Add full date to stdout tests

clang-format
2026-01-02 09:57:55 +08:00 · 2025-11-28 17:30:23 +02:00 · 2025-11-28 17:21:14 +02:00 · 2025-11-28 17:10:57 +02:00 · 2025-11-28 15:48:07 +02:00 · 2025-11-01 18:03:07 +02:00
75 changed files with 5881 additions and 5670 deletions
--- a/.github/workflows/coverity_scan.yml
+++ b/.github/workflows/coverity_scan.yml
@@ -0,0 +1,52 @@
+name: coverity-linux
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  coverity_scan:
+    runs-on: ubuntu-latest
+    name: Coverity Scan
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y curl build-essential cmake pkg-config libsystemd-dev
+
+      - name: Download Coverity Tool
+        run: |
+          curl -s -L --output coverity_tool.tgz "https://scan.coverity.com/download/linux64?token=${{ secrets.COVERITY_TOKEN }}&project=gabime%2Fspdlog"
+          mkdir coverity_tool
+          tar -C coverity_tool --strip-components=1 -xf coverity_tool.tgz
+          echo "$PWD/coverity_tool/bin" >> $GITHUB_PATH
+
+      - name: Build with Coverity
+        run: |
+          mkdir build && cd build
+          cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=17
+          cd ..
+          cov-build --dir cov-int make -C build -j4
+
+      - name: Submit results to Coverity
+        run: |
+          tar czf cov-int.tgz cov-int
+          response=$(curl --silent --show-error --fail \
+            --form email="${{ secrets.EMAIL }}" \
+            --form token="${{ secrets.COVERITY_TOKEN }}" \
+            --form file=@cov-int.tgz \
+            --form version="GitHub PR #${{ github.event.pull_request.number }}" \
+            --form description="CI run for PR" \
+            https://scan.coverity.com/builds?project=gabime%2Fspdlog)
+
+          echo "$response"
+
+          if echo "$response" | grep -qi "Build successfully submitted"; then
+            echo "Coverity upload succeeded"
+          else
+            echo "Coverity upload failed or was rejected"
+            exit 1
+          fi
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -18,9 +18,8 @@ jobs:
      fail-fast: false
      matrix:
        config:
-          - { compiler: gcc, version: 7, build_type: Release, cppstd: 11 }
-          - { compiler: gcc, version: 9, build_type: Release, cppstd: 17 }
-          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 20 }
+          - { compiler: gcc, version: 9, build_type: Release, cppstd: 11 }
+          - { compiler: gcc, version: 11, build_type: Debug, cppstd: 17 }
          - { compiler: gcc, version: 12, build_type: Release, cppstd: 20 }
          - { compiler: gcc, version: 12, build_type: Debug, cppstd: 20, asan: ON }
          - { compiler: clang, version: 12, build_type: Debug, cppstd: 17 }
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -9,6 +9,15 @@ jobs:
  build:
    runs-on: macOS-latest
    name: "macOS Clang (C++11, Release)"
+    strategy:
+      fail-fast: true
+      matrix:
+        config:
+            - USE_STD_FORMAT: 'ON'
+              BUILD_EXAMPLE: 'OFF'
+            - USE_STD_FORMAT: 'OFF'
+              BUILD_EXAMPLE: 'ON'
+              
    steps:
      - uses: actions/checkout@v4
      - name: Build
@@ -17,12 +26,13 @@ jobs:
          cmake .. \
            -DCMAKE_BUILD_TYPE=Release \
            -DCMAKE_CXX_STANDARD=11 \
-            -DSPDLOG_BUILD_EXAMPLE=ON \
-            -DSPDLOG_BUILD_EXAMPLE_HO=ON \
+            -DSPDLOG_BUILD_EXAMPLE=${{ 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
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -75,74 +75,5 @@ jobs:
        run: |
          build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe

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

-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: CMake ${{ matrix.config.GENERATOR }} CXX=${{matrix.config.CXX_STANDARD}} WCHAR=${{matrix.config.WCHAR_FILES}} STD_FORMAT=${{matrix.config.USE_STD_FORMAT}}
-        shell: pwsh
-        run: |
-          mkdir build
-          cd build
-          cmake -G "${{ matrix.config.GENERATOR }}"  -A x64 `
-            -D CMAKE_BUILD_TYPE=${{ matrix.config.BUILD_TYPE }} `
-            -D BUILD_SHARED_LIBS=${{ matrix.config.BUILD_SHARED }} `
-            -D SPDLOG_WCHAR_SUPPORT=${{ matrix.config.WCHAR }} `
-            -D SPDLOG_WCHAR_FILENAMES=${{ matrix.config.WCHAR_FILES }} `
-            -D SPDLOG_BUILD_EXAMPLE=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_EXAMPLE_HO=${{ matrix.config.BUILD_EXAMPLE }} `
-            -D SPDLOG_BUILD_TESTS=ON `
-            -D SPDLOG_BUILD_TESTS_HO=OFF `
-            -D SPDLOG_BUILD_WARNINGS=${{ matrix.config.FATAL_ERRORS }} `
-            -D SPDLOG_USE_STD_FORMAT=${{ matrix.config.USE_STD_FORMAT }} `
-            -D CMAKE_CXX_STANDARD=${{ matrix.config.CXX_STANDARD }} ..
-
-      - name: Build
-        shell: pwsh
-        run: |
-          cd build
-          cmake --build  . --parallel --config ${{ matrix.config.BUILD_TYPE }}
-
-      - name: Run Tests
-        shell: pwsh
-        env:
-          PATH: ${{ env.PATH }};${{ github.workspace }}\build\_deps\catch2-build\src\${{ matrix.config.BUILD_TYPE }};${{ github.workspace }}\build\${{ matrix.config.BUILD_TYPE }}
-        run: |
-          build\tests\${{ matrix.config.BUILD_TYPE }}\spdlog-utests.exe
+  
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,7 +19,11 @@ include(GNUInstallDirs)
 # Set default build to release
 # ---------------------------------------------------------------------------------------
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
-    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
+    # Set CMAKE_BUILD_TYPE only if this project is top-level
+    if((DEFINED PROJECT_IS_TOP_LEVEL AND PROJECT_IS_TOP_LEVEL) OR (NOT DEFINED PROJECT_IS_TOP_LEVEL
+                                                                   AND CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR))
+        set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
+    endif()
 endif()

 # ---------------------------------------------------------------------------------------
@@ -33,7 +37,6 @@ elseif(NOT CMAKE_CXX_STANDARD)
    set(CMAKE_CXX_STANDARD_REQUIRED ON)
 endif()

-
 set(CMAKE_CXX_EXTENSIONS OFF)

 if(CMAKE_SYSTEM_NAME MATCHES "CYGWIN" OR CMAKE_SYSTEM_NAME MATCHES "MSYS" OR CMAKE_SYSTEM_NAME MATCHES "MINGW")
@@ -63,6 +66,9 @@ option(SPDLOG_ENABLE_PCH "Build static or shared library using precompiled heade
 # build position independent code
 option(SPDLOG_BUILD_PIC "Build position independent code (-fPIC)" OFF)

+# debug build postfix
+set(SPDLOG_DEBUG_POSTFIX "d" CACHE STRING "Filename postfix for libraries in debug builds")
+
 # example options
 option(SPDLOG_BUILD_EXAMPLE "Build example" ${SPDLOG_MASTER_PROJECT})
 option(SPDLOG_BUILD_EXAMPLE_HO "Build header only example" OFF)
@@ -91,6 +97,7 @@ option(SPDLOG_USE_STD_FORMAT "Use std::format instead of fmt library." OFF)
 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)
+option(SPDLOG_NO_TZ_OFFSET "Omit %z timezone offset (use on platforms without tm_gmtoff)" OFF)

 if(SPDLOG_FMT_EXTERNAL AND SPDLOG_FMT_EXTERNAL_HO)
    message(FATAL_ERROR "SPDLOG_FMT_EXTERNAL and SPDLOG_FMT_EXTERNAL_HO are mutually exclusive")
@@ -108,15 +115,15 @@ endif()
 if(WIN32)
    option(SPDLOG_WCHAR_SUPPORT "Support wchar api" OFF)
    option(SPDLOG_WCHAR_FILENAMES "Support wchar filenames" OFF)
-    option(SPDLOG_WCHAR_CONSOLE "Support wchar output to console" OFF)    
+    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)
    set(SPDLOG_WCHAR_CONSOLE OFF CACHE BOOL "non supported option" FORCE)
 endif()

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

 if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
@@ -133,6 +140,7 @@ option(
    "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)
@@ -191,7 +199,7 @@ spdlog_enable_warnings(spdlog)

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

 if(COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
    configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/pch.h.in ${PROJECT_BINARY_DIR}/spdlog_pch.h @ONLY)
@@ -201,9 +209,9 @@ endif()
 # sanitizer support
 if(SPDLOG_SANITIZE_ADDRESS)
    spdlog_enable_addr_sanitizer(spdlog)
-elseif (SPDLOG_SANITIZE_THREAD)
+elseif(SPDLOG_SANITIZE_THREAD)
    spdlog_enable_thread_sanitizer(spdlog)
-endif ()
+endif()

 # ---------------------------------------------------------------------------------------
 # Header only version
@@ -238,6 +246,22 @@ if(SPDLOG_FMT_EXTERNAL OR SPDLOG_FMT_EXTERNAL_HO)
    set(PKG_CONFIG_REQUIRES fmt) # add dependency to pkg-config
 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
 # ---------------------------------------------------------------------------------------
@@ -263,7 +287,8 @@ foreach(
    SPDLOG_NO_TLS
    SPDLOG_NO_ATOMIC_LEVELS
    SPDLOG_DISABLE_DEFAULT_LOGGER
-    SPDLOG_USE_STD_FORMAT)
+    SPDLOG_USE_STD_FORMAT
+    SPDLOG_NO_TZ_OFFSET)
    if(${SPDLOG_OPTION})
        target_compile_definitions(spdlog PUBLIC ${SPDLOG_OPTION})
        target_compile_definitions(spdlog_header_only INTERFACE ${SPDLOG_OPTION})
@@ -274,9 +299,13 @@ if(MSVC)
    target_compile_options(spdlog PRIVATE "/Zc:__cplusplus")
    target_compile_options(spdlog_header_only INTERFACE "/Zc:__cplusplus")
    if(SPDLOG_MSVC_UTF8)
-	    target_compile_options(spdlog PUBLIC "/utf-8")
-	    target_compile_options(spdlog_header_only INTERFACE "/utf-8")    
-     endif()
+        # fmtlib requires the /utf-8 flag when building with msvc. see https://github.com/fmtlib/fmt/pull/4159 on the
+        # purpose of the additional
+        # "$<$<AND:$<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()

 # ---------------------------------------------------------------------------------------
@@ -284,12 +313,13 @@ endif()
 # ---------------------------------------------------------------------------------------
 if(SPDLOG_NO_EXCEPTIONS)
    if(NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
-        target_compile_definitions(spdlog PUBLIC FMT_EXCEPTIONS=0)
+        target_compile_definitions(spdlog PUBLIC FMT_USE_EXCEPTIONS=0)
    endif()
    if(NOT MSVC)
        target_compile_options(spdlog PRIVATE -fno-exceptions)
    else()
        target_compile_options(spdlog PRIVATE /EHs-c-)
+        target_compile_definitions(spdlog PRIVATE _HAS_EXCEPTIONS=0)
    endif()
 endif()
 # ---------------------------------------------------------------------------------------
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Fast C++ logging library

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

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

 ## Platforms
 * Linux, FreeBSD, OpenBSD, Solaris, AIX
@@ -36,6 +36,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
 * Gentoo: `emerge dev-libs/spdlog`
 * Arch Linux: `pacman -S spdlog`
 * openSUSE: `sudo zypper in spdlog-devel`
+* ALT Linux: `apt-get install libspdlog-devel`
 * vcpkg: `vcpkg install spdlog`
 * conan: `conan install --requires=spdlog/[*]`
 * conda: `conda install -c conda-forge spdlog`
@@ -47,7 +48,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
 * Headers only or compiled
 * Feature-rich formatting, using the excellent [fmt](https://github.com/fmtlib/fmt) library.
 * Asynchronous mode (optional)
-* [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) formatting.
+* [Custom](https://github.com/gabime/spdlog/wiki/Custom-formatting) formatting.
 * Multi/Single threaded loggers.
 * Various log targets:
  * Rotating log files.
@@ -57,7 +58,7 @@ see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/
  * Windows event log.
  * Windows debugger (```OutputDebugString(..)```).
  * Log to Qt widgets ([example](#log-to-qt-with-nice-colors)).
-  * Easily [extendable](https://github.com/gabime/spdlog/wiki/4.-Sinks#implementing-your-own-sink) with custom log targets.
+  * Easily [extendable](https://github.com/gabime/spdlog/wiki/Sinks#implementing-your-own-sink) with custom log targets.
 * Log filtering - log levels can be modified at runtime as well as compile time.
 * Support for loading log levels from argv or environment var.
 * [Backtrace](#backtrace-support) support - store debug messages in a ring buffer and display them later on demand.
@@ -79,7 +80,7 @@ int main()
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:<30}", "left aligned");
    
-    spdlog::set_level(spdlog::level::debug); // Set global log level to debug
+    spdlog::set_level(spdlog::level::debug); // Set *global* log level to debug
    spdlog::debug("This message should be displayed..");    
    
    // change log pattern
@@ -223,7 +224,7 @@ void binary_example()
 ```c++

 // create a logger with 2 targets, with different log levels and formats.
-// The console will show only warnings or errors, while the file will log all.
+// The console will show only warnings or errors, while the file will log all. 
 void multi_sink_example()
 {
    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
@@ -240,6 +241,29 @@ void multi_sink_example()
 }
 ```

+---
+#### Register several loggers - change global level
+```c++
+
+// Creation of loggers. Set levels to all registered loggers. 
+void set_level_example()
+{
+    auto logger1 = spdlog::basic_logger_mt("logger1", "logs/logger1.txt");
+    auto logger2 = spdlog::basic_logger_mt("logger2", "logs/logger2.txt");
+
+    spdlog::set_default_logger(logger2);
+    spdlog::default_logger()->set_level(spdlog::level::trace); // set level for the default logger (logger2) to trace
+
+    spdlog::trace("trace message to the logger2 (specified as default)");
+
+    spdlog::set_level(spdlog::level::off) // (sic!) set level for *all* registered loggers to off (disable)
+  
+    logger1.warn("warn message will not appear because the level set to off");
+    logger2.warn("warn message will not appear because the level set to off");
+    spdlog::warn("warn message will not appear because the level set to off");
+}
+```
+
 ---
 #### User-defined callbacks about log events
 ```c++
@@ -303,7 +327,7 @@ 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);
    }
 };

@@ -387,6 +411,9 @@ void android_example()
 int main (int argc, char *argv[])
 {
    spdlog::cfg::load_env_levels();
+    // or specify the env variable name:
+    // MYAPP_LEVEL=info,mylogger=trace && ./example
+    // spdlog::cfg::load_env_levels("MYAPP_LEVEL");
    // or from the command line:
    // ./example SPDLOG_LEVEL=info,mylogger=trace
    // #include "spdlog/cfg/argv.h" // for loading levels from argv
@@ -463,7 +490,7 @@ void mdc_example()
 ---
 ## Benchmarks

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

 #### Synchronous mode
 ```
@@ -515,10 +542,12 @@ Below are some [benchmarks](https://github.com/gabime/spdlog/blob/v1.x/bench/ben
 ```

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

 ---

-Thanks to [JetBrains](https://www.jetbrains.com/?from=spdlog) for donating product licenses to help develop **spdlog** <a href="https://www.jetbrains.com/?from=spdlog"><img src="logos/jetbrains-variant-4.svg" width="94" align="center" /></a>
-
-
+### Powered by
+<a href="https://jb.gg/OpenSource">
+  <img src="https://resources.jetbrains.com/storage/products/company/brand/logos/jetbrains.svg" alt="JetBrains logo" width="200">
+</a>
--- a/cmake/pch.h.in
+++ b/cmake/pch.h.in
@@ -10,7 +10,6 @@

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

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

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

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

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

 // spdlog
-#include <spdlog/common.h>
+#include <spdlog/common.h>
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -33,41 +33,41 @@ void mdc_example();
 #include "spdlog/fmt/ostr.h"  // support for user defined types

 int main(int, char *[]) {
-    // Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
-    load_levels_example();
-
-    spdlog::info("Welcome to spdlog version {}.{}.{}  !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR,
-                 SPDLOG_VER_PATCH);
-
-    spdlog::warn("Easy padding in numbers like {:08d}", 12);
-    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
-    spdlog::info("Support for floats {:03.2f}", 1.23456);
-    spdlog::info("Positional args are {1} {0}..", "too", "supported");
-    spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");
-
-    // Runtime log levels
-    spdlog::set_level(spdlog::level::info);  // Set global log level to info
-    spdlog::debug("This message should not be displayed!");
-    spdlog::set_level(spdlog::level::trace);  // Set specific logger's log level
-    spdlog::debug("This message should be displayed..");
-
-    // Customize msg format for all loggers
-    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
-    spdlog::info("This an info message with custom format");
-    spdlog::set_pattern("%+");  // back to default format
-    spdlog::set_level(spdlog::level::info);
-
-    // Backtrace support
-    // Loggers can store in a ring buffer all messages (including debug/trace) for later inspection.
-    // When needed, call dump_backtrace() to see what happened:
-    spdlog::enable_backtrace(10);  // create ring buffer with capacity of 10  messages
-    for (int i = 0; i < 100; i++) {
-        spdlog::debug("Backtrace message {}", i);  // not logged..
-    }
-    // e.g. if some error happened:
-    spdlog::dump_backtrace();  // log them now!
-
    try {
+        // Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
+        load_levels_example();
+
+        spdlog::info("Welcome to spdlog version {}.{}.{}  !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR,
+                     SPDLOG_VER_PATCH);
+
+        spdlog::warn("Easy padding in numbers like {:08d}", 12);
+        spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
+        spdlog::info("Support for floats {:03.2f}", 1.23456);
+        spdlog::info("Positional args are {1} {0}..", "too", "supported");
+        spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");
+
+        // Runtime log levels
+        spdlog::set_level(spdlog::level::info);  // Set global log level to info
+        spdlog::debug("This message should not be displayed!");
+        spdlog::set_level(spdlog::level::trace);  // Set specific logger's log level
+        spdlog::debug("This message should be displayed..");
+
+        // Customize msg format for all loggers
+        spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
+        spdlog::info("This an info message with custom format");
+        spdlog::set_pattern("%+");  // back to default format
+        spdlog::set_level(spdlog::level::info);
+
+        // Backtrace support
+        // Loggers can store in a ring buffer all messages (including debug/trace) for later
+        // inspection. When needed, call dump_backtrace() to see what happened:
+        spdlog::enable_backtrace(10);  // create ring buffer with capacity of 10  messages
+        for (int i = 0; i < 100; i++) {
+            spdlog::debug("Backtrace message {}", i);  // not logged..
+        }
+        // e.g. if some error happened:
+        spdlog::dump_backtrace();  // log them now!
+
        stdout_logger_example();
        basic_example();
        rotating_example();
@@ -148,6 +148,9 @@ void load_levels_example() {
    // Set the log level to "info" and mylogger to "trace":
    // SPDLOG_LEVEL=info,mylogger=trace && ./example
    spdlog::cfg::load_env_levels();
+    // or specify the env variable name:
+    // MYAPP_LEVEL=info,mylogger=trace && ./example
+    // spdlog::cfg::load_env_levels("MYAPP_LEVEL");
    // or from command line:
    // ./example SPDLOG_LEVEL=info,mylogger=trace
    // #include "spdlog/cfg/argv.h" // for loading levels from argv
@@ -266,7 +269,7 @@ void multi_sink_example() {
 struct my_type {
    int i = 0;
    explicit my_type(int i)
-        : i(i){}
+        : i(i) {}
 };

 #ifndef SPDLOG_USE_STD_FORMAT  // when using fmtlib
@@ -281,7 +284,7 @@ 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
@@ -368,25 +371,23 @@ void replace_default_logger_example() {
    // store the old logger so we don't break other examples.
    auto old_logger = spdlog::default_logger();

-    auto new_logger =
-        spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
-    spdlog::set_default_logger(new_logger);
+    auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/somelog.txt", true);
+    spdlog::set_default_logger(std::move(new_logger));
    spdlog::set_level(spdlog::level::info);
    spdlog::debug("This message should not be displayed!");
    spdlog::set_level(spdlog::level::trace);
    spdlog::debug("This message should be displayed..");
-
-    spdlog::set_default_logger(old_logger);
+    spdlog::set_default_logger(std::move(old_logger));
 }

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

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

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

 // get the global thread pool.
--- a/include/spdlog/async_logger-inl.h
+++ b/include/spdlog/async_logger-inl.h
@@ -33,7 +33,7 @@ SPDLOG_INLINE spdlog::async_logger::async_logger(std::string logger_name,
 // send the log message to the thread pool
 SPDLOG_INLINE void spdlog::async_logger::sink_it_(const details::log_msg &msg){
    SPDLOG_TRY{if (auto pool_ptr = thread_pool_.lock()){
-        pool_ptr->post_log(shared_from_this(), msg, overflow_policy_);
+        pool_ptr -> post_log(shared_from_this(), msg, overflow_policy_);
 }
 else {
    throw_spdlog_ex("async log: thread pool doesn't exist anymore");
@@ -45,7 +45,7 @@ SPDLOG_LOGGER_CATCH(msg.source)
 // send flush request to the thread pool
 SPDLOG_INLINE void spdlog::async_logger::flush_(){
    SPDLOG_TRY{if (auto pool_ptr = thread_pool_.lock()){
-        pool_ptr->post_flush(shared_from_this(), overflow_policy_);
+        pool_ptr -> post_flush(shared_from_this(), overflow_policy_);
 }
 else {
    throw_spdlog_ex("async flush: thread pool doesn't exist anymore");
--- a/include/spdlog/cfg/env.h
+++ b/include/spdlog/cfg/env.h
@@ -25,8 +25,8 @@

 namespace spdlog {
 namespace cfg {
-inline void load_env_levels() {
-    auto env_val = details::os::getenv("SPDLOG_LEVEL");
+inline void load_env_levels(const char* var = "SPDLOG_LEVEL") {
+    auto env_val = details::os::getenv(var);
    if (!env_val.empty()) {
        helpers::load_levels(env_val);
    }
--- a/include/spdlog/cfg/helpers-inl.h
+++ b/include/spdlog/cfg/helpers-inl.h
@@ -9,7 +9,6 @@

 #include <spdlog/details/os.h>
 #include <spdlog/details/registry.h>
-#include <spdlog/spdlog.h>

 #include <algorithm>
 #include <sstream>
@@ -36,7 +35,7 @@ inline std::string &trim_(std::string &str) {
    return str;
 }

-// return (name,value) trimmed pair from given "name=value" string.
+// return (name,value) trimmed pair from the given "name = value" string.
 // return empty string on missing parts
 // "key=val" => ("key", "val")
 // " key  =  val " => ("key", "val")
@@ -55,7 +54,7 @@ inline std::pair<std::string, std::string> extract_kv_(char sep, const std::stri
    return std::make_pair(trim_(k), trim_(v));
 }

-// return vector of key/value pairs from sequence of "K1=V1,K2=V2,.."
+// return vector of key/value pairs from a sequence of "K1=V1,K2=V2,.."
 // "a=AAA,b=BBB,c=CCC,.." => {("a","AAA"),("b","BBB"),("c", "CCC"),...}
 inline std::unordered_map<std::string, std::string> extract_key_vals_(const std::string &str) {
    std::string token;
@@ -72,7 +71,7 @@ inline std::unordered_map<std::string, std::string> extract_key_vals_(const std:
 }

 SPDLOG_INLINE void load_levels(const std::string &input) {
-    if (input.empty() || input.size() > 512) {
+    if (input.empty() || input.size() >= 32768) {
        return;
    }

@@ -82,14 +81,14 @@ SPDLOG_INLINE void load_levels(const std::string &input) {
    bool global_level_found = false;

    for (auto &name_level : key_vals) {
-        auto &logger_name = name_level.first;
-        auto level_name = to_lower_(name_level.second);
+        const auto &logger_name = name_level.first;
+        const auto &level_name = to_lower_(name_level.second);
        auto level = level::from_str(level_name);
        // ignore unrecognized level names
        if (level == level::off && level_name != "off") {
            continue;
        }
-        if (logger_name.empty())  // no logger name indicate global level
+        if (logger_name.empty())  // no logger name indicates global level
        {
            global_level_found = true;
            global_level = level;
--- a/include/spdlog/common.h
+++ b/include/spdlog/common.h
@@ -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 {
--- a/include/spdlog/details/file_helper-inl.h
+++ b/include/spdlog/details/file_helper-inl.h
@@ -11,10 +11,8 @@
 #include <spdlog/details/os.h>

 #include <cerrno>
-#include <chrono>
 #include <cstdio>
 #include <string>
-#include <thread>
 #include <tuple>

 namespace spdlog {
@@ -101,7 +99,8 @@ SPDLOG_INLINE void file_helper::write(const memory_buf_t &buf) {
    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);
    }
 }
--- a/include/spdlog/details/os-inl.h
+++ b/include/spdlog/details/os-inl.h
@@ -23,7 +23,6 @@

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

@@ -245,15 +244,16 @@ SPDLOG_INLINE size_t filesize(FILE *f) {
 #endif

 // Return utc offset in minutes or throw spdlog_ex on failure
+#if !defined(SPDLOG_NO_TZ_OFFSET)
 SPDLOG_INLINE int utc_minutes_offset(const std::tm &tm) {
-#ifdef _WIN32
-    #if _WIN32_WINNT < _WIN32_WINNT_WS08
+    #ifdef _WIN32
+        #if _WIN32_WINNT < _WIN32_WINNT_WS08
    TIME_ZONE_INFORMATION tzinfo;
    auto rv = ::GetTimeZoneInformation(&tzinfo);
-    #else
+        #else
    DYNAMIC_TIME_ZONE_INFORMATION tzinfo;
    auto rv = ::GetDynamicTimeZoneInformation(&tzinfo);
-    #endif
+        #endif
    if (rv == TIME_ZONE_ID_INVALID) throw_spdlog_ex("Failed getting timezone info. ", errno);

    int offset = -tzinfo.Bias;
@@ -263,46 +263,12 @@ SPDLOG_INLINE int utc_minutes_offset(const std::tm &tm) {
        offset -= tzinfo.StandardBias;
    }
    return offset;
-#else
-
-    #if defined(sun) || defined(__sun) || defined(_AIX) || \
-        (defined(__NEWLIB__) && !defined(__TM_GMTOFF)) ||  \
-        (!defined(_BSD_SOURCE) && !defined(_GNU_SOURCE))
-    // 'tm_gmtoff' field is BSD extension and it's missing on SunOS/Solaris
-    struct helper {
-        static long int calculate_gmt_offset(const std::tm &localtm = details::os::localtime(),
-                                             const std::tm &gmtm = details::os::gmtime()) {
-            int local_year = localtm.tm_year + (1900 - 1);
-            int gmt_year = gmtm.tm_year + (1900 - 1);
-
-            long int days = (
-                // difference in day of year
-                localtm.tm_yday -
-                gmtm.tm_yday
-
-                // + intervening leap days
-                + ((local_year >> 2) - (gmt_year >> 2)) - (local_year / 100 - gmt_year / 100) +
-                ((local_year / 100 >> 2) - (gmt_year / 100 >> 2))
-
-                // + difference in years * 365 */
-                + static_cast<long int>(local_year - gmt_year) * 365);
-
-            long int hours = (24 * days) + (localtm.tm_hour - gmtm.tm_hour);
-            long int mins = (60 * hours) + (localtm.tm_min - gmtm.tm_min);
-            long int secs = (60 * mins) + (localtm.tm_sec - gmtm.tm_sec);
-
-            return secs;
-        }
-    };
-
-    auto offset_seconds = helper::calculate_gmt_offset(tm);
    #else
    auto offset_seconds = tm.tm_gmtoff;
-    #endif
-
    return static_cast<int>(offset_seconds / 60);
-#endif
+    #endif
 }
+#endif  // SPDLOG_NO_TZ_OFFSET

 // Return current thread id as size_t
 // It exists because the std::this_thread::get_id() is much slower(especially
@@ -482,15 +448,14 @@ SPDLOG_INLINE void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target) {
    }

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

    if (result_size > 0) {
        target.resize(result_size);
-        result_size = ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(),
-                                            result_size);
+        result_size =
+            ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(), result_size);
        if (result_size > 0) {
-            assert(result_size == target.size());
+            assert(result_size == static_cast<int>(target.size()));
            return;
        }
    }
@@ -563,21 +528,21 @@ SPDLOG_INLINE filename_t dir_name(const filename_t &path) {
    return pos != filename_t::npos ? path.substr(0, pos) : filename_t{};
 }

+#ifdef _MSC_VER
+    #pragma warning(push)
+    #pragma warning(disable : 4996)
+#endif  // _MSC_VER
 std::string SPDLOG_INLINE getenv(const char *field) {
-#if defined(_MSC_VER)
-    #if defined(__cplusplus_winrt)
+#if defined(_MSC_VER) && defined(__cplusplus_winrt)
    return std::string{};  // not supported under uwp
-    #else
-    size_t len = 0;
-    char buf[128];
-    bool ok = ::getenv_s(&len, buf, sizeof(buf), field) == 0;
-    return ok ? buf : std::string{};
-    #endif
-#else  // revert to getenv
-    char *buf = ::getenv(field);
+#else
+    char *buf = std::getenv(field);
    return buf ? buf : std::string{};
 #endif
 }
+#ifdef _MSC_VER
+    #pragma warning(pop)
+#endif  // _MSC_VER

 // Do fsync by FILE handlerpointer
 // Return true on success
@@ -589,6 +554,18 @@ 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
--- a/include/spdlog/details/os.h
+++ b/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
--- a/include/spdlog/details/registry-inl.h
+++ b/include/spdlog/details/registry-inl.h
@@ -54,6 +54,11 @@ SPDLOG_INLINE void registry::register_logger(std::shared_ptr<logger> new_logger)
    register_logger_(std::move(new_logger));
 }

+SPDLOG_INLINE void registry::register_or_replace(std::shared_ptr<logger> new_logger) {
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    register_or_replace_(std::move(new_logger));
+}
+
 SPDLOG_INLINE void registry::initialize_logger(std::shared_ptr<logger> new_logger) {
    std::lock_guard<std::mutex> lock(logger_map_mutex_);
    new_logger->set_formatter(formatter_->clone());
@@ -96,7 +101,7 @@ SPDLOG_INLINE std::shared_ptr<logger> registry::default_logger() {
 SPDLOG_INLINE logger *registry::get_default_raw() { return default_logger_.get(); }

 // set default logger.
-// default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
+// the default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
 SPDLOG_INLINE void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
    std::lock_guard<std::mutex> lock(logger_map_mutex_);
    if (new_default_logger != nullptr) {
@@ -252,10 +257,14 @@ SPDLOG_INLINE void registry::throw_if_exists_(const std::string &logger_name) {
 }

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

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

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

    void throw_if_exists_(const std::string &logger_name);
    void register_logger_(std::shared_ptr<logger> new_logger);
+    void register_or_replace_(std::shared_ptr<logger> new_logger);
    bool set_level_from_cfg_(logger *logger);
    std::mutex logger_map_mutex_, flusher_mutex_;
    std::recursive_mutex tp_mutex_;
--- a/include/spdlog/details/tcp_client-windows.h
+++ b/include/spdlog/details/tcp_client-windows.h
@@ -58,8 +58,81 @@ public:

    SOCKET fd() const { return socket_; }

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

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

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

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

    ~tcp_client() { close(); }

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

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

+        if (timeout_ms > 0) {
+            // Set timeouts for send and recv
+            ::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, (const char *)&tv, sizeof(tv));
+            ::setsockopt(socket_, SOL_SOCKET, SO_SNDTIMEO, (const char *)&tv, sizeof(tv));
+        }
+
        // set TCP_NODELAY
        int enable_flag = 1;
        ::setsockopt(socket_, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char *>(&enable_flag),
--- a/include/spdlog/details/thread_pool-inl.h
+++ b/include/spdlog/details/thread_pool-inl.h
@@ -35,11 +35,10 @@ SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
 SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
                                       size_t threads_n,
                                       std::function<void()> on_thread_start)
-    : thread_pool(q_max_items, threads_n, on_thread_start, [] {}) {}
+    : thread_pool(q_max_items, threads_n, std::move(on_thread_start), [] {}) {}

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

 // message all threads to terminate gracefully join them
 SPDLOG_INLINE thread_pool::~thread_pool() {
@@ -95,8 +94,7 @@ void SPDLOG_INLINE thread_pool::worker_loop_() {
 }

 // process next message in the queue
-// return true if this thread should still be active (while no terminate msg
-// was received)
+// returns true if this thread should still be active (while no terminated msg was received)
 bool SPDLOG_INLINE thread_pool::process_next_msg_() {
    async_msg incoming_async_msg;
    q_.dequeue(incoming_async_msg);
--- a/include/spdlog/fmt/bin_to_hex.h
+++ b/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;
@@ -142,8 +142,8 @@ struct formatter<spdlog::details::dump_info<T>, char> {

    // format the given bytes range as hex
    template <typename FormatContext, typename Container>
-    auto format(const spdlog::details::dump_info<Container> &the_range, FormatContext &ctx) const
-        -> decltype(ctx.out()) {
+    auto format(const spdlog::details::dump_info<Container> &the_range,
+                FormatContext &ctx) const -> decltype(ctx.out()) {
        SPDLOG_CONSTEXPR const char *hex_upper = "0123456789ABCDEF";
        SPDLOG_CONSTEXPR const char *hex_lower = "0123456789abcdef";
        const char *hex_chars = use_uppercase ? hex_upper : hex_lower;
--- a/include/spdlog/fmt/bundled/args.h
+++ b/include/spdlog/fmt/bundled/args.h
@@ -17,7 +17,6 @@
 #include "format.h"  // std_string_view

 FMT_BEGIN_NAMESPACE
-
 namespace detail {

 template <typename T> struct is_reference_wrapper : std::false_type {};
@@ -72,19 +71,13 @@ class dynamic_arg_list {
 * It can be implicitly converted into `fmt::basic_format_args` for passing
 * into type-erased formatting functions such as `fmt::vformat`.
 */
-template <typename Context>
-class dynamic_format_arg_store
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
-    // Workaround a GCC template argument substitution bug.
-    : public basic_format_args<Context>
-#endif
-{
+FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
 private:
  using char_type = typename Context::char_type;

  template <typename T> struct need_copy {
    static constexpr detail::type mapped_type =
-        detail::mapped_type_constant<T, Context>::value;
+        detail::mapped_type_constant<T, char_type>::value;

    enum {
      value = !(detail::is_reference_wrapper<T>::value ||
@@ -97,7 +90,7 @@ class dynamic_format_arg_store
  };

  template <typename T>
-  using stored_type = conditional_t<
+  using stored_t = conditional_t<
      std::is_convertible<T, std::basic_string<char_type>>::value &&
          !detail::is_reference_wrapper<T>::value,
      std::basic_string<char_type>, T>;
@@ -112,41 +105,37 @@ class dynamic_format_arg_store

  friend class basic_format_args<Context>;

-  auto get_types() const -> unsigned long long {
-    return detail::is_unpacked_bit | data_.size() |
-           (named_info_.empty()
-                ? 0ULL
-                : static_cast<unsigned long long>(detail::has_named_args_bit));
-  }
-
  auto data() const -> const basic_format_arg<Context>* {
    return named_info_.empty() ? data_.data() : data_.data() + 1;
  }

  template <typename T> void emplace_arg(const T& arg) {
-    data_.emplace_back(detail::make_arg<Context>(arg));
+    data_.emplace_back(arg);
  }

  template <typename T>
  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
-    if (named_info_.empty()) {
-      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
-      data_.insert(data_.begin(), {zero_ptr, 0});
-    }
-    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
+    if (named_info_.empty())
+      data_.insert(data_.begin(), basic_format_arg<Context>(nullptr, 0));
+    data_.emplace_back(detail::unwrap(arg.value));
    auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
      data->pop_back();
    };
    std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
        guard{&data_, pop_one};
    named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
-    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
+    data_[0] = {named_info_.data(), named_info_.size()};
    guard.release();
  }

 public:
  constexpr dynamic_format_arg_store() = default;

+  operator basic_format_args<Context>() const {
+    return basic_format_args<Context>(data(), static_cast<int>(data_.size()),
+                                      !named_info_.empty());
+  }
+
  /**
   * Adds an argument into the dynamic store for later passing to a formatting
   * function.
@@ -164,7 +153,7 @@ class dynamic_format_arg_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));
+      emplace_arg(dynamic_args_.push<stored_t<T>>(arg));
    else
      emplace_arg(detail::unwrap(arg));
  }
@@ -200,7 +189,7 @@ class dynamic_format_arg_store
        dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
    if (detail::const_check(need_copy<T>::value)) {
      emplace_arg(
-          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
+          fmt::arg(arg_name, dynamic_args_.push<stored_t<T>>(arg.value)));
    } else {
      emplace_arg(fmt::arg(arg_name, arg.value));
    }
@@ -210,17 +199,20 @@ class dynamic_format_arg_store
  void clear() {
    data_.clear();
    named_info_.clear();
-    dynamic_args_ = detail::dynamic_arg_list();
+    dynamic_args_ = {};
  }

  /// 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");
+               "set of arguments includes set of named arguments");
    data_.reserve(new_cap);
    named_info_.reserve(new_cap_named);
  }
+
+  /// Returns the number of elements in the store.
+  auto size() const noexcept -> size_t { return data_.size(); }
 };

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

 namespace detail {

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

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

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

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

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

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

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

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

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

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

 FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept
@@ -330,41 +364,39 @@ FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept
 namespace detail {

 template <typename Char> struct ansi_color_escape {
-  FMT_CONSTEXPR ansi_color_escape(detail::color_type text_color,
+  FMT_CONSTEXPR ansi_color_escape(color_type text_color,
                                  const char* esc) noexcept {
    // If we have a terminal color, we need to output another escape code
    // sequence.
-    if (!text_color.is_rgb) {
+    if (text_color.is_terminal_color()) {
      bool is_background = esc == string_view("\x1b[48;2;");
-      uint32_t value = text_color.value.term_color;
+      uint32_t value = text_color.value();
      // Background ASCII codes are the same as the foreground ones but with
      // 10 more.
      if (is_background) value += 10u;

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

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

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

    for (int i = 0; i < 7; i++) {
      buffer[i] = static_cast<Char>(esc[i]);
    }
-    rgb color(text_color.value.rgb_color);
+    rgb color(text_color.value());
    to_esc(color.r, buffer + 7, ';');
    to_esc(color.g, buffer + 11, ';');
    to_esc(color.b, buffer + 15, 'm');
-    buffer[19] = static_cast<Char>(0);
+    size = 19;
  }
  FMT_CONSTEXPR ansi_color_escape(emphasis em) noexcept {
    uint8_t em_codes[num_emphases] = {};
@@ -377,26 +409,28 @@ template <typename Char> struct ansi_color_escape {
    if (has_emphasis(em, emphasis::conceal)) em_codes[6] = 8;
    if (has_emphasis(em, emphasis::strikethrough)) em_codes[7] = 9;

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

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

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

  static FMT_CONSTEXPR void to_esc(uint8_t c, Char* out,
                                   char delimiter) noexcept {
@@ -412,13 +446,13 @@ template <typename Char> struct ansi_color_escape {
 };

 template <typename Char>
-FMT_CONSTEXPR auto make_foreground_color(detail::color_type foreground) noexcept
+FMT_CONSTEXPR auto make_foreground_color(color_type foreground) noexcept
    -> ansi_color_escape<Char> {
  return ansi_color_escape<Char>(foreground, "\x1b[38;2;");
 }

 template <typename Char>
-FMT_CONSTEXPR auto make_background_color(detail::color_type background) noexcept
+FMT_CONSTEXPR auto make_background_color(color_type background) noexcept
    -> ansi_color_escape<Char> {
  return ansi_color_escape<Char>(background, "\x1b[48;2;");
 }
@@ -434,40 +468,33 @@ template <typename Char> inline void reset_color(buffer<Char>& buffer) {
  buffer.append(reset_color.begin(), reset_color.end());
 }

-template <typename T> struct styled_arg : detail::view {
+template <typename T> struct styled_arg : view {
  const T& value;
  text_style style;
  styled_arg(const T& v, text_style s) : value(v), style(s) {}
 };

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

-inline void vprint(FILE* f, const text_style& ts, string_view fmt,
-                   format_args args) {
+inline void vprint(FILE* f, text_style ts, string_view fmt, format_args args) {
  auto buf = memory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
  print(f, FMT_STRING("{}"), string_view(buf.begin(), buf.size()));
@@ -483,9 +510,8 @@ inline void vprint(FILE* f, const text_style& ts, string_view fmt,
 *                "Elapsed time: {0:.2f} seconds", 1.23);
 */
 template <typename... T>
-void print(FILE* f, const text_style& ts, format_string<T...> fmt,
-           T&&... args) {
-  vprint(f, ts, fmt, fmt::make_format_args(args...));
+void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) {
+  vprint(f, ts, fmt.str, vargs<T...>{{args...}});
 }

 /**
@@ -498,11 +524,11 @@ void print(FILE* f, const text_style& ts, format_string<T...> fmt,
 *                "Elapsed time: {0:.2f} seconds", 1.23);
 */
 template <typename... T>
-void print(const text_style& ts, format_string<T...> fmt, T&&... args) {
+void print(text_style ts, format_string<T...> fmt, T&&... args) {
  return print(stdout, ts, fmt, std::forward<T>(args)...);
 }

-inline auto vformat(const text_style& ts, string_view fmt, format_args args)
+inline auto vformat(text_style ts, string_view fmt, format_args args)
    -> std::string {
  auto buf = memory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
@@ -522,16 +548,16 @@ inline auto vformat(const text_style& ts, string_view fmt, format_args args)
 * ```
 */
 template <typename... T>
-inline auto format(const text_style& ts, format_string<T...> fmt, T&&... args)
+inline auto format(text_style ts, format_string<T...> fmt, T&&... args)
    -> std::string {
-  return fmt::vformat(ts, fmt, fmt::make_format_args(args...));
+  return fmt::vformat(ts, fmt.str, vargs<T...>{{args...}});
 }

 /// Formats a string with the given text_style and writes the output to `out`.
 template <typename OutputIt,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-auto vformat_to(OutputIt out, const text_style& ts, string_view fmt,
-                format_args args) -> OutputIt {
+auto vformat_to(OutputIt out, text_style ts, string_view fmt, format_args args)
+    -> OutputIt {
  auto&& buf = detail::get_buffer<char>(out);
  detail::vformat_to(buf, ts, fmt, args);
  return detail::get_iterator(buf, out);
@@ -549,9 +575,9 @@ auto vformat_to(OutputIt out, const text_style& ts, string_view fmt,
 */
 template <typename OutputIt, typename... T,
          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-inline auto format_to(OutputIt out, const text_style& ts,
-                      format_string<T...> fmt, T&&... args) -> OutputIt {
-  return vformat_to(out, ts, fmt, fmt::make_format_args(args...));
+inline auto format_to(OutputIt out, text_style ts, format_string<T...> fmt,
+                      T&&... args) -> OutputIt {
+  return vformat_to(out, ts, fmt.str, vargs<T...>{{args...}});
 }

 template <typename T, typename Char>
@@ -560,31 +586,30 @@ struct formatter<detail::styled_arg<T>, Char> : formatter<T, Char> {
  auto format(const detail::styled_arg<T>& arg, FormatContext& ctx) const
      -> decltype(ctx.out()) {
    const auto& ts = arg.style;
-    const auto& value = arg.value;
    auto out = ctx.out();

    bool has_style = false;
    if (ts.has_emphasis()) {
      has_style = true;
      auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
-      out = std::copy(emphasis.begin(), emphasis.end(), out);
+      out = detail::copy<Char>(emphasis.begin(), emphasis.end(), out);
    }
    if (ts.has_foreground()) {
      has_style = true;
      auto foreground =
          detail::make_foreground_color<Char>(ts.get_foreground());
-      out = std::copy(foreground.begin(), foreground.end(), out);
+      out = detail::copy<Char>(foreground.begin(), foreground.end(), out);
    }
    if (ts.has_background()) {
      has_style = true;
      auto background =
          detail::make_background_color<Char>(ts.get_background());
-      out = std::copy(background.begin(), background.end(), out);
+      out = detail::copy<Char>(background.begin(), background.end(), out);
    }
-    out = formatter<T, Char>::format(value, ctx);
+    out = formatter<T, Char>::format(arg.value, ctx);
    if (has_style) {
      auto reset_color = string_view("\x1b[0m");
-      out = std::copy(reset_color.begin(), reset_color.end(), out);
+      out = detail::copy<Char>(reset_color.begin(), reset_color.end(), out);
    }
    return out;
  }
--- a/include/spdlog/fmt/bundled/compile.h
+++ b/include/spdlog/fmt/bundled/compile.h
@@ -19,14 +19,6 @@ FMT_BEGIN_NAMESPACE
 // A compile-time string which is compiled into fast formatting code.
 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> {};

@@ -42,34 +34,45 @@ struct is_compiled_string : std::is_base_of<compiled_string, S> {};
 *     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::compiled_string, explicit)
+#  define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::compiled_string)
 #else
 #  define FMT_COMPILE(s) FMT_STRING(s)
 #endif

+/**
+ * Converts a string literal into a format string that will be parsed at
+ * compile time and converted into efficient formatting code. Requires support
+ * for class types in constant template parameters (a C++20 feature).
+ *
+ *  **Example**:
+ *
+ *     // Converts 42 into std::string using the most efficient method and no
+ *     // runtime format string processing.
+ *     using namespace fmt::literals;
+ *     std::string s = fmt::format("{}"_cf, 42);
+ */
 #if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct udl_compiled_string : compiled_string {
-  using char_type = Char;
-  explicit constexpr operator basic_string_view<char_type>() const {
-    return {Str.data, N - 1};
-  }
-};
+inline namespace literals {
+template <detail::fixed_string Str> constexpr auto operator""_cf() {
+  return FMT_COMPILE(Str.data);
+}
+}  // namespace literals
 #endif

+namespace detail {
+
 template <typename T, typename... Tail>
-auto first(const T& value, const Tail&...) -> const T& {
+constexpr auto first(const T& value, const Tail&...) -> const T& {
  return value;
 }

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

 // Returns a reference to the argument at index N from [first, rest...].
 template <int N, typename T, typename... Args>
-constexpr const auto& get([[maybe_unused]] const T& first,
-                          [[maybe_unused]] const Args&... rest) {
+constexpr auto get([[maybe_unused]] const T& first,
+                   [[maybe_unused]] const Args&... rest) -> const auto& {
  static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
  if constexpr (N == 0)
    return first;
@@ -77,9 +80,32 @@ constexpr const auto& get([[maybe_unused]] const T& first,
    return detail::get<N - 1>(rest...);
 }

+#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
+template <int N, typename T, typename... Args, typename Char>
+constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
+  if constexpr (is_static_named_arg<T>()) {
+    if (name == T::name) return N;
+  }
+  if constexpr (sizeof...(Args) > 0)
+    return get_arg_index_by_name<N + 1, Args...>(name);
+  (void)name;  // Workaround an MSVC bug about "unused" parameter.
+  return -1;
+}
+#  endif
+
+template <typename... Args, typename Char>
+FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
+#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
+  if constexpr (sizeof...(Args) > 0)
+    return get_arg_index_by_name<0, Args...>(name);
+#  endif
+  (void)name;
+  return -1;
+}
+
 template <typename Char, typename... Args>
-constexpr int get_arg_index_by_name(basic_string_view<Char> name,
-                                    type_list<Args...>) {
+constexpr auto get_arg_index_by_name(basic_string_view<Char> name,
+                                     type_list<Args...>) -> int {
  return get_arg_index_by_name<Args...>(name);
 }

@@ -99,8 +125,8 @@ template <typename Char> struct text {
  basic_string_view<Char> data;
  using char_type = Char;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
    return write<Char>(out, data);
  }
 };
@@ -109,8 +135,8 @@ template <typename Char>
 struct is_compiled_format<text<Char>> : std::true_type {};

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

@@ -118,8 +144,8 @@ template <typename Char> struct code_unit {
  Char value;
  using char_type = Char;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&...) const -> OutputIt {
    *out++ = value;
    return out;
  }
@@ -127,7 +153,7 @@ template <typename Char> struct code_unit {

 // This ensures that the argument type is convertible to `const T&`.
 template <typename T, int N, typename... Args>
-constexpr const T& get_arg_checked(const Args&... args) {
+constexpr auto get_arg_checked(const Args&... args) -> const T& {
  const auto& arg = detail::get<N>(args...);
  if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>()) {
    return arg.value;
@@ -140,17 +166,18 @@ template <typename Char>
 struct is_compiled_format<code_unit<Char>> : std::true_type {};

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

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

@@ -163,10 +190,10 @@ template <typename Char> struct runtime_named_field {
  basic_string_view<Char> name;

  template <typename OutputIt, typename T>
-  constexpr static bool try_format_argument(
+  constexpr static auto try_format_argument(
      OutputIt& out,
      // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
-      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) {
+      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) -> bool {
    if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
      if (arg_name == arg.name) {
        out = write<Char>(out, arg.value);
@@ -176,8 +203,8 @@ template <typename Char> struct runtime_named_field {
    return false;
  }

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
    bool found = (try_format_argument(out, name, args) || ...);
    if (!found) {
      FMT_THROW(format_error("argument with specified name is not found"));
@@ -190,17 +217,17 @@ template <typename Char>
 struct is_compiled_format<runtime_named_field<Char>> : std::true_type {};

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

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

@@ -212,8 +239,8 @@ template <typename L, typename R> struct concat {
  R rhs;
  using char_type = typename L::char_type;

-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
+  template <typename OutputIt, typename... T>
+  constexpr auto format(OutputIt out, const T&... args) const -> OutputIt {
    out = lhs.format(out, args...);
    return rhs.format(out, args...);
  }
@@ -223,14 +250,14 @@ template <typename L, typename R>
 struct is_compiled_format<concat<L, R>> : std::true_type {};

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

 struct unknown_format {};

 template <typename Char>
-constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
+constexpr auto parse_text(basic_string_view<Char> str, size_t pos) -> size_t {
  for (size_t size = str.size(); pos != size; ++pos) {
    if (str[pos] == '{' || str[pos] == '}') break;
  }
@@ -263,8 +290,8 @@ template <typename T, typename Char> struct parse_specs_result {
 enum { manual_indexing_id = -1 };

 template <typename T, typename Char>
-constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
-                                                  size_t pos, int next_arg_id) {
+constexpr auto parse_specs(basic_string_view<Char> str, size_t pos,
+                           int next_arg_id) -> parse_specs_result<T, Char> {
  str.remove_prefix(pos);
  auto ctx =
      compile_parse_context<Char>(str, max_value<int>(), nullptr, next_arg_id);
@@ -275,32 +302,36 @@ constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
 }

 template <typename Char> struct arg_id_handler {
+  arg_id_kind kind;
  arg_ref<Char> arg_id;

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

 template <typename Char> struct parse_arg_id_result {
+  arg_id_kind kind;
  arg_ref<Char> arg_id;
  const Char* arg_id_end;
 };

 template <int ID, typename Char>
 constexpr auto parse_arg_id(const Char* begin, const Char* end) {
-  auto handler = arg_id_handler<Char>{arg_ref<Char>{}};
+  auto handler = arg_id_handler<Char>{arg_id_kind::none, arg_ref<Char>{}};
  auto arg_id_end = parse_arg_id(begin, end, handler);
-  return parse_arg_id_result<Char>{handler.arg_id, arg_id_end};
+  return parse_arg_id_result<Char>{handler.kind, handler.arg_id, arg_id_end};
 }

 template <typename T, typename Enable = void> struct field_type {
@@ -363,18 +394,18 @@ constexpr auto compile_format_string(S fmt) {
      constexpr char_type c =
          arg_id_end_pos != str.size() ? str[arg_id_end_pos] : char_type();
      static_assert(c == '}' || c == ':', "missing '}' in format string");
-      if constexpr (arg_id_result.arg_id.kind == arg_id_kind::index) {
+      if constexpr (arg_id_result.kind == arg_id_kind::index) {
        static_assert(
            ID == manual_indexing_id || ID == 0,
            "cannot switch from automatic to manual argument indexing");
-        constexpr auto arg_index = arg_id_result.arg_id.val.index;
+        constexpr auto arg_index = arg_id_result.arg_id.index;
        return parse_replacement_field_then_tail<get_type<arg_index, Args>,
                                                 Args, arg_id_end_pos,
                                                 arg_index, manual_indexing_id>(
            fmt);
-      } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
+      } else if constexpr (arg_id_result.kind == arg_id_kind::name) {
        constexpr auto arg_index =
-            get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
+            get_arg_index_by_name(arg_id_result.arg_id.name, Args{});
        if constexpr (arg_index >= 0) {
          constexpr auto next_id =
              ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
@@ -383,8 +414,7 @@ constexpr auto compile_format_string(S fmt) {
              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},
-              fmt);
+              runtime_named_field<char_type>{arg_id_result.arg_id.name}, fmt);
        } else if constexpr (c == ':') {
          return unknown_format();  // no type info for specs parsing
        }
@@ -405,7 +435,7 @@ constexpr auto compile_format_string(S fmt) {
 }

 template <typename... Args, typename S,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+          FMT_ENABLE_IF(is_compiled_string<S>::value)>
 constexpr auto compile(S fmt) {
  constexpr auto str = basic_string_view<typename S::char_type>(fmt);
  if constexpr (str.size() == 0) {
@@ -423,27 +453,28 @@ FMT_BEGIN_EXPORT

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

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

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

-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
-                                                           Args&&... args) {
+template <typename S, typename... T,
+          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+FMT_INLINE FMT_CONSTEXPR_STRING auto format(const S&, T&&... args)
+    -> std::basic_string<typename S::char_type> {
  if constexpr (std::is_same<typename S::char_type, char>::value) {
    constexpr auto str = basic_string_view<typename S::char_type>(S());
    if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
@@ -456,72 +487,97 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
      }
    }
  }
-  constexpr auto compiled = detail::compile<Args...>(S());
+  constexpr auto compiled = detail::compile<T...>(S());
  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
                             detail::unknown_format>()) {
    return fmt::format(
        static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
+        std::forward<T>(args)...);
  } else {
-    return fmt::format(compiled, std::forward<Args>(args)...);
+    return fmt::format(compiled, std::forward<T>(args)...);
  }
 }

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

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

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

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

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

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

 FMT_END_EXPORT
 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/fmt.license.rst
+++ b/include/spdlog/fmt/bundled/fmt.license.rst
@@ -1,4 +1,4 @@
-Copyright (c) 2012 - present, Victor Zverovich
+Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors

 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
--- a/include/spdlog/fmt/bundled/format-inl.h
+++ b/include/spdlog/fmt/bundled/format-inl.h
@@ -14,10 +14,6 @@
 #  include <climits>
 #  include <cmath>
 #  include <exception>
-
-#  if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
-#    include <locale>
-#  endif
 #endif

 #if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
@@ -26,17 +22,58 @@

 #include "format.h"

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

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

 FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
                                string_view message) noexcept {
@@ -61,86 +98,67 @@ FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
  FMT_ASSERT(out.size() <= inline_buffer_size, "");
 }

-FMT_FUNC void report_error(format_func func, int error_code,
-                           const char* message) noexcept {
+FMT_FUNC void do_report_error(format_func func, int error_code,
+                              const char* message) noexcept {
  memory_buffer full_message;
  func(full_message, error_code, message);
-  // Don't use fwrite_fully because the latter may throw.
+  // Don't use fwrite_all because the latter may throw.
  if (std::fwrite(full_message.data(), full_message.size(), 1, stderr) > 0)
    std::fputc('\n', stderr);
 }

 // A wrapper around fwrite that throws on error.
-inline void fwrite_fully(const void* ptr, size_t count, FILE* stream) {
+inline void fwrite_all(const void* ptr, size_t count, FILE* stream) {
  size_t written = std::fwrite(ptr, 1, count, stream);
  if (written < count)
    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
 }

-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template <typename Locale>
-locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
-  static_assert(std::is_same<Locale, std::locale>::value, "");
-}
-
-template <typename Locale> auto locale_ref::get() const -> Locale {
-  static_assert(std::is_same<Locale, std::locale>::value, "");
-  return locale_ ? *static_cast<const std::locale*>(locale_) : std::locale();
-}
-
 template <typename Char>
 FMT_FUNC auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char> {
-  auto& facet = std::use_facet<std::numpunct<Char>>(loc.get<std::locale>());
+  auto&& facet = use_facet<numpunct<Char>>(loc.get<locale>());
  auto grouping = facet.grouping();
  auto thousands_sep = grouping.empty() ? Char() : facet.thousands_sep();
  return {std::move(grouping), thousands_sep};
 }
 template <typename Char>
 FMT_FUNC auto decimal_point_impl(locale_ref loc) -> Char {
-  return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>())
-      .decimal_point();
+  return use_facet<numpunct<Char>>(loc.get<locale>()).decimal_point();
 }
-#else
-template <typename Char>
-FMT_FUNC auto thousands_sep_impl(locale_ref) -> thousands_sep_result<Char> {
-  return {"\03", FMT_STATIC_THOUSANDS_SEPARATOR};
-}
-template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref) {
-  return '.';
-}
-#endif

+#if FMT_USE_LOCALE
 FMT_FUNC auto write_loc(appender out, loc_value value,
                        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.
  using facet = format_facet<std::locale>;
  if (std::has_facet<facet>(locale))
-    return std::use_facet<facet>(locale).put(out, value, specs);
+    return use_facet<facet>(locale).put(out, value, specs);
  return facet(locale).put(out, value, specs);
-#endif
 }
+#endif
 }  // namespace detail

 FMT_FUNC void report_error(const char* message) {
+#if FMT_MSC_VERSION || defined(__NVCC__)
+  // Silence unreachable code warnings in MSVC and NVCC because these
+  // are nearly impossible to fix in a generic code.
+  volatile bool b = true;
+  if (!b) return;
+#endif
  FMT_THROW(format_error(message));
 }

 template <typename Locale> typename Locale::id format_facet<Locale>::id;

-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 template <typename Locale> format_facet<Locale>::format_facet(Locale& loc) {
-  auto& numpunct = std::use_facet<std::numpunct<char>>(loc);
-  grouping_ = numpunct.grouping();
-  if (!grouping_.empty()) separator_ = std::string(1, numpunct.thousands_sep());
+  auto& np = detail::use_facet<detail::numpunct<char>>(loc);
+  grouping_ = np.grouping();
+  if (!grouping_.empty()) separator_ = std::string(1, np.thousands_sep());
 }

+#if FMT_USE_LOCALE
 template <>
 FMT_API FMT_FUNC auto format_facet<std::locale>::do_put(
    appender out, loc_value val, const format_specs& specs) const -> bool {
@@ -163,11 +181,11 @@ inline auto operator==(basic_fp<F> x, basic_fp<F> y) -> bool {
 }

 // Compilers should be able to optimize this into the ror instruction.
-FMT_CONSTEXPR inline auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
+FMT_INLINE auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
  r &= 31;
  return (n >> r) | (n << (32 - r));
 }
-FMT_CONSTEXPR inline auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
+FMT_INLINE auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
  r &= 63;
  return (n >> r) | (n << (64 - r));
 }
@@ -201,7 +219,7 @@ inline auto floor_log10_pow2_minus_log10_4_over_3(int e) noexcept -> int {
  return (e * 631305 - 261663) >> 21;
 }

-FMT_INLINE_VARIABLE constexpr struct {
+FMT_INLINE_VARIABLE constexpr struct div_small_pow10_infos_struct {
  uint32_t divisor;
  int shift_amount;
 } div_small_pow10_infos[] = {{10, 16}, {100, 16}};
@@ -264,7 +282,7 @@ template <> struct cache_accessor<float> {
  static auto get_cached_power(int k) noexcept -> uint64_t {
    FMT_ASSERT(k >= float_info<float>::min_k && k <= float_info<float>::max_k,
               "k is out of range");
-    static constexpr const uint64_t pow10_significands[] = {
+    static constexpr uint64_t pow10_significands[] = {
        0x81ceb32c4b43fcf5, 0xa2425ff75e14fc32, 0xcad2f7f5359a3b3f,
        0xfd87b5f28300ca0e, 0x9e74d1b791e07e49, 0xc612062576589ddb,
        0xf79687aed3eec552, 0x9abe14cd44753b53, 0xc16d9a0095928a28,
@@ -359,7 +377,7 @@ template <> struct cache_accessor<double> {
    FMT_ASSERT(k >= float_info<double>::min_k && k <= float_info<double>::max_k,
               "k is out of range");

-    static constexpr const uint128_fallback pow10_significands[] = {
+    static constexpr uint128_fallback pow10_significands[] = {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
      {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
      {0x9faacf3df73609b1, 0x77b191618c54e9ad},
@@ -1026,7 +1044,7 @@ template <> struct cache_accessor<double> {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
    return pow10_significands[k - float_info<double>::min_k];
 #else
-    static constexpr const uint64_t powers_of_5_64[] = {
+    static constexpr uint64_t powers_of_5_64[] = {
        0x0000000000000001, 0x0000000000000005, 0x0000000000000019,
        0x000000000000007d, 0x0000000000000271, 0x0000000000000c35,
        0x0000000000003d09, 0x000000000001312d, 0x000000000005f5e1,
@@ -1086,7 +1104,7 @@ template <> struct cache_accessor<double> {
    return {r.high(), r.low() == 0};
  }

-  static auto compute_delta(cache_entry_type const& cache, int beta) noexcept
+  static auto compute_delta(const cache_entry_type& cache, int beta) noexcept
      -> uint32_t {
    return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta));
  }
@@ -1138,8 +1156,8 @@ auto is_left_endpoint_integer_shorter_interval(int exponent) noexcept -> bool {
         exponent <= case_shorter_interval_left_endpoint_upper_threshold;
 }

-// Remove trailing zeros from n and return the number of zeros removed (float)
-FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
+// Remove trailing zeros from n and return the number of zeros removed (float).
+FMT_INLINE auto remove_trailing_zeros(uint32_t& n, int s = 0) noexcept -> int {
  FMT_ASSERT(n != 0, "");
  // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
  constexpr uint32_t mod_inv_5 = 0xcccccccd;
@@ -1159,22 +1177,19 @@ FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
  return s;
 }

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

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

  // If n is not divisible by 10^8, work with n itself.
@@ -1199,7 +1214,7 @@ FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {

 // The main algorithm for shorter interval case
 template <typename T>
-FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
+FMT_INLINE auto shorter_interval_case(int exponent) noexcept -> decimal_fp<T> {
  decimal_fp<T> ret_value;
  // Compute k and beta
  const int minus_k = floor_log10_pow2_minus_log10_4_over_3(exponent);
@@ -1425,7 +1440,7 @@ FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,

 FMT_FUNC void report_system_error(int error_code,
                                  const char* message) noexcept {
-  report_error(format_system_error, error_code, message);
+  do_report_error(format_system_error, error_code, message);
 }

 FMT_FUNC auto vformat(string_view fmt, format_args args) -> std::string {
@@ -1438,6 +1453,15 @@ FMT_FUNC auto vformat(string_view fmt, format_args args) -> std::string {

 namespace detail {

+FMT_FUNC void vformat_to(buffer<char>& buf, string_view fmt, format_args args,
+                         locale_ref loc) {
+  auto out = appender(buf);
+  if (fmt.size() == 2 && equal2(fmt.data(), "{}"))
+    return args.get(0).visit(default_arg_formatter<char>{out});
+  parse_format_string(fmt,
+                      format_handler<>{parse_context<>(fmt), {out, args, loc}});
+}
+
 template <typename T> struct span {
  T* data;
  size_t size;
@@ -1506,7 +1530,7 @@ template <typename F> class glibc_file : public file_base<F> {
  }

  void init_buffer() {
-    if (this->file_->_IO_write_ptr) return;
+    if (this->file_->_IO_write_ptr < this->file_->_IO_write_end) return;
    // Force buffer initialization by placing and removing a char in a buffer.
    putc_unlocked(0, this->file_);
    --this->file_->_IO_write_ptr;
@@ -1526,10 +1550,11 @@ template <typename F> class glibc_file : public file_base<F> {

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

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

  void flush() { fflush_unlocked(this->file_); }
@@ -1553,7 +1578,7 @@ template <typename F> class apple_file : public file_base<F> {
  void init_buffer() {
    if (this->file_->_p) return;
    // Force buffer initialization by placing and removing a char in a buffer.
-    putc_unlocked(0, this->file_);
+    if (!FMT_CLANG_ANALYZER) putc_unlocked(0, this->file_);
    --this->file_->_p;
    ++this->file_->_w;
  }
@@ -1574,7 +1599,7 @@ template <typename F> class apple_file : public file_base<F> {
    this->file_->_w -= size;
  }

-  bool needs_flush() const {
+  auto needs_flush() const -> bool {
    if ((this->file_->_flags & line_buffered) == 0) return false;
    return memchr(this->file_->_p + this->file_->_w, '\n',
                  to_unsigned(-this->file_->_w));
@@ -1615,7 +1640,7 @@ template <typename F> class fallback_file : public file_base<F> {
 };

 #ifndef FMT_USE_FALLBACK_FILE
-#  define FMT_USE_FALLBACK_FILE 1
+#  define FMT_USE_FALLBACK_FILE 0
 #endif

 template <typename F,
@@ -1692,7 +1717,7 @@ FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args,
  auto buffer = memory_buffer();
  detail::vformat_to(buffer, fmt, args);
  if (newline) buffer.push_back('\n');
-  fwrite_fully(buffer.data(), buffer.size(), f);
+  fwrite_all(buffer.data(), buffer.size(), f);
 }
 #endif

@@ -1704,7 +1729,7 @@ FMT_FUNC void print(std::FILE* f, string_view text) {
    if (write_console(fd, text)) return;
  }
 #endif
-  fwrite_fully(text.data(), text.size(), f);
+  fwrite_all(text.data(), text.size(), f);
 }
 }  // namespace detail

--- a/include/spdlog/fmt/bundled/format.h
+++ b/include/spdlog/fmt/bundled/format.h
--- a/include/spdlog/fmt/bundled/locale.h
+++ b/include/spdlog/fmt/bundled/locale.h
@@ -1,2 +0,0 @@
-#include "xchar.h"
-#warning fmt/locale.h is deprecated, include fmt/format.h or fmt/xchar.h instead
--- a/include/spdlog/fmt/bundled/os.h
+++ b/include/spdlog/fmt/bundled/os.h
@@ -29,7 +29,8 @@
 #  if (FMT_HAS_INCLUDE(<fcntl.h>) || defined(__APPLE__) || \
       defined(__linux__)) &&                              \
      (!defined(WINAPI_FAMILY) ||                          \
-       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+       (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)) &&    \
+      !defined(__wasm__)
 #    include <fcntl.h>  // for O_RDONLY
 #    define FMT_USE_FCNTL 1
 #  else
@@ -118,7 +119,7 @@ FMT_API void format_windows_error(buffer<char>& out, int error_code,
                                  const char* message) noexcept;
 }

-FMT_API std::system_error vwindows_error(int error_code, string_view format_str,
+FMT_API std::system_error vwindows_error(int error_code, string_view fmt,
                                         format_args args);

 /**
@@ -146,10 +147,10 @@ FMT_API std::system_error vwindows_error(int error_code, string_view format_str,
 *                                "cannot open file '{}'", filename);
 *     }
 */
-template <typename... Args>
-std::system_error windows_error(int error_code, string_view message,
-                                const Args&... args) {
-  return vwindows_error(error_code, message, fmt::make_format_args(args...));
+template <typename... T>
+auto windows_error(int error_code, string_view message, const T&... args)
+    -> std::system_error {
+  return vwindows_error(error_code, message, vargs<T...>{{args...}});
 }

 // Reports a Windows error without throwing an exception.
@@ -164,8 +165,8 @@ inline auto system_category() noexcept -> const std::error_category& {
 // std::system is not available on some platforms such as iOS (#2248).
 #ifdef __OSX__
 template <typename S, typename... Args, typename Char = char_t<S>>
-void say(const S& format_str, Args&&... args) {
-  std::system(format("say \"{}\"", format(format_str, args...)).c_str());
+void say(const S& fmt, Args&&... args) {
+  std::system(format("say \"{}\"", format(fmt, args...)).c_str());
 }
 #endif

@@ -176,24 +177,24 @@ class buffered_file {

  friend class file;

-  explicit buffered_file(FILE* f) : file_(f) {}
+  inline explicit buffered_file(FILE* f) : file_(f) {}

 public:
  buffered_file(const buffered_file&) = delete;
  void operator=(const buffered_file&) = delete;

  // Constructs a buffered_file object which doesn't represent any file.
-  buffered_file() noexcept : file_(nullptr) {}
+  inline buffered_file() noexcept : file_(nullptr) {}

  // Destroys the object closing the file it represents if any.
  FMT_API ~buffered_file() noexcept;

 public:
-  buffered_file(buffered_file&& other) noexcept : file_(other.file_) {
+  inline buffered_file(buffered_file&& other) noexcept : file_(other.file_) {
    other.file_ = nullptr;
  }

-  auto operator=(buffered_file&& other) -> buffered_file& {
+  inline auto operator=(buffered_file&& other) -> buffered_file& {
    close();
    file_ = other.file_;
    other.file_ = nullptr;
@@ -207,13 +208,13 @@ class buffered_file {
  FMT_API void close();

  // Returns the pointer to a FILE object representing this file.
-  auto get() const noexcept -> FILE* { return file_; }
+  inline auto get() const noexcept -> FILE* { return file_; }

  FMT_API auto descriptor() const -> int;

  template <typename... T>
  inline void print(string_view fmt, const T&... args) {
-    const auto& vargs = fmt::make_format_args(args...);
+    fmt::vargs<T...> vargs = {{args...}};
    detail::is_locking<T...>() ? fmt::vprint_buffered(file_, fmt, vargs)
                               : fmt::vprint(file_, fmt, vargs);
  }
@@ -248,7 +249,7 @@ class FMT_API file {
  };

  // Constructs a file object which doesn't represent any file.
-  file() noexcept : fd_(-1) {}
+  inline file() noexcept : fd_(-1) {}

  // Opens a file and constructs a file object representing this file.
  file(cstring_view path, int oflag);
@@ -257,10 +258,10 @@ class FMT_API file {
  file(const file&) = delete;
  void operator=(const file&) = delete;

-  file(file&& other) noexcept : fd_(other.fd_) { other.fd_ = -1; }
+  inline file(file&& other) noexcept : fd_(other.fd_) { other.fd_ = -1; }

  // Move assignment is not noexcept because close may throw.
-  auto operator=(file&& other) -> file& {
+  inline auto operator=(file&& other) -> file& {
    close();
    fd_ = other.fd_;
    other.fd_ = -1;
@@ -271,7 +272,7 @@ class FMT_API file {
  ~file() noexcept;

  // Returns the file descriptor.
-  auto descriptor() const noexcept -> int { return fd_; }
+  inline auto descriptor() const noexcept -> int { return fd_; }

  // Closes the file.
  void close();
@@ -324,9 +325,9 @@ auto getpagesize() -> long;
 namespace detail {

 struct buffer_size {
-  buffer_size() = default;
+  constexpr buffer_size() = default;
  size_t value = 0;
-  auto operator=(size_t val) const -> buffer_size {
+  FMT_CONSTEXPR auto operator=(size_t val) const -> buffer_size {
    auto bs = buffer_size();
    bs.value = val;
    return bs;
@@ -337,7 +338,7 @@ struct ostream_params {
  int oflag = file::WRONLY | file::CREATE | file::TRUNC;
  size_t buffer_size = BUFSIZ > 32768 ? BUFSIZ : 32768;

-  ostream_params() {}
+  constexpr ostream_params() {}

  template <typename... T>
  ostream_params(T... params, int new_oflag) : ostream_params(params...) {
@@ -358,59 +359,47 @@ struct ostream_params {
 #  endif
 };

-class file_buffer final : public buffer<char> {
+}  // namespace detail
+
+FMT_INLINE_VARIABLE constexpr auto buffer_size = detail::buffer_size();
+
+/// A fast buffered 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 detail::buffer<char> {
 private:
  file file_;

-  FMT_API static void grow(buffer<char>& buf, size_t);
+  ostream(cstring_view path, const detail::ostream_params& params);
+
+  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) noexcept;
-  FMT_API ~file_buffer();
+  ostream(ostream&& other) noexcept;
+  ~ostream();

-  void flush() {
+  operator writer() {
+    detail::buffer<char>& buf = *this;
+    return buf;
+  }
+
+  inline void flush() {
    if (size() == 0) return;
    file_.write(data(), size() * sizeof(data()[0]));
    clear();
  }

-  void close() {
-    flush();
-    file_.close();
-  }
-};
-
-}  // namespace detail
-
-constexpr auto buffer_size = detail::buffer_size();
-
-/// 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)
-  detail::file_buffer buffer_;
-
-  ostream(cstring_view path, const detail::ostream_params& params)
-      : buffer_(path, params) {}
-
- public:
-  ostream(ostream&& other) : buffer_(std::move(other.buffer_)) {}
-
-  ~ostream();
-
-  void flush() { buffer_.flush(); }
-
  template <typename... T>
  friend auto output_file(cstring_view path, T... params) -> ostream;

-  void close() { buffer_.close(); }
+  inline void close() {
+    flush();
+    file_.close();
+  }

  /// Formats `args` according to specifications in `fmt` and writes the
  /// output to the file.
  template <typename... T> void print(format_string<T...> fmt, T&&... args) {
-    vformat_to(appender(buffer_), fmt, fmt::make_format_args(args...));
+    vformat_to(appender(*this), fmt.str, vargs<T...>{{args...}});
  }
 };

--- a/include/spdlog/fmt/bundled/ostream.h
+++ b/include/spdlog/fmt/bundled/ostream.h
@@ -22,11 +22,19 @@

 #include "chrono.h"  // formatbuf

+#ifdef _MSVC_STL_UPDATE
+#  define FMT_MSVC_STL_UPDATE _MSVC_STL_UPDATE
+#elif defined(_MSC_VER) && _MSC_VER < 1912  // VS 15.5
+#  define FMT_MSVC_STL_UPDATE _MSVC_LANG
+#else
+#  define FMT_MSVC_STL_UPDATE 0
+#endif
+
 FMT_BEGIN_NAMESPACE
 namespace detail {

-// Generate a unique explicit instantion in every translation unit using a tag
-// type in an anonymous namespace.
+// Generate a unique explicit instantiation in every translation unit using a
+// tag type in an anonymous namespace.
 namespace {
 struct file_access_tag {};
 }  // namespace
@@ -35,53 +43,18 @@ class file_access {
  friend auto get_file(BufType& obj) -> FILE* { return obj.*FileMemberPtr; }
 };

-#if FMT_MSC_VERSION
+#if FMT_MSVC_STL_UPDATE
 template class file_access<file_access_tag, std::filebuf,
                           &std::filebuf::_Myfile>;
 auto get_file(std::filebuf&) -> FILE*;
 #endif

-inline auto write_ostream_unicode(std::ostream& os, fmt::string_view data)
-    -> bool {
-  FILE* f = nullptr;
-#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__) && FMT_USE_RTTI
-  auto* rdbuf = os.rdbuf();
-  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
-    f = sfbuf->file();
-  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
-    f = fbuf->file();
-  else
-    return false;
-#else
-  ignore_unused(os, data, f);
-#endif
-#ifdef _WIN32
-  if (f) {
-    int fd = _fileno(f);
-    if (_isatty(fd)) {
-      os.flush();
-      return write_console(fd, data);
-    }
-  }
-#endif
-  return false;
-}
-inline auto write_ostream_unicode(std::wostream&,
-                                  fmt::basic_string_view<wchar_t>) -> bool {
-  return false;
-}
-
 // Write the content of buf to os.
 // It is a separate function rather than a part of vprint to simplify testing.
 template <typename Char>
 void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
  const Char* buf_data = buf.data();
-  using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
+  using unsigned_streamsize = make_unsigned_t<std::streamsize>;
  unsigned_streamsize size = buf.size();
  unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
  do {
@@ -92,21 +65,9 @@ void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
  } while (size != 0);
 }

-template <typename Char, typename T>
-void format_value(buffer<Char>& buf, const T& value) {
-  auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
-  auto&& output = std::basic_ostream<Char>(&format_buf);
-#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
-  output.imbue(std::locale::classic());  // The default is always unlocalized.
-#endif
-  output << value;
-  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
-}
-
 template <typename T> struct streamed_view {
  const T& value;
 };
-
 }  // namespace detail

 // Formats an object of type T that has an overloaded ostream operator<<.
@@ -117,7 +78,11 @@ struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
  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);
+    auto&& formatbuf = detail::formatbuf<std::basic_streambuf<Char>>(buffer);
+    auto&& output = std::basic_ostream<Char>(&formatbuf);
+    output.imbue(std::locale::classic());  // The default is always unlocalized.
+    output << value;
+    output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
    return formatter<basic_string_view<Char>, Char>::format(
        {buffer.data(), buffer.size()}, ctx);
  }
@@ -148,24 +113,30 @@ constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
  return {value};
 }

-namespace detail {
-
-inline void vprint_directly(std::ostream& os, string_view format_str,
-                            format_args args) {
+inline void vprint(std::ostream& os, string_view fmt, format_args args) {
  auto buffer = memory_buffer();
-  detail::vformat_to(buffer, format_str, args);
-  detail::write_buffer(os, buffer);
-}
-
-}  // namespace detail
-
-FMT_EXPORT template <typename Char>
-void vprint(std::basic_ostream<Char>& os,
-            basic_string_view<type_identity_t<Char>> format_str,
-            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;
+  detail::vformat_to(buffer, fmt, args);
+  FILE* f = nullptr;
+#if FMT_MSVC_STL_UPDATE && FMT_USE_RTTI
+  if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
+    f = detail::get_file(*buf);
+#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();
+  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
+    f = fbuf->file();
+#endif
+#ifdef _WIN32
+  if (f) {
+    int fd = _fileno(f);
+    if (_isatty(fd)) {
+      os.flush();
+      if (detail::write_console(fd, {buffer.data(), buffer.size()})) return;
+    }
+  }
+#endif
+  detail::ignore_unused(f);
  detail::write_buffer(os, buffer);
 }

@@ -178,32 +149,17 @@ void vprint(std::basic_ostream<Char>& os,
 */
 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::use_utf8())
-    vprint(os, fmt, vargs);
-  else
-    detail::vprint_directly(os, fmt, vargs);
-}
-
-FMT_EXPORT
-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<buffered_context<wchar_t>>(args...));
+  fmt::vargs<T...> vargs = {{args...}};
+  if (detail::const_check(detail::use_utf8)) return vprint(os, fmt.str, vargs);
+  auto buffer = memory_buffer();
+  detail::vformat_to(buffer, fmt.str, vargs);
+  detail::write_buffer(os, buffer);
 }

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

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/printf.h
+++ b/include/spdlog/fmt/bundled/printf.h
@@ -9,7 +9,7 @@
 #define FMT_PRINTF_H_

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

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

-template <typename T> struct printf_formatter {
-  printf_formatter() = delete;
-};
-
 template <typename Char> class basic_printf_context {
 private:
  basic_appender<Char> out_;
@@ -33,8 +29,7 @@ template <typename Char> class basic_printf_context {

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

  /// Constructs a `printf_context` object. References to the arguments are
  /// stored in the context object so make sure they have appropriate lifetimes.
@@ -45,7 +40,7 @@ template <typename Char> class basic_printf_context {
  auto out() -> basic_appender<Char> { return out_; }
  void advance_to(basic_appender<Char>) {}

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

  auto arg(int id) const -> basic_format_arg<basic_printf_context> {
    return args_.get(id);
@@ -54,14 +49,30 @@ template <typename Char> class basic_printf_context {

 namespace detail {

+// Return the result via the out param to workaround gcc bug 77539.
+template <bool IS_CONSTEXPR, typename T, typename Ptr = const T*>
+FMT_CONSTEXPR auto find(Ptr first, Ptr last, T value, Ptr& out) -> bool {
+  for (out = first; out != last; ++out) {
+    if (*out == value) return true;
+  }
+  return false;
+}
+
+template <>
+inline auto find<false, char>(const char* first, const char* last, char value,
+                              const char*& out) -> bool {
+  out =
+      static_cast<const char*>(memchr(first, value, to_unsigned(last - first)));
+  return out != nullptr;
+}
+
 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
-template <bool IsSigned> struct int_checker {
+template <bool IS_SIGNED> struct int_checker {
  template <typename T> static auto fits_in_int(T value) -> bool {
-    unsigned max = to_unsigned(max_value<int>());
-    return value <= max;
+    return value <= to_unsigned(max_value<int>());
  }
-  static auto fits_in_int(bool) -> bool { return true; }
+  inline static auto fits_in_int(bool) -> bool { return true; }
 };

 template <> struct int_checker<true> {
@@ -69,7 +80,7 @@ template <> struct int_checker<true> {
    return value >= (std::numeric_limits<int>::min)() &&
           value <= max_value<int>();
  }
-  static auto fits_in_int(int) -> bool { return true; }
+  inline static auto fits_in_int(int) -> bool { return true; }
 };

 struct printf_precision_handler {
@@ -77,7 +88,7 @@ struct printf_precision_handler {
  auto operator()(T value) -> int {
    if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
      report_error("number is too big");
-    return (std::max)(static_cast<int>(value), 0);
+    return max_of(static_cast<int>(value), 0);
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
@@ -127,25 +138,19 @@ template <typename T, typename Context> class arg_converter {
    using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
    if (const_check(sizeof(target_type) <= sizeof(int))) {
      // Extra casts are used to silence warnings.
-      if (is_signed) {
-        auto n = static_cast<int>(static_cast<target_type>(value));
-        arg_ = detail::make_arg<Context>(n);
-      } else {
-        using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
-        auto n = static_cast<unsigned>(static_cast<unsigned_type>(value));
-        arg_ = detail::make_arg<Context>(n);
-      }
+      using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
+      if (is_signed)
+        arg_ = static_cast<int>(static_cast<target_type>(value));
+      else
+        arg_ = static_cast<unsigned>(static_cast<unsigned_type>(value));
    } else {
-      if (is_signed) {
-        // glibc's printf doesn't sign extend arguments of smaller types:
-        //   std::printf("%lld", -42);  // prints "4294967254"
-        // but we don't have to do the same because it's a UB.
-        auto n = static_cast<long long>(value);
-        arg_ = detail::make_arg<Context>(n);
-      } else {
-        auto n = static_cast<typename make_unsigned_or_bool<U>::type>(value);
-        arg_ = detail::make_arg<Context>(n);
-      }
+      // glibc's printf doesn't sign extend arguments of smaller types:
+      //   std::printf("%lld", -42);  // prints "4294967254"
+      // but we don't have to do the same because it's a UB.
+      if (is_signed)
+        arg_ = static_cast<long long>(value);
+      else
+        arg_ = static_cast<typename make_unsigned_or_bool<U>::type>(value);
    }
  }

@@ -172,8 +177,7 @@ template <typename Context> class char_converter {

  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  void operator()(T value) {
-    auto c = static_cast<typename Context::char_type>(value);
-    arg_ = detail::make_arg<Context>(c);
+    arg_ = static_cast<typename Context::char_type>(value);
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
@@ -194,13 +198,13 @@ class printf_width_handler {
  format_specs& specs_;

 public:
-  explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
+  inline 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 {
    auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
    if (detail::is_negative(value)) {
-      specs_.align = align::left;
+      specs_.set_align(align::left);
      width = 0 - width;
    }
    unsigned int_max = to_unsigned(max_value<int>());
@@ -234,69 +238,74 @@ 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;
+    s.set_type(presentation_type::none);
    write_bytes<Char>(this->out, is_string ? "(null)" : "(nil)", s);
  }

+  template <typename T> void write(T value) {
+    detail::write<Char>(this->out, value, this->specs, this->locale);
+  }
+
 public:
  printf_arg_formatter(basic_appender<Char> iter, format_specs& s,
                       context_type& ctx)
      : base(make_arg_formatter(iter, s)), context_(ctx) {}

-  void operator()(monostate value) { base::operator()(value); }
+  void operator()(monostate value) { write(value); }

  template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
  void operator()(T value) {
    // MSVC2013 fails to compile separate overloads for bool and Char so use
    // std::is_same instead.
    if (!std::is_same<T, Char>::value) {
-      base::operator()(value);
+      write(value);
      return;
    }
    format_specs s = this->specs;
-    if (s.type != presentation_type::none && s.type != presentation_type::chr) {
+    if (s.type() != presentation_type::none &&
+        s.type() != presentation_type::chr) {
      return (*this)(static_cast<int>(value));
    }
-    s.sign = sign::none;
-    s.alt = false;
-    s.fill = ' ';  // Ignore '0' flag for char types.
+    s.set_sign(sign::none);
+    s.clear_alt();
+    s.set_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 (s.align == align::none || s.align == align::numeric)
-      s.align = align::right;
-    write<Char>(this->out, static_cast<Char>(value), s);
+    if (s.align() == align::none || s.align() == align::numeric)
+      s.set_align(align::right);
+    detail::write<Char>(this->out, static_cast<Char>(value), s);
  }

  template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
  void operator()(T value) {
-    base::operator()(value);
+    write(value);
  }

  void operator()(const char* value) {
    if (value)
-      base::operator()(value);
+      write(value);
    else
-      write_null_pointer(this->specs.type != presentation_type::pointer);
+      write_null_pointer(this->specs.type() != presentation_type::pointer);
  }

  void operator()(const wchar_t* value) {
    if (value)
-      base::operator()(value);
+      write(value);
    else
-      write_null_pointer(this->specs.type != presentation_type::pointer);
+      write_null_pointer(this->specs.type() != presentation_type::pointer);
  }

-  void operator()(basic_string_view<Char> value) { base::operator()(value); }
+  void operator()(basic_string_view<Char> value) { write(value); }

  void operator()(const void* value) {
    if (value)
-      base::operator()(value);
+      write(value);
    else
      write_null_pointer();
  }

  void operator()(typename basic_format_arg<context_type>::handle handle) {
-    auto parse_ctx = basic_format_parse_context<Char>({});
+    auto parse_ctx = parse_context<Char>({});
    handle.format(parse_ctx, context_);
  }
 };
@@ -305,23 +314,14 @@ template <typename Char>
 void parse_flags(format_specs& specs, const Char*& it, const Char* end) {
  for (; it != end; ++it) {
    switch (*it) {
-    case '-':
-      specs.align = align::left;
-      break;
-    case '+':
-      specs.sign = sign::plus;
-      break;
-    case '0':
-      specs.fill = '0';
-      break;
+    case '-': specs.set_align(align::left); break;
+    case '+': specs.set_sign(sign::plus); break;
+    case '0': specs.set_fill('0'); break;
    case ' ':
-      if (specs.sign != sign::plus) specs.sign = sign::space;
+      if (specs.sign() != sign::plus) specs.set_sign(sign::space);
      break;
-    case '#':
-      specs.alt = true;
-      break;
-    default:
-      return;
+    case '#': specs.set_alt(); break;
+    default:  return;
    }
  }
 }
@@ -339,7 +339,7 @@ auto parse_header(const Char*& it, const Char* end, format_specs& specs,
      ++it;
      arg_index = value != -1 ? value : max_value<int>();
    } else {
-      if (c == '0') specs.fill = '0';
+      if (c == '0') specs.set_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.
@@ -369,43 +369,22 @@ inline auto parse_printf_presentation_type(char c, type t, bool& upper)
  using pt = presentation_type;
  constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
  switch (c) {
-  case 'd':
-    return in(t, integral_set) ? pt::dec : pt::none;
-  case 'o':
-    return in(t, integral_set) ? pt::oct : pt::none;
-  case 'X':
-    upper = true;
-    FMT_FALLTHROUGH;
-  case 'x':
-    return in(t, integral_set) ? pt::hex : pt::none;
-  case 'E':
-    upper = true;
-    FMT_FALLTHROUGH;
-  case 'e':
-    return in(t, float_set) ? pt::exp : pt::none;
-  case 'F':
-    upper = true;
-    FMT_FALLTHROUGH;
-  case 'f':
-    return in(t, float_set) ? pt::fixed : pt::none;
-  case 'G':
-    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':
-    return in(t, string_set | cstring_set) ? pt::string : pt::none;
-  case 'p':
-    return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
-  default:
-    return pt::none;
+  case 'd': return in(t, integral_set) ? pt::dec : pt::none;
+  case 'o': return in(t, integral_set) ? pt::oct : pt::none;
+  case 'X': upper = true; FMT_FALLTHROUGH;
+  case 'x': return in(t, integral_set) ? pt::hex : pt::none;
+  case 'E': upper = true; FMT_FALLTHROUGH;
+  case 'e': return in(t, float_set) ? pt::exp : pt::none;
+  case 'F': upper = true; FMT_FALLTHROUGH;
+  case 'f': return in(t, float_set) ? pt::fixed : pt::none;
+  case 'G': 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': return in(t, string_set | cstring_set) ? pt::string : pt::none;
+  case 'p': return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
+  default:  return pt::none;
  }
 }

@@ -415,7 +394,7 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
  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);
+  auto parse_ctx = parse_context<Char>(format);

  // Returns the argument with specified index or, if arg_index is -1, the next
  // argument.
@@ -424,7 +403,9 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
      arg_index = parse_ctx.next_arg_id();
    else
      parse_ctx.check_arg_id(--arg_index);
-    return detail::get_arg(context, arg_index);
+    auto arg = context.arg(arg_index);
+    if (!arg) report_error("argument not found");
+    return arg;
  };

  const Char* start = parse_ctx.begin();
@@ -444,7 +425,7 @@ 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();
-    specs.align = align::right;
+    specs.set_align(align::right);

    // Parse argument index, flags and width.
    int arg_index = parse_header(it, end, specs, get_arg);
@@ -468,9 +449,9 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
    auto arg = get_arg(arg_index);
    // For d, i, o, u, x, and X conversion specifiers, if a precision is
    // specified, the '0' flag is ignored
-    if (specs.precision >= 0 && arg.is_integral()) {
+    if (specs.precision >= 0 && is_integral_type(arg.type())) {
      // Ignore '0' for non-numeric types or if '-' present.
-      specs.fill = ' ';
+      specs.set_fill(' ');
    }
    if (specs.precision >= 0 && arg.type() == type::cstring_type) {
      auto str = arg.visit(get_cstring<Char>());
@@ -478,15 +459,16 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
      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);
+      arg = sv;
    }
-    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 = ' ';  // Ignore '0' flag for non-numeric types or if '-'
-                           // flag is also present.
+    if (specs.alt() && arg.visit(is_zero_int())) specs.clear_alt();
+    if (specs.fill_unit<Char>() == '0') {
+      if (is_arithmetic_type(arg.type()) && specs.align() != align::left) {
+        specs.set_align(align::numeric);
+      } else {
+        // Ignore '0' flag for non-numeric types or if '-' flag is also present.
+        specs.set_fill(' ');
+      }
    }

    // Parse length and convert the argument to the required type.
@@ -511,44 +493,34 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
        convert_arg<long>(arg, t);
      }
      break;
-    case 'j':
-      convert_arg<intmax_t>(arg, t);
-      break;
-    case 'z':
-      convert_arg<size_t>(arg, t);
-      break;
-    case 't':
-      convert_arg<std::ptrdiff_t>(arg, t);
-      break;
+    case 'j': convert_arg<intmax_t>(arg, t); break;
+    case 'z': convert_arg<size_t>(arg, t); break;
+    case 't': convert_arg<std::ptrdiff_t>(arg, t); break;
    case 'L':
      // printf produces garbage when 'L' is omitted for long double, no
      // need to do the same.
      break;
-    default:
-      --it;
-      convert_arg<void>(arg, c);
+    default: --it; convert_arg<void>(arg, c);
    }

    // Parse type.
    if (it == end) report_error("invalid format string");
    char type = static_cast<char>(*it++);
-    if (arg.is_integral()) {
+    if (is_integral_type(arg.type())) {
      // Normalize type.
      switch (type) {
      case 'i':
-      case 'u':
-        type = 'd';
-        break;
+      case 'u': type = 'd'; break;
      case 'c':
        arg.visit(char_converter<basic_printf_context<Char>>(arg));
        break;
      }
    }
    bool upper = false;
-    specs.type = parse_printf_presentation_type(type, arg.type(), upper);
-    if (specs.type == presentation_type::none)
+    specs.set_type(parse_printf_presentation_type(type, arg.type(), upper));
+    if (specs.type() == presentation_type::none)
      report_error("invalid format specifier");
-    specs.upper = upper;
+    if (upper) specs.set_upper();

    start = it;

@@ -583,7 +555,7 @@ inline auto vsprintf(basic_string_view<Char> fmt,
    -> std::basic_string<Char> {
  auto buf = basic_memory_buffer<Char>();
  detail::vprintf(buf, fmt, args);
-  return to_string(buf);
+  return {buf.data(), buf.size()};
 }

 /**
@@ -594,15 +566,19 @@ inline auto vsprintf(basic_string_view<Char> fmt,
 *
 *     std::string message = fmt::sprintf("The answer is %d", 42);
 */
-template <typename S, typename... T, typename Char = char_t<S>>
-inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
-  return vsprintf(detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
+template <typename... T>
+inline auto sprintf(string_view fmt, const T&... args) -> std::string {
+  return vsprintf(fmt, make_printf_args(args...));
+}
+template <typename... T>
+FMT_DEPRECATED auto sprintf(basic_string_view<wchar_t> fmt, const T&... args)
+    -> std::wstring {
+  return vsprintf(fmt, make_printf_args<wchar_t>(args...));
 }

 template <typename Char>
-inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
-                     typename vprintf_args<Char>::type args) -> int {
+auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
+              typename vprintf_args<Char>::type args) -> int {
  auto buf = basic_memory_buffer<Char>();
  detail::vprintf(buf, fmt, args);
  size_t size = buf.size();
@@ -619,17 +595,14 @@ inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
 *
 *     fmt::fprintf(stderr, "Don't %s!", "panic");
 */
-template <typename S, typename... T, typename Char = char_t<S>>
-inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
-  return vfprintf(f, detail::to_string_view(fmt),
-                  make_printf_args<Char>(args...));
+template <typename... T>
+inline auto fprintf(std::FILE* f, string_view fmt, const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args(args...));
 }
-
-template <typename Char>
-FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
-                                   typename vprintf_args<Char>::type args)
-    -> int {
-  return vfprintf(stdout, fmt, args);
+template <typename... T>
+FMT_DEPRECATED auto fprintf(std::FILE* f, basic_string_view<wchar_t> fmt,
+                            const T&... args) -> int {
+  return vfprintf(f, fmt, make_printf_args<wchar_t>(args...));
 }

 /**
@@ -644,11 +617,6 @@ template <typename... T>
 inline auto printf(string_view fmt, const T&... args) -> int {
  return vfprintf(stdout, fmt, make_printf_args(args...));
 }
-template <typename... T>
-FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
-                                  const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
-}

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

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

@@ -40,29 +39,16 @@ template <typename T> class is_set {
  template <typename> static void check(...);

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

-template <typename... Ts> struct conditional_helper {};
-
-template <typename T, typename _ = void> struct is_range_ : std::false_type {};
-
-#if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
-
-#  define FMT_DECLTYPE_RETURN(val)  \
-    ->decltype(val) { return val; } \
-    static_assert(                  \
-        true, "")  // This makes it so that a semicolon is required after the
-                   // macro, which helps clang-format handle the formatting.
-
 // C array overload
-template <typename T, std::size_t N>
+template <typename T, size_t N>
 auto range_begin(const T (&arr)[N]) -> const T* {
  return arr;
 }
-template <typename T, std::size_t N>
-auto range_end(const T (&arr)[N]) -> const T* {
+template <typename T, size_t N> auto range_end(const T (&arr)[N]) -> const T* {
  return arr + N;
 }

@@ -76,9 +62,13 @@ struct has_member_fn_begin_end_t<T, void_t<decltype(*std::declval<T>().begin()),

 // Member function overloads.
 template <typename T>
-auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
+auto range_begin(T&& rng) -> decltype(static_cast<T&&>(rng).begin()) {
+  return static_cast<T&&>(rng).begin();
+}
 template <typename T>
-auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
+auto range_end(T&& rng) -> decltype(static_cast<T&&>(rng).end()) {
+  return static_cast<T&&>(rng).end();
+}

 // ADL overloads. Only participate in overload resolution if member functions
 // are not found.
@@ -115,21 +105,20 @@ struct has_mutable_begin_end<
              // SFINAE properly unless there are distinct types
              int>> : std::true_type {};

+template <typename T, typename _ = void> struct is_range_ : std::false_type {};
 template <typename T>
 struct is_range_<T, void>
    : std::integral_constant<bool, (has_const_begin_end<T>::value ||
                                    has_mutable_begin_end<T>::value)> {};
-#  undef FMT_DECLTYPE_RETURN
-#endif

 // tuple_size and tuple_element check.
 template <typename T> class is_tuple_like_ {
-  template <typename U>
-  static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
+  template <typename U, typename V = typename std::remove_cv<U>::type>
+  static auto check(U* p) -> decltype(std::tuple_size<V>::value, 0);
  template <typename> static void check(...);

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

@@ -163,7 +152,7 @@ using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
 template <typename T, typename C, bool = is_tuple_like_<T>::value>
 class is_tuple_formattable_ {
 public:
-  static constexpr const bool value = false;
+  static constexpr bool value = false;
 };
 template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
  template <size_t... Is>
@@ -179,7 +168,7 @@ template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
                                       C>::value)...>{}));

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

@@ -217,7 +206,7 @@ template <typename Char, typename... T>
 using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;

 using std::get;
-template <typename Tuple, typename Char, std::size_t... Is>
+template <typename Tuple, typename Char, size_t... Is>
 auto get_formatters(index_sequence<Is...>)
    -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
 }  // namespace tuple
@@ -228,7 +217,7 @@ template <typename R> struct range_reference_type_impl {
  using type = decltype(*detail::range_begin(std::declval<R&>()));
 };

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

@@ -266,12 +255,12 @@ 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 Char> struct parse_empty_specs {
  template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
    f.parse(ctx);
    detail::maybe_set_debug_format(f, true);
  }
-  ParseContext& ctx;
+  parse_context<Char>& ctx;
 };
 template <typename FormatContext> struct format_tuple_element {
  using char_type = typename FormatContext::char_type;
@@ -290,14 +279,15 @@ template <typename FormatContext> struct format_tuple_element {

 }  // namespace detail

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

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

 template <typename Tuple, typename Char>
@@ -327,11 +317,17 @@ struct formatter<Tuple, Char,
    closing_bracket_ = close;
  }

-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    auto it = ctx.begin();
-    if (it != ctx.end() && *it != '}') report_error("invalid format specifier");
-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
+    auto end = ctx.end();
+    if (it != end && detail::to_ascii(*it) == 'n') {
+      ++it;
+      set_brackets({}, {});
+      set_separator({});
+    }
+    if (it != end && *it != '}') report_error("invalid format specifier");
+    ctx.advance_to(it);
+    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
    return it;
  }

@@ -346,44 +342,24 @@ struct formatter<Tuple, Char,
  }
 };

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

 namespace detail {
-template <typename Context> struct range_mapper {
-  using mapper = arg_mapper<Context>;
-
-  template <typename T,
-            FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
-  static auto map(T&& value) -> T&& {
-    return static_cast<T&&>(value);
-  }
-  template <typename T,
-            FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
-  static auto map(T&& value)
-      -> decltype(mapper().map(static_cast<T&&>(value))) {
-    return mapper().map(static_cast<T&&>(value));
-  }
-};

 template <typename Char, typename Element>
-using range_formatter_type =
-    formatter<remove_cvref_t<decltype(range_mapper<buffered_context<Char>>{}
-                                          .map(std::declval<Element>()))>,
-              Char>;
+using range_formatter_type = formatter<remove_cvref_t<Element>, Char>;

 template <typename R>
 using maybe_const_range =
    conditional_t<has_const_begin_end<R>::value, const R, R>;

-// Workaround a bug in MSVC 2015 and earlier.
-#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
 template <typename R, typename Char>
 struct is_formattable_delayed
    : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
-#endif
 }  // namespace detail

 template <typename...> struct conjunction : std::true_type {};
@@ -392,6 +368,7 @@ template <typename P1, typename... Pn>
 struct conjunction<P1, Pn...>
    : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};

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

@@ -415,7 +392,7 @@ struct range_formatter<
    auto buf = basic_memory_buffer<Char>();
    for (; it != end; ++it) buf.push_back(*it);
    auto specs = format_specs();
-    specs.type = presentation_type::debug;
+    specs.set_type(presentation_type::debug);
    return detail::write<Char>(
        out, basic_string_view<Char>(buf.data(), buf.size()), specs);
  }
@@ -443,8 +420,7 @@ struct range_formatter<
    closing_bracket_ = close;
  }

-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    auto it = ctx.begin();
    auto end = ctx.end();
    detail::maybe_set_debug_format(underlying_, true);
@@ -486,7 +462,6 @@ struct range_formatter<

  template <typename R, typename FormatContext>
  auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
-    auto mapper = detail::range_mapper<buffered_context<Char>>();
    auto out = ctx.out();
    auto it = detail::range_begin(range);
    auto end = detail::range_end(range);
@@ -498,7 +473,7 @@ struct range_formatter<
      if (i > 0) out = detail::copy<Char>(separator_, out);
      ctx.advance_to(out);
      auto&& item = *it;  // Need an lvalue
-      out = underlying_.format(mapper.map(item), ctx);
+      out = underlying_.format(item, ctx);
      ++i;
    }
    out = detail::copy<Char>(closing_bracket_, out);
@@ -521,13 +496,8 @@ struct formatter<
            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>
-#endif
-        >::value>> {
+            range_format_kind<R, Char>::value != range_format::debug_string>,
+        detail::is_formattable_delayed<R, Char>>::value>> {
 private:
  using range_type = detail::maybe_const_range<R>;
  range_formatter<detail::uncvref_type<range_type>, Char> range_formatter_;
@@ -543,8 +513,7 @@ struct formatter<
                                  detail::string_literal<Char, '}'>{});
  }

-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    return range_formatter_.parse(ctx);
  }

@@ -559,7 +528,9 @@ struct formatter<
 template <typename R, typename Char>
 struct formatter<
    R, Char,
-    enable_if_t<range_format_kind<R, Char>::value == range_format::map>> {
+    enable_if_t<conjunction<
+        bool_constant<range_format_kind<R, Char>::value == range_format::map>,
+        detail::is_formattable_delayed<R, Char>>::value>> {
 private:
  using map_type = detail::maybe_const_range<R>;
  using element_type = detail::uncvref_type<map_type>;
@@ -571,8 +542,7 @@ struct formatter<
 public:
  FMT_CONSTEXPR formatter() {}

-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    auto it = ctx.begin();
    auto end = ctx.end();
    if (it != end) {
@@ -586,7 +556,7 @@ struct formatter<
      }
      ctx.advance_to(it);
    }
-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
+    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
    return it;
  }

@@ -596,12 +566,11 @@ struct formatter<
    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::for_each2(formatters_, value,
                        detail::format_tuple_element<FormatContext>{
                            0, ctx, detail::string_literal<Char, ':', ' '>{}});
      ++i;
@@ -631,8 +600,7 @@ struct formatter<
  formatter<string_type, Char> underlying_;

 public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    return underlying_.parse(ctx);
  }

@@ -673,22 +641,22 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
 #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>&&>;
+  using view = 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* {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& 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 format(view& value, FormatContext& ctx) const -> decltype(ctx.out()) {
+    using iter =
+        conditional_t<std::is_copy_constructible<view>::value, It, It&>;
+    iter it = value.begin;
    auto out = ctx.out();
    if (it == value.end) return out;
    out = value_formatter_.format(*it, ctx);
@@ -703,6 +671,123 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
  }
 };

+FMT_EXPORT
+template <typename Tuple, typename Char> struct tuple_join_view : detail::view {
+  const Tuple& tuple;
+  basic_string_view<Char> sep;
+
+  tuple_join_view(const Tuple& t, basic_string_view<Char> s)
+      : tuple(t), sep{s} {}
+};
+
+// Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
+// support in tuple_join. It is disabled by default because of issues with
+// the dynamic width and precision.
+#ifndef FMT_TUPLE_JOIN_SPECIFIERS
+#  define FMT_TUPLE_JOIN_SPECIFIERS 0
+#endif
+
+template <typename Tuple, typename Char>
+struct formatter<tuple_join_view<Tuple, Char>, Char,
+                 enable_if_t<is_tuple_like<Tuple>::value>> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return do_parse(ctx, std::tuple_size<Tuple>());
+  }
+
+  template <typename FormatContext>
+  auto format(const tuple_join_view<Tuple, Char>& value,
+              FormatContext& ctx) const -> typename FormatContext::iterator {
+    return do_format(value, ctx, std::tuple_size<Tuple>());
+  }
+
+ private:
+  decltype(detail::tuple::get_formatters<Tuple, Char>(
+      detail::tuple_index_sequence<Tuple>())) formatters_;
+
+  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
+                              std::integral_constant<size_t, 0>)
+      -> const Char* {
+    return ctx.begin();
+  }
+
+  template <size_t N>
+  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
+                              std::integral_constant<size_t, N>)
+      -> const Char* {
+    auto end = ctx.begin();
+#if FMT_TUPLE_JOIN_SPECIFIERS
+    end = std::get<std::tuple_size<Tuple>::value - N>(formatters_).parse(ctx);
+    if (N > 1) {
+      auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
+      if (end != end1)
+        report_error("incompatible format specs for tuple elements");
+    }
+#endif
+    return end;
+  }
+
+  template <typename FormatContext>
+  auto do_format(const tuple_join_view<Tuple, Char>&, FormatContext& ctx,
+                 std::integral_constant<size_t, 0>) const ->
+      typename FormatContext::iterator {
+    return ctx.out();
+  }
+
+  template <typename FormatContext, size_t N>
+  auto do_format(const tuple_join_view<Tuple, Char>& value, FormatContext& ctx,
+                 std::integral_constant<size_t, N>) const ->
+      typename FormatContext::iterator {
+    using std::get;
+    auto out =
+        std::get<std::tuple_size<Tuple>::value - N>(formatters_)
+            .format(get<std::tuple_size<Tuple>::value - N>(value.tuple), ctx);
+    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>());
+  }
+};
+
+namespace detail {
+// Check if T has an interface like a container adaptor (e.g. std::stack,
+// std::queue, std::priority_queue).
+template <typename T> class is_container_adaptor_like {
+  template <typename U> static auto check(U* p) -> typename U::container_type;
+  template <typename> static void check(...);
+
+ public:
+  static constexpr bool value =
+      !std::is_void<decltype(check<T>(nullptr))>::value;
+};
+
+template <typename Container> struct all {
+  const Container& c;
+  auto begin() const -> typename Container::const_iterator { return c.begin(); }
+  auto end() const -> typename Container::const_iterator { return c.end(); }
+};
+}  // namespace detail
+
+template <typename T, typename Char>
+struct formatter<
+    T, Char,
+    enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
+                            bool_constant<range_format_kind<T, Char>::value ==
+                                          range_format::disabled>>::value>>
+    : formatter<detail::all<typename T::container_type>, Char> {
+  using all = detail::all<typename T::container_type>;
+  template <typename FormatContext>
+  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
+    struct getter : T {
+      static auto get(const T& v) -> all {
+        return {v.*(&getter::c)};  // Access c through the derived class.
+      }
+    };
+    return formatter<all>::format(getter::get(value), ctx);
+  }
+};
+
+FMT_BEGIN_EXPORT
+
 /// Returns a view that formats the iterator range `[begin, end)` with elements
 /// separated by `sep`.
 template <typename It, typename Sentinel>
@@ -724,128 +809,13 @@ auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
 *     fmt::print("{:02}", fmt::join(v, ", "));
 *     // Output: 01, 02, 03
 */
-template <typename Range>
+template <typename Range, FMT_ENABLE_IF(!is_tuple_like<Range>::value)>
 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;
-
-  tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
-      : tuple(t), sep{s} {}
-};
-
-// Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
-// support in tuple_join. It is disabled by default because of issues with
-// the dynamic width and precision.
-#ifndef FMT_TUPLE_JOIN_SPECIFIERS
-#  define FMT_TUPLE_JOIN_SPECIFIERS 0
-#endif
-
-template <typename Char, typename... T>
-struct formatter<tuple_join_view<Char, T...>, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
-  }
-
-  template <typename FormatContext>
-  auto format(const tuple_join_view<Char, T...>& value,
-              FormatContext& ctx) const -> typename FormatContext::iterator {
-    return do_format(value, ctx,
-                     std::integral_constant<size_t, sizeof...(T)>());
-  }
-
- private:
-  std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
-                              std::integral_constant<size_t, 0>)
-      -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename ParseContext, size_t N>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
-                              std::integral_constant<size_t, N>)
-      -> decltype(ctx.begin()) {
-    auto end = ctx.begin();
-#if FMT_TUPLE_JOIN_SPECIFIERS
-    end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
-    if (N > 1) {
-      auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
-      if (end != end1)
-        report_error("incompatible format specs for tuple elements");
-    }
-#endif
-    return end;
-  }
-
-  template <typename FormatContext>
-  auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
-                 std::integral_constant<size_t, 0>) const ->
-      typename FormatContext::iterator {
-    return ctx.out();
-  }
-
-  template <typename FormatContext, size_t N>
-  auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
-                 std::integral_constant<size_t, N>) const ->
-      typename FormatContext::iterator {
-    auto out = std::get<sizeof...(T) - N>(formatters_)
-                   .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
-    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>());
-  }
-};
-
-namespace detail {
-// Check if T has an interface like a container adaptor (e.g. std::stack,
-// std::queue, std::priority_queue).
-template <typename T> class is_container_adaptor_like {
-  template <typename U> static auto check(U* p) -> typename U::container_type;
-  template <typename> static void check(...);
-
- public:
-  static constexpr const bool value =
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-};
-
-template <typename Container> struct all {
-  const Container& c;
-  auto begin() const -> typename Container::const_iterator { return c.begin(); }
-  auto end() const -> typename Container::const_iterator { return c.end(); }
-};
-}  // namespace detail
-
-template <typename T, typename Char>
-struct formatter<
-    T, Char,
-    enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
-                            bool_constant<range_format_kind<T, Char>::value ==
-                                          range_format::disabled>>::value>>
-    : formatter<detail::all<typename T::container_type>, Char> {
-  using all = detail::all<typename T::container_type>;
-  template <typename FormatContext>
-  auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
-    struct getter : T {
-      static auto get(const T& t) -> all {
-        return {t.*(&getter::c)};  // Access c through the derived class.
-      }
-    };
-    return formatter<all>::format(getter::get(t), ctx);
-  }
-};
-
-FMT_BEGIN_EXPORT
-
 /**
 * Returns an object that formats `std::tuple` with elements separated by `sep`.
 *
@@ -855,9 +825,9 @@ FMT_BEGIN_EXPORT
 *     fmt::print("{}", fmt::join(t, ", "));
 *     // Output: 1, a
 */
-template <typename... T>
-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
-    -> tuple_join_view<char, T...> {
+template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
+FMT_CONSTEXPR auto join(const Tuple& tuple, string_view sep)
+    -> tuple_join_view<Tuple, char> {
  return {tuple, sep};
 }

--- a/include/spdlog/fmt/bundled/std.h
+++ b/include/spdlog/fmt/bundled/std.h
@@ -15,18 +15,18 @@
 #  include <atomic>
 #  include <bitset>
 #  include <complex>
-#  include <cstdlib>
 #  include <exception>
+#  include <functional>  // std::reference_wrapper
 #  include <memory>
 #  include <thread>
 #  include <type_traits>
-#  include <typeinfo>
-#  include <utility>
-#  include <vector>
+#  include <typeinfo>  // std::type_info
+#  include <utility>   // std::make_index_sequence

 // Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
-#    if FMT_HAS_INCLUDE(<filesystem>)
+#    if FMT_HAS_INCLUDE(<filesystem>) && \
+        (!defined(FMT_CPP_LIB_FILESYSTEM) || FMT_CPP_LIB_FILESYSTEM != 0)
 #      include <filesystem>
 #    endif
 #    if FMT_HAS_INCLUDE(<variant>)
@@ -60,27 +60,26 @@
 #  endif
 #endif

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

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

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

 template <typename Char, typename PathChar>
 auto get_path_string(const std::filesystem::path& p,
@@ -109,155 +108,9 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
  }
 }

-}  // namespace detail
-
-FMT_EXPORT
-template <typename Char> struct formatter<std::filesystem::path, Char> {
- private:
-  format_specs specs_;
-  detail::arg_ref<Char> width_ref_;
-  bool debug_ = false;
-  char path_type_ = 0;
-
- public:
-  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
-
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end) return it;
-
-    it = detail::parse_align(it, end, specs_);
-    if (it == end) return it;
-
-    it = detail::parse_dynamic_spec(it, end, specs_.width, width_ref_, ctx);
-    if (it != end && *it == '?') {
-      debug_ = true;
-      ++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_;
-    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);
-    if (!debug_) {
-      auto s = detail::get_path_string<Char>(p, path_string);
-      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
-    }
-    auto quoted = basic_memory_buffer<Char>();
-    detail::write_escaped_path(quoted, p, path_string);
-    return detail::write(ctx.out(),
-                         basic_string_view<Char>(quoted.data(), quoted.size()),
-                         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

-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <std::size_t N, typename Char>
-struct formatter<std::bitset<N>, Char> : nested_formatter<string_view> {
- private:
-  // Functor because C++11 doesn't support generic lambdas.
-  struct writer {
-    const std::bitset<N>& bs;
-
-    template <typename OutputIt>
-    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
-      for (auto pos = N; pos > 0; --pos) {
-        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
-      }
-
-      return out;
-    }
-  };
-
- public:
-  template <typename FormatContext>
-  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return write_padded(ctx, writer{bs});
-  }
-};
-
-FMT_EXPORT
-template <typename Char>
-struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
-FMT_END_NAMESPACE
-
-#ifdef __cpp_lib_optional
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <typename T, typename Char>
-struct formatter<std::optional<T>, Char,
-                 std::enable_if_t<is_formattable<T, Char>::value>> {
- private:
-  formatter<T, Char> underlying_;
-  static constexpr basic_string_view<Char> optional =
-      detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
-                             '('>{};
-  static constexpr basic_string_view<Char> none =
-      detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
-
-  template <class U>
-  FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
-      -> decltype(u.set_debug_format(set)) {
-    u.set_debug_format(set);
-  }
-
-  template <class U>
-  FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
-
- public:
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    maybe_set_debug_format(underlying_, true);
-    return underlying_.parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(const std::optional<T>& opt, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    if (!opt) return detail::write<Char>(ctx.out(), none);
-
-    auto out = ctx.out();
-    out = detail::write<Char>(out, optional);
-    ctx.advance_to(out);
-    out = underlying_.format(*opt, ctx);
-    return detail::write(out, ')');
-  }
-};
-FMT_END_NAMESPACE
-#endif  // __cpp_lib_optional
-
 #if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
 template <typename Char, typename OutputIt, typename T>
 auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
  if constexpr (has_to_string_view<T>::value)
@@ -265,179 +118,33 @@ auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
  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
-template <> struct formatter<std::source_location> {
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const std::source_location& loc, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-    out = detail::write(out, loc.file_name());
-    out = detail::write(out, ':');
-    out = detail::write<char>(out, loc.line());
-    out = detail::write(out, ':');
-    out = detail::write<char>(out, loc.column());
-    out = detail::write(out, ": ");
-    out = detail::write(out, loc.function_name());
-    return out;
-  }
-};
-FMT_END_NAMESPACE
 #endif

 #if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using variant_index_sequence =
-    std::make_index_sequence<std::variant_size<T>::value>;

 template <typename> struct is_variant_like_ : std::false_type {};
 template <typename... Types>
 struct is_variant_like_<std::variant<Types...>> : std::true_type {};

-// formattable element check.
-template <typename T, typename C> class is_variant_formattable_ {
-  template <std::size_t... Is>
-  static std::conjunction<
-      is_formattable<std::variant_alternative_t<Is, T>, C>...>
-      check(std::index_sequence<Is...>);
+template <typename Variant, typename Char> class is_variant_formattable {
+  template <size_t... Is>
+  static auto check(std::index_sequence<Is...>) -> std::conjunction<
+      is_formattable<std::variant_alternative_t<Is, Variant>, Char>...>;

 public:
-  static constexpr const bool value =
-      decltype(check(variant_index_sequence<T>{}))::value;
+  static constexpr bool value = decltype(check(
+      std::make_index_sequence<std::variant_size<Variant>::value>()))::value;
 };

-}  // namespace detail
-
-template <typename T> struct is_variant_like {
-  static constexpr const bool value = detail::is_variant_like_<T>::value;
-};
-
-template <typename T, typename C> struct is_variant_formattable {
-  static constexpr const bool value =
-      detail::is_variant_formattable_<T, C>::value;
-};
-
-FMT_EXPORT
-template <typename Char> struct formatter<std::monostate, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const std::monostate&, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return detail::write<Char>(ctx.out(), "monostate");
-  }
-};
-
-FMT_EXPORT
-template <typename Variant, typename Char>
-struct formatter<
-    Variant, Char,
-    std::enable_if_t<std::conjunction_v<
-        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const Variant& value, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-
-    out = detail::write<Char>(out, "variant(");
-    FMT_TRY {
-      std::visit(
-          [&](const auto& v) {
-            out = detail::write_escaped_alternative<Char>(out, v);
-          },
-          value);
-    }
-    FMT_CATCH(const std::bad_variant_access&) {
-      detail::write<Char>(out, "valueless by exception");
-    }
-    *out++ = ')';
-    return out;
-  }
-};
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_VARIANT

-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <typename Char> struct formatter<std::error_code, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-    out = detail::write_bytes<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>
+template <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;
+  size_t size = 0;
  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);

@@ -473,10 +180,10 @@ auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
  } else {
    demangled_name_view = string_view(ti.name());
  }
-  return detail::write_bytes<Char>(out, demangled_name_view);
+  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) {
+  for (size_t i = 0; i < demangled_name.size(); ++i) {
    auto sub = demangled_name;
    sub.remove_prefix(i);
    if (sub.starts_with("enum ")) {
@@ -495,41 +202,368 @@ auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
  }
  return out;
 #  else
-  return detail::write_bytes<Char>(out, string_view(ti.name()));
+  return detail::write_bytes<char>(out, string_view(ti.name()));
 #  endif
 }

+#endif  // FMT_USE_RTTI
+
+template <typename T, typename Enable = void>
+struct has_flip : std::false_type {};
+
+template <typename T>
+struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
+    : std::true_type {};
+
+template <typename T> struct is_bit_reference_like {
+  static constexpr bool value = std::is_convertible<T, bool>::value &&
+                                std::is_nothrow_assignable<T, bool>::value &&
+                                has_flip<T>::value;
+};
+
+// Workaround for libc++ incompatibility with C++ standard.
+// According to the Standard, `bitset::operator[] const` returns bool.
+#if defined(_LIBCPP_VERSION) && !defined(FMT_IMPORT_STD)
+template <typename C>
+struct is_bit_reference_like<std::__bit_const_reference<C>> {
+  static constexpr bool value = true;
+};
+#endif
+
+template <typename T, typename Enable = void>
+struct has_format_as : std::false_type {};
+template <typename T>
+struct has_format_as<T, void_t<decltype(format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
+template <typename T, typename Enable = void>
+struct has_format_as_member : std::false_type {};
+template <typename T>
+struct has_format_as_member<
+    T, void_t<decltype(formatter<T>::format_as(std::declval<const T&>()))>>
+    : std::true_type {};
+
 }  // namespace detail

-FMT_EXPORT
-template <typename Char>
-struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
-                 > {
+template <typename T, typename Deleter>
+auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
+  return p.get();
+}
+template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
+  return p.get();
+}
+
+#if FMT_CPP_LIB_FILESYSTEM
+
+class path : public std::filesystem::path {
 public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
+  auto display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{}"), base);
+  }
+  auto system_string() const -> std::string { return string(); }
+
+  auto generic_display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{:g}"), base);
+  }
+  auto generic_system_string() const -> std::string { return generic_string(); }
+};
+
+template <typename Char> struct formatter<std::filesystem::path, Char> {
+ private:
+  format_specs specs_;
+  detail::arg_ref<Char> width_ref_;
+  bool debug_ = false;
+  char path_type_ = 0;
+
+ public:
+  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
+
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
+    auto it = ctx.begin(), end = ctx.end();
+    if (it == end) return it;
+
+    it = detail::parse_align(it, end, specs_);
+    if (it == end) return it;
+
+    Char c = *it;
+    if ((c >= '0' && c <= '9') || c == '{')
+      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
+    if (it != end && *it == '?') {
+      debug_ = true;
+      ++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_;
+    auto path_string =
+        !path_type_ ? p.native()
+                    : p.generic_string<std::filesystem::path::value_type>();
+
+    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
+                                ctx);
+    if (!debug_) {
+      auto s = detail::get_path_string<Char>(p, path_string);
+      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
+    }
+    auto quoted = basic_memory_buffer<Char>();
+    detail::write_escaped_path(quoted, p, path_string);
+    return detail::write(ctx.out(),
+                         basic_string_view<Char>(quoted.data(), quoted.size()),
+                         specs);
+  }
+};
+
+#endif  // FMT_CPP_LIB_FILESYSTEM
+
+template <size_t N, typename Char>
+struct formatter<std::bitset<N>, Char>
+    : nested_formatter<basic_string_view<Char>, Char> {
+ private:
+  // This is a functor because C++11 doesn't support generic lambdas.
+  struct writer {
+    const std::bitset<N>& bs;
+
+    template <typename OutputIt>
+    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
+      for (auto pos = N; pos > 0; --pos)
+        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
+      return out;
+    }
+  };
+
+ public:
+  template <typename FormatContext>
+  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return this->write_padded(ctx, writer{bs});
+  }
+};
+
+template <typename Char>
+struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
+
+#ifdef __cpp_lib_optional
+template <typename T, typename Char>
+struct formatter<std::optional<T>, Char,
+                 std::enable_if_t<is_formattable<T, Char>::value>> {
+ private:
+  formatter<T, Char> underlying_;
+  static constexpr basic_string_view<Char> optional =
+      detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
+                             '('>{};
+  static constexpr basic_string_view<Char> none =
+      detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
+
+  template <class U>
+  FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
+      -> decltype(u.set_debug_format(set)) {
+    u.set_debug_format(set);
+  }
+
+  template <class U>
+  FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
+
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
+    maybe_set_debug_format(underlying_, true);
+    return underlying_.parse(ctx);
+  }
+
+  template <typename FormatContext>
+  auto format(const std::optional<T>& opt, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    if (!opt) return detail::write<Char>(ctx.out(), none);
+
+    auto out = ctx.out();
+    out = detail::write<Char>(out, optional);
+    ctx.advance_to(out);
+    out = underlying_.format(*opt, ctx);
+    return detail::write(out, ')');
+  }
+};
+#endif  // __cpp_lib_optional
+
+#ifdef __cpp_lib_expected
+template <typename T, typename E, typename Char>
+struct formatter<std::expected<T, E>, Char,
+                 std::enable_if_t<(std::is_void<T>::value ||
+                                   is_formattable<T, Char>::value) &&
+                                  is_formattable<E, Char>::value>> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    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(");
+      if constexpr (!std::is_void<T>::value)
+        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;
+  }
+};
+#endif  // __cpp_lib_expected
+
+#ifdef __cpp_lib_source_location
+template <> struct formatter<std::source_location> {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
+
+  template <typename FormatContext>
+  auto format(const std::source_location& loc, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    out = detail::write(out, loc.file_name());
+    out = detail::write(out, ':');
+    out = detail::write<char>(out, loc.line());
+    out = detail::write(out, ':');
+    out = detail::write<char>(out, loc.column());
+    out = detail::write(out, ": ");
+    out = detail::write(out, loc.function_name());
+    return out;
+  }
+};
+#endif
+
+#if FMT_CPP_LIB_VARIANT
+
+template <typename T> struct is_variant_like {
+  static constexpr bool value = detail::is_variant_like_<T>::value;
+};
+
+template <typename Char> struct formatter<std::monostate, Char> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const std::monostate&, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return detail::write<Char>(ctx.out(), "monostate");
+  }
+};
+
+template <typename Variant, typename Char>
+struct formatter<Variant, Char,
+                 std::enable_if_t<std::conjunction_v<
+                     is_variant_like<Variant>,
+                     detail::is_variant_formattable<Variant, Char>>>> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const Variant& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+
+    out = detail::write<Char>(out, "variant(");
+    FMT_TRY {
+      std::visit(
+          [&](const auto& v) {
+            out = detail::write_escaped_alternative<Char>(out, v);
+          },
+          value);
+    }
+    FMT_CATCH(const std::bad_variant_access&) {
+      detail::write<Char>(out, "valueless by exception");
+    }
+    *out++ = ')';
+    return out;
+  }
+};
+
+#endif  // FMT_CPP_LIB_VARIANT
+
+template <> struct formatter<std::error_code> {
+ private:
+  format_specs specs_;
+  detail::arg_ref<char> width_ref_;
+  bool debug_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
+    auto it = ctx.begin(), end = ctx.end();
+    if (it == end) return it;
+
+    it = detail::parse_align(it, end, specs_);
+
+    char c = *it;
+    if (it != end && ((c >= '0' && c <= '9') || c == '{'))
+      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
+
+    if (it != end && *it == '?') {
+      debug_ = true;
+      ++it;
+    }
+    if (it != end && *it == 's') {
+      specs_.set_type(presentation_type::string);
+      ++it;
+    }
+    return it;
+  }
+
+  template <typename FormatContext>
+  FMT_CONSTEXPR20 auto format(const std::error_code& ec,
+                              FormatContext& ctx) const -> decltype(ctx.out()) {
+    auto specs = specs_;
+    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
+                                ctx);
+    auto buf = memory_buffer();
+    if (specs_.type() == presentation_type::string) {
+      buf.append(ec.message());
+    } else {
+      buf.append(string_view(ec.category().name()));
+      buf.push_back(':');
+      detail::write<char>(appender(buf), ec.value());
+    }
+    auto quoted = memory_buffer();
+    auto str = string_view(buf.data(), buf.size());
+    if (debug_) {
+      detail::write_escaped_string<char>(std::back_inserter(quoted), str);
+      str = string_view(quoted.data(), quoted.size());
+    }
+    return detail::write<char>(ctx.out(), str, specs);
+  }
+};
+
+#if FMT_USE_RTTI
+template <> struct formatter<std::type_info> {
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
    return ctx.begin();
  }

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

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

 public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
    auto it = ctx.begin();
    auto end = ctx.end();
    if (it == end || *it == '}') return it;
@@ -546,47 +580,18 @@ struct formatter<
    auto out = ctx.out();
 #if FMT_USE_RTTI
    if (with_typename_) {
-      out = detail::write_demangled_name<Char>(out, typeid(ex));
+      out = detail::write_demangled_name(out, typeid(ex));
      *out++ = ':';
      *out++ = ' ';
    }
 #endif
-    return detail::write_bytes<Char>(out, string_view(ex.what()));
+    return detail::write_bytes<char>(out, string_view(ex.what()));
  }
 };

-namespace detail {
-
-template <typename T, typename Enable = void>
-struct has_flip : std::false_type {};
-
-template <typename T>
-struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
-    : std::true_type {};
-
-template <typename T> struct is_bit_reference_like {
-  static constexpr const bool value =
-      std::is_convertible<T, bool>::value &&
-      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
-};
-
-#ifdef _LIBCPP_VERSION
-
-// Workaround for libc++ incompatibility with C++ standard.
-// According to the Standard, `bitset::operator[] const` returns bool.
-template <typename C>
-struct is_bit_reference_like<std::__bit_const_reference<C>> {
-  static constexpr const bool value = true;
-};
-
-#endif
-
-}  // namespace detail
-
 // We can't use std::vector<bool, Allocator>::reference and
 // std::bitset<N>::reference because the compiler can't deduce Allocator and N
 // in partial specialization.
-FMT_EXPORT
 template <typename BitRef, typename Char>
 struct formatter<BitRef, Char,
                 enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
@@ -598,15 +603,6 @@ struct formatter<BitRef, Char,
  }
 };

-template <typename T, typename Deleter>
-auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
-  return p.get();
-}
-template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
-  return p.get();
-}
-
-FMT_EXPORT
 template <typename T, typename Char>
 struct formatter<std::atomic<T>, Char,
                 enable_if_t<is_formattable<T, Char>::value>>
@@ -619,7 +615,6 @@ struct formatter<std::atomic<T>, Char,
 };

 #ifdef __cpp_lib_atomic_flag_test
-FMT_EXPORT
 template <typename Char>
 struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
  template <typename FormatContext>
@@ -630,7 +625,6 @@ struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
 };
 #endif  // __cpp_lib_atomic_flag_test

-FMT_EXPORT
 template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
 private:
  detail::dynamic_format_specs<Char> specs_;
@@ -643,7 +637,7 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
    if (c.real() != 0) {
      *out++ = Char('(');
      out = detail::write<Char>(out, c.real(), specs, ctx.locale());
-      specs.sign = sign::plus;
+      specs.set_sign(sign::plus);
      out = detail::write<Char>(out, c.imag(), specs, ctx.locale());
      if (!detail::isfinite(c.imag())) *out++ = Char(' ');
      *out++ = Char('i');
@@ -657,8 +651,7 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
  }

 public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
    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);
@@ -668,12 +661,11 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
  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.dynamic()) {
+      detail::handle_dynamic_spec(specs.dynamic_width(), specs.width,
+                                  specs.width_ref, ctx);
+      detail::handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
+                                  specs.precision_ref, ctx);
    }

    if (specs.width == 0) return do_format(c, specs, ctx, ctx.out());
@@ -681,12 +673,12 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {

    auto outer_specs = format_specs();
    outer_specs.width = specs.width;
-    outer_specs.fill = specs.fill;
-    outer_specs.align = specs.align;
+    outer_specs.copy_fill_from(specs);
+    outer_specs.set_align(specs.align());

    specs.width = 0;
-    specs.fill = {};
-    specs.align = align::none;
+    specs.set_fill({});
+    specs.set_align(align::none);

    do_format(c, specs, ctx, basic_appender<Char>(buf));
    return detail::write<Char>(ctx.out(),
@@ -695,5 +687,21 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
  }
 };

+template <typename T, typename Char>
+struct formatter<std::reference_wrapper<T>, Char,
+                 // Guard against format_as because reference_wrapper is
+                 // implicitly convertible to T&.
+                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value &&
+                             !detail::has_format_as<T>::value &&
+                             !detail::has_format_as_member<T>::value>>
+    : formatter<remove_cvref_t<T>, Char> {
+  template <typename FormatContext>
+  auto format(std::reference_wrapper<T> ref, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return formatter<remove_cvref_t<T>, Char>::format(ref.get(), ctx);
+  }
+};
+
 FMT_END_NAMESPACE
+
 #endif  // FMT_STD_H_
--- a/include/spdlog/fmt/bundled/xchar.h
+++ b/include/spdlog/fmt/bundled/xchar.h
@@ -10,11 +10,12 @@

 #include "color.h"
 #include "format.h"
+#include "ostream.h"
 #include "ranges.h"

 #ifndef FMT_MODULE
 #  include <cwchar>
-#  if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
+#  if FMT_USE_LOCALE
 #    include <locale>
 #  endif
 #endif
@@ -34,7 +35,8 @@ struct format_string_char<
 };

 template <typename S>
-struct format_string_char<S, enable_if_t<is_compile_string<S>::value>> {
+struct format_string_char<
+    S, enable_if_t<std::is_base_of<detail::compile_string, S>::value>> {
  using type = typename S::char_type;
 };

@@ -43,7 +45,7 @@ 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
+#if FMT_USE_LOCALE
  auto& numpunct =
      std::use_facet<std::numpunct<wchar_t>>(loc.get<std::locale>());
  auto separator = std::wstring();
@@ -53,36 +55,72 @@ inline auto write_loc(basic_appender<wchar_t> out, loc_value value,
 #endif
  return false;
 }
+
+template <typename Char>
+void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
+                basic_format_args<buffered_context<Char>> args,
+                locale_ref loc = {}) {
+  static_assert(!std::is_same<Char, char>::value, "");
+  auto out = basic_appender<Char>(buf);
+  parse_format_string(
+      fmt, format_handler<Char>{parse_context<Char>(fmt), {out, args, loc}});
+}
 }  // namespace detail

 FMT_BEGIN_EXPORT

 using wstring_view = basic_string_view<wchar_t>;
-using wformat_parse_context = basic_format_parse_context<wchar_t>;
+using wformat_parse_context = parse_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>;

-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
-// Workaround broken conversion on older gcc.
-template <typename... Args> using wformat_string = wstring_view;
-inline auto runtime(wstring_view s) -> wstring_view { return s; }
-#else
-template <typename... Args>
-using wformat_string = basic_format_string<wchar_t, type_identity_t<Args>...>;
+template <typename Char, typename... T> struct basic_fstring {
+ private:
+  basic_string_view<Char> str_;
+
+  static constexpr int num_static_named_args =
+      detail::count_static_named_args<T...>();
+
+  using checker = detail::format_string_checker<
+      Char, static_cast<int>(sizeof...(T)), num_static_named_args,
+      num_static_named_args != detail::count_named_args<T...>()>;
+
+  using arg_pack = detail::arg_pack<T...>;
+
+ public:
+  using t = basic_fstring;
+
+  template <typename S,
+            FMT_ENABLE_IF(
+                std::is_convertible<const S&, basic_string_view<Char>>::value)>
+  FMT_CONSTEVAL FMT_ALWAYS_INLINE basic_fstring(const S& s) : str_(s) {
+    if (FMT_USE_CONSTEVAL)
+      detail::parse_format_string<Char>(s, checker(s, arg_pack()));
+  }
+  template <typename S,
+            FMT_ENABLE_IF(std::is_base_of<detail::compile_string, S>::value&&
+                              std::is_same<typename S::char_type, Char>::value)>
+  FMT_ALWAYS_INLINE basic_fstring(const S&) : str_(S()) {
+    FMT_CONSTEXPR auto sv = basic_string_view<Char>(S());
+    FMT_CONSTEXPR int ignore =
+        (parse_format_string(sv, checker(sv, arg_pack())), 0);
+    detail::ignore_unused(ignore);
+  }
+  basic_fstring(runtime_format_string<Char> fmt) : str_(fmt.str) {}
+
+  operator basic_string_view<Char>() const { return str_; }
+  auto get() const -> basic_string_view<Char> { return str_; }
+};
+
+template <typename Char, typename... T>
+using basic_format_string = basic_fstring<Char, T...>;
+
+template <typename... T>
+using wformat_string = typename basic_format_string<wchar_t, T...>::t;
 inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
  return {{s}};
 }
-#endif
-
-template <> struct is_char<wchar_t> : std::true_type {};
-template <> struct is_char<char16_t> : std::true_type {};
-template <> struct is_char<char32_t> : std::true_type {};
-
-#ifdef __cpp_char8_t
-template <>
-struct is_char<char8_t> : bool_constant<detail::is_utf8_enabled()> {};
-#endif

 template <typename... T>
 constexpr auto make_wformat_args(T&... args)
@@ -90,14 +128,13 @@ constexpr auto make_wformat_args(T&... args)
  return fmt::make_format_args<wformat_context>(args...);
 }

+#if !FMT_USE_NONTYPE_TEMPLATE_ARGS
 inline namespace literals {
-#if FMT_USE_USER_DEFINED_LITERALS && !FMT_USE_NONTYPE_TEMPLATE_ARGS
-constexpr auto operator""_a(const wchar_t* s, size_t)
-    -> detail::udl_arg<wchar_t> {
+inline auto operator""_a(const wchar_t* s, size_t) -> detail::udl_arg<wchar_t> {
  return {s};
 }
-#endif
 }  // namespace literals
+#endif

 template <typename It, typename Sentinel>
 auto join(It begin, Sentinel end, wstring_view sep)
@@ -105,9 +142,9 @@ auto join(It begin, Sentinel end, wstring_view sep)
  return {begin, end, sep};
 }

-template <typename Range>
+template <typename Range, FMT_ENABLE_IF(!is_tuple_like<Range>::value)>
 auto join(Range&& range, wstring_view sep)
-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>,
+    -> join_view<decltype(std::begin(range)), decltype(std::end(range)),
                 wchar_t> {
  return join(std::begin(range), std::end(range), sep);
 }
@@ -118,19 +155,19 @@ 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...> {
+template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
+auto join(const Tuple& tuple, basic_string_view<wchar_t> sep)
+    -> tuple_join_view<Tuple, wchar_t> {
  return {tuple, sep};
 }

 template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
-auto vformat(basic_string_view<Char> format_str,
-             typename detail::vformat_args<Char>::type args)
+auto vformat(basic_string_view<Char> fmt,
+             basic_format_args<buffered_context<Char>> args)
    -> std::basic_string<Char> {
  auto buf = basic_memory_buffer<Char>();
-  detail::vformat_to(buf, format_str, args);
-  return to_string(buf);
+  detail::vformat_to(buf, fmt, args);
+  return {buf.data(), buf.size()};
 }

 template <typename... T>
@@ -151,40 +188,38 @@ 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),
+auto format(const S& fmt, T&&... args) -> std::basic_string<Char> {
+  return vformat(detail::to_string_view(fmt),
                 fmt::make_format_args<buffered_context<Char>>(args...));
 }

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

-template <typename Locale, typename S, typename... T,
+template <typename S, typename... T,
          typename Char = detail::format_string_char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format(const Locale& loc, const S& format_str, T&&... args)
+          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+inline auto format(locale_ref loc, const S& fmt, T&&... args)
    -> std::basic_string<Char> {
-  return detail::vformat(
-      loc, detail::to_string_view(format_str),
-      fmt::make_format_args<buffered_context<Char>>(args...));
+  return vformat(loc, detail::to_string_view(fmt),
+                 fmt::make_format_args<buffered_context<Char>>(args...));
 }

 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,
-                typename detail::vformat_args<Char>::type args) -> OutputIt {
+auto vformat_to(OutputIt out, const S& fmt,
+                basic_format_args<buffered_context<Char>> args) -> OutputIt {
  auto&& buf = detail::get_buffer<Char>(out);
-  detail::vformat_to(buf, detail::to_string_view(format_str), args);
+  detail::vformat_to(buf, detail::to_string_view(fmt), args);
  return detail::get_iterator(buf, out);
 }

@@ -198,42 +233,37 @@ inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
                    fmt::make_format_args<buffered_context<Char>>(args...));
 }

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

-template <typename OutputIt, typename Locale, typename S, typename... T,
+template <typename OutputIt, typename S, typename... T,
          typename Char = detail::format_string_char_t<S>,
          bool enable = detail::is_output_iterator<OutputIt, Char>::value &&
-                        detail::is_locale<Locale>::value &&
                        detail::is_exotic_char<Char>::value>
-inline auto format_to(OutputIt out, const Locale& loc, const S& format_str,
-                      T&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
-  return vformat_to(out, loc, detail::to_string_view(format_str),
+inline auto format_to(OutputIt out, locale_ref loc, const S& fmt, T&&... args)
+    -> typename std::enable_if<enable, OutputIt>::type {
+  return vformat_to(out, loc, detail::to_string_view(fmt),
                    fmt::make_format_args<buffered_context<Char>>(args...));
 }

 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,
-                         typename detail::vformat_args<Char>::type args)
+inline auto vformat_to_n(OutputIt out, size_t n, basic_string_view<Char> fmt,
+                         basic_format_args<buffered_context<Char>> args)
    -> format_to_n_result<OutputIt> {
  using traits = detail::fixed_buffer_traits;
  auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
-  detail::vformat_to(buf, format_str, args);
+  detail::vformat_to(buf, fmt, args);
  return {buf.out(), buf.count()};
 }

@@ -287,29 +317,33 @@ template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
  return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
 }

-inline auto vformat(const text_style& ts, wstring_view fmt, wformat_args args)
+inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
    -> std::wstring {
  auto buf = wmemory_buffer();
  detail::vformat_to(buf, ts, fmt, args);
-  return fmt::to_string(buf);
+  return {buf.data(), buf.size()};
 }

 template <typename... T>
-inline auto format(const text_style& ts, wformat_string<T...> fmt, T&&... args)
+inline auto format(text_style ts, wformat_string<T...> fmt, T&&... args)
    -> std::wstring {
  return fmt::vformat(ts, fmt, fmt::make_wformat_args(args...));
 }

-template <typename... T>
-FMT_DEPRECATED void print(std::FILE* f, const text_style& ts,
-                          wformat_string<T...> fmt, const T&... args) {
-  vprint(f, ts, fmt, fmt::make_wformat_args(args...));
+inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
+  auto buffer = basic_memory_buffer<wchar_t>();
+  detail::vformat_to(buffer, fmt, args);
+  detail::write_buffer(os, buffer);
 }

 template <typename... T>
-FMT_DEPRECATED void print(const text_style& ts, wformat_string<T...> fmt,
-                          const T&... args) {
-  return print(stdout, ts, fmt, args...);
+void print(std::wostream& os, wformat_string<T...> fmt, T&&... args) {
+  vprint(os, fmt, fmt::make_format_args<buffered_context<wchar_t>>(args...));
+}
+
+template <typename... T>
+void println(std::wostream& os, wformat_string<T...> fmt, T&&... args) {
+  print(os, L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
 }

 /// Converts `value` to `std::wstring` using the default format for type `T`.
--- a/include/spdlog/fmt/fmt.h
+++ b/include/spdlog/fmt/fmt.h
@@ -20,11 +20,7 @@
    #ifndef FMT_USE_WINDOWS_H
        #define FMT_USE_WINDOWS_H 0
    #endif
-
-    #include <spdlog/fmt/bundled/core.h>
    #include <spdlog/fmt/bundled/format.h>
-
 #else  // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
-    #include <fmt/core.h>
    #include <fmt/format.h>
 #endif
--- a/include/spdlog/logger-inl.h
+++ b/include/spdlog/logger-inl.h
@@ -57,7 +57,7 @@ SPDLOG_INLINE void logger::swap(spdlog::logger &other) SPDLOG_NOEXCEPT {
    std::swap(tracer_, other.tracer_);
 }

-SPDLOG_INLINE void swap(logger &a, logger &b) { a.swap(b); }
+SPDLOG_INLINE void swap(logger &a, logger &b) noexcept { a.swap(b); }

 SPDLOG_INLINE void logger::set_level(level::level_enum log_level) { level_.store(log_level); }

@@ -163,12 +163,12 @@ SPDLOG_INLINE void logger::dump_backtrace_() {
    }
 }

-SPDLOG_INLINE bool logger::should_flush_(const details::log_msg &msg) {
+SPDLOG_INLINE bool logger::should_flush_(const details::log_msg &msg) const {
    auto flush_level = flush_level_.load(std::memory_order_relaxed);
    return (msg.level >= flush_level) && (msg.level != level::off);
 }

-SPDLOG_INLINE void logger::err_handler_(const std::string &msg) {
+SPDLOG_INLINE void logger::err_handler_(const std::string &msg) const {
    if (custom_err_handler_) {
        custom_err_handler_(msg);
    } else {
--- a/include/spdlog/logger.h
+++ b/include/spdlog/logger.h
@@ -363,14 +363,14 @@ protected:
    virtual void sink_it_(const details::log_msg &msg);
    virtual void flush_();
    void dump_backtrace_();
-    bool should_flush_(const details::log_msg &msg);
+    bool should_flush_(const details::log_msg &msg) const;

    // handle errors during logging.
    // default handler prints the error to stderr at max rate of 1 message/sec.
-    void err_handler_(const std::string &msg);
+    void err_handler_(const std::string &msg) const;
 };

-void swap(logger &a, logger &b);
+void swap(logger &a, logger &b) noexcept;

 }  // namespace spdlog

--- a/include/spdlog/mdc.h
+++ b/include/spdlog/mdc.h
@@ -12,12 +12,14 @@

 #include <spdlog/common.h>

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

 namespace spdlog {
 class SPDLOG_API mdc {
--- a/include/spdlog/pattern_formatter-inl.h
+++ b/include/spdlog/pattern_formatter-inl.h
@@ -70,6 +70,9 @@ public:
            pad_it(remaining_pad_);
        } else if (padinfo_.truncate_) {
            long new_size = static_cast<long>(dest_.size()) + remaining_pad_;
+            if (new_size < 0) {
+                new_size = 0;
+            }
            dest_.resize(static_cast<size_t>(new_size));
        }
    }
@@ -264,7 +267,7 @@ public:
        : flag_formatter(padinfo) {}

    void format(const details::log_msg &, const std::tm &tm_time, memory_buf_t &dest) override {
-        const size_t field_size = 10;
+        const size_t field_size = 8;
        ScopedPadder p(field_size, padinfo_, dest);

        fmt_helper::pad2(tm_time.tm_mon + 1, dest);
@@ -507,6 +510,7 @@ public:
 };

 // ISO 8601 offset from UTC in timezone (+-HH:MM)
+// If SPDLOG_NO_TZ_OFFSET is defined, print "+??.??" instead.
 template <typename ScopedPadder>
 class z_formatter final : public flag_formatter {
 public:
@@ -521,6 +525,10 @@ public:
        const size_t field_size = 6;
        ScopedPadder p(field_size, padinfo_, dest);

+#ifdef SPDLOG_NO_TZ_OFFSET
+        const char *str = "+??:??";
+        dest.append(str, str + 6);
+#else
        auto total_minutes = get_cached_offset(msg, tm_time);
        bool is_negative = total_minutes < 0;
        if (is_negative) {
@@ -533,6 +541,7 @@ public:
        fmt_helper::pad2(total_minutes / 60, dest);  // hours
        dest.push_back(':');
        fmt_helper::pad2(total_minutes % 60, dest);  // minutes
+#endif  // SPDLOG_NO_TZ_OFFSET
    }

 private:
@@ -926,9 +935,8 @@ private:
    memory_buf_t cached_datetime_;

 #ifndef SPDLOG_NO_TLS
-    mdc_formatter<null_scoped_padder> mdc_formatter_{padding_info{}};
+    mdc_formatter<null_scoped_padder> mdc_formatter_{padding_info {}};
 #endif
-
 };

 }  // namespace details
@@ -1152,12 +1160,10 @@ SPDLOG_INLINE void pattern_formatter::handle_flag_(char flag, details::padding_i
            formatters_.push_back(details::make_unique<details::T_formatter<Padder>>(padding));
            need_localtime_ = true;
            break;
-
        case ('z'):  // timezone
            formatters_.push_back(details::make_unique<details::z_formatter<Padder>>(padding));
            need_localtime_ = true;
            break;
-
        case ('P'):  // pid
            formatters_.push_back(details::make_unique<details::pid_formatter<Padder>>(padding));
            break;
--- a/include/spdlog/sinks/ansicolor_sink-inl.h
+++ b/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 +111,16 @@ 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>
--- a/include/spdlog/sinks/ansicolor_sink.h
+++ b/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 override;
+    void set_pattern(const std::string &pattern) 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);
 };

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

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

 private:
    custom_log_callback callback_;
--- a/include/spdlog/sinks/daily_file_sink.h
+++ b/include/spdlog/sinks/daily_file_sink.h
@@ -62,7 +62,6 @@ 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.
- * 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.
 */
--- a/include/spdlog/sinks/dup_filter_sink.h
+++ b/include/spdlog/sinks/dup_filter_sink.h
@@ -40,22 +40,21 @@ template <typename Mutex>
 class dup_filter_sink : public dist_sink<Mutex> {
 public:
    template <class Rep, class Period>
-    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration,
-                             level::level_enum notification_level = level::info)
-        : max_skip_duration_{max_skip_duration},
-          log_level_{notification_level} {}
+    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration)
+        : max_skip_duration_{max_skip_duration} {}

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

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

@@ -65,7 +64,7 @@ protected:
            auto msg_size = ::snprintf(buf, sizeof(buf), "Skipped %u duplicate messages..",
                                       static_cast<unsigned>(skip_counter_));
            if (msg_size > 0 && static_cast<size_t>(msg_size) < sizeof(buf)) {
-                details::log_msg skipped_msg{msg.source, msg.logger_name, log_level_,
+                details::log_msg skipped_msg{msg.source, msg.logger_name, skipped_msg_log_level_,
                                             string_view_t{buf, static_cast<size_t>(msg_size)}};
                dist_sink<Mutex>::sink_it_(skipped_msg);
            }
--- a/include/spdlog/sinks/null_sink.h
+++ b/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 {}
--- a/include/spdlog/sinks/ringbuffer_sink.h
+++ b/include/spdlog/sinks/ringbuffer_sink.h
@@ -21,7 +21,11 @@ template <typename Mutex>
 class ringbuffer_sink final : public base_sink<Mutex> {
 public:
    explicit ringbuffer_sink(size_t n_items)
-        : q_{n_items} {}
+        : q_{n_items} {
+        if (n_items == 0) {
+            throw_spdlog_ex("ringbuffer_sink: n_items cannot be zero");
+        }
+    }

    std::vector<details::log_msg_buffer> last_raw(size_t lim = 0) {
        std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
--- a/include/spdlog/sinks/rotating_file_sink-inl.h
+++ b/include/spdlog/sinks/rotating_file_sink-inl.h
@@ -14,7 +14,6 @@
 #include <spdlog/fmt/fmt.h>

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

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

-    filename_t basename, ext;
+    filename_t basename;
+    filename_t ext;
    std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
    return fmt_lib::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{}.{}{}")), basename, index, ext);
 }
@@ -69,6 +69,41 @@ 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>::set_max_size(std::size_t max_size) {
+    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
+    if (max_size == 0) {
+        throw_spdlog_ex("rotating sink set_max_size: max_size arg cannot be zero");
+    }
+    max_size_ = max_size;
+}
+
+template <typename Mutex>
+SPDLOG_INLINE std::size_t rotating_file_sink<Mutex>::get_max_size() {
+    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
+    return max_size_;
+}
+
+template <typename Mutex>
+SPDLOG_INLINE void rotating_file_sink<Mutex>::set_max_files(std::size_t max_files) {
+    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
+    if (max_files > MaxFiles) {
+        throw_spdlog_ex("rotating sink set_max_files: max_files arg cannot exceed 200000");
+    }
+    max_files_ = max_files;
+}
+
+template <typename Mutex>
+std::size_t rotating_file_sink<Mutex>::get_max_files() {
+    std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
+    return max_files_;
+}
+
 template <typename Mutex>
 SPDLOG_INLINE void rotating_file_sink<Mutex>::sink_it_(const details::log_msg &msg) {
    memory_buf_t formatted;
--- a/include/spdlog/sinks/rotating_file_sink.h
+++ b/include/spdlog/sinks/rotating_file_sink.h
@@ -8,7 +8,6 @@
 #include <spdlog/details/synchronous_factory.h>
 #include <spdlog/sinks/base_sink.h>

-#include <chrono>
 #include <mutex>
 #include <string>

@@ -21,6 +20,7 @@ namespace sinks {
 template <typename Mutex>
 class rotating_file_sink final : public base_sink<Mutex> {
 public:
+    static constexpr size_t MaxFiles = 200000;
    rotating_file_sink(filename_t base_filename,
                       std::size_t max_size,
                       std::size_t max_files,
@@ -28,6 +28,11 @@ 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();
+    void set_max_size(std::size_t max_size);
+    std::size_t get_max_size();
+    void set_max_files(std::size_t max_files);
+    std::size_t get_max_files();

 protected:
    void sink_it_(const details::log_msg &msg) override;
@@ -41,7 +46,7 @@ private:
    // log.3.txt -> delete
    void rotate_();

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

@@ -60,25 +65,24 @@ using rotating_file_sink_st = rotating_file_sink<details::null_mutex>;
 //
 // factory functions
 //
-
 template <typename Factory = spdlog::synchronous_factory>
-inline std::shared_ptr<logger> rotating_logger_mt(const std::string &logger_name,
-                                                  const filename_t &filename,
-                                                  size_t max_file_size,
-                                                  size_t max_files,
-                                                  bool rotate_on_open = false,
-                                                  const file_event_handlers &event_handlers = {}) {
+std::shared_ptr<logger> rotating_logger_mt(const std::string &logger_name,
+                                           const filename_t &filename,
+                                           size_t max_file_size,
+                                           size_t max_files,
+                                           bool rotate_on_open = false,
+                                           const file_event_handlers &event_handlers = {}) {
    return Factory::template create<sinks::rotating_file_sink_mt>(
        logger_name, filename, max_file_size, max_files, rotate_on_open, event_handlers);
 }

 template <typename Factory = spdlog::synchronous_factory>
-inline std::shared_ptr<logger> rotating_logger_st(const std::string &logger_name,
-                                                  const filename_t &filename,
-                                                  size_t max_file_size,
-                                                  size_t max_files,
-                                                  bool rotate_on_open = false,
-                                                  const file_event_handlers &event_handlers = {}) {
+std::shared_ptr<logger> rotating_logger_st(const std::string &logger_name,
+                                           const filename_t &filename,
+                                           size_t max_file_size,
+                                           size_t max_files,
+                                           bool rotate_on_open = false,
+                                           const file_event_handlers &event_handlers = {}) {
    return Factory::template create<sinks::rotating_file_sink_st>(
        logger_name, filename, max_file_size, max_files, rotate_on_open, event_handlers);
 }
--- a/include/spdlog/sinks/stdout_sinks-inl.h
+++ b/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
 }

--- a/include/spdlog/sinks/tcp_sink.h
+++ b/include/spdlog/sinks/tcp_sink.h
@@ -31,6 +31,8 @@ namespace sinks {
 struct tcp_sink_config {
    std::string server_host;
    int server_port;
+    int timeout_ms =
+        0;  // The timeout for all 3 major socket operations that is connect, send, and recv
    bool lazy_connect = false;  // if true connect on first log call instead of on construction

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

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

@@ -58,7 +72,7 @@ protected:
        spdlog::memory_buf_t formatted;
        spdlog::sinks::base_sink<Mutex>::formatter_->format(msg, formatted);
        if (!client_.is_connected()) {
-            client_.connect(config_.server_host, config_.server_port);
+            client_.connect(config_.server_host, config_.server_port, config_.timeout_ms);
        }
        client_.send(formatted.data(), formatted.size());
    }
--- a/include/spdlog/sinks/wincolor_sink-inl.h
+++ b/include/spdlog/sinks/wincolor_sink-inl.h
@@ -137,10 +137,10 @@ void SPDLOG_INLINE wincolor_sink<ConsoleMutex>::print_range_(const memory_buf_t
 #if defined(SPDLOG_UTF8_TO_WCHAR_CONSOLE)
        wmemory_buf_t wformatted;
        details::os::utf8_to_wstrbuf(string_view_t(formatted.data() + start, end - start),
-            wformatted);
+                                     wformatted);
        auto size = static_cast<DWORD>(wformatted.size());
        auto ignored = ::WriteConsoleW(static_cast<HANDLE>(out_handle_), wformatted.data(), size,
-            nullptr, nullptr);
+                                       nullptr, nullptr);
 #else
        auto size = static_cast<DWORD>(end - start);
        auto ignored = ::WriteConsoleA(static_cast<HANDLE>(out_handle_), formatted.data() + start,
--- a/include/spdlog/sinks/wincolor_sink.h
+++ b/include/spdlog/sinks/wincolor_sink.h
@@ -31,10 +31,10 @@ public:

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

 protected:
--- a/include/spdlog/spdlog-inl.h
+++ b/include/spdlog/spdlog-inl.h
@@ -59,6 +59,10 @@ SPDLOG_INLINE void register_logger(std::shared_ptr<logger> logger) {
    details::registry::instance().register_logger(std::move(logger));
 }

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

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

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

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

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

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

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

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

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

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

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

--- a/include/spdlog/tweakme.h
+++ b/include/spdlog/tweakme.h
@@ -104,6 +104,13 @@
 //
 // #define SPDLOG_LEVEL_NAMES { "MY TRACE", "MY DEBUG", "MY INFO", "MY WARNING", "MY ERROR", "MY
 // CRITICAL", "OFF" }
+//
+// For C++17 use string_view_literals:
+//
+// #include <string_view>
+// using namespace std::string_view_literals;
+// #define SPDLOG_LEVEL_NAMES { "MY TRACE"sv, "MY DEBUG"sv, "MY INFO"sv, "MY WARNING"sv, "MY
+// ERROR"sv, "MY CRITICAL"sv, "OFF"sv }
 ///////////////////////////////////////////////////////////////////////////////

 ///////////////////////////////////////////////////////////////////////////////
--- a/include/spdlog/version.h
+++ b/include/spdlog/version.h
@@ -4,7 +4,7 @@
 #pragma once

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

 #define SPDLOG_TO_VERSION(major, minor, patch) (major * 10000 + minor * 100 + patch)
--- a/src/bundled_fmtlib_format.cpp
+++ b/src/bundled_fmtlib_format.cpp
@@ -11,6 +11,12 @@
    #include <spdlog/fmt/bundled/format-inl.h>

 FMT_BEGIN_NAMESPACE
+
+#if FMT_USE_LOCALE
+template FMT_API locale_ref::locale_ref(const std::locale& loc);
+template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
+#endif
+
 namespace detail {

 template FMT_API auto dragonbox::to_decimal(float x) noexcept
@@ -18,28 +24,22 @@ template FMT_API auto dragonbox::to_decimal(float x) noexcept
 template FMT_API auto dragonbox::to_decimal(double x) noexcept
    -> dragonbox::decimal_fp<double>;

-#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
-
 // Explicit instantiations for char.

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

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

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

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

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

 }  // namespace detail
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -19,9 +19,9 @@ if(Catch2_FOUND)
 else()
    message(STATUS "Bundled version of Catch will be downloaded and used.")
    include(FetchContent)
-    FetchContent_Declare(Catch2
-            GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-            GIT_TAG 53d0d913a422d356b23dd927547febdf69ee9081 # v3.5.0
+    FetchContent_Declare(
+        Catch2 GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+        GIT_TAG 53d0d913a422d356b23dd927547febdf69ee9081 # v3.5.0
    )
    FetchContent_MakeAvailable(Catch2)
 endif()
@@ -48,7 +48,9 @@ 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
+    test_ringbuffer.cpp)

 if(NOT SPDLOG_NO_EXCEPTIONS)
    list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
@@ -58,10 +60,6 @@ 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)
@@ -74,10 +72,10 @@ function(spdlog_prepare_test test_target spdlog_lib)
    target_link_libraries(${test_target} PRIVATE Catch2::Catch2WithMain)
    if(SPDLOG_SANITIZE_ADDRESS)
        spdlog_enable_addr_sanitizer(${test_target})
-    elseif (SPDLOG_SANITIZE_THREAD)
+    elseif(SPDLOG_SANITIZE_THREAD)
        spdlog_enable_thread_sanitizer(${test_target})
-    endif ()
-    add_test(NAME ${test_target} COMMAND ${test_target})
+    endif()
+    add_test(NAME ${test_target} COMMAND ${test_target} --order decl)
    set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()

--- a/tests/test_cfg.cpp
+++ b/tests/test_cfg.cpp
@@ -19,6 +19,15 @@ TEST_CASE("env", "[cfg]") {
 #endif
    load_env_levels();
    REQUIRE(l1->level() == spdlog::level::warn);
+
+#ifdef CATCH_PLATFORM_WINDOWS
+    _putenv_s("MYAPP_LEVEL", "l1=trace");
+#else
+    setenv("MYAPP_LEVEL", "l1=trace", 1);
+#endif
+    load_env_levels("MYAPP_LEVEL");
+    REQUIRE(l1->level() == spdlog::level::trace);
+
    spdlog::set_default_logger(spdlog::create<test_sink_st>("cfg-default"));
    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
 }
--- a/tests/test_custom_callbacks.cpp
+++ b/tests/test_custom_callbacks.cpp
@@ -16,7 +16,9 @@ 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);

--- a/tests/test_daily_logger.cpp
+++ b/tests/test_daily_logger.cpp
@@ -46,12 +46,8 @@ TEST_CASE("daily_logger with dateonly calculator", "[daily_logger]") {

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

--- a/tests/test_file_logging.cpp
+++ b/tests/test_file_logging.cpp
@@ -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;
@@ -74,14 +94,11 @@ TEST_CASE("rotating_file_logger2", "[rotating_logger]") {
        // next logger can rename the first output file.
        spdlog::drop(logger->name());
    }
-
    auto logger = spdlog::rotating_logger_mt("logger", basename, max_size, 2, true);
    for (int i = 0; i < 10; ++i) {
        logger->info("Test message {}", i);
    }
-
    logger->flush();
-
    require_message_count(ROTATING_LOG, 10);

    for (int i = 0; i < 1000; i++) {
@@ -101,3 +118,70 @@ 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);
+}
+
+// test changing the max size of the rotating file sink
+TEST_CASE("rotating_file_logger5", "[rotating_logger]") {
+    prepare_logdir();
+    size_t max_size = 5 * 1024;
+    size_t max_files = 2;
+    spdlog::filename_t basename = SPDLOG_FILENAME_T(ROTATING_LOG);
+    auto sink =
+        std::make_shared<spdlog::sinks::rotating_file_sink_st>(basename, max_size, max_files);
+    auto logger = std::make_shared<spdlog::logger>("rotating_sink_logger", sink);
+    logger->set_pattern("%v");
+
+    REQUIRE(sink->get_max_size() == max_size);
+    REQUIRE(sink->get_max_files() == max_files);
+    max_size = 7 * 1024;
+    max_files = 3;
+
+    sink->set_max_size(max_size);
+    sink->set_max_files(max_files);
+    REQUIRE(sink->get_max_size() == max_size);
+    REQUIRE(sink->get_max_files() == max_files);
+
+    const auto message = std::string(200, 'x');
+    assert(message.size() < max_size);
+    const auto n_messages = max_files * max_size / message.size();
+    for (size_t i = 0; i < n_messages; ++i) {
+        logger->info(message);
+    }
+    logger.reset();  // force flush and close the file
+
+    // validate that the files were rotated correctly with the new max size and max files
+    for (size_t i = 0; i <= max_files; i++) {
+        // calc filenames
+        // e.g. rotating_log, rotating_log.0 rotating_log.1, rotating_log.2, etc.
+        std::ostringstream oss;
+        oss << ROTATING_LOG;
+        if (i > 0) {
+            oss << '.' << i;
+        }
+        const auto filename = oss.str();
+        const auto filesize = get_filesize(filename);
+        REQUIRE(filesize <= max_size);
+        if (i > 0) {
+            REQUIRE(filesize >= max_size - message.size() - 2);
+        }
+    }
+}
--- a/tests/test_misc.cpp
+++ b/tests/test_misc.cpp
@@ -1,8 +1,12 @@
+#ifdef _WIN32  // to prevent fopen warning on windows
+    #define _CRT_SECURE_NO_WARNINGS
+#endif
+
 #include "includes.h"
 #include "test_sink.h"

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

@@ -178,10 +182,43 @@ TEST_CASE("utf8 to utf16 conversion using windows api", "[windows utf]") {
    spdlog::details::os::utf8_to_wstrbuf("abc", buffer);
    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L"abc"));

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

-    spdlog::details::os::utf8_to_wstrbuf("\xe3\x81\xad\xe3\x81\x93", buffer); // "Neko" in hiragana.
+    spdlog::details::os::utf8_to_wstrbuf("\xe3\x81\xad\xe3\x81\x93",
+                                         buffer);  // "Neko" in hiragana.
    REQUIRE(std::wstring(buffer.data(), buffer.size()) == std::wstring(L"\x306d\x3053"));
 }
 #endif
+
+struct auto_closer {
+    FILE* fp = nullptr;
+    explicit auto_closer(FILE* f)
+        : fp(f) {}
+    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::create_dir;
+    using spdlog::details::os::fwrite_bytes;
+    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));
+}
--- a/tests/test_pattern_formatter.cpp
+++ b/tests/test_pattern_formatter.cpp
@@ -1,6 +1,8 @@
 #include "includes.h"
 #include "test_sink.h"

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

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

+// log to str and return it with time
+template <typename... Args>
+static std::string log_to_str_with_time(spdlog::log_clock::time_point log_time,
+                                        const std::string &msg,
+                                        const Args &...args) {
+    std::ostringstream oss;
+    auto oss_sink = std::make_shared<spdlog::sinks::ostream_sink_mt>(oss);
+    spdlog::logger oss_logger("pattern_tester", oss_sink);
+    oss_logger.set_level(spdlog::level::info);
+
+    oss_logger.set_formatter(
+        std::unique_ptr<spdlog::formatter>(new spdlog::pattern_formatter(args...)));
+
+    oss_logger.log(log_time, {}, spdlog::level::info, msg);
+    return oss.str();
+}
+
 TEST_CASE("custom eol", "[pattern_formatter]") {
    std::string msg = "Hello custom eol test";
    std::string eol = ";)";
@@ -58,6 +77,20 @@ TEST_CASE("date MM/DD/YY ", "[pattern_formatter]") {
            oss.str());
 }

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

+TEST_CASE("register_or_replace", "[registry]") {
+    spdlog::drop_all();
+    auto logger1 = std::make_shared<spdlog::logger>(
+        tested_logger_name, std::make_shared<spdlog::sinks::null_sink_st>());
+    spdlog::register_logger(logger1);
+    REQUIRE(spdlog::get(tested_logger_name) == logger1);
+
+    auto logger2 = std::make_shared<spdlog::logger>(
+        tested_logger_name, std::make_shared<spdlog::sinks::null_sink_st>());
+    spdlog::register_or_replace(logger2);
+    REQUIRE(spdlog::get(tested_logger_name) == logger2);
+}
+
 TEST_CASE("apply_all", "[registry]") {
    spdlog::drop_all();
    auto logger = std::make_shared<spdlog::logger>(tested_logger_name,
--- a/tests/test_ringbuffer.cpp
+++ b/tests/test_ringbuffer.cpp
@@ -0,0 +1,52 @@
+#include "includes.h"
+#include "spdlog/sinks/ringbuffer_sink.h"
+
+TEST_CASE("ringbuffer invalid size", "[ringbuffer]") {
+    REQUIRE_THROWS_AS(spdlog::sinks::ringbuffer_sink_mt(0), spdlog::spdlog_ex);
+}
+
+TEST_CASE("ringbuffer stores formatted messages", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg1"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg2"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "msg3"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 3);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("msg1{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("msg2{}", default_eol));
+    REQUIRE(formatted[2] == spdlog::fmt_lib::format("msg3{}", default_eol));
+}
+
+TEST_CASE("ringbuffer overrun keeps last items", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(2);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "first"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "second"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "third"});
+
+    auto formatted = sink.last_formatted();
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("second{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("third{}", default_eol));
+}
+
+TEST_CASE("ringbuffer retrieval limit", "[ringbuffer]") {
+    spdlog::sinks::ringbuffer_sink_st sink(3);
+    sink.set_pattern("%v");
+
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "A"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "B"});
+    sink.log(spdlog::details::log_msg{"test", spdlog::level::info, "C"});
+
+    auto formatted = sink.last_formatted(2);
+    REQUIRE(formatted.size() == 2);
+    using spdlog::details::os::default_eol;
+    REQUIRE(formatted[0] == spdlog::fmt_lib::format("B{}", default_eol));
+    REQUIRE(formatted[1] == spdlog::fmt_lib::format("C{}", default_eol));
+}
--- a/tests/test_sink.h
+++ b/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_);
--- a/tests/test_stdout_api.cpp
+++ b/tests/test_stdout_api.cpp
@@ -5,6 +5,7 @@
 #include "includes.h"
 #include "spdlog/sinks/stdout_sinks.h"
 #include "spdlog/sinks/stdout_color_sinks.h"
+
 TEST_CASE("stdout_st", "[stdout]") {
    auto l = spdlog::stdout_logger_st("test");
    l->set_pattern("%+");
@@ -72,8 +73,14 @@ TEST_CASE("stderr_color_mt", "[stderr]") {
    spdlog::drop_all();
 }

-#ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
+TEST_CASE("show_utc_offset", "[stdout]") {
+    auto l = spdlog::stdout_color_mt("test");
+    l->set_pattern("[%c %z] [%n] [%^%l%$] %v");
+    l->info("Full date");
+    spdlog::drop_all();
+}

+#ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
 TEST_CASE("wchar_api", "[stdout]") {
    auto l = spdlog::stdout_logger_st("wchar_logger");
    l->set_pattern("%+");
@@ -86,5 +93,4 @@ TEST_CASE("wchar_api", "[stdout]") {
    SPDLOG_LOGGER_DEBUG(l, L"Test SPDLOG_LOGGER_DEBUG {}", L"param");
    spdlog::drop_all();
 }
-
 #endif
--- a/tests/test_stopwatch.cpp
+++ b/tests/test_stopwatch.cpp
@@ -5,7 +5,7 @@
 TEST_CASE("stopwatch1", "[stopwatch]") {
    using std::chrono::milliseconds;
    using clock = std::chrono::steady_clock;
-    milliseconds wait_ms(200);
+    milliseconds wait_ms(500);
    milliseconds tolerance_ms(250);
    auto start = clock::now();
    spdlog::stopwatch sw;
@@ -22,7 +22,7 @@ TEST_CASE("stopwatch2", "[stopwatch]") {
    using std::chrono::milliseconds;
    using clock = std::chrono::steady_clock;

-    clock::duration wait_duration(milliseconds(200));
+    clock::duration wait_duration(milliseconds(500));
    clock::duration tolerance_duration(milliseconds(250));

    auto test_sink = std::make_shared<test_sink_st>();
--- a/tests/utils.cpp
+++ b/tests/utils.cpp
@@ -50,9 +50,8 @@ void require_message_count(const std::string &filename, const std::size_t messag
 std::size_t get_filesize(const std::string &filename) {
    std::ifstream ifs(filename, std::ifstream::ate | std::ifstream::binary);
    if (!ifs) {
-        throw std::runtime_error("Failed open file ");
+        throw std::runtime_error("Failed open file " + filename);
    }
-
    return static_cast<std::size_t>(ifs.tellg());
 }
Author	SHA1	Message	Date
gabime	2f10538576	Add full date to stdout tests	2025-11-28 17:30:23 +02:00
gabime	a2339c5463	Add full date to stdout tests	2025-11-28 17:21:14 +02:00
gabime	2a528b9068	clang-format	2025-11-28 17:10:57 +02:00
gabime	6af5c48d83	Fix issue #3483	2025-11-28 15:48:07 +02:00
Aleksandr	3f7e502859	fix sign-compare warning (#3479 )	2025-11-01 18:03:07 +02:00
Ashish Ahuja	dd3ca04a7a	set CMAKE_BUILD_TYPE only in top-level project (#3480 )	2025-11-01 17:55:59 +02:00
gabime	486b55554f	Version 1.16.0	2025-10-11 15:53:05 +03:00
gabime	1bea38edcc	clang-format	2025-10-11 15:50:16 +03:00
gabime	4418909af2	Bump fmt to 12.0.0	2025-10-11 15:18:15 +03:00
Angelio Mason	f1d748e5e3	Remove the fileapi.h include in os-inl.h (#3444 ) * Replaced fileapi.h include with windows.h, as instructed in https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-flushfilebuffers Otherwise this causes compilation error on older sdks. * Removed the fileapi.h include entirely, since windows.h is already included before --------- Co-authored-by: MasonAngelio <MasonAngelio>	2025-08-07 23:47:11 +03:00
Vitaly	3edc8036db	Run tests in the order they are declared in the source file. (#3451 ) Fixes an issue with running tests in random order in Catch2 3.9.0+.	2025-08-07 23:38:29 +03:00
Mihir Patel	9ecdf5c8a1	Added timeout for TCP calls such as connect, send, recv (#3432 ) * Now lets test on windows * I guess testing on windows passes. * Update tcp_client-windows.h Added default value to argument * Final edit * Update tcp_client-windows.h Changed improper misplaced includes.	2025-07-17 23:47:35 +03:00
Gabi Melman	737347d2df	Update linux.yml	2025-07-16 09:55:57 +03:00
Alexander	4f2b3d52f9	Update README.md (#3437 ) * Update README.md add example showcasing 2 loggers and `spdlog::set_level()` which set level not only to default logger, but to all registed loggers * Update README.md * simplify * simplify	2025-07-16 08:59:51 +03:00
Joshua Chapman	4397dac510	chore(cmake): add option to override CMAKE_DEBUG_POSTFIX (#3433 ) This will make it possible to use the pkg-config with CMake debug build.	2025-07-08 22:52:42 +03:00
Gabi Melman	6fd67ce169	Update windows.yml remove msvc 2019 build	2025-07-06 10:08:55 +03:00
Gabi Melman	4619e18a16	Update windows.yml	2025-07-06 09:53:42 +03:00
Gabi Melman	a6215527f4	Fix ringbuffer tests for newline (#3436 )	2025-07-06 08:38:48 +03:00
VZ	287333ee00	Remove unnecessary and inconsistent "final" from color sinks (#3430 ) The use of "final" differed between ansicolor_sink and wincolor_sink, resulting in the code inheriting from std{err,out}_color_sink classes, which are defined as one or the other on different platforms, being able to override most of the functions under non-Windows platforms, but not under Windows. This seems gratuitously inconsistent, so just remove all "final" keywords from both classes, especially because there doesn't seem any good reason to use it and the other sink classes don't use it (with the exception of base_sink, which is special). This also incidentally fixes using "final override" in most places but "override final" in wincolor_sink.h. Fixes #3429.	2025-06-30 07:39:32 +03:00
电线杆	ad725d34cc	Use std::getenv #3414 (#3415 )	2025-06-08 23:16:34 +03:00
Gabi Melman	e655dbb685	Fix issue #3408 Remove including core.h or base.h	2025-06-07 13:44:09 +03:00
gabime	b18a234ed6	Fix coverity ci	2025-05-12 17:44:17 +03:00
Gabi Melman	5d89b5b91c	Update jetbrains logo (#3401 ) * Update jetbrains logo	2025-05-12 16:04:04 +03:00
Gabi Melman	37ff466454	Add coverity scan to CI and fix warnings (#3400 ) * Move callback function in thread_pool ctor * Added const qualifiers to logger.h * Remove unused includes from file_helper-inl.h * Fix comments and remove unused include from helpers-inl.h * Fix typo in comment for set_default_logger method. * Use `std::move` for `old_logger` in `set_default_logger`. * Use std::move in example * Wrap `main` content in try block for exception safety. * Added coverity to ci	2025-05-12 15:36:07 +03:00
Gabi Melman	677a2d93e6	Update test_stopwatch.cpp	2025-05-09 13:22:39 +03:00
Gabi Melman	6fa36017cf	Version 1.15.3	2025-05-09 08:55:57 +03:00
Gabi Melman	c73b8cc400	Update comment	2025-05-09 02:50:11 +03:00
Gabi Melman	7ca6a4fb27	Update commemt	2025-05-09 02:49:36 +03:00
Gabi Melman	070e1c9747	Update comment	2025-05-09 02:46:10 +03:00
Gabi Melman	0d31acae28	Fmt 11.2.0 (#3399 ) * Bump fmt to 11.2.0	2025-05-08 20:13:03 +03:00
Gabi Melman	943fcbd761	Register replace logger (#3398 ) * Add register_or_replace(logger) to atomically replace logger in registry * fix some comments	2025-05-08 15:42:54 +03:00
Gabi Melman	7e022c4300	Feature 3379 (#3397 ) * Fix #3379 * clang format	2025-05-08 14:02:00 +03:00
Hinageshi	548b264254	Fix warning C4530 (#3393 ) * Fix warning C4530 * Rename FMT_EXCEPTIONS to FMT_USE_EXCEPTIONS	2025-04-23 19:46:25 +03:00
Tihran Katolikian	847db3375f	dup_filter_sink: remove notification_level argument; use last message log level for notification instead (#3390 )	2025-04-18 20:45:56 +03:00
Dmitry Kozlovtsev	bb8694b50f	Fix links for #3380 (#3381 )	2025-04-14 19:22:47 +03:00
Christoph Gringmuth	cec28bf839	Fix links to local reference. (#3378 ) Enables local navigation in IDE and removes links to branch.	2025-04-10 17:58:19 +03:00
Gabi Melman	bd0609d7a0	Update README.md	2025-04-10 17:06:12 +03:00
Christoph Gringmuth	1f4959c832	Fix link to wiki. (#3377 )	2025-04-10 17:04:23 +03:00
gabime	48bcf39a66	Version 1.15.2	2025-03-29 14:01:07 +03:00
Gabi Melman	9c58257480	Fix zformatter on Apple and POSIX.1-2024 conforming platform (#3366 ) * Add test case for #3351 (wrong GMT offset in SunOS/Solaris fallback) * Fix #3352 (Missing test for Apple / POSIX.1-2024 chooses buggy workaround) Apple platforms have had the tm_gmtoff-field at least since Mac OS X 10.0, as are POSIX.1-2024 conforming systems, which are also required to support it. This has the unfortunate effect to use the SunOS/Solaris fallback, which doesn't compute the correct value if the passed value of tm isn't the current system time, i.e. localtime(::time()) (#3351). * Fixed GMT offset test --------- Co-authored-by: toh <toh@ableton.com>	2025-03-29 13:44:11 +03:00
gabime	faa0a7a9c5	Bump fmt to version 11.1.4	2025-03-17 16:56:21 +02:00
Gabi Melman	10320184df	Fixed issue #3360 (#3361 )	2025-03-17 15:46:31 +02:00
Александр	3335c380a0	Update README.md (#3338 ) How to install this package in ALT Linux.	2025-02-11 19:10:50 +02:00
Gabi Melman	f355b3d58f	Fix test_daily_logger	2025-02-01 13:08:54 +02:00
Gabi Melman	ac432c3602	Gabime/v1.15.1 (#3332 ) * Updated bundled fmt to version 11.1.3 * Bump version to 1.15.1	2025-02-01 12:09:54 +02:00
Janusz Chorko	3c23c27d2d	Revert "fix: Compatibility with external fmtlib 11.1.1 (#3312 )" (#3331 ) This reverts commit `7f8060d5b2`.	2025-02-01 11:15:04 +02:00
Ken Matsui	ae1de0dc8c	Support custom environment variables for load_env_levels (#3327 ) SPDLOG_LEVEL is currently supported to control log levels via load_env_levels. This patch adds support for other environment variable names, such as MYAPP_LEVEL, for load_env_levels.	2025-01-23 23:00:23 +02:00
Gabi Melman	7cbf2a6967	Gabime/ansicolor sink improvements (#3323 ) * Added lock to set_color_mode in asnicolor_sink * Added const qualifiers to some ansicolor_sink functions	2025-01-18 11:58:32 +02:00
Alexander	57505989b7	SPDLOG_LEVEL_NAMES, comment use string_view_literals (#3291 ) * SPDLOG_LEVEL_NAMES, comment use string_view_literals * SPDLOG_LEVEL_NAMES, comment use string_view_literals	2025-01-18 11:57:43 +02:00
gabime	96a7d2a1d4	Format CMakeLists.txt	2025-01-12 08:37:47 +02:00
Gabi Melman	d71555306a	Added SPDLOG_FWRITE_UNLOCKED option to CMakeLists.txt (#3318 ) * Added SPDLOG_FWRITE_UNLOCKED option to CMakeLists.txt * Update CMakeLists.txt	2025-01-12 08:02:39 +02:00
koniarik	ad0f31c009	Enabled bin_to_hex utest for stdformat, fixed std::formatter (#3315 ) * Enabled bin_to_hex utest for stdformat, and fixed std::formatter * fixed usage of \ in macos.yml * explicitly cast diff variable in test_sink * moved from ::iterator to decltype * added fix for custom callbacks --------- Co-authored-by: Jan Koniarik <veverak@Jans-MacBook-Pro.local>	2025-01-11 17:21:39 +02:00
jdrouhard	96a8f6250c	fix: remove unused to_string_view overload in fmt >= 11.1 (#3314 )	2025-01-10 00:58:46 +02:00
Christian Blichmann	7f8060d5b2	fix: Compatibility with external fmtlib 11.1.1 (#3312 ) Include fmtlib's `xchar` header to include `fmt::basic_format_string`. Otherwise, compilation with an external fmtlib 11.1.1 fails with ``` In file included from include/spdlog/spdlog.h:12: include/spdlog/common.h:369:49: error: no template named 'basic_format_string' in namespace 'fmt'; did you mean 'std::basic_format_string'? 369 \| inline fmt::basic_string_view<T> to_string_view(fmt::basic_format_string<T, Args...> fmt) { \| ^~~~~ ``` Signed-off-by: Christian Blichmann <cblichmann@google.com>	2025-01-08 00:59:12 +02:00
Rui Chen	276ee5f5c0	fix: update to_string_view function for fmt 11.1 (#3301 ) Signed-off-by: Rui Chen <rui@chenrui.dev>	2024-12-26 09:13:57 +02:00
Matteo Del Seppia	24dde318fe	Adding lock to rotate_now() (#3281 )	2024-12-03 09:53:34 +02:00
Matteo Del Seppia	65e388e82b	Adding on demand truncation for basic file sinks (#3280 ) * Adding support to truncate on demand for basic file sink * Remove unnecessary file close * Adding lock in basic_file_sink truncate()	2024-12-03 01:38:51 +02:00
Gabi Melman	1e6250e183	Gabime/fwrite unlocked (#3276 ) * Use locking fwrite_unlocked if possible * Added compile definitions to header_only	2024-12-01 14:16:52 +02:00
hjs-ast	951c5b9987	Allow manual rotation of rotating_file_sink (#3269 ) * Allow manual rotation of rotating_file_sink * Rename rotation method * Attempted fix for tests on Windows * Apply review mark-ups	2024-11-28 17:37:29 +02:00
Gabi Melman	15f539685b	Update null_sink to be final (#3267 )	2024-11-25 00:32:47 +02:00
Gabi Melman	43dcb3982d	Update CMakeLists.txt comment	2024-11-22 12:14:47 +02:00
Gabi Melman	0efef2af24	Update CMakeLists.txt comment	2024-11-22 12:12:32 +02:00
Gabi Melman	018d8aa266	Update CMakeLists.txt	2024-11-22 12:10:53 +02:00
Gabi Melman	35b0417fbe	Update CMakeLists.txt comment	2024-11-22 12:09:48 +02:00
Gabi Melman	94526fa8e8	Update CMakeLists.txt comment	2024-11-22 12:07:39 +02:00
Gabi Melman	633003f40a	Update CMakeLists.txt comment	2024-11-22 11:50:05 +02:00
miyanyan	9edab1b5a1	pass /utf-8 only when compiler is MSVC (#3260 )	2024-11-22 11:42:35 +02:00
LiAuTraver	1245bf8e8a	add explicit mt:: and std:: to avoid ambiguous call when both std::format_to and mt::format_to are present (#3259 )	2024-11-18 16:41:27 +02:00
F1F88	51a0deca2c	docs: Removed duplicate line in daily_file_sink comment (#3249 )	2024-11-09 21:41:00 +02:00