR auto do_format(const std::complex<T>& c,
+                               detail::dynamic_format_specs<Char>& specs,
+                               FormatContext& ctx, OutputIt out) const
+      -> OutputIt {
+    if (c.real() != 0) {
+      *out++ = Char('(');
+      out = detail::write<Char>(out, c.real(), specs, ctx.locale());
+      specs.sign = sign::plus;
+      out = detail::write<Char>(out, c.imag(), specs, ctx.locale());
+      if (!detail::isfinite(c.imag())) *out++ = Char(' ');
+      *out++ = Char('i');
+      *out++ = Char(')');
+      return out;
+    }
+    out = detail::write<Char>(out, c.imag(), specs, ctx.locale());
+    if (!detail::isfinite(c.imag())) *out++ = Char(' ');
+    *out++ = Char('i');
+    return out;
+  }
+
+ public:
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    if (ctx.begin() == ctx.end() || *ctx.begin() == '}') return ctx.begin();
+    return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
+                              detail::type_constant<T, Char>::value);
+  }
+
+  template <typename FormatContext>
+  auto format(const std::complex<T>& c, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto specs = specs_;
+    if (specs.width_ref.kind != detail::arg_id_kind::none ||
+        specs.precision_ref.kind != detail::arg_id_kind::none) {
+      detail::handle_dynamic_spec<detail::width_checker>(specs.width,
+                                                         specs.width_ref, ctx);
+      detail::handle_dynamic_spec<detail::precision_checker>(
+          specs.precision, specs.precision_ref, ctx);
+    }
+
+    if (specs.width == 0) return do_format(c, specs, ctx, ctx.out());
+    auto buf = basic_memory_buffer<Char>();
+
+    auto outer_specs = format_specs();
+    outer_specs.width = specs.width;
+    outer_specs.fill = specs.fill;
+    outer_specs.align = specs.align;
+
+    specs.width = 0;
+    specs.fill = {};
+    specs.align = align::none;
+
+    do_format(c, specs, ctx, basic_appender<Char>(buf));
+    return detail::write<Char>(ctx.out(),
+                               basic_string_view<Char>(buf.data(), buf.size()),
+                               outer_specs);
+  }
+};
+
 FMT_END_NAMESPACE
 #endif  // FMT_STD_H_

include/spdlog/fmt/bundled/xchar.h

@@ -8,12 +8,15 @@
 #ifndef FMT_XCHAR_H_
 #define FMT_XCHAR_H_
 
-#include <cwchar>
-
+#include "color.h"
 #include "format.h"
+#include "ranges.h"
 
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-#  include <locale>
+#ifndef FMT_MODULE
+#  include <cwchar>
+#  if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
+#    include <locale>
+#  endif
 #endif
 
 FMT_BEGIN_NAMESPACE
@@ -22,9 +25,24 @@ namespace detail {
 template <typename T>
 using is_exotic_char = bool_constant<!std::is_same<T, char>::value>;
 
-inline auto write_loc(std::back_insert_iterator<detail::buffer<wchar_t>> out,
-                      loc_value value, const format_specs<wchar_t>& specs,
-                      locale_ref loc) -> bool {
+template <typename S, typename = void> struct format_string_char {};
+
+template <typename S>
+struct format_string_char<
+    S, void_t<decltype(sizeof(detail::to_string_view(std::declval<S>())))>> {
+  using type = char_t<S>;
+};
+
+template <typename S>
+struct format_string_char<S, enable_if_t<is_compile_string<S>::value>> {
+  using type = typename S::char_type;
+};
+
+template <typename S>
+using format_string_char_t = typename format_string_char<S>::type;
+
+inline auto write_loc(basic_appender<wchar_t> out, loc_value value,
+                      const format_specs& specs, locale_ref loc) -> bool {
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
   auto& numpunct =
       std::use_facet<std::numpunct<wchar_t>>(loc.get<std::locale>());
@@ -41,7 +59,7 @@ FMT_BEGIN_EXPORT
 
 using wstring_view = basic_string_view<wchar_t>;
 using wformat_parse_context = basic_format_parse_context<wchar_t>;
-using wformat_context = buffer_context<wchar_t>;
+using wformat_context = buffered_context<wchar_t>;
 using wformat_args = basic_format_args<wformat_context>;
 using wmemory_buffer = basic_memory_buffer<wchar_t>;
 
@@ -58,14 +76,18 @@ inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
 #endif
 
 template <> struct is_char<wchar_t> : std::true_type {};
-template <> struct is_char<detail::char8_type> : 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(const T&... args)
-    -> format_arg_store<wformat_context, T...> {
-  return {args...};
+constexpr auto make_wformat_args(T&... args)
+    -> decltype(fmt::make_format_args<wformat_context>(args...)) {
+  return fmt::make_format_args<wformat_context>(args...);
 }
 
 inline namespace literals {
@@ -96,9 +118,15 @@ auto join(std::initializer_list<T> list, wstring_view sep)
   return join(std::begin(list), std::end(list), sep);
 }
 
+template <typename... T>
+auto join(const std::tuple<T...>& tuple, basic_string_view<wchar_t> sep)
+    -> tuple_join_view<wchar_t, T...> {
+  return {tuple, sep};
+}
+
 template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
 auto vformat(basic_string_view<Char> format_str,
-             basic_format_args<buffer_context<type_identity_t<Char>>> args)
+             typename detail::vformat_args<Char>::type args)
     -> std::basic_string<Char> {
   auto buf = basic_memory_buffer<Char>();
   detail::vformat_to(buf, format_str, args);
@@ -110,63 +138,74 @@ auto format(wformat_string<T...> fmt, T&&... args) -> std::wstring {
   return vformat(fmt::wstring_view(fmt), fmt::make_wformat_args(args...));
 }
 
+template <typename OutputIt, typename... T>
+auto format_to(OutputIt out, wformat_string<T...> fmt, T&&... args)
+    -> OutputIt {
+  return vformat_to(out, fmt::wstring_view(fmt),
+                    fmt::make_wformat_args(args...));
+}
+
 // Pass char_t as a default template parameter instead of using
 // std::basic_string<char_t<S>> to reduce the symbol size.
-template <typename S, typename... T, typename Char = char_t<S>,
+template <typename S, typename... T,
+          typename Char = detail::format_string_char_t<S>,
           FMT_ENABLE_IF(!std::is_same<Char, char>::value &&
                         !std::is_same<Char, wchar_t>::value)>
 auto format(const S& format_str, T&&... args) -> std::basic_string<Char> {
   return vformat(detail::to_string_view(format_str),
-                 fmt::make_format_args<buffer_context<Char>>(args...));
+                 fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
-template <typename Locale, typename S, typename Char = char_t<S>,
+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& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
+inline auto vformat(const Locale& loc, const S& format_str,
+                    typename detail::vformat_args<Char>::type args)
     -> std::basic_string<Char> {
   return detail::vformat(loc, detail::to_string_view(format_str), args);
 }
 
-template <typename Locale, typename S, typename... T, typename Char = char_t<S>,
+template <typename Locale, 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& format_str, T&&... args)
     -> std::basic_string<Char> {
-  return detail::vformat(loc, detail::to_string_view(format_str),
-                         fmt::make_format_args<buffer_context<Char>>(args...));
+  return detail::vformat(
+      loc, detail::to_string_view(format_str),
+      fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
-template <typename OutputIt, typename S, typename Char = char_t<S>,
+template <typename OutputIt, typename S,
+          typename Char = detail::format_string_char_t<S>,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                             detail::is_exotic_char<Char>::value)>
 auto vformat_to(OutputIt out, const S& format_str,
-                basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> OutputIt {
+                typename detail::vformat_args<Char>::type args) -> OutputIt {
   auto&& buf = detail::get_buffer<Char>(out);
   detail::vformat_to(buf, detail::to_string_view(format_str), args);
   return detail::get_iterator(buf, out);
 }
 
 template <typename OutputIt, typename S, typename... T,
-          typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_exotic_char<Char>::value)>
+          typename Char = detail::format_string_char_t<S>,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value &&
+                        !std::is_same<Char, char>::value &&
+                        !std::is_same<Char, wchar_t>::value)>
 inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
   return vformat_to(out, detail::to_string_view(fmt),
-                    fmt::make_format_args<buffer_context<Char>>(args...));
+                    fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
 template <typename Locale, typename S, typename OutputIt, typename... Args,
-          typename Char = char_t<S>,
+          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& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) -> OutputIt {
+inline auto vformat_to(OutputIt out, const Locale& loc, const S& format_str,
+                       typename detail::vformat_args<Char>::type args)
+    -> OutputIt {
   auto&& buf = detail::get_buffer<Char>(out);
   vformat_to(buf, detail::to_string_view(format_str), args,
              detail::locale_ref(loc));
@@ -174,7 +213,7 @@ inline auto vformat_to(
 }
 
 template <typename OutputIt, typename Locale, typename S, typename... T,
-          typename Char = char_t<S>,
+          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>
@@ -182,15 +221,15 @@ inline auto format_to(OutputIt out, const Locale& loc, const S& format_str,
                       T&&... args) ->
     typename std::enable_if<enable, OutputIt>::type {
   return vformat_to(out, loc, detail::to_string_view(format_str),
-                    fmt::make_format_args<buffer_context<Char>>(args...));
+                    fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
 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> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
+inline auto vformat_to_n(OutputIt out, size_t n,
+                         basic_string_view<Char> format_str,
+                         typename detail::vformat_args<Char>::type args)
     -> format_to_n_result<OutputIt> {
   using traits = detail::fixed_buffer_traits;
   auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
@@ -199,21 +238,22 @@ inline auto vformat_to_n(
 }
 
 template <typename OutputIt, typename S, typename... T,
-          typename Char = char_t<S>,
+          typename Char = detail::format_string_char_t<S>,
           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
                             detail::is_exotic_char<Char>::value)>
 inline auto format_to_n(OutputIt out, size_t n, const S& fmt, T&&... args)
     -> format_to_n_result<OutputIt> {
-  return vformat_to_n(out, n, detail::to_string_view(fmt),
-                      fmt::make_format_args<buffer_context<Char>>(args...));
+  return vformat_to_n(out, n, fmt::basic_string_view<Char>(fmt),
+                      fmt::make_format_args<buffered_context<Char>>(args...));
 }
 
-template <typename S, typename... T, typename Char = char_t<S>,
+template <typename S, typename... T,
+          typename Char = detail::format_string_char_t<S>,
           FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
 inline auto formatted_size(const S& fmt, T&&... args) -> size_t {
   auto buf = detail::counting_buffer<Char>();
   detail::vformat_to(buf, detail::to_string_view(fmt),
-                     fmt::make_format_args<buffer_context<Char>>(args...));
+                     fmt::make_format_args<buffered_context<Char>>(args...));
   return buf.count();
 }
 
@@ -247,9 +287,32 @@ template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
   return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
 }
 
-/**
-  Converts *value* to ``std::wstring`` using the default format for type *T*.
- */
+inline auto vformat(const text_style& ts, wstring_view fmt, wformat_args args)
+    -> std::wstring {
+  auto buf = wmemory_buffer();
+  detail::vformat_to(buf, ts, fmt, args);
+  return fmt::to_string(buf);
+}
+
+template <typename... T>
+inline auto format(const text_style& ts, wformat_string<T...> fmt, T&&... args)
+    -> std::wstring {
+  return fmt::vformat(ts, fmt, fmt::make_wformat_args(args...));
+}
+
+template <typename... T>
+FMT_DEPRECATED void print(std::FILE* f, 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...);
+}
+
+/// Converts `value` to `std::wstring` using the default format for type `T`.
 template <typename T> inline auto to_wstring(const T& value) -> std::wstring {
   return format(FMT_STRING(L"{}"), value);
 }

include/spdlog/fmt/fmt.h

@@ -20,11 +20,12 @@
     #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>
+    #include <fmt/xchar.h>
 #endif

include/spdlog/mdc.h

@@ -1,36 +1,50 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
 #pragma once
 
+#if defined(SPDLOG_NO_TLS)
+    #error "This header requires thread local storage support, but SPDLOG_NO_TLS is defined."
+#endif
+
 #include <map>
 #include <string>
 
 #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).
+//
+// 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!
+
 namespace spdlog {
-    class SPDLOG_API mdc {
-    public:
-        using mdc_map_t = std::map<std::string, std::string>;
+class SPDLOG_API mdc {
+public:
+    using mdc_map_t = std::map<std::string, std::string>;
 
-        static void put(const std::string &key, const std::string &value) {
-            get_context()[key] = value;
+    static void put(const std::string &key, const std::string &value) {
+        get_context()[key] = value;
+    }
+
+    static std::string get(const std::string &key) {
+        auto &context = get_context();
+        auto it = context.find(key);
+        if (it != context.end()) {
+            return it->second;
         }
+        return "";
+    }
 
-        static std::string get(const std::string &key) {
-            auto &context = get_context();
-            auto it = context.find(key);
-            if (it != context.end()) {
-                return it->second;
-            }
-            return "";
-        }
+    static void remove(const std::string &key) { get_context().erase(key); }
 
-        static void remove(const std::string &key) { get_context().erase(key); }
+    static void clear() { get_context().clear(); }
 
-        static void clear() { get_context().clear(); }
-
-        static mdc_map_t &get_context() {
-            static thread_local mdc_map_t context;
-            return context;
-        }
-    };
+    static mdc_map_t &get_context() {
+        static thread_local mdc_map_t context;
+        return context;
+    }
+};
 
 }  // namespace spdlog

include/spdlog/pattern_formatter-inl.h

@@ -10,7 +10,11 @@
 #include <spdlog/details/fmt_helper.h>
 #include <spdlog/details/log_msg.h>
 #include <spdlog/details/os.h>
-#include <spdlog/mdc.h>
+
+#ifndef SPDLOG_NO_TLS
+    #include <spdlog/mdc.h>
+#endif
+
 #include <spdlog/fmt/fmt.h>
 #include <spdlog/formatter.h>
 
@@ -176,7 +180,7 @@ public:
 
 // Abbreviated month
 static const std::array<const char *, 12> months{
-    {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sept", "Oct", "Nov", "Dec"}};
+    {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}};
 
 template <typename ScopedPadder>
 class b_formatter final : public flag_formatter {
@@ -786,11 +790,12 @@ private:
 
 // Class for formatting Mapped Diagnostic Context (MDC) in log messages.
 // Example: [logger-name] [info] [mdc_key_1:mdc_value_1 mdc_key_2:mdc_value_2] some message
+#ifndef SPDLOG_NO_TLS
 template <typename ScopedPadder>
 class mdc_formatter : public flag_formatter {
 public:
     explicit mdc_formatter(padding_info padinfo)
-            : flag_formatter(padinfo) {}
+        : flag_formatter(padinfo) {}
 
     void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override {
         auto &mdc_map = mdc::get_context();
@@ -802,7 +807,7 @@ public:
         }
     }
 
-    void format_mdc(const mdc::mdc_map_t &mdc_map, memory_buf_t &dest){
+    void format_mdc(const mdc::mdc_map_t &mdc_map, memory_buf_t &dest) {
         auto last_element = --mdc_map.end();
         for (auto it = mdc_map.begin(); it != mdc_map.end(); ++it) {
             auto &pair = *it;
@@ -824,8 +829,7 @@ public:
         }
     }
 };
-
-
+#endif
 
 // Full info formatter
 // pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] [%s:%#] %v
@@ -903,6 +907,7 @@ public:
             dest.push_back(' ');
         }
 
+#ifndef SPDLOG_NO_TLS
         // add mdc if present
         auto &mdc_map = mdc::get_context();
         if (!mdc_map.empty()) {
@@ -911,6 +916,7 @@ public:
             dest.push_back(']');
             dest.push_back(' ');
         }
+#endif
         // fmt_helper::append_string_view(msg.msg(), dest);
         fmt_helper::append_string_view(msg.payload, dest);
     }
@@ -918,11 +924,13 @@ public:
 private:
     std::chrono::seconds cache_timestamp_{0};
     memory_buf_t cached_datetime_;
+
+#ifndef SPDLOG_NO_TLS
     mdc_formatter<null_scoped_padder> mdc_formatter_{padding_info{}};
+#endif
+
 };
 
-
-
 }  // namespace details
 
 SPDLOG_INLINE pattern_formatter::pattern_formatter(std::string pattern,
@@ -1215,9 +1223,11 @@ SPDLOG_INLINE void pattern_formatter::handle_flag_(char flag, details::padding_i
                     padding));
             break;
 
+#ifndef SPDLOG_NO_TLS  // mdc formatter requires TLS support
         case ('&'):
             formatters_.push_back(details::make_unique<details::mdc_formatter<Padder>>(padding));
             break;
+#endif
 
         default:  // Unknown flag appears as is
             auto unknown_flag = details::make_unique<details::aggregate_formatter>();

include/spdlog/sinks/ansicolor_sink-inl.h

@@ -20,7 +20,7 @@ SPDLOG_INLINE ansicolor_sink<ConsoleMutex>::ansicolor_sink(FILE *target_file, co
       formatter_(details::make_unique<spdlog::pattern_formatter>())
 
 {
-    set_color_mode(mode);
+    set_color_mode_(mode);
     colors_.at(level::trace) = to_string_(white);
     colors_.at(level::debug) = to_string_(cyan);
     colors_.at(level::info) = to_string_(green);
@@ -82,12 +82,18 @@ SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::set_formatter(
 }
 
 template <typename ConsoleMutex>
-SPDLOG_INLINE bool ansicolor_sink<ConsoleMutex>::should_color() {
+SPDLOG_INLINE bool ansicolor_sink<ConsoleMutex>::should_color() const {
     return should_do_colors_;
 }
 
 template <typename ConsoleMutex>
 SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::set_color_mode(color_mode mode) {
+    std::lock_guard<mutex_t> lock(mutex_);
+    set_color_mode_(mode);
+}
+
+template <typename ConsoleMutex>
+SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::set_color_mode_(color_mode mode) {
     switch (mode) {
         case color_mode::always:
             should_do_colors_ = true;
@@ -105,15 +111,15 @@ 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) {
-    fwrite(color_code.data(), sizeof(char), color_code.size(), target_file_);
+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_);
 }
 
 template <typename ConsoleMutex>
 SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::print_range_(const memory_buf_t &formatted,
                                                               size_t start,
-                                                              size_t end) {
-    fwrite(formatted.data() + start, sizeof(char), end - start, target_file_);
+                                                              size_t end) const {
+    details::os::fwrite_bytes(formatted.data() + start, end - start, target_file_);
 }
 
 template <typename ConsoleMutex>

include/spdlog/sinks/ansicolor_sink.h

@@ -36,11 +36,11 @@ public:
 
     void set_color(level::level_enum color_level, string_view_t color);
     void set_color_mode(color_mode mode);
-    bool should_color();
+    bool should_color() const;
 
     void log(const details::log_msg &msg) override;
     void flush() override;
-    void set_pattern(const std::string &pattern) final;
+    void set_pattern(const std::string &pattern) final override;
     void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) override;
 
     // Formatting codes
@@ -84,8 +84,9 @@ private:
     bool should_do_colors_;
     std::unique_ptr<spdlog::formatter> formatter_;
     std::array<std::string, level::n_levels> colors_;
-    void print_ccode_(const string_view_t &color_code);
-    void print_range_(const memory_buf_t &formatted, size_t start, size_t end);
+    void set_color_mode_(color_mode mode);
+    void print_ccode_(const string_view_t &color_code) const;
+    void print_range_(const memory_buf_t &formatted, size_t start, size_t end) const;
     static std::string to_string_(const string_view_t &sv);
 };
 

include/spdlog/sinks/base_sink.h

@@ -28,10 +28,10 @@ public:
     base_sink &operator=(const base_sink &) = delete;
     base_sink &operator=(base_sink &&) = delete;
 
-    void log(const details::log_msg &msg) final;
-    void flush() final;
-    void set_pattern(const std::string &pattern) final;
-    void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) final;
+    void log(const details::log_msg &msg) final override;
+    void flush() final override;
+    void set_pattern(const std::string &pattern) final override;
+    void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) final override;
 
 protected:
     // sink formatter

include/spdlog/sinks/basic_file_sink-inl.h

@@ -26,6 +26,12 @@ SPDLOG_INLINE const filename_t &basic_file_sink<Mutex>::filename() const {
     return file_helper_.filename();
 }
 
+template <typename Mutex>
+SPDLOG_INLINE void basic_file_sink<Mutex>::truncate() {
+    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
+    file_helper_.reopen(true);
+}
+
 template <typename Mutex>
 SPDLOG_INLINE void basic_file_sink<Mutex>::sink_it_(const details::log_msg &msg) {
     memory_buf_t formatted;

include/spdlog/sinks/basic_file_sink.h

@@ -23,6 +23,7 @@ public:
                              bool truncate = false,
                              const file_event_handlers &event_handlers = {});
     const filename_t &filename() const;
+    void truncate();
 
 protected:
     void sink_it_(const details::log_msg &msg) override;

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/daily_file_sink.h

@@ -62,6 +62,8 @@ struct daily_filename_format_calculator {
  * Rotating file sink based on date.
  * If truncate != false , the created file will be truncated.
  * If max_files > 0, retain only the last max_files and delete previous.
+ * Note that old log files from previous executions will not be deleted by this class,
+ * rotation and deletion is only applied while the program is running.
  */
 template <typename Mutex, typename FileNameCalc = daily_filename_calculator>
 class daily_file_sink final : public base_sink<Mutex> {

include/spdlog/sinks/hourly_file_sink.h

@@ -39,6 +39,8 @@ struct hourly_filename_calculator {
  * Rotating file sink based on time.
  * If truncate != false , the created file will be truncated.
  * If max_files > 0, retain only the last max_files and delete previous.
+ * Note that old log files from previous executions will not be deleted by this class,
+ * rotation and deletion is only applied while the program is running.
  */
 template <typename Mutex, typename FileNameCalc = hourly_filename_calculator>
 class hourly_file_sink final : public base_sink<Mutex> {

include/spdlog/sinks/msvc_sink.h

@@ -32,7 +32,7 @@ class msvc_sink : public base_sink<Mutex> {
 public:
     msvc_sink() = default;
     msvc_sink(bool check_debugger_present)
-        : check_debugger_present_{check_debugger_present} {};
+        : check_debugger_present_{check_debugger_present} {}
 
 protected:
     void sink_it_(const details::log_msg &msg) override {

include/spdlog/sinks/null_sink.h

@@ -13,7 +13,7 @@ namespace spdlog {
 namespace sinks {
 
 template <typename Mutex>
-class null_sink : public base_sink<Mutex> {
+class null_sink final : public base_sink<Mutex> {
 protected:
     void sink_it_(const details::log_msg &) override {}
     void flush_() override {}

include/spdlog/sinks/rotating_file_sink-inl.h

@@ -60,7 +60,7 @@ SPDLOG_INLINE filename_t rotating_file_sink<Mutex>::calc_filename(const filename
 
     filename_t basename, ext;
     std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
-    return fmt_lib::format(SPDLOG_FILENAME_T("{}.{}{}"), basename, index, ext);
+    return fmt_lib::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{}.{}{}")), basename, index, ext);
 }
 
 template <typename Mutex>
@@ -69,6 +69,12 @@ SPDLOG_INLINE filename_t rotating_file_sink<Mutex>::filename() {
     return file_helper_.filename();
 }
 
+template <typename Mutex>
+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>::sink_it_(const details::log_msg &msg) {
     memory_buf_t formatted;

include/spdlog/sinks/rotating_file_sink.h

@@ -28,6 +28,7 @@ public:
                        const file_event_handlers &event_handlers = {});
     static filename_t calc_filename(const filename_t &filename, std::size_t index);
     filename_t filename();
+    void rotate_now();
 
 protected:
     void sink_it_(const details::log_msg &msg) override;

include/spdlog/sinks/stdout_sinks-inl.h

@@ -10,6 +10,7 @@
 #include <memory>
 #include <spdlog/details/console_globals.h>
 #include <spdlog/pattern_formatter.h>
+#include <spdlog/details/os.h>
 
 #ifdef _WIN32
     // under windows using fwrite to non-binary stream results in \r\r\n (see issue #1675)
@@ -22,7 +23,7 @@
 
     #include <io.h>     // _get_osfhandle(..)
     #include <stdio.h>  // _fileno(..)
-#endif                  // WIN32
+#endif                  // _WIN32
 
 namespace spdlog {
 
@@ -44,7 +45,7 @@ SPDLOG_INLINE stdout_sink_base<ConsoleMutex>::stdout_sink_base(FILE *file)
     if (handle_ == INVALID_HANDLE_VALUE && file != stdout && file != stderr) {
         throw_spdlog_ex("spdlog::stdout_sink_base: _get_osfhandle() failed", errno);
     }
-#endif  // WIN32
+#endif  // _WIN32
 }
 
 template <typename ConsoleMutex>
@@ -67,8 +68,8 @@ SPDLOG_INLINE void stdout_sink_base<ConsoleMutex>::log(const details::log_msg &m
     std::lock_guard<mutex_t> lock(mutex_);
     memory_buf_t formatted;
     formatter_->format(msg, formatted);
-    ::fwrite(formatted.data(), sizeof(char), formatted.size(), file_);
-#endif                // WIN32
+    details::os::fwrite_bytes(formatted.data(), formatted.size(), file_);
+#endif                // _WIN32
     ::fflush(file_);  // flush every line to terminal
 }
 

include/spdlog/sinks/syslog_sink.h

@@ -64,13 +64,14 @@ protected:
     //
     // Simply maps spdlog's log level to syslog priority level.
     //
-    int syslog_prio_from_level(const details::log_msg &msg) const {
+    virtual int syslog_prio_from_level(const details::log_msg &msg) const {
         return syslog_levels_.at(static_cast<levels_array::size_type>(msg.level));
     }
 
-private:
     using levels_array = std::array<int, 7>;
     levels_array syslog_levels_;
+
+private:
     // must store the ident because the man says openlog might use the pointer as
     // is and not a string copy
     const std::string ident_;

include/spdlog/sinks/wincolor_sink-inl.h

@@ -134,9 +134,18 @@ void SPDLOG_INLINE wincolor_sink<ConsoleMutex>::print_range_(const memory_buf_t
                                                              size_t start,
                                                              size_t end) {
     if (end > start) {
+#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);
+        auto size = static_cast<DWORD>(wformatted.size());
+        auto ignored = ::WriteConsoleW(static_cast<HANDLE>(out_handle_), wformatted.data(), size,
+            nullptr, nullptr);
+#else
         auto size = static_cast<DWORD>(end - start);
         auto ignored = ::WriteConsoleA(static_cast<HANDLE>(out_handle_), formatted.data() + start,
                                        size, nullptr, nullptr);
+#endif
         (void)(ignored);
     }
 }

include/spdlog/spdlog-inl.h

@@ -20,16 +20,6 @@ SPDLOG_INLINE std::shared_ptr<logger> get(const std::string &name) {
     return details::registry::instance().get(name);
 }
 
-#if __cplusplus >= 201703L  // C++17
-SPDLOG_INLINE std::shared_ptr<logger> get(std::string_view name) {
-    return details::registry::instance().get(name);
-}
-
-SPDLOG_INLINE std::shared_ptr<logger> get(const char *name) {
-    return details::registry::instance().get(name);
-}
-#endif
-
 SPDLOG_INLINE void set_formatter(std::unique_ptr<spdlog::formatter> formatter) {
     details::registry::instance().set_formatter(std::move(formatter));
 }

include/spdlog/spdlog.h

@@ -20,10 +20,6 @@
 #include <memory>
 #include <string>
 
-#if __cplusplus >= 201703L  // C++17
-    #include <string_view>
-#endif
-
 namespace spdlog {
 
 using default_factory = synchronous_factory;
@@ -54,10 +50,6 @@ SPDLOG_API void initialize_logger(std::shared_ptr<logger> logger);
 // exist.
 // example: spdlog::get("my_logger")->info("hello {}", "world");
 SPDLOG_API std::shared_ptr<logger> get(const std::string &name);
-#if __cplusplus >= 201703L  // C++17
-SPDLOG_API std::shared_ptr<logger> get(std::string_view name);
-SPDLOG_API std::shared_ptr<logger> get(const char *name);
-#endif
 
 // Set global formatter. Each sink in each logger will get a clone of this object
 SPDLOG_API void set_formatter(std::unique_ptr<spdlog::formatter> formatter);

include/spdlog/version.h

@@ -4,7 +4,7 @@
 #pragma once
 
 #define SPDLOG_VER_MAJOR 1
-#define SPDLOG_VER_MINOR 14
+#define SPDLOG_VER_MINOR 15
 #define SPDLOG_VER_PATCH 0
 
 #define SPDLOG_TO_VERSION(major, minor, patch) (major * 10000 + minor * 100 + patch)

src/bundled_fmtlib_format.cpp

@@ -13,29 +13,31 @@
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
-template FMT_API auto dragonbox::to_decimal(float x) noexcept -> dragonbox::decimal_fp<float>;
-template FMT_API auto dragonbox::to_decimal(double x) noexcept -> dragonbox::decimal_fp<double>;
+template FMT_API auto dragonbox::to_decimal(float x) noexcept
+    -> dragonbox::decimal_fp<float>;
+template FMT_API auto dragonbox::to_decimal(double x) noexcept
+    -> dragonbox::decimal_fp<double>;
 
-    #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 template FMT_API locale_ref::locale_ref(const std::locale& loc);
 template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
-    #endif
+#endif
 
 // Explicit instantiations for char.
 
-template FMT_API auto thousands_sep_impl(locale_ref) -> thousands_sep_result<char>;
+template FMT_API auto thousands_sep_impl(locale_ref)
+    -> thousands_sep_result<char>;
 template FMT_API auto decimal_point_impl(locale_ref) -> char;
 
 template FMT_API void buffer<char>::append(const char*, const char*);
 
-template FMT_API void vformat_to(buffer<char>&,
-                                 string_view,
-                                 typename vformat_args<>::type,
-                                 locale_ref);
+template FMT_API void vformat_to(buffer<char>&, string_view,
+                                 typename vformat_args<>::type, locale_ref);
 
 // Explicit instantiations for wchar_t.
 
-template FMT_API auto thousands_sep_impl(locale_ref) -> thousands_sep_result<wchar_t>;
+template FMT_API auto thousands_sep_impl(locale_ref)
+    -> thousands_sep_result<wchar_t>;
 template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
 
 template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);

tests/CMakeLists.txt

@@ -48,7 +48,8 @@ set(SPDLOG_UTESTS_SOURCES
     test_cfg.cpp
     test_time_point.cpp
     test_stopwatch.cpp
-    test_circular_q.cpp)
+    test_circular_q.cpp
+    test_bin_to_hex.cpp)
 
 if(NOT SPDLOG_NO_EXCEPTIONS)
     list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
@@ -58,10 +59,6 @@ if(systemd_FOUND)
     list(APPEND SPDLOG_UTESTS_SOURCES test_systemd.cpp)
 endif()
 
-if(NOT SPDLOG_USE_STD_FORMAT)
-    list(APPEND SPDLOG_UTESTS_SOURCES test_bin_to_hex.cpp)
-endif()
-
 enable_testing()
 
 function(spdlog_prepare_test test_target spdlog_lib)
@@ -73,8 +70,10 @@ function(spdlog_prepare_test test_target spdlog_lib)
     endif()
     target_link_libraries(${test_target} PRIVATE Catch2::Catch2WithMain)
     if(SPDLOG_SANITIZE_ADDRESS)
-        spdlog_enable_sanitizer(${test_target})
-    endif()
+        spdlog_enable_addr_sanitizer(${test_target})
+    elseif (SPDLOG_SANITIZE_THREAD)
+        spdlog_enable_thread_sanitizer(${test_target})
+    endif ()
     add_test(NAME ${test_target} COMMAND ${test_target})
     set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()

tests/includes.h

@@ -26,7 +26,12 @@
 #include "spdlog/spdlog.h"
 #include "spdlog/async.h"
 #include "spdlog/details/fmt_helper.h"
-#include "spdlog/mdc.h"
+#include "spdlog/details/os.h"
+
+#ifndef SPDLOG_NO_TLS
+    #include "spdlog/mdc.h"
+#endif
+
 #include "spdlog/sinks/basic_file_sink.h"
 #include "spdlog/sinks/daily_file_sink.h"
 #include "spdlog/sinks/null_sink.h"

tests/test_async.cpp

@@ -93,50 +93,6 @@ TEST_CASE("flush", "[async]") {
     REQUIRE(test_sink->flush_counter() == 1);
 }
 
-TEST_CASE("multithread flush", "[async]") {
-    auto test_sink = std::make_shared<spdlog::sinks::test_sink_mt>();
-    size_t queue_size = 2;
-    size_t messages = 10;
-    size_t n_threads = 10;
-    size_t flush_count = 1024;
-    std::mutex mtx;
-    std::vector<std::string> errmsgs;
-    {
-        auto tp = std::make_shared<spdlog::details::thread_pool>(queue_size, 1);
-        auto logger = std::make_shared<spdlog::async_logger>(
-            "as", test_sink, tp, spdlog::async_overflow_policy::discard_new);
-
-        logger->set_error_handler([&](const std::string &) {
-            std::unique_lock<std::mutex> lock(mtx);
-            errmsgs.push_back("Broken promise");
-        });
-
-        for (size_t i = 0; i < messages; i++) {
-            logger->info("Hello message #{}", i);
-        }
-
-        std::vector<std::thread> threads;
-        for (size_t i = 0; i < n_threads; i++) {
-            threads.emplace_back([logger, flush_count] {
-                for (size_t j = 0; j < flush_count; j++) {
-                    // flush does not throw exception even if failed.
-                    // Instead, the error handler is invoked.
-                    logger->flush();
-                }
-            });
-        }
-
-        for (auto &t : threads) {
-            t.join();
-        }
-    }
-    REQUIRE(test_sink->flush_counter() >= 1);
-    REQUIRE(test_sink->flush_counter() + errmsgs.size() == n_threads * flush_count);
-    if (errmsgs.size() > 0) { 
-        REQUIRE(errmsgs[0] == "Broken promise"); 
-    }
-}
-
 TEST_CASE("async periodic flush", "[async]") {
     auto logger = spdlog::create_async<spdlog::sinks::test_sink_mt>("as");
     auto test_sink = std::static_pointer_cast<spdlog::sinks::test_sink_mt>(logger->sinks()[0]);

tests/test_create_dir.cpp

@@ -81,3 +81,64 @@ TEST_CASE("dir_name", "[create_dir]") {
     REQUIRE(dir_name(SPDLOG_FILENAME_T("../file.txt")) == SPDLOG_FILENAME_T(".."));
     REQUIRE(dir_name(SPDLOG_FILENAME_T("./file.txt")) == SPDLOG_FILENAME_T("."));
 }
+
+#ifdef _WIN32
+
+    //
+    // test windows cases when drive letter is given e.g. C:\\some-folder
+    //
+    #include <windows.h>
+    #include <fileapi.h>
+
+std::string get_full_path(const std::string &relative_folder_path) {
+    char full_path[MAX_PATH];
+
+    DWORD result = ::GetFullPathNameA(relative_folder_path.c_str(), MAX_PATH, full_path, nullptr);
+    // Return an empty string if failed to get full path
+    return result > 0 && result < MAX_PATH ? std::string(full_path) : std::string();
+}
+
+std::wstring get_full_path(const std::wstring &relative_folder_path) {
+    wchar_t full_path[MAX_PATH];
+    DWORD result = ::GetFullPathNameW(relative_folder_path.c_str(), MAX_PATH, full_path, nullptr);
+    return result > 0 && result < MAX_PATH ? std::wstring(full_path) : std::wstring();
+}
+
+spdlog::filename_t::value_type find_non_existing_drive() {
+    for (char drive = 'A'; drive <= 'Z'; ++drive) {
+        std::string root_path = std::string(1, drive) + ":\\";
+        UINT drive_type = GetDriveTypeA(root_path.c_str());
+        if (drive_type == DRIVE_NO_ROOT_DIR) {
+            return static_cast<spdlog::filename_t::value_type>(drive);
+        }
+    }
+    return '\0';  // No available drive found
+}
+
+TEST_CASE("create_abs_path1", "[create_dir]") {
+    prepare_logdir();
+    auto abs_path = get_full_path(SPDLOG_FILENAME_T("test_logs\\logdir1"));
+    REQUIRE(!abs_path.empty());
+    REQUIRE(create_dir(abs_path) == true);
+}
+
+TEST_CASE("create_abs_path2", "[create_dir]") {
+    prepare_logdir();
+    auto abs_path = get_full_path(SPDLOG_FILENAME_T("test_logs/logdir2"));
+    REQUIRE(!abs_path.empty());
+    REQUIRE(create_dir(abs_path) == true);
+}
+
+TEST_CASE("non_existing_drive", "[create_dir]") {
+    prepare_logdir();
+    spdlog::filename_t path;
+
+    auto non_existing_drive = find_non_existing_drive();
+    path += non_existing_drive;
+    path += SPDLOG_FILENAME_T(":\\");
+    REQUIRE(create_dir(path) == false);
+    path += SPDLOG_FILENAME_T("subdir");
+    REQUIRE(create_dir(path) == false);
+}
+// #endif  // SPDLOG_WCHAR_FILENAMES
+#endif  // _WIN32

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);
-            lines.emplace_back(formatted.begin(), formatted.end() - eol_len);
+            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_file_logging.cpp

@@ -45,6 +45,26 @@ TEST_CASE("flush_on", "[flush_on]") {
                                     default_eol, default_eol, default_eol));
 }
 
+TEST_CASE("simple_file_logger", "[truncate]") {
+    prepare_logdir();
+    const spdlog::filename_t filename = SPDLOG_FILENAME_T(SIMPLE_LOG);
+    const bool truncate = true;
+    const auto sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>(filename, truncate);
+    const auto logger = std::make_shared<spdlog::logger>("simple_file_logger", sink);
+
+    logger->info("Test message {}", 3.14);
+    logger->info("Test message {}", 2.71);
+    logger->flush();
+    REQUIRE(count_lines(SIMPLE_LOG) == 2);
+    
+    sink->truncate();
+    REQUIRE(count_lines(SIMPLE_LOG) == 0);
+
+    logger->info("Test message {}", 6.28);
+    logger->flush();
+    REQUIRE(count_lines(SIMPLE_LOG) == 1);
+}
+
 TEST_CASE("rotating_file_logger1", "[rotating_logger]") {
     prepare_logdir();
     size_t max_size = 1024 * 10;
@@ -101,3 +121,23 @@ TEST_CASE("rotating_file_logger3", "[rotating_logger]") {
     REQUIRE_THROWS_AS(spdlog::rotating_logger_mt("logger", basename, max_size, 0),
                       spdlog::spdlog_ex);
 }
+
+// test on-demand rotation of logs
+TEST_CASE("rotating_file_logger4", "[rotating_logger]") {
+    prepare_logdir();
+    size_t max_size = 1024 * 10;
+    spdlog::filename_t basename = SPDLOG_FILENAME_T(ROTATING_LOG);
+    auto sink = std::make_shared<spdlog::sinks::rotating_file_sink_st>(basename, max_size, 2);
+    auto logger = std::make_shared<spdlog::logger>("rotating_sink_logger", sink);
+
+    logger->info("Test message - pre-rotation");
+    logger->flush();
+
+    sink->rotate_now();
+
+    logger->info("Test message - post-rotation");
+    logger->flush();
+
+    REQUIRE(get_filesize(ROTATING_LOG) > 0);
+    REQUIRE(get_filesize(ROTATING_LOG ".1") > 0);
+}

tests/test_misc.cpp

@@ -1,3 +1,7 @@
+#ifdef _WIN32 // to prevent fopen warning on windows
+#define _CRT_SECURE_NO_WARNINGS
+#endif
+
 #include "includes.h"
 #include "test_sink.h"
 
@@ -105,9 +109,9 @@ TEST_CASE("clone-logger", "[clone]") {
 }
 
 TEST_CASE("clone async", "[clone]") {
-    using spdlog::sinks::test_sink_st;
+    using spdlog::sinks::test_sink_mt;
     spdlog::init_thread_pool(4, 1);
-    auto test_sink = std::make_shared<test_sink_st>();
+    auto test_sink = std::make_shared<test_sink_mt>();
     auto logger = std::make_shared<spdlog::async_logger>("orig", test_sink, spdlog::thread_pool());
     logger->set_pattern("%v");
     auto cloned = logger->clone("clone");
@@ -167,3 +171,52 @@ TEST_CASE("default logger API", "[default logger]") {
     spdlog::drop_all();
     spdlog::set_pattern("%v");
 }
+
+#if (defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT) || defined(SPDLOG_WCHAR_FILENAMES)) && defined(_WIN32)
+TEST_CASE("utf8 to utf16 conversion using windows api", "[windows utf]") {
+    spdlog::wmemory_buf_t buffer;
+
+    spdlog::details::os::utf8_to_wstrbuf("", buffer);
+    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L""));
+
+    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.
+    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.
+    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) {}
+    auto_closer(const auto_closer&) = delete;
+    auto_closer& operator=(const auto_closer&) = delete;
+    ~auto_closer() {
+        if (fp != nullptr) (void)std::fclose(fp);
+    }
+};
+
+TEST_CASE("os::fwrite_bytes", "[os]") {
+    using spdlog::details::os::fwrite_bytes;
+    using spdlog::details::os::create_dir;
+    const char* filename = "log_tests/test_fwrite_bytes.txt";
+    const char *msg = "hello";
+    prepare_logdir();
+    REQUIRE(create_dir(SPDLOG_FILENAME_T("log_tests")) == true);
+    {
+        auto_closer closer(std::fopen(filename, "wb"));
+        REQUIRE(closer.fp != nullptr);
+        REQUIRE(fwrite_bytes(msg, std::strlen(msg), closer.fp) == true);
+        REQUIRE(fwrite_bytes(msg, 0, closer.fp) == true);
+        std::fflush(closer.fp);
+        REQUIRE(spdlog::details::os::filesize(closer.fp) == 5);
+    }
+    // fwrite_bytes should return false on write failure
+    auto_closer closer(std::fopen(filename, "r"));
+    REQUIRE(closer.fp != nullptr);
+    REQUIRE_FALSE(fwrite_bytes("Hello", 5, closer.fp));
+}

tests/test_pattern_formatter.cpp

@@ -501,6 +501,7 @@ TEST_CASE("override need_localtime", "[pattern_formatter]") {
     }
 }
 
+#ifndef SPDLOG_NO_TLS
 TEST_CASE("mdc formatter test-1", "[pattern_formatter]") {
     spdlog::mdc::put("mdc_key_1", "mdc_value_1");
     spdlog::mdc::put("mdc_key_2", "mdc_value_2");
@@ -628,3 +629,4 @@ TEST_CASE("mdc empty", "[pattern_formatter]") {
 
     SECTION("Tear down") { spdlog::mdc::clear(); }
 }
+#endif

tests/test_sink.h

@@ -47,8 +47,9 @@ 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; 
         if (lines_.size() < lines_to_save) {
-            lines_.emplace_back(formatted.begin(), formatted.end() - eol_len);
+            lines_.emplace_back(formatted.begin(), formatted.end() - static_cast<diff_t>(eol_len));
         }
         msg_counter_++;
         std::this_thread::sleep_for(delay_);