version 1.8.2

version 1.9.0
Bump fmt to version 7.1.3
2025-09-29 09:59:33 +08:00 · 2020-12-11 16:40:52 +02:00 · 2020-12-11 16:37:37 +02:00 · 2020-12-11 16:32:39 +02:00 · 2020-11-26 11:03:46 +02:00 · 2020-11-26 09:45:39 +01:00
58 changed files with 6060 additions and 3125 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,14 +1,6 @@
 # Copyright(c) 2019 spdlog authors Distributed under the MIT License (http://opensource.org/licenses/MIT)

-cmake_minimum_required(VERSION 3.2)
-
-if(${CMAKE_VERSION} VERSION_LESS 3.11)
-    cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
-else()
-    cmake_policy(VERSION 3.11)
-endif()
-
-enable_language(C)
+cmake_minimum_required(VERSION 3.10)

 # ---------------------------------------------------------------------------------------
 # Start spdlog project
@@ -40,7 +32,7 @@ endif()

 set(CMAKE_CXX_EXTENSIONS OFF)

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

@@ -200,7 +192,8 @@ endif()
 # Misc definitions according to tweak options
 # ---------------------------------------------------------------------------------------
 set(SPDLOG_WCHAR_TO_UTF8_SUPPORT ${SPDLOG_WCHAR_SUPPORT})
-foreach(SPDLOG_OPTION
+foreach(
+    SPDLOG_OPTION
    SPDLOG_WCHAR_TO_UTF8_SUPPORT
    SPDLOG_WCHAR_FILENAMES
    SPDLOG_NO_EXCEPTIONS
@@ -208,8 +201,7 @@ foreach(SPDLOG_OPTION
    SPDLOG_PREVENT_CHILD_FD
    SPDLOG_NO_THREAD_ID
    SPDLOG_NO_TLS
-    SPDLOG_NO_ATOMIC_LEVELS
-)
+    SPDLOG_NO_ATOMIC_LEVELS)
    if(${SPDLOG_OPTION})
        target_compile_definitions(spdlog PUBLIC ${SPDLOG_OPTION})
        target_compile_definitions(spdlog_header_only INTERFACE ${SPDLOG_OPTION})
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ $ cmake .. && make -j
 * Homebrew: `brew install spdlog`
 * MacPorts: `sudo port install spdlog`
 * FreeBSD:  `cd /usr/ports/devel/spdlog/ && make install clean`
-* Fedora: `yum install spdlog`
+* Fedora: `dnf install spdlog`
 * Gentoo: `emerge dev-libs/spdlog`
 * Arch Linux: `pacman -S spdlog`
 * vcpkg: `vcpkg install spdlog`
@@ -56,7 +56,6 @@ $ cmake .. && make -j
 #### Basic usage
 ```c++
 #include "spdlog/spdlog.h"
-#include "spdlog/sinks/basic_file_sink.h"

 int main() 
 {
@@ -79,10 +78,6 @@ int main()
    // define SPDLOG_ACTIVE_LEVEL to desired level
    SPDLOG_TRACE("Some trace message with param {}", 42);
    SPDLOG_DEBUG("Some debug message");
-    
-    // Set the default logger to file logger
-    auto file_logger = spdlog::basic_logger_mt("basic_logger", "logs/basic.txt");
-    spdlog::set_default_logger(file_logger);            
 }

 ```
@@ -169,6 +164,20 @@ spdlog::flush_every(std::chrono::seconds(3));

 ```

+---
+#### Stopwatch
+```c++
+// Stopwatch support for spdlog
+#include "spdlog/stopwatch.h"
+void stopwatch_example()
+{
+    spdlog::stopwatch sw;    
+    spdlog::debug("Elapsed {}", sw);
+    spdlog::debug("Elapsed {:.3}", sw);       
+}
+
+```
+
 ---
 #### Log binary data in hex
 ```c++
@@ -179,6 +188,7 @@ spdlog::flush_every(std::chrono::seconds(3));
 // {:s} - don't separate each byte with space.
 // {:p} - don't print the position on each line start.
 // {:n} - don't split the output to lines.
+// {:a} - show ASCII if :n is not set.

 #include "spdlog/fmt/bin_to_hex.h"

--- a/bench/CMakeLists.txt
+++ b/bench/CMakeLists.txt
@@ -1,6 +1,6 @@
 # Copyright(c) 2019 spdlog authors Distributed under the MIT License (http://opensource.org/licenses/MIT)

-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.10)
 project(spdlog_bench CXX)

 if(NOT TARGET spdlog)
@@ -9,7 +9,24 @@ if(NOT TARGET spdlog)
 endif()

 find_package(Threads REQUIRED)
-find_package(benchmark CONFIG REQUIRED)
+find_package(benchmark CONFIG)
+if (NOT benchmark_FOUND)
+    message(STATUS "Using CMake Version ${CMAKE_VERSION}")
+    if (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.11.0")
+        # User can fetch googlebenchmark 			
+        message(STATUS "Downloading GoogleBenchmark")
+        include(FetchContent)
+        set(BENCHMARK_ENABLE_GTEST_TESTS OFF CACHE INTERNAL "")
+        # Do not build and run googlebenchmark tests
+        FetchContent_Declare(googlebenchmark
+            GIT_REPOSITORY https://github.com/google/benchmark.git
+            GIT_TAG v1.5.2)
+
+        FetchContent_MakeAvailable(googlebenchmark)
+    else()
+        message(FATAL_ERROR "GoogleBenchmark is missing. Use CMake >= 3.11 or download it")
+    endif()
+endif()

 add_executable(bench bench.cpp)
 spdlog_enable_warnings(bench)
--- a/bench/async_bench.cpp
+++ b/bench/async_bench.cpp
@@ -9,7 +9,7 @@
 #include "spdlog/spdlog.h"
 #include "spdlog/async.h"
 #include "spdlog/sinks/basic_file_sink.h"
-#include "spdlog/sinks/stdout_color_sinks.h"
+#include "spdlog/fmt/bundled/locale.h"

 #include "utils.h"
 #include <atomic>
@@ -48,14 +48,14 @@ int count_lines(const char *filename)

 void verify_file(const char *filename, int expected_count)
 {
-    spdlog::info("Verifying {} to contain {:n} line..", filename, expected_count);
+    spdlog::info("Verifying {} to contain {} line..", filename, expected_count);
    auto count = count_lines(filename);
    if (count != expected_count)
    {
-        spdlog::error("Test failed. {} has {:n} lines instead of {:n}", filename, count, expected_count);
+        spdlog::error("Test failed. {} has {} lines instead of {}", filename, count, expected_count);
        exit(1);
    }
-    spdlog::info("Line count OK ({:n})\n", count);
+    spdlog::info("Line count OK ({})\n", count);
 }

 #ifdef _MSC_VER
@@ -98,11 +98,12 @@ int main(int argc, char *argv[])

        auto slot_size = sizeof(spdlog::details::async_msg);
        spdlog::info("-------------------------------------------------");
-        spdlog::info("Messages     : {:n}", howmany);
-        spdlog::info("Threads      : {:n}", threads);
-        spdlog::info("Queue        : {:n} slots", queue_size);
-        spdlog::info("Queue memory : {:n} x {} = {:n} KB ", queue_size, slot_size, (queue_size * slot_size) / 1024);
-        spdlog::info("Total iters  : {:n}", iters);
+        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Messages     : {:L}", howmany));
+        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Threads      : {:L}", threads));
+        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Queue        : {:L} slots", queue_size));
+        spdlog::info(fmt::format(
+            std::locale("en_US.UTF-8"), "Queue memory : {:L} x {:L} = {:L} KB ", queue_size, slot_size, (queue_size * slot_size) / 1024));
+        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Total iters  : {:L}", iters));
        spdlog::info("-------------------------------------------------");

        const char *filename = "logs/basic_async.log";
@@ -175,5 +176,5 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> logger, int thread_co

    auto delta = high_resolution_clock::now() - start;
    auto delta_d = duration_cast<duration<double>>(delta).count();
-    spdlog::info("Elapsed: {} secs\t {:n}/sec", delta_d, int(howmany / delta_d));
+    spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Elapsed: {} secs\t {:L}/sec", delta_d, int(howmany / delta_d)));
 }
--- a/bench/bench.cpp
+++ b/bench/bench.cpp
@@ -11,6 +11,7 @@
 #include "spdlog/sinks/daily_file_sink.h"
 #include "spdlog/sinks/null_sink.h"
 #include "spdlog/sinks/rotating_file_sink.h"
+#include "spdlog/fmt/bundled/locale.h"

 #include "utils.h"
 #include <atomic>
@@ -32,7 +33,7 @@ static const int max_threads = 1000;
 void bench_threaded_logging(size_t threads, int iters)
 {
    spdlog::info("**************************************************************");
-    spdlog::info("Multi threaded: {:n} threads, {:n} messages", threads, iters);
+    spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Multi threaded: {:L} threads, {:L} messages", threads, iters));
    spdlog::info("**************************************************************");

    auto basic_mt = spdlog::basic_logger_mt("basic_mt", "logs/basic_mt.log", true);
@@ -68,7 +69,7 @@ void bench_threaded_logging(size_t threads, int iters)
 void bench_single_threaded(int iters)
 {
    spdlog::info("**************************************************************");
-    spdlog::info("Single threaded: {:n} messages", iters);
+    spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Single threaded: {} messages", iters));
    spdlog::info("**************************************************************");

    auto basic_st = spdlog::basic_logger_st("basic_st", "logs/basic_st.log", true);
@@ -152,7 +153,8 @@ void bench(int howmany, std::shared_ptr<spdlog::logger> log)
    auto delta = high_resolution_clock::now() - start;
    auto delta_d = duration_cast<duration<double>>(delta).count();

-    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16n}/sec", log->name(), delta_d, int(howmany / delta_d));
+    spdlog::info(
+        fmt::format(std::locale("en_US.UTF-8"), "{:<30} Elapsed: {:0.2f} secs {:>16L}/sec", log->name(), delta_d, int(howmany / delta_d)));
    spdlog::drop(log->name());
 }

@@ -182,7 +184,8 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> log, size_t thread_co

    auto delta = high_resolution_clock::now() - start;
    auto delta_d = duration_cast<duration<double>>(delta).count();
-    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16n}/sec", log->name(), delta_d, int(howmany / delta_d));
+    spdlog::info(
+        fmt::format(std::locale("en_US.UTF-8"), "{:<30} Elapsed: {:0.2f} secs {:>16L}/sec", log->name(), delta_d, int(howmany / delta_d)));
    spdlog::drop(log->name());
 }

@@ -205,7 +208,7 @@ void bench_default_api(int howmany, std::shared_ptr<spdlog::logger> log)
    auto delta_d = duration_cast<duration<double>>(delta).count();
    spdlog::drop(log->name());
    spdlog::set_default_logger(std::move(orig_default));
-    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16n}/sec", log->name(), delta_d, int(howmany / delta_d));
+    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16}/sec", log->name(), delta_d, int(howmany / delta_d));
 }

 void bench_c_string(int howmany, std::shared_ptr<spdlog::logger> log)
@@ -232,7 +235,7 @@ void bench_c_string(int howmany, std::shared_ptr<spdlog::logger> log)
    auto delta_d = duration_cast<duration<double>>(delta).count();
    spdlog::drop(log->name());
    spdlog::set_default_logger(std::move(orig_default));
-    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16n}/sec", log->name(), delta_d, int(howmany / delta_d));
+    spdlog::info("{:<30} Elapsed: {:0.2f} secs {:>16}/sec", log->name(), delta_d, int(howmany / delta_d));
 }

 */
--- a/cmake/spdlogCPack.cmake
+++ b/cmake/spdlogCPack.cmake
@@ -18,23 +18,37 @@ set(CPACK_PACKAGE_RELOCATABLE ON CACHE BOOL "Build relocatable package")

 set(CPACK_RPM_PACKAGE_LICENSE "MIT")
 set(CPACK_RPM_PACKAGE_GROUP "Development/Libraries")
+set(CPACK_DEBIAN_PACKAGE_SECTION "libs")
 set(CPACK_RPM_PACKAGE_URL ${CPACK_PROJECT_URL})
+set(CPACK_DEBIAN_PACKAGE_HOMEPAGE ${CPACK_PROJECT_URL})
 set(CPACK_RPM_PACKAGE_DESCRIPTION "Very fast, header-only/compiled, C++ logging library.")
+set(CPACK_DEBIAN_PACKAGE_DESCRIPTION "Very fast, header-only/compiled, C++ logging library.")

 if(CPACK_PACKAGE_NAME)
    set(CPACK_RPM_FILE_NAME "${CPACK_PACKAGE_NAME}-${CPACK_PACKAGE_VERSION}")
+    set(CPACK_DEBIAN_FILE_NAME "${CPACK_PACKAGE_NAME}-${CPACK_PACKAGE_VERSION}")
 else()
    set(CPACK_RPM_FILE_NAME "${PROJECT_NAME}-${CPACK_PACKAGE_VERSION}")
+    set(CPACK_DEBIAN_FILE_NAME "${PROJECT_NAME}-${CPACK_PACKAGE_VERSION}")
+    set(CPACK_RPM_PACKAGE_NAME "${PROJECT_NAME}")
+    set(CPACK_DEBIAN_PACKAGE_NAME "${PROJECT_NAME}")
 endif()

 if(CPACK_RPM_PACKAGE_RELEASE)
    set(CPACK_RPM_FILE_NAME "${CPACK_RPM_FILE_NAME}-${CPACK_RPM_PACKAGE_RELEASE}")
 endif()
+if(CPACK_DEBIAN_PACKAGE_RELEASE)
+    set(CPACK_DEBIAN_FILE_NAME "${CPACK_DEBIAN_FILE_NAME}-${CPACK_DEBIAN_PACKAGE_RELEASE}")
+endif()

 if(CPACK_RPM_PACKAGE_ARCHITECTURE)
    set(CPACK_RPM_FILE_NAME "${CPACK_RPM_FILE_NAME}.${CPACK_RPM_PACKAGE_ARCHITECTURE}")
 endif()
+if(CPACK_DEBIAN_PACKAGE_ARCHITECTURE)
+    set(CPACK_DEBIAN_FILE_NAME "${CPACK_DEBIAN_FILE_NAME}.${CPACK_DEBIAN_PACKAGE_ARCHITECTURE}")
+endif()
 set(CPACK_RPM_FILE_NAME "${CPACK_RPM_FILE_NAME}.rpm")
+set(CPACK_DEBIAN_FILE_NAME "${CPACK_DEBIAN_FILE_NAME}.deb")

 if(NOT CPACK_PACKAGE_RELOCATABLE)
    # Depend on pkgconfig rpm to create the system pkgconfig folder
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@@ -1,6 +1,6 @@
 # Copyright(c) 2019 spdlog authors Distributed under the MIT License (http://opensource.org/licenses/MIT)

-cmake_minimum_required(VERSION 3.2)
+cmake_minimum_required(VERSION 3.10)
 project(spdlog_examples CXX)

 if(NOT TARGET spdlog)
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -13,6 +13,7 @@ void rotating_example();
 void daily_example();
 void async_example();
 void binary_example();
+void stopwatch_example();
 void trace_example();
 void multi_sink_example();
 void user_defined_example();
@@ -71,6 +72,7 @@ int main(int, char *[])
        user_defined_example();
        err_handler_example();
        trace_example();
+        stopwatch_example();
        custom_flags_example();

        // Flush all *registered* loggers using a worker thread every 3 seconds.
@@ -192,6 +194,16 @@ void trace_example()
    SPDLOG_LOGGER_TRACE(logger, "another trace message");
 }

+// stopwatch example
+#include "spdlog/stopwatch.h"
+#include <thread>
+void stopwatch_example()
+{
+    spdlog::stopwatch sw;
+    std::this_thread::sleep_for(std::chrono::milliseconds(123));
+    spdlog::info("Stopwatch: {} seconds", sw);
+}
+
 // A logger with multiple sinks (stdout and file) - each with a different format and log level.
 void multi_sink_example()
 {
--- a/include/spdlog/cfg/argv.h
+++ b/include/spdlog/cfg/argv.h
@@ -21,7 +21,7 @@ namespace spdlog {
 namespace cfg {

 // search for SPDLOG_LEVEL= in the args and use it to init the levels
-void load_argv_levels(int argc, const char **argv)
+inline void load_argv_levels(int argc, const char **argv)
 {
    const std::string spdlog_level_prefix = "SPDLOG_LEVEL=";
    for (int i = 1; i < argc; i++)
@@ -30,13 +30,12 @@ void load_argv_levels(int argc, const char **argv)
        if (arg.find(spdlog_level_prefix) == 0)
        {
            auto levels_string = arg.substr(spdlog_level_prefix.size());
-            auto levels = helpers::extract_levels(levels_string);
-            details::registry::instance().update_levels(std::move(levels));
+            helpers::load_levels(levels_string);
        }
    }
 }

-void load_argv_levels(int argc, char **argv)
+inline void load_argv_levels(int argc, char **argv)
 {
    load_argv_levels(argc, const_cast<const char **>(argv));
 }
--- a/include/spdlog/cfg/env.h
+++ b/include/spdlog/cfg/env.h
@@ -17,7 +17,7 @@
 // export SPDLOG_LEVEL=debug
 //
 // turn off all logging except for logger1:
-// export SPDLOG_LEVEL="off,logger1=debug"
+// export SPDLOG_LEVEL="*=off,logger1=debug"
 //

 // turn off all logging except for logger1 and logger2:
@@ -25,11 +25,13 @@

 namespace spdlog {
 namespace cfg {
-void load_env_levels()
+inline void load_env_levels()
 {
    auto env_val = details::os::getenv("SPDLOG_LEVEL");
-    auto levels = helpers::extract_levels(env_val);
-    details::registry::instance().update_levels(std::move(levels));
+    if (!env_val.empty())
+    {
+        helpers::load_levels(env_val);
+    }
 }

 } // namespace cfg
--- a/include/spdlog/cfg/helpers-inl.h
+++ b/include/spdlog/cfg/helpers-inl.h
@@ -11,6 +11,7 @@
 #include <spdlog/details/os.h>
 #include <spdlog/details/registry.h>

+#include <algorithm>
 #include <string>
 #include <utility>
 #include <sstream>
@@ -78,24 +79,40 @@ inline std::unordered_map<std::string, std::string> extract_key_vals_(const std:
    return rv;
 }

-SPDLOG_INLINE log_levels extract_levels(const std::string &input)
+SPDLOG_INLINE void load_levels(const std::string &input)
 {
+    if (input.empty() || input.size() > 512)
+    {
+        return;
+    }
+
    auto key_vals = extract_key_vals_(input);
-    log_levels rv;
+    std::unordered_map<std::string, level::level_enum> levels;
+    level::level_enum global_level = level::info;
+    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);
        auto level = level::from_str(level_name);
-        // fallback to "info" if unrecognized level name
+        // ignore unrecognized level names
        if (level == level::off && level_name != "off")
        {
-            level = level::info;
+            continue;
        }
-        rv.set(logger_name, level);
+        if (logger_name.empty()) // no logger name indicate global level
+        {
+            global_level_found = true;
+            global_level = level;
        }
-    return rv;
+        else
+        {
+            levels[logger_name] = level;
+        }
+    }
+
+    details::registry::instance().set_levels(std::move(levels), global_level_found ? &global_level : nullptr);
 }

 } // namespace helpers
--- a/include/spdlog/cfg/helpers.h
+++ b/include/spdlog/cfg/helpers.h
@@ -3,7 +3,8 @@

 #pragma once

-#include <spdlog/cfg/log_levels.h>
+#include <spdlog/common.h>
+#include <unordered_map>

 namespace spdlog {
 namespace cfg {
@@ -17,7 +18,7 @@ namespace helpers {
 // turn off all logging except for logger1: "off,logger1=debug"
 // turn off all logging except for logger1 and logger2: "off,logger1=debug,logger2=info"
 //
-SPDLOG_API log_levels extract_levels(const std::string &txt);
+SPDLOG_API void load_levels(const std::string &txt);
 } // namespace helpers

 } // namespace cfg
--- a/include/spdlog/cfg/log_levels.h
+++ b/include/spdlog/cfg/log_levels.h
@@ -1,47 +0,0 @@
-// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
-// Distributed under the MIT License (http://opensource.org/licenses/MIT)
-
-#pragma once
-
-#include <spdlog/common.h>
-#include <string>
-#include <unordered_map>
-
-namespace spdlog {
-namespace cfg {
-class log_levels
-{
-    std::unordered_map<std::string, spdlog::level::level_enum> levels_;
-    spdlog::level::level_enum default_level_ = level::info;
-
-public:
-    void set(const std::string &logger_name, level::level_enum lvl)
-    {
-        if (logger_name.empty())
-        {
-            default_level_ = lvl;
-        }
-        else
-        {
-            levels_[logger_name] = lvl;
-        }
-    }
-
-    void set_default(level::level_enum lvl)
-    {
-        default_level_ = lvl;
-    }
-
-    level::level_enum get(const std::string &logger_name)
-    {
-        auto it = levels_.find(logger_name);
-        return it != levels_.end() ? it->second : default_level_;
-    }
-
-    level::level_enum default_level()
-    {
-        return default_level_;
-    }
-};
-} // namespace cfg
-} // namespace spdlog
--- a/include/spdlog/common.h
+++ b/include/spdlog/common.h
@@ -167,7 +167,6 @@ SPDLOG_API string_view_t &to_string_view(spdlog::level::level_enum l) SPDLOG_NOE
 SPDLOG_API const char *to_short_c_str(spdlog::level::level_enum l) SPDLOG_NOEXCEPT;
 SPDLOG_API spdlog::level::level_enum from_str(const std::string &name) SPDLOG_NOEXCEPT;

-using level_hasher = std::hash<int>;
 } // namespace level

 //
--- a/include/spdlog/details/mpmc_blocking_q.h
+++ b/include/spdlog/details/mpmc_blocking_q.h
@@ -110,6 +110,12 @@ public:
        return q_.overrun_counter();
    }

+    size_t size()
+    {
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        return q_.size();
+    }
+
 private:
    std::mutex queue_mutex_;
    std::condition_variable push_cv_;
--- a/include/spdlog/details/registry-inl.h
+++ b/include/spdlog/details/registry-inl.h
@@ -67,7 +67,11 @@ SPDLOG_INLINE void registry::initialize_logger(std::shared_ptr<logger> new_logge
        new_logger->set_error_handler(err_handler_);
    }

-    new_logger->set_level(levels_.get(new_logger->name()));
+    // set new level according to previously configured level or default level
+    auto it = log_levels_.find(new_logger->name());
+    auto new_level = it != log_levels_.end() ? it->second : global_log_level_;
+    new_logger->set_level(new_level);
+
    new_logger->flush_on(flush_level_);

    if (backtrace_n_messages_ > 0)
@@ -171,7 +175,7 @@ SPDLOG_INLINE void registry::set_level(level::level_enum log_level)
    {
        l.second->set_level(log_level);
    }
-    levels_.set_default(log_level);
+    global_log_level_ = log_level;
 }

 SPDLOG_INLINE void registry::flush_on(level::level_enum log_level)
@@ -263,14 +267,24 @@ SPDLOG_INLINE void registry::set_automatic_registration(bool automatic_registrat
    automatic_registration_ = automatic_registration;
 }

-SPDLOG_INLINE void registry::update_levels(cfg::log_levels levels)
+SPDLOG_INLINE void registry::set_levels(log_levels levels, level::level_enum *global_level)
 {
    std::lock_guard<std::mutex> lock(logger_map_mutex_);
-    levels_ = std::move(levels);
-    for (auto &l : loggers_)
+    log_levels_ = std::move(levels);
+    auto global_level_requested = global_level != nullptr;
+    global_log_level_ = global_level_requested ? *global_level : global_log_level_;
+
+    for (auto &logger : loggers_)
    {
-        auto &logger = l.second;
-        logger->set_level(levels_.get(logger->name()));
+        auto logger_entry = log_levels_.find(logger.first);
+        if (logger_entry != log_levels_.end())
+        {
+            logger.second->set_level(logger_entry->second);
+        }
+        else if (global_level_requested)
+        {
+            logger.second->set_level(*global_level);
+        }
    }
 }

--- a/include/spdlog/details/registry.h
+++ b/include/spdlog/details/registry.h
@@ -9,7 +9,6 @@
 // This class is thread safe

 #include <spdlog/common.h>
-#include <spdlog/cfg/log_levels.h>

 #include <chrono>
 #include <functional>
@@ -28,6 +27,7 @@ class periodic_worker;
 class SPDLOG_API registry
 {
 public:
+    using log_levels = std::unordered_map<std::string, level::level_enum>;
    registry(const registry &) = delete;
    registry &operator=(const registry &) = delete;

@@ -80,7 +80,8 @@ public:

    void set_automatic_registration(bool automatic_registration);

-    void update_levels(cfg::log_levels levels);
+    // set levels for all existing/future loggers. global_level can be null if should not set.
+    void set_levels(log_levels levels, level::level_enum *global_level);

    static registry &instance();

@@ -90,11 +91,13 @@ private:

    void throw_if_exists_(const std::string &logger_name);
    void register_logger_(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_;
    std::unordered_map<std::string, std::shared_ptr<logger>> loggers_;
-    cfg::log_levels levels_;
+    log_levels log_levels_;
    std::unique_ptr<formatter> formatter_;
+    spdlog::level::level_enum global_log_level_ = level::info;
    level::level_enum flush_level_ = level::off;
    void (*err_handler_)(const std::string &msg);
    std::shared_ptr<thread_pool> tp_;
--- a/include/spdlog/details/tcp_client-windows.h
+++ b/include/spdlog/details/tcp_client-windows.h
@@ -8,8 +8,8 @@
 #include <spdlog/common.h>
 #include <spdlog/details/os.h>

-#include <windows.h>
 #include <winsock2.h>
+#include <windows.h>
 #include <ws2tcpip.h>
 #include <stdlib.h>
 #include <stdio.h>
--- a/include/spdlog/details/tcp_client.h
+++ b/include/spdlog/details/tcp_client.h
@@ -75,7 +75,11 @@ public:
        int last_errno = 0;
        for (auto *rp = addrinfo_result; rp != nullptr; rp = rp->ai_next)
        {
-            int const flags = SOCK_CLOEXEC;
+#if defined(SOCK_CLOEXEC)
+            const int flags = SOCK_CLOEXEC;
+#else
+            const int flags = 0;
+#endif
            socket_ = ::socket(rp->ai_family, rp->ai_socktype | flags, rp->ai_protocol);
            if (socket_ == -1)
            {
@@ -87,13 +91,10 @@ public:
            {
                break;
            }
-            else
-            {
            last_errno = errno;
            ::close(socket_);
            socket_ = -1;
        }
-        }
        ::freeaddrinfo(addrinfo_result);
        if (socket_ == -1)
        {
--- a/include/spdlog/details/thread_pool-inl.h
+++ b/include/spdlog/details/thread_pool-inl.h
@@ -68,6 +68,11 @@ size_t SPDLOG_INLINE thread_pool::overrun_counter()
    return q_.overrun_counter();
 }

+size_t SPDLOG_INLINE thread_pool::queue_size()
+{
+    return q_.size();
+}
+
 void SPDLOG_INLINE thread_pool::post_async_msg_(async_msg &&new_msg, async_overflow_policy overflow_policy)
 {
    if (overflow_policy == async_overflow_policy::block)
--- a/include/spdlog/details/thread_pool.h
+++ b/include/spdlog/details/thread_pool.h
@@ -97,6 +97,7 @@ public:
    void post_log(async_logger_ptr &&worker_ptr, const details::log_msg &msg, async_overflow_policy overflow_policy);
    void post_flush(async_logger_ptr &&worker_ptr, async_overflow_policy overflow_policy);
    size_t overrun_counter();
+    size_t queue_size();

 private:
    q_type q_;
--- a/include/spdlog/fmt/bin_to_hex.h
+++ b/include/spdlog/fmt/bin_to_hex.h
@@ -9,7 +9,7 @@

 //
 // Support for logging binary data as hex
-// format flags:
+// format flags, any combination of the followng:
 // {:X} - print in uppercase.
 // {:s} - don't separate each byte with space.
 // {:p} - don't print the position on each line start.
--- a/include/spdlog/fmt/bundled/chrono.h
+++ b/include/spdlog/fmt/bundled/chrono.h
@@ -48,7 +48,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
    // From fits in To without any problem.
  } else {
    // From does not always fit in To, resort to a dynamic check.
-    if (from < T::min() || from > T::max()) {
+    if (from < (T::min)() || from > (T::max)()) {
      // outside range.
      ec = 1;
      return {};
@@ -72,43 +72,27 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
  static_assert(F::is_integer, "From must be integral");
  static_assert(T::is_integer, "To must be integral");

-  if (F::is_signed && !T::is_signed) {
+  if (detail::const_check(F::is_signed && !T::is_signed)) {
    // From may be negative, not allowed!
-    if (fmt::internal::is_negative(from)) {
+    if (fmt::detail::is_negative(from)) {
      ec = 1;
      return {};
    }
-
    // From is positive. Can it always fit in To?
-    if (F::digits <= T::digits) {
-      // yes, From always fits in To.
-    } else {
-      // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>(T::max())) {
+    if (F::digits > T::digits &&
+        from > static_cast<From>(detail::max_value<To>())) {
      ec = 1;
      return {};
    }
  }
-  }

-  if (!F::is_signed && T::is_signed) {
-    // can from be held in To?
-    if (F::digits < T::digits) {
-      // yes, From always fits in To.
-    } else {
-      // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>(T::max())) {
-        // outside range.
+  if (!F::is_signed && T::is_signed && F::digits >= T::digits &&
+      from > static_cast<From>(detail::max_value<To>())) {
    ec = 1;
    return {};
  }
+  return static_cast<To>(from);  // Lossless conversion.
 }
-  }
-
-  // reaching here means all is ok for lossless conversion.
-  return static_cast<To>(from);
-
-}  // function

 template <typename To, typename From,
          FMT_ENABLE_IF(std::is_same<From, To>::value)>
@@ -141,7 +125,7 @@ FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {

  // catch the only happy case
  if (std::isfinite(from)) {
-    if (from >= T::lowest() && from <= T::max()) {
+    if (from >= T::lowest() && from <= (T::max)()) {
      return static_cast<To>(from);
    }
    // not within range.
@@ -190,17 +174,16 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
  // safe conversion to IntermediateRep
  IntermediateRep count =
      lossless_integral_conversion<IntermediateRep>(from.count(), ec);
-  if (ec) {
-    return {};
-  }
+  if (ec) return {};
  // multiply with Factor::num without overflow or underflow
-  if (Factor::num != 1) {
-    const auto max1 = internal::max_value<IntermediateRep>() / Factor::num;
+  if (detail::const_check(Factor::num != 1)) {
+    const auto max1 = detail::max_value<IntermediateRep>() / Factor::num;
    if (count > max1) {
      ec = 1;
      return {};
    }
-    const auto min1 = std::numeric_limits<IntermediateRep>::min() / Factor::num;
+    const auto min1 =
+        (std::numeric_limits<IntermediateRep>::min)() / Factor::num;
    if (count < min1) {
      ec = 1;
      return {};
@@ -208,17 +191,9 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
    count *= Factor::num;
  }

-  // this can't go wrong, right? den>0 is checked earlier.
-  if (Factor::den != 1) {
-    count /= Factor::den;
-  }
-  // convert to the to type, safely
-  using ToRep = typename To::rep;
-  const ToRep tocount = lossless_integral_conversion<ToRep>(count, ec);
-  if (ec) {
-    return {};
-  }
-  return To{tocount};
+  if (detail::const_check(Factor::den != 1)) count /= Factor::den;
+  auto tocount = lossless_integral_conversion<typename To::rep>(count, ec);
+  return ec ? To() : To(tocount);
 }

 /**
@@ -269,7 +244,7 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,

  // multiply with Factor::num without overflow or underflow
  if (Factor::num != 1) {
-    constexpr auto max1 = internal::max_value<IntermediateRep>() /
+    constexpr auto max1 = detail::max_value<IntermediateRep>() /
                          static_cast<IntermediateRep>(Factor::num);
    if (count > max1) {
      ec = 1;
@@ -306,12 +281,12 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
 // Usage: f FMT_NOMACRO()
 #define FMT_NOMACRO

-namespace internal {
+namespace detail {
 inline null<> localtime_r FMT_NOMACRO(...) { return null<>(); }
 inline null<> localtime_s(...) { return null<>(); }
 inline null<> gmtime_r(...) { return null<>(); }
 inline null<> gmtime_s(...) { return null<>(); }
-}  // namespace internal
+}  // namespace detail

 // Thread-safe replacement for std::localtime
 inline std::tm localtime(std::time_t time) {
@@ -322,22 +297,22 @@ inline std::tm localtime(std::time_t time) {
    dispatcher(std::time_t t) : time_(t) {}

    bool run() {
-      using namespace fmt::internal;
+      using namespace fmt::detail;
      return handle(localtime_r(&time_, &tm_));
    }

    bool handle(std::tm* tm) { return tm != nullptr; }

-    bool handle(internal::null<>) {
-      using namespace fmt::internal;
+    bool handle(detail::null<>) {
+      using namespace fmt::detail;
      return fallback(localtime_s(&tm_, &time_));
    }

    bool fallback(int res) { return res == 0; }

 #if !FMT_MSC_VER
-    bool fallback(internal::null<>) {
-      using namespace fmt::internal;
+    bool fallback(detail::null<>) {
+      using namespace fmt::detail;
      std::tm* tm = std::localtime(&time_);
      if (tm) tm_ = *tm;
      return tm != nullptr;
@@ -350,6 +325,11 @@ inline std::tm localtime(std::time_t time) {
  return lt.tm_;
 }

+inline std::tm localtime(
+    std::chrono::time_point<std::chrono::system_clock> time_point) {
+  return localtime(std::chrono::system_clock::to_time_t(time_point));
+}
+
 // Thread-safe replacement for std::gmtime
 inline std::tm gmtime(std::time_t time) {
  struct dispatcher {
@@ -359,21 +339,21 @@ inline std::tm gmtime(std::time_t time) {
    dispatcher(std::time_t t) : time_(t) {}

    bool run() {
-      using namespace fmt::internal;
+      using namespace fmt::detail;
      return handle(gmtime_r(&time_, &tm_));
    }

    bool handle(std::tm* tm) { return tm != nullptr; }

-    bool handle(internal::null<>) {
-      using namespace fmt::internal;
+    bool handle(detail::null<>) {
+      using namespace fmt::detail;
      return fallback(gmtime_s(&tm_, &time_));
    }

    bool fallback(int res) { return res == 0; }

 #if !FMT_MSC_VER
-    bool fallback(internal::null<>) {
+    bool fallback(detail::null<>) {
      std::tm* tm = std::gmtime(&time_);
      if (tm) tm_ = *tm;
      return tm != nullptr;
@@ -386,17 +366,33 @@ inline std::tm gmtime(std::time_t time) {
  return gt.tm_;
 }

-namespace internal {
-inline std::size_t strftime(char* str, std::size_t count, const char* format,
+inline std::tm gmtime(
+    std::chrono::time_point<std::chrono::system_clock> time_point) {
+  return gmtime(std::chrono::system_clock::to_time_t(time_point));
+}
+
+namespace detail {
+inline size_t strftime(char* str, size_t count, const char* format,
                       const std::tm* time) {
  return std::strftime(str, count, format, time);
 }

-inline std::size_t strftime(wchar_t* str, std::size_t count,
-                            const wchar_t* format, const std::tm* time) {
+inline size_t strftime(wchar_t* str, size_t count, const wchar_t* format,
+                       const std::tm* time) {
  return std::wcsftime(str, count, format, time);
 }
-}  // namespace internal
+}  // namespace detail
+
+template <typename Char>
+struct formatter<std::chrono::time_point<std::chrono::system_clock>, Char>
+    : formatter<std::tm, Char> {
+  template <typename FormatContext>
+  auto format(std::chrono::time_point<std::chrono::system_clock> val,
+              FormatContext& ctx) -> decltype(ctx.out()) {
+    std::tm time = localtime(val);
+    return formatter<std::tm, Char>::format(time, ctx);
+  }
+};

 template <typename Char> struct formatter<std::tm, Char> {
  template <typename ParseContext>
@@ -405,7 +401,7 @@ template <typename Char> struct formatter<std::tm, Char> {
    if (it != ctx.end() && *it == ':') ++it;
    auto end = it;
    while (end != ctx.end() && *end != '}') ++end;
-    tm_format.reserve(internal::to_unsigned(end - it + 1));
+    tm_format.reserve(detail::to_unsigned(end - it + 1));
    tm_format.append(it, end);
    tm_format.push_back('\0');
    return end;
@@ -414,11 +410,10 @@ template <typename Char> struct formatter<std::tm, Char> {
  template <typename FormatContext>
  auto format(const std::tm& tm, FormatContext& ctx) -> decltype(ctx.out()) {
    basic_memory_buffer<Char> buf;
-    std::size_t start = buf.size();
+    size_t start = buf.size();
    for (;;) {
-      std::size_t size = buf.capacity() - start;
-      std::size_t count =
-          internal::strftime(&buf[start], size, &tm_format[0], &tm);
+      size_t size = buf.capacity() - start;
+      size_t count = detail::strftime(&buf[start], size, &tm_format[0], &tm);
      if (count != 0) {
        buf.resize(start + count);
        break;
@@ -430,7 +425,7 @@ template <typename Char> struct formatter<std::tm, Char> {
        // https://github.com/fmtlib/fmt/issues/367
        break;
      }
-      const std::size_t MIN_GROWTH = 10;
+      const size_t MIN_GROWTH = 10;
      buf.reserve(buf.capacity() + (size > MIN_GROWTH ? size : MIN_GROWTH));
    }
    return std::copy(buf.begin(), buf.end(), ctx.out());
@@ -439,7 +434,7 @@ template <typename Char> struct formatter<std::tm, Char> {
  basic_memory_buffer<Char> tm_format;
 };

-namespace internal {
+namespace detail {
 template <typename Period> FMT_CONSTEXPR const char* get_units() {
  return nullptr;
 }
@@ -768,19 +763,25 @@ OutputIt format_duration_value(OutputIt out, Rep val, int precision) {
  return format_to(out, std::is_floating_point<Rep>::value ? fp_f : format,
                   val);
 }
+template <typename Char, typename OutputIt>
+OutputIt copy_unit(string_view unit, OutputIt out, Char) {
+  return std::copy(unit.begin(), unit.end(), out);
+}
+
+template <typename OutputIt>
+OutputIt copy_unit(string_view unit, OutputIt out, wchar_t) {
+  // This works when wchar_t is UTF-32 because units only contain characters
+  // that have the same representation in UTF-16 and UTF-32.
+  utf8_to_utf16 u(unit);
+  return std::copy(u.c_str(), u.c_str() + u.size(), out);
+}

 template <typename Char, typename Period, typename OutputIt>
 OutputIt format_duration_unit(OutputIt out) {
-  if (const char* unit = get_units<Period>()) {
-    string_view s(unit);
-    if (const_check(std::is_same<Char, wchar_t>())) {
-      utf8_to_utf16 u(s);
-      return std::copy(u.c_str(), u.c_str() + u.size(), out);
-    }
-    return std::copy(s.begin(), s.end(), out);
-  }
+  if (const char* unit = get_units<Period>())
+    return copy_unit(string_view(unit), out, Char());
  const Char num_f[] = {'[', '{', '}', ']', 's', 0};
-  if (Period::den == 1) return format_to(out, num_f, Period::num);
+  if (const_check(Period::den == 1)) return format_to(out, num_f, Period::num);
  const Char num_def_f[] = {'[', '{', '}', '/', '{', '}', ']', 's', 0};
  return format_to(out, num_def_f, Period::num, Period::den);
 }
@@ -874,9 +875,9 @@ struct chrono_formatter {
    if (isnan(value)) return write_nan();
    uint32_or_64_or_128_t<int> n =
        to_unsigned(to_nonnegative_int(value, max_value<int>()));
-    int num_digits = internal::count_digits(n);
+    int num_digits = detail::count_digits(n);
    if (width > num_digits) out = std::fill_n(out, width - num_digits, '0');
-    out = format_decimal<char_type>(out, n, num_digits);
+    out = format_decimal<char_type>(out, n, num_digits).end;
  }

  void write_nan() { std::copy_n("nan", 3, out); }
@@ -1004,14 +1005,14 @@ struct chrono_formatter {
    out = format_duration_unit<char_type, Period>(out);
  }
 };
-}  // namespace internal
+}  // namespace detail

 template <typename Rep, typename Period, typename Char>
 struct formatter<std::chrono::duration<Rep, Period>, Char> {
 private:
  basic_format_specs<Char> specs;
  int precision;
-  using arg_ref_type = internal::arg_ref<Char>;
+  using arg_ref_type = detail::arg_ref<Char>;
  arg_ref_type width_ref;
  arg_ref_type precision_ref;
  mutable basic_string_view<Char> format_str;
@@ -1032,7 +1033,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
      return arg_ref_type(arg_id);
    }

-    FMT_CONSTEXPR arg_ref_type make_arg_ref(internal::auto_id) {
+    FMT_CONSTEXPR arg_ref_type make_arg_ref(detail::auto_id) {
      return arg_ref_type(context.next_arg_id());
    }

@@ -1062,17 +1063,17 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
    auto begin = ctx.begin(), end = ctx.end();
    if (begin == end || *begin == '}') return {begin, begin};
    spec_handler handler{*this, ctx, format_str};
-    begin = internal::parse_align(begin, end, handler);
+    begin = detail::parse_align(begin, end, handler);
    if (begin == end) return {begin, begin};
-    begin = internal::parse_width(begin, end, handler);
+    begin = detail::parse_width(begin, end, handler);
    if (begin == end) return {begin, begin};
    if (*begin == '.') {
      if (std::is_floating_point<Rep>::value)
-        begin = internal::parse_precision(begin, end, handler);
+        begin = detail::parse_precision(begin, end, handler);
      else
        handler.on_error("precision not allowed for this argument type");
    }
-    end = parse_chrono_format(begin, end, internal::chrono_format_checker());
+    end = parse_chrono_format(begin, end, detail::chrono_format_checker());
    return {begin, end};
  }

@@ -1083,7 +1084,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
      -> decltype(ctx.begin()) {
    auto range = do_parse(ctx);
    format_str = basic_string_view<Char>(
-        &*range.begin, internal::to_unsigned(range.end - range.begin));
+        &*range.begin, detail::to_unsigned(range.end - range.begin));
    return range.end;
  }

@@ -1094,23 +1095,21 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
    // is not specified.
    basic_memory_buffer<Char> buf;
    auto out = std::back_inserter(buf);
-    using range = internal::output_range<decltype(ctx.out()), Char>;
-    internal::basic_writer<range> w(range(ctx.out()));
-    internal::handle_dynamic_spec<internal::width_checker>(specs.width,
-                                                           width_ref, ctx);
-    internal::handle_dynamic_spec<internal::precision_checker>(
-        precision, precision_ref, ctx);
+    detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref,
+                                                       ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(precision,
+                                                           precision_ref, ctx);
    if (begin == end || *begin == '}') {
-      out = internal::format_duration_value<Char>(out, d.count(), precision);
-      internal::format_duration_unit<Char, Period>(out);
+      out = detail::format_duration_value<Char>(out, d.count(), precision);
+      detail::format_duration_unit<Char, Period>(out);
    } else {
-      internal::chrono_formatter<FormatContext, decltype(out), Rep, Period> f(
+      detail::chrono_formatter<FormatContext, decltype(out), Rep, Period> f(
          ctx, out, d);
      f.precision = precision;
      parse_chrono_format(begin, end, f);
    }
-    w.write(buf.data(), buf.size(), specs);
-    return w.out();
+    return detail::write(
+        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
  }
 };

--- a/include/spdlog/fmt/bundled/color.h
+++ b/include/spdlog/fmt/bundled/color.h
@@ -198,7 +198,7 @@ struct rgb {
  uint8_t b;
 };

-namespace internal {
+namespace detail {

 // color is a struct of either a rgb color or a terminal color.
 struct color_type {
@@ -221,7 +221,7 @@ struct color_type {
    uint32_t rgb_color;
  } value;
 };
-}  // namespace internal
+}  // namespace detail

 // Experimental text formatting support.
 class text_style {
@@ -298,11 +298,11 @@ class text_style {
  FMT_CONSTEXPR bool has_emphasis() const FMT_NOEXCEPT {
    return static_cast<uint8_t>(ems) != 0;
  }
-  FMT_CONSTEXPR internal::color_type get_foreground() const FMT_NOEXCEPT {
+  FMT_CONSTEXPR detail::color_type get_foreground() const FMT_NOEXCEPT {
    FMT_ASSERT(has_foreground(), "no foreground specified for this style");
    return foreground_color;
  }
-  FMT_CONSTEXPR internal::color_type get_background() const FMT_NOEXCEPT {
+  FMT_CONSTEXPR detail::color_type get_background() const FMT_NOEXCEPT {
    FMT_ASSERT(has_background(), "no background specified for this style");
    return background_color;
  }
@@ -313,7 +313,7 @@ class text_style {

 private:
  FMT_CONSTEXPR text_style(bool is_foreground,
-                           internal::color_type text_color) FMT_NOEXCEPT
+                           detail::color_type text_color) FMT_NOEXCEPT
      : set_foreground_color(),
        set_background_color(),
        ems() {
@@ -326,23 +326,23 @@ class text_style {
    }
  }

-  friend FMT_CONSTEXPR_DECL text_style fg(internal::color_type foreground)
+  friend FMT_CONSTEXPR_DECL text_style fg(detail::color_type foreground)
      FMT_NOEXCEPT;
-  friend FMT_CONSTEXPR_DECL text_style bg(internal::color_type background)
+  friend FMT_CONSTEXPR_DECL text_style bg(detail::color_type background)
      FMT_NOEXCEPT;

-  internal::color_type foreground_color;
-  internal::color_type background_color;
+  detail::color_type foreground_color;
+  detail::color_type background_color;
  bool set_foreground_color;
  bool set_background_color;
  emphasis ems;
 };

-FMT_CONSTEXPR text_style fg(internal::color_type foreground) FMT_NOEXCEPT {
+FMT_CONSTEXPR text_style fg(detail::color_type foreground) FMT_NOEXCEPT {
  return text_style(/*is_foreground=*/true, foreground);
 }

-FMT_CONSTEXPR text_style bg(internal::color_type background) FMT_NOEXCEPT {
+FMT_CONSTEXPR text_style bg(detail::color_type background) FMT_NOEXCEPT {
  return text_style(/*is_foreground=*/false, background);
 }

@@ -350,21 +350,21 @@ FMT_CONSTEXPR text_style operator|(emphasis lhs, emphasis rhs) FMT_NOEXCEPT {
  return text_style(lhs) | rhs;
 }

-namespace internal {
+namespace detail {

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

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

@@ -398,7 +398,7 @@ template <typename Char> struct ansi_color_escape {
    if (em_bits & static_cast<uint8_t>(emphasis::strikethrough))
      em_codes[3] = 9;

-    std::size_t index = 0;
+    size_t index = 0;
    for (int i = 0; i < 4; ++i) {
      if (!em_codes[i]) continue;
      buffer[index++] = static_cast<Char>('\x1b');
@@ -429,14 +429,14 @@ template <typename Char> struct ansi_color_escape {

 template <typename Char>
 FMT_CONSTEXPR ansi_color_escape<Char> make_foreground_color(
-    internal::color_type foreground) FMT_NOEXCEPT {
-  return ansi_color_escape<Char>(foreground, internal::data::foreground_color);
+    detail::color_type foreground) FMT_NOEXCEPT {
+  return ansi_color_escape<Char>(foreground, detail::data::foreground_color);
 }

 template <typename Char>
 FMT_CONSTEXPR ansi_color_escape<Char> make_background_color(
-    internal::color_type background) FMT_NOEXCEPT {
-  return ansi_color_escape<Char>(background, internal::data::background_color);
+    detail::color_type background) FMT_NOEXCEPT {
+  return ansi_color_escape<Char>(background, detail::data::background_color);
 }

 template <typename Char>
@@ -455,71 +455,71 @@ inline void fputs<wchar_t>(const wchar_t* chars, FILE* stream) FMT_NOEXCEPT {
 }

 template <typename Char> inline void reset_color(FILE* stream) FMT_NOEXCEPT {
-  fputs(internal::data::reset_color, stream);
+  fputs(detail::data::reset_color, stream);
 }

 template <> inline void reset_color<wchar_t>(FILE* stream) FMT_NOEXCEPT {
-  fputs(internal::data::wreset_color, stream);
+  fputs(detail::data::wreset_color, stream);
 }

 template <typename Char>
-inline void reset_color(basic_memory_buffer<Char>& buffer) FMT_NOEXCEPT {
+inline void reset_color(buffer<Char>& buffer) FMT_NOEXCEPT {
  const char* begin = data::reset_color;
  const char* end = begin + sizeof(data::reset_color) - 1;
  buffer.append(begin, end);
 }

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

 template <typename S, typename Char = char_t<S>>
 void vprint(std::FILE* f, const text_style& ts, const S& format,
-            basic_format_args<buffer_context<Char>> args) {
+            basic_format_args<buffer_context<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buf;
-  internal::vformat_to(buf, ts, to_string_view(format), args);
+  detail::vformat_to(buf, ts, to_string_view(format), args);
  buf.push_back(Char(0));
-  internal::fputs(buf.data(), f);
+  detail::fputs(buf.data(), f);
 }

 /**
+  \rst
  Formats a string and prints it to the specified file stream using ANSI
  escape sequences to specify text formatting.
-  Example:
+
+  **Example**::
+
    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
               "Elapsed time: {0:.2f} seconds", 1.23);
+  \endrst
 */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 void print(std::FILE* f, const text_style& ts, const S& format_str,
           const Args&... args) {
-  internal::check_format_string<Args...>(format_str);
-  using context = buffer_context<char_t<S>>;
-  format_arg_store<context, Args...> as{args...};
-  vprint(f, ts, format_str, basic_format_args<context>(as));
+  vprint(f, ts, format_str,
+         fmt::make_args_checked<Args...>(format_str, args...));
 }

 /**
@@ -530,7 +530,7 @@ void print(std::FILE* f, const text_style& ts, const S& format_str,
               "Elapsed time: {0:.2f} seconds", 1.23);
 */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 void print(const text_style& ts, const S& format_str, const Args&... args) {
  return print(stdout, ts, format_str, args...);
 }
@@ -540,7 +540,7 @@ inline std::basic_string<Char> vformat(
    const text_style& ts, const S& format_str,
    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buf;
-  internal::vformat_to(buf, ts, to_string_view(format_str), args);
+  detail::vformat_to(buf, ts, to_string_view(format_str), args);
  return fmt::to_string(buf);
 }

@@ -560,7 +560,42 @@ template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
                                      const Args&... args) {
  return vformat(ts, to_string_view(format_str),
-                 internal::make_args_checked<Args...>(format_str, args...));
+                 fmt::make_args_checked<Args...>(format_str, args...));
+}
+
+/**
+  Formats a string with the given text_style and writes the output to ``out``.
+ */
+template <typename OutputIt, typename Char,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+OutputIt vformat_to(
+    OutputIt out, const text_style& ts, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  detail::vformat_to(buf, ts, format_str, args);
+  return detail::get_iterator(buf);
+}
+
+/**
+  \rst
+  Formats arguments with the given text_style, writes the result to the output
+  iterator ``out`` and returns the iterator past the end of the output range.
+
+  **Example**::
+
+    std::vector<char> out;
+    fmt::format_to(std::back_inserter(out),
+                   fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
+  \endrst
+*/
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value&&
+              detail::is_string<S>::value>
+inline auto format_to(OutputIt out, const text_style& ts, const S& format_str,
+                      Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  return vformat_to(out, ts, to_string_view(format_str),
+                    fmt::make_args_checked<Args...>(format_str, args...));
 }

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/compile.h
+++ b/include/spdlog/fmt/bundled/compile.h
@@ -13,7 +13,33 @@
 #include "format.h"

 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
+
+// A compile-time string which is compiled into fast formatting code.
+class compiled_string {};
+
+template <typename S>
+struct is_compiled_string : std::is_base_of<compiled_string, S> {};
+
+/**
+  \rst
+  Converts a string literal *s* into a format string that will be parsed at
+  compile time and converted into efficient formatting code. Requires C++17
+  ``constexpr if`` compiler support.
+
+  **Example**::
+
+    // Converts 42 into std::string using the most efficient method and no
+    // runtime format string processing.
+    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
+  \endrst
+ */
+#define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::detail::compiled_string)
+
+template <typename T, typename... Tail>
+const T& first(const T& value, const Tail&...) {
+  return value;
+}

 // Part of a compiled format string. It can be either literal text or a
 // replacement field.
@@ -62,13 +88,15 @@ template <typename Char> struct part_counter {
    if (begin != end) ++num_parts;
  }

-  FMT_CONSTEXPR void on_arg_id() { ++num_parts; }
-  FMT_CONSTEXPR void on_arg_id(int) { ++num_parts; }
-  FMT_CONSTEXPR void on_arg_id(basic_string_view<Char>) { ++num_parts; }
+  FMT_CONSTEXPR int on_arg_id() { return ++num_parts, 0; }
+  FMT_CONSTEXPR int on_arg_id(int) { return ++num_parts, 0; }
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
+    return ++num_parts, 0;
+  }

-  FMT_CONSTEXPR void on_replacement_field(const Char*) {}
+  FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}

-  FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
+  FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
                                            const Char* end) {
    // Find the matching brace.
    unsigned brace_counter = 0;
@@ -116,25 +144,28 @@ class format_string_compiler : public error_handler {
      handler_(part::make_text({begin, to_unsigned(end - begin)}));
  }

-  FMT_CONSTEXPR void on_arg_id() {
+  FMT_CONSTEXPR int on_arg_id() {
    part_ = part::make_arg_index(parse_context_.next_arg_id());
+    return 0;
  }

-  FMT_CONSTEXPR void on_arg_id(int id) {
+  FMT_CONSTEXPR int on_arg_id(int id) {
    parse_context_.check_arg_id(id);
    part_ = part::make_arg_index(id);
+    return 0;
  }

-  FMT_CONSTEXPR void on_arg_id(basic_string_view<Char> id) {
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char> id) {
    part_ = part::make_arg_name(id);
+    return 0;
  }

-  FMT_CONSTEXPR void on_replacement_field(const Char* ptr) {
+  FMT_CONSTEXPR void on_replacement_field(int, const Char* ptr) {
    part_.arg_id_end = ptr;
    handler_(part_);
  }

-  FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
+  FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
                                            const Char* end) {
    auto repl = typename part::replacement();
    dynamic_specs_handler<basic_format_parse_context<Char>> handler(
@@ -160,23 +191,24 @@ FMT_CONSTEXPR void compile_format_string(basic_string_view<Char> format_str,
      format_string_compiler<Char, PartHandler>(format_str, handler));
 }

-template <typename Range, typename Context, typename Id>
+template <typename OutputIt, typename Context, typename Id>
 void format_arg(
-    basic_format_parse_context<typename Range::value_type>& parse_ctx,
+    basic_format_parse_context<typename Context::char_type>& parse_ctx,
    Context& ctx, Id arg_id) {
-  ctx.advance_to(
-      visit_format_arg(arg_formatter<Range>(ctx, &parse_ctx), ctx.arg(arg_id)));
+  ctx.advance_to(visit_format_arg(
+      arg_formatter<OutputIt, typename Context::char_type>(ctx, &parse_ctx),
+      ctx.arg(arg_id)));
 }

 // vformat_to is defined in a subnamespace to prevent ADL.
 namespace cf {
-template <typename Context, typename Range, typename CompiledFormat>
-auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)
-    -> typename Context::iterator {
+template <typename Context, typename OutputIt, typename CompiledFormat>
+auto vformat_to(OutputIt out, CompiledFormat& cf,
+                basic_format_args<Context> args) -> typename Context::iterator {
  using char_type = typename Context::char_type;
  basic_format_parse_context<char_type> parse_ctx(
      to_string_view(cf.format_str_));
-  Context ctx(out.begin(), args);
+  Context ctx(out, args);

  const auto& parts = cf.parts();
  for (auto part_it = std::begin(parts); part_it != std::end(parts);
@@ -197,12 +229,12 @@ auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)

    case format_part_t::kind::arg_index:
      advance_to(parse_ctx, part.arg_id_end);
-      internal::format_arg<Range>(parse_ctx, ctx, value.arg_index);
+      detail::format_arg<OutputIt>(parse_ctx, ctx, value.arg_index);
      break;

    case format_part_t::kind::arg_name:
      advance_to(parse_ctx, part.arg_id_end);
-      internal::format_arg<Range>(parse_ctx, ctx, value.str);
+      detail::format_arg<OutputIt>(parse_ctx, ctx, value.str);
      break;

    case format_part_t::kind::replacement: {
@@ -226,7 +258,9 @@ auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)

      advance_to(parse_ctx, part.arg_id_end);
      ctx.advance_to(
-          visit_format_arg(arg_formatter<Range>(ctx, nullptr, &specs), arg));
+          visit_format_arg(arg_formatter<OutputIt, typename Context::char_type>(
+                               ctx, nullptr, &specs),
+                           arg));
      break;
    }
    }
@@ -240,7 +274,7 @@ struct basic_compiled_format {};
 template <typename S, typename = void>
 struct compiled_format_base : basic_compiled_format {
  using char_type = char_t<S>;
-  using parts_container = std::vector<internal::format_part<char_type>>;
+  using parts_container = std::vector<detail::format_part<char_type>>;

  parts_container compiled_parts;

@@ -305,7 +339,7 @@ struct compiled_format_base<S, enable_if_t<is_compile_string<S>::value>>
  const parts_container& parts() const {
    static FMT_CONSTEXPR_DECL const auto compiled_parts =
        compile_to_parts<char_type, num_format_parts>(
-            internal::to_string_view(S()));
+            detail::to_string_view(S()));
    return compiled_parts.data;
  }
 };
@@ -318,8 +352,8 @@ class compiled_format : private compiled_format_base<S> {
 private:
  basic_string_view<char_type> format_str_;

-  template <typename Context, typename Range, typename CompiledFormat>
-  friend auto cf::vformat_to(Range out, CompiledFormat& cf,
+  template <typename Context, typename OutputIt, typename CompiledFormat>
+  friend auto cf::vformat_to(OutputIt out, CompiledFormat& cf,
                             basic_format_args<Context> args) ->
      typename Context::iterator;

@@ -334,7 +368,8 @@ template <typename... Args> 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(const T& first, const Args&... rest) {
+constexpr const auto& get([[maybe_unused]] const T& first,
+                          [[maybe_unused]] const Args&... rest) {
  static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
  if constexpr (N == 0)
    return first;
@@ -359,8 +394,7 @@ template <typename Char> struct text {

  template <typename OutputIt, typename... Args>
  OutputIt format(OutputIt out, const Args&...) const {
-    // TODO: reserve
-    return copy_str<Char>(data.begin(), data.end(), out);
+    return write<Char>(out, data);
  }
 };

@@ -373,32 +407,18 @@ constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
  return {{&s[pos], size}};
 }

-template <typename Char, typename OutputIt, typename T,
-          std::enable_if_t<std::is_integral_v<T>, int> = 0>
-OutputIt format_default(OutputIt out, T value) {
-  // TODO: reserve
-  format_int fi(value);
-  return std::copy(fi.data(), fi.data() + fi.size(), out);
-}
+template <typename Char> struct code_unit {
+  Char value;
+  using char_type = Char;

-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, double value) {
-  writer w(out);
-  w.write(value);
-  return w.out();
+  template <typename OutputIt, typename... Args>
+  OutputIt format(OutputIt out, const Args&...) const {
+    return write<Char>(out, value);
  }
+};

-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, Char value) {
-  *out++ = value;
-  return out;
-}
-
-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, const Char* value) {
-  auto length = std::char_traits<Char>::length(value);
-  return copy_str<Char>(value, value + length, out);
-}
+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 {
@@ -408,13 +428,32 @@ template <typename Char, typename T, int N> struct field {
  OutputIt format(OutputIt out, const Args&... args) const {
    // This ensures that the argument type is convertile to `const T&`.
    const T& arg = get<N>(args...);
-    return format_default<Char>(out, arg);
+    return write<Char>(out, arg);
  }
 };

 template <typename Char, typename T, int N>
 struct is_compiled_format<field<Char, T, N>> : 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 {
+  using char_type = Char;
+  mutable formatter<T, Char> fmt;
+
+  template <typename OutputIt, typename... Args>
+  OutputIt format(OutputIt out, const Args&... args) const {
+    // This ensures that the argument type is convertile to `const T&`.
+    const T& arg = get<N>(args...);
+    const auto& vargs =
+        make_format_args<basic_format_context<OutputIt, Char>>(args...);
+    basic_format_context<OutputIt, Char> ctx(out, vargs);
+    return fmt.format(arg, ctx);
+  }
+};
+
+template <typename Char, typename T, int N>
+struct is_compiled_format<spec_field<Char, T, N>> : std::true_type {};
+
 template <typename L, typename R> struct concat {
  L lhs;
  R rhs;
@@ -450,7 +489,8 @@ constexpr auto compile_format_string(S format_str);

 template <typename Args, size_t POS, int ID, typename T, typename S>
 constexpr auto parse_tail(T head, S format_str) {
-  if constexpr (POS != to_string_view(format_str).size()) {
+  if constexpr (POS !=
+                basic_string_view<typename S::char_type>(format_str).size()) {
    constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
    if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
                               unknown_format>())
@@ -462,6 +502,22 @@ constexpr auto parse_tail(T head, S format_str) {
  }
 }

+template <typename T, typename Char> struct parse_specs_result {
+  formatter<T, Char> fmt;
+  size_t end;
+  int next_arg_id;
+};
+
+template <typename T, typename Char>
+constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
+                                                  size_t pos, int arg_id) {
+  str.remove_prefix(pos);
+  auto ctx = basic_format_parse_context<Char>(str, {}, arg_id + 1);
+  auto f = formatter<T, Char>();
+  auto end = f.parse(ctx);
+  return {f, pos + (end - str.data()) + 1, ctx.next_arg_id()};
+}
+
 // Compiles a non-empty format string and returns the compiled representation
 // or unknown_format() on unrecognized input.
 template <typename Args, size_t POS, int ID, typename S>
@@ -475,12 +531,13 @@ constexpr auto compile_format_string(S format_str) {
      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
    } else if constexpr (str[POS + 1] == '}') {
      using type = get_type<ID, Args>;
-      if constexpr (std::is_same<type, int>::value) {
      return parse_tail<Args, POS + 2, ID + 1>(field<char_type, type, ID>(),
                                               format_str);
-      } else {
-        return unknown_format();
-      }
+    } else if constexpr (str[POS + 1] == ':') {
+      using type = get_type<ID, Args>;
+      constexpr auto result = parse_specs<type>(str, POS + 2, ID);
+      return parse_tail<Args, result.end, result.next_arg_id>(
+          spec_field<char_type, type, ID>{result.fmt}, format_str);
    } else {
      return unknown_format();
    }
@@ -490,104 +547,153 @@ constexpr auto compile_format_string(S format_str) {
    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
  } else {
    constexpr auto end = parse_text(str, POS + 1);
+    if constexpr (end - POS > 1) {
      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
                                       format_str);
+    } else {
+      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
+                                       format_str);
+    }
  }
 }
-#endif  // __cpp_if_constexpr
-}  // namespace internal

-#if FMT_USE_CONSTEXPR
-#  ifdef __cpp_if_constexpr
 template <typename... Args, typename S,
-          FMT_ENABLE_IF(is_compile_string<S>::value)>
+          FMT_ENABLE_IF(is_compile_string<S>::value ||
+                        detail::is_compiled_string<S>::value)>
 constexpr auto compile(S format_str) {
  constexpr basic_string_view<typename S::char_type> str = format_str;
  if constexpr (str.size() == 0) {
-    return internal::make_text(str, 0, 0);
+    return detail::make_text(str, 0, 0);
  } else {
    constexpr auto result =
-        internal::compile_format_string<internal::type_list<Args...>, 0, 0>(
+        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
            format_str);
    if constexpr (std::is_same<remove_cvref_t<decltype(result)>,
-                               internal::unknown_format>()) {
-      return internal::compiled_format<S, Args...>(to_string_view(format_str));
+                               detail::unknown_format>()) {
+      return detail::compiled_format<S, Args...>(to_string_view(format_str));
    } else {
      return result;
    }
  }
 }
-
-template <typename CompiledFormat, typename... Args,
-          typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(internal::is_compiled_format<CompiledFormat>::value)>
-std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
-  basic_memory_buffer<Char> buffer;
-  cf.format(std::back_inserter(buffer), args...);
-  return to_string(buffer);
-}
-
-template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(internal::is_compiled_format<CompiledFormat>::value)>
-OutputIt format_to(OutputIt out, const CompiledFormat& cf,
-                   const Args&... args) {
-  return cf.format(out, args...);
-}
 #else
 template <typename... Args, typename S,
          FMT_ENABLE_IF(is_compile_string<S>::value)>
-constexpr auto compile(S format_str) -> internal::compiled_format<S, Args...> {
-  return internal::compiled_format<S, Args...>(to_string_view(format_str));
+constexpr auto compile(S format_str) -> detail::compiled_format<S, Args...> {
+  return detail::compiled_format<S, Args...>(to_string_view(format_str));
 }
 #endif  // __cpp_if_constexpr
-#endif    // FMT_USE_CONSTEXPR

 // Compiles the format string which must be a string literal.
 template <typename... Args, typename Char, size_t N>
 auto compile(const Char (&format_str)[N])
-    -> internal::compiled_format<const Char*, Args...> {
-  return internal::compiled_format<const Char*, Args...>(
+    -> detail::compiled_format<const Char*, Args...> {
+  return detail::compiled_format<const Char*, Args...>(
      basic_string_view<Char>(format_str, N - 1));
 }
+}  // namespace detail
+
+// DEPRECATED! use FMT_COMPILE instead.
+template <typename... Args>
+FMT_DEPRECATED auto compile(const Args&... args)
+    -> decltype(detail::compile(args...)) {
+  return detail::compile(args...);
+}
+
+#if FMT_USE_CONSTEXPR
+#  ifdef __cpp_if_constexpr

 template <typename CompiledFormat, typename... Args,
          typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(std::is_base_of<internal::basic_compiled_format,
-                                        CompiledFormat>::value)>
-std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
+          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
+FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
+                                          const Args&... args) {
  basic_memory_buffer<Char> buffer;
-  using range = buffer_range<Char>;
-  using context = buffer_context<Char>;
-  internal::cf::vformat_to<context>(range(buffer), cf,
-                                    make_format_args<context>(args...));
+  cf.format(detail::buffer_appender<Char>(buffer), args...);
  return to_string(buffer);
 }

 template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(std::is_base_of<internal::basic_compiled_format,
+          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
+OutputIt format_to(OutputIt out, const CompiledFormat& cf,
+                   const Args&... args) {
+  return cf.format(out, args...);
+}
+#  endif  // __cpp_if_constexpr
+#endif    // FMT_USE_CONSTEXPR
+
+template <typename CompiledFormat, typename... Args,
+          typename Char = typename CompiledFormat::char_type,
+          FMT_ENABLE_IF(std::is_base_of<detail::basic_compiled_format,
+                                        CompiledFormat>::value)>
+std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
+  basic_memory_buffer<Char> buffer;
+  using context = buffer_context<Char>;
+  detail::cf::vformat_to<context>(detail::buffer_appender<Char>(buffer), cf,
+                                  make_format_args<context>(args...));
+  return to_string(buffer);
+}
+
+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) {
+#ifdef __cpp_if_constexpr
+  if constexpr (std::is_same<typename S::char_type, char>::value) {
+    constexpr basic_string_view<typename S::char_type> str = S();
+    if (str.size() == 2 && str[0] == '{' && str[1] == '}')
+      return fmt::to_string(detail::first(args...));
+  }
+#endif
+  constexpr auto compiled = detail::compile<Args...>(S());
+  return format(compiled, std::forward<Args>(args)...);
+}
+
+template <typename OutputIt, typename CompiledFormat, typename... Args,
+          FMT_ENABLE_IF(std::is_base_of<detail::basic_compiled_format,
                                        CompiledFormat>::value)>
 OutputIt format_to(OutputIt out, const CompiledFormat& cf,
                   const Args&... args) {
  using char_type = typename CompiledFormat::char_type;
-  using range = internal::output_range<OutputIt, char_type>;
  using context = format_context_t<OutputIt, char_type>;
-  return internal::cf::vformat_to<context>(range(out), cf,
+  return detail::cf::vformat_to<context>(out, cf,
                                         make_format_args<context>(args...));
 }

-template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value)>
-format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
-                                         const CompiledFormat& cf,
-                                         const Args&... args) {
+template <typename OutputIt, typename S, typename... Args,
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+OutputIt format_to(OutputIt out, const S&, const Args&... args) {
+  constexpr auto compiled = detail::compile<Args...>(S());
+  return format_to(out, compiled, args...);
+}
+
+template <typename OutputIt, typename CompiledFormat, typename... Args>
+auto format_to_n(OutputIt out, size_t n, const CompiledFormat& cf,
+                 const Args&... args) ->
+    typename std::enable_if<
+        detail::is_output_iterator<OutputIt,
+                                   typename CompiledFormat::char_type>::value &&
+            std::is_base_of<detail::basic_compiled_format,
+                            CompiledFormat>::value,
+        format_to_n_result<OutputIt>>::type {
  auto it =
-      format_to(internal::truncating_iterator<OutputIt>(out, n), cf, args...);
+      format_to(detail::truncating_iterator<OutputIt>(out, n), cf, args...);
+  return {it.base(), it.count()};
+}
+
+template <typename OutputIt, typename S, typename... Args,
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n, const S&,
+                                         const Args&... args) {
+  constexpr auto compiled = detail::compile<Args...>(S());
+  auto it = format_to(detail::truncating_iterator<OutputIt>(out, n), compiled,
+                      args...);
  return {it.base(), it.count()};
 }

 template <typename CompiledFormat, typename... Args>
-std::size_t formatted_size(const CompiledFormat& cf, const Args&... args) {
-  return format_to(internal::counting_iterator(), cf, args...).count();
+size_t formatted_size(const CompiledFormat& cf, const Args&... args) {
+  return format_to(detail::counting_iterator(), cf, args...).count();
 }

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/core.h
+++ b/include/spdlog/fmt/bundled/core.h
--- a/include/spdlog/fmt/bundled/format-inl.h
+++ b/include/spdlog/fmt/bundled/format-inl.h
--- 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
@@ -14,63 +14,49 @@

 FMT_BEGIN_NAMESPACE

-namespace internal {
-template <typename Char>
-typename buffer_context<Char>::iterator vformat_to(
-    const std::locale& loc, buffer<Char>& buf,
-    basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  using range = buffer_range<Char>;
-  return vformat_to<arg_formatter<range>>(buf, to_string_view(format_str), args,
-                                          internal::locale_ref(loc));
-}
-
+namespace detail {
 template <typename Char>
 std::basic_string<Char> vformat(
    const std::locale& loc, basic_string_view<Char> format_str,
    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buffer;
-  internal::vformat_to(loc, buffer, format_str, args);
+  detail::vformat_to(buffer, format_str, args, detail::locale_ref(loc));
  return fmt::to_string(buffer);
 }
-}  // namespace internal
+}  // namespace detail

 template <typename S, typename Char = char_t<S>>
 inline std::basic_string<Char> vformat(
    const std::locale& loc, const S& format_str,
    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  return internal::vformat(loc, to_string_view(format_str), args);
+  return detail::vformat(loc, to_string_view(format_str), args);
 }

 template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const std::locale& loc,
                                      const S& format_str, Args&&... args) {
-  return internal::vformat(
-      loc, to_string_view(format_str),
-      internal::make_args_checked<Args...>(format_str, args...));
+  return detail::vformat(loc, to_string_view(format_str),
+                         fmt::make_args_checked<Args...>(format_str, args...));
 }

 template <typename S, typename OutputIt, typename... Args,
-          typename Char = enable_if_t<
-              internal::is_output_iterator<OutputIt>::value, char_t<S>>>
+          typename Char = char_t<S>,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
 inline OutputIt vformat_to(
    OutputIt out, const std::locale& loc, const S& format_str,
-    format_args_t<type_identity_t<OutputIt>, Char> args) {
-  using range = internal::output_range<OutputIt, Char>;
-  return vformat_to<arg_formatter<range>>(
-      range(out), to_string_view(format_str), args, internal::locale_ref(loc));
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  vformat_to(buf, to_string_view(format_str), args, detail::locale_ref(loc));
+  return detail::get_iterator(buf);
 }

 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value&&
-                            internal::is_string<S>::value)>
-inline OutputIt format_to(OutputIt out, const std::locale& loc,
-                          const S& format_str, Args&&... args) {
-  internal::check_format_string<Args...>(format_str);
-  using context = format_context_t<OutputIt, char_t<S>>;
-  format_arg_store<context, Args...> as{args...};
-  return vformat_to(out, loc, to_string_view(format_str),
-                    basic_format_args<context>(as));
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to(OutputIt out, const std::locale& loc,
+                      const S& format_str, Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to(out, loc, to_string_view(format_str), vargs);
 }

 FMT_END_NAMESPACE
--- a/include/spdlog/fmt/bundled/os.h
+++ b/include/spdlog/fmt/bundled/os.h
@@ -0,0 +1,480 @@
+// Formatting library for C++ - optional OS-specific functionality
+//
+// Copyright (c) 2012 - present, Victor Zverovich
+// All rights reserved.
+//
+// For the license information refer to format.h.
+
+#ifndef FMT_OS_H_
+#define FMT_OS_H_
+
+#if defined(__MINGW32__) || defined(__CYGWIN__)
+// Workaround MinGW bug https://sourceforge.net/p/mingw/bugs/2024/.
+#  undef __STRICT_ANSI__
+#endif
+
+#include <cerrno>
+#include <clocale>  // for locale_t
+#include <cstddef>
+#include <cstdio>
+#include <cstdlib>  // for strtod_l
+
+#if defined __APPLE__ || defined(__FreeBSD__)
+#  include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+#endif
+
+#include "format.h"
+
+// UWP doesn't provide _pipe.
+#if FMT_HAS_INCLUDE("winapifamily.h")
+#  include <winapifamily.h>
+#endif
+#if (FMT_HAS_INCLUDE(<fcntl.h>) || defined(__APPLE__) || \
+     defined(__linux__)) &&                              \
+    (!defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+#  include <fcntl.h>  // for O_RDONLY
+#  define FMT_USE_FCNTL 1
+#else
+#  define FMT_USE_FCNTL 0
+#endif
+
+#ifndef FMT_POSIX
+#  if defined(_WIN32) && !defined(__MINGW32__)
+// Fix warnings about deprecated symbols.
+#    define FMT_POSIX(call) _##call
+#  else
+#    define FMT_POSIX(call) call
+#  endif
+#endif
+
+// Calls to system functions are wrapped in FMT_SYSTEM for testability.
+#ifdef FMT_SYSTEM
+#  define FMT_POSIX_CALL(call) FMT_SYSTEM(call)
+#else
+#  define FMT_SYSTEM(call) ::call
+#  ifdef _WIN32
+// Fix warnings about deprecated symbols.
+#    define FMT_POSIX_CALL(call) ::_##call
+#  else
+#    define FMT_POSIX_CALL(call) ::call
+#  endif
+#endif
+
+// Retries the expression while it evaluates to error_result and errno
+// equals to EINTR.
+#ifndef _WIN32
+#  define FMT_RETRY_VAL(result, expression, error_result) \
+    do {                                                  \
+      (result) = (expression);                            \
+    } while ((result) == (error_result) && errno == EINTR)
+#else
+#  define FMT_RETRY_VAL(result, expression, error_result) result = (expression)
+#endif
+
+#define FMT_RETRY(result, expression) FMT_RETRY_VAL(result, expression, -1)
+
+FMT_BEGIN_NAMESPACE
+
+/**
+  \rst
+  A reference to a null-terminated string. It can be constructed from a C
+  string or ``std::string``.
+
+  You can use one of the following type aliases for common character types:
+
+  +---------------+-----------------------------+
+  | Type          | Definition                  |
+  +===============+=============================+
+  | cstring_view  | basic_cstring_view<char>    |
+  +---------------+-----------------------------+
+  | wcstring_view | basic_cstring_view<wchar_t> |
+  +---------------+-----------------------------+
+
+  This class is most useful as a parameter type to allow passing
+  different types of strings to a function, for example::
+
+    template <typename... Args>
+    std::string format(cstring_view format_str, const Args & ... args);
+
+    format("{}", 42);
+    format(std::string("{}"), 42);
+  \endrst
+ */
+template <typename Char> class basic_cstring_view {
+ private:
+  const Char* data_;
+
+ public:
+  /** Constructs a string reference object from a C string. */
+  basic_cstring_view(const Char* s) : data_(s) {}
+
+  /**
+    \rst
+    Constructs a string reference from an ``std::string`` object.
+    \endrst
+   */
+  basic_cstring_view(const std::basic_string<Char>& s) : data_(s.c_str()) {}
+
+  /** Returns the pointer to a C string. */
+  const Char* c_str() const { return data_; }
+};
+
+using cstring_view = basic_cstring_view<char>;
+using wcstring_view = basic_cstring_view<wchar_t>;
+
+// An error code.
+class error_code {
+ private:
+  int value_;
+
+ public:
+  explicit error_code(int value = 0) FMT_NOEXCEPT : value_(value) {}
+
+  int get() const FMT_NOEXCEPT { return value_; }
+};
+
+#ifdef _WIN32
+namespace detail {
+// A converter from UTF-16 to UTF-8.
+// It is only provided for Windows since other systems support UTF-8 natively.
+class utf16_to_utf8 {
+ private:
+  memory_buffer buffer_;
+
+ public:
+  utf16_to_utf8() {}
+  FMT_API explicit utf16_to_utf8(wstring_view s);
+  operator string_view() const { return string_view(&buffer_[0], size()); }
+  size_t size() const { return buffer_.size() - 1; }
+  const char* c_str() const { return &buffer_[0]; }
+  std::string str() const { return std::string(&buffer_[0], size()); }
+
+  // Performs conversion returning a system error code instead of
+  // throwing exception on conversion error. This method may still throw
+  // in case of memory allocation error.
+  FMT_API int convert(wstring_view s);
+};
+
+FMT_API void format_windows_error(buffer<char>& out, int error_code,
+                                  string_view message) FMT_NOEXCEPT;
+}  // namespace detail
+
+/** A Windows error. */
+class windows_error : public system_error {
+ private:
+  FMT_API void init(int error_code, string_view format_str, format_args args);
+
+ public:
+  /**
+   \rst
+   Constructs a :class:`fmt::windows_error` object with the description
+   of the form
+
+   .. parsed-literal::
+     *<message>*: *<system-message>*
+
+   where *<message>* is the formatted message and *<system-message>* is the
+   system message corresponding to the error code.
+   *error_code* is a Windows error code as given by ``GetLastError``.
+   If *error_code* is not a valid error code such as -1, the system message
+   will look like "error -1".
+
+   **Example**::
+
+     // This throws a windows_error with the description
+     //   cannot open file 'madeup': The system cannot find the file specified.
+     // or similar (system message may vary).
+     const char *filename = "madeup";
+     LPOFSTRUCT of = LPOFSTRUCT();
+     HFILE file = OpenFile(filename, &of, OF_READ);
+     if (file == HFILE_ERROR) {
+       throw fmt::windows_error(GetLastError(),
+                                "cannot open file '{}'", filename);
+     }
+   \endrst
+  */
+  template <typename... Args>
+  windows_error(int error_code, string_view message, const Args&... args) {
+    init(error_code, message, make_format_args(args...));
+  }
+};
+
+// Reports a Windows error without throwing an exception.
+// Can be used to report errors from destructors.
+FMT_API void report_windows_error(int error_code,
+                                  string_view message) FMT_NOEXCEPT;
+#endif  // _WIN32
+
+// A buffered file.
+class buffered_file {
+ private:
+  FILE* file_;
+
+  friend class file;
+
+  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() FMT_NOEXCEPT : file_(nullptr) {}
+
+  // Destroys the object closing the file it represents if any.
+  FMT_API ~buffered_file() FMT_NOEXCEPT;
+
+ public:
+  buffered_file(buffered_file&& other) FMT_NOEXCEPT : file_(other.file_) {
+    other.file_ = nullptr;
+  }
+
+  buffered_file& operator=(buffered_file&& other) {
+    close();
+    file_ = other.file_;
+    other.file_ = nullptr;
+    return *this;
+  }
+
+  // Opens a file.
+  FMT_API buffered_file(cstring_view filename, cstring_view mode);
+
+  // Closes the file.
+  FMT_API void close();
+
+  // Returns the pointer to a FILE object representing this file.
+  FILE* get() const FMT_NOEXCEPT { return file_; }
+
+  // We place parentheses around fileno to workaround a bug in some versions
+  // of MinGW that define fileno as a macro.
+  FMT_API int(fileno)() const;
+
+  void vprint(string_view format_str, format_args args) {
+    fmt::vprint(file_, format_str, args);
+  }
+
+  template <typename... Args>
+  inline void print(string_view format_str, const Args&... args) {
+    vprint(format_str, make_format_args(args...));
+  }
+};
+
+#if FMT_USE_FCNTL
+// A file. Closed file is represented by a file object with descriptor -1.
+// Methods that are not declared with FMT_NOEXCEPT may throw
+// fmt::system_error in case of failure. Note that some errors such as
+// closing the file multiple times will cause a crash on Windows rather
+// than an exception. You can get standard behavior by overriding the
+// invalid parameter handler with _set_invalid_parameter_handler.
+class file {
+ private:
+  int fd_;  // File descriptor.
+
+  // Constructs a file object with a given descriptor.
+  explicit file(int fd) : fd_(fd) {}
+
+ public:
+  // Possible values for the oflag argument to the constructor.
+  enum {
+    RDONLY = FMT_POSIX(O_RDONLY),  // Open for reading only.
+    WRONLY = FMT_POSIX(O_WRONLY),  // Open for writing only.
+    RDWR = FMT_POSIX(O_RDWR),      // Open for reading and writing.
+    CREATE = FMT_POSIX(O_CREAT),   // Create if the file doesn't exist.
+    APPEND = FMT_POSIX(O_APPEND)   // Open in append mode.
+  };
+
+  // Constructs a file object which doesn't represent any file.
+  file() FMT_NOEXCEPT : fd_(-1) {}
+
+  // Opens a file and constructs a file object representing this file.
+  FMT_API file(cstring_view path, int oflag);
+
+ public:
+  file(const file&) = delete;
+  void operator=(const file&) = delete;
+
+  file(file&& other) FMT_NOEXCEPT : fd_(other.fd_) { other.fd_ = -1; }
+
+  file& operator=(file&& other) FMT_NOEXCEPT {
+    close();
+    fd_ = other.fd_;
+    other.fd_ = -1;
+    return *this;
+  }
+
+  // Destroys the object closing the file it represents if any.
+  FMT_API ~file() FMT_NOEXCEPT;
+
+  // Returns the file descriptor.
+  int descriptor() const FMT_NOEXCEPT { return fd_; }
+
+  // Closes the file.
+  FMT_API void close();
+
+  // Returns the file size. The size has signed type for consistency with
+  // stat::st_size.
+  FMT_API long long size() const;
+
+  // Attempts to read count bytes from the file into the specified buffer.
+  FMT_API size_t read(void* buffer, size_t count);
+
+  // Attempts to write count bytes from the specified buffer to the file.
+  FMT_API size_t write(const void* buffer, size_t count);
+
+  // Duplicates a file descriptor with the dup function and returns
+  // the duplicate as a file object.
+  FMT_API static file dup(int fd);
+
+  // Makes fd be the copy of this file descriptor, closing fd first if
+  // necessary.
+  FMT_API void dup2(int fd);
+
+  // Makes fd be the copy of this file descriptor, closing fd first if
+  // necessary.
+  FMT_API void dup2(int fd, error_code& ec) FMT_NOEXCEPT;
+
+  // Creates a pipe setting up read_end and write_end file objects for reading
+  // and writing respectively.
+  FMT_API static void pipe(file& read_end, file& write_end);
+
+  // Creates a buffered_file object associated with this file and detaches
+  // this file object from the file.
+  FMT_API buffered_file fdopen(const char* mode);
+};
+
+// Returns the memory page size.
+long getpagesize();
+
+namespace detail {
+
+struct buffer_size {
+  size_t value = 0;
+  buffer_size operator=(size_t val) const {
+    auto bs = buffer_size();
+    bs.value = val;
+    return bs;
+  }
+};
+
+struct ostream_params {
+  int oflag = file::WRONLY | file::CREATE;
+  size_t buffer_size = BUFSIZ > 32768 ? BUFSIZ : 32768;
+
+  ostream_params() {}
+
+  template <typename... T>
+  ostream_params(T... params, int oflag) : ostream_params(params...) {
+    this->oflag = oflag;
+  }
+
+  template <typename... T>
+  ostream_params(T... params, detail::buffer_size bs)
+      : ostream_params(params...) {
+    this->buffer_size = bs.value;
+  }
+};
+}  // namespace detail
+
+static constexpr detail::buffer_size buffer_size;
+
+// A fast output stream which is not thread-safe.
+class ostream final : private detail::buffer<char> {
+ private:
+  file file_;
+
+  void flush() {
+    if (size() == 0) return;
+    file_.write(data(), size());
+    clear();
+  }
+
+  FMT_API void grow(size_t) override final;
+
+  ostream(cstring_view path, const detail::ostream_params& params)
+      : file_(path, params.oflag) {
+    set(new char[params.buffer_size], params.buffer_size);
+  }
+
+ public:
+  ostream(ostream&& other)
+      : detail::buffer<char>(other.data(), other.size(), other.capacity()),
+        file_(std::move(other.file_)) {
+    other.set(nullptr, 0);
+  }
+  ~ostream() {
+    flush();
+    delete[] data();
+  }
+
+  template <typename... T>
+  friend ostream output_file(cstring_view path, T... params);
+
+  void close() {
+    flush();
+    file_.close();
+  }
+
+  template <typename S, typename... Args>
+  void print(const S& format_str, const Args&... args) {
+    format_to(detail::buffer_appender<char>(*this), format_str, args...);
+  }
+};
+
+/**
+  Opens a file for writing. Supported parameters passed in `params`:
+  * ``<integer>``: Output flags (``file::WRONLY | file::CREATE`` by default)
+  * ``buffer_size=<integer>``: Output buffer size
+ */
+template <typename... T>
+inline ostream output_file(cstring_view path, T... params) {
+  return {path, detail::ostream_params(params...)};
+}
+#endif  // FMT_USE_FCNTL
+
+#ifdef FMT_LOCALE
+// A "C" numeric locale.
+class locale {
+ private:
+#  ifdef _WIN32
+  using locale_t = _locale_t;
+
+  static void freelocale(locale_t loc) { _free_locale(loc); }
+
+  static double strtod_l(const char* nptr, char** endptr, _locale_t loc) {
+    return _strtod_l(nptr, endptr, loc);
+  }
+#  endif
+
+  locale_t locale_;
+
+ public:
+  using type = locale_t;
+  locale(const locale&) = delete;
+  void operator=(const locale&) = delete;
+
+  locale() {
+#  ifndef _WIN32
+    locale_ = FMT_SYSTEM(newlocale(LC_NUMERIC_MASK, "C", nullptr));
+#  else
+    locale_ = _create_locale(LC_NUMERIC, "C");
+#  endif
+    if (!locale_) FMT_THROW(system_error(errno, "cannot create locale"));
+  }
+  ~locale() { freelocale(locale_); }
+
+  type get() const { return locale_; }
+
+  // Converts string to floating-point number and advances str past the end
+  // of the parsed input.
+  double strtod(const char*& str) const {
+    char* end = nullptr;
+    double result = strtod_l(str, &end, locale_);
+    str = end;
+    return result;
+  }
+};
+using Locale FMT_DEPRECATED_ALIAS = locale;
+#endif  // FMT_LOCALE
+FMT_END_NAMESPACE
+
+#endif  // FMT_OS_H_
--- a/include/spdlog/fmt/bundled/ostream.h
+++ b/include/spdlog/fmt/bundled/ostream.h
@@ -14,10 +14,10 @@

 FMT_BEGIN_NAMESPACE

-template <typename CHar> class basic_printf_parse_context;
+template <typename Char> class basic_printf_parse_context;
 template <typename OutputIt, typename Char> class basic_printf_context;

-namespace internal {
+namespace detail {

 template <class Char> class formatbuf : public std::basic_streambuf<Char> {
 private:
@@ -49,17 +49,27 @@ template <class Char> class formatbuf : public std::basic_streambuf<Char> {
  }
 };

+struct converter {
+  template <typename T, FMT_ENABLE_IF(is_integral<T>::value)> converter(T);
+};
+
 template <typename Char> struct test_stream : std::basic_ostream<Char> {
 private:
-  // Hide all operator<< from std::basic_ostream<Char>.
-  void_t<> operator<<(null<>);
-  void_t<> operator<<(const Char*);
-
-  template <typename T, FMT_ENABLE_IF(std::is_convertible<T, int>::value &&
-                                      !std::is_enum<T>::value)>
-  void_t<> operator<<(T);
+  void_t<> operator<<(converter);
 };

+// Hide insertion operators for built-in types.
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, Char);
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, signed char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, unsigned char);
+
 // Checks if T has a user-defined operator<< (e.g. not a member of
 // std::ostream).
 template <typename T, typename Char> class is_streamable {
@@ -80,7 +90,7 @@ template <typename T, typename Char> class is_streamable {

 // Write the content of buf to os.
 template <typename Char>
-void write(std::basic_ostream<Char>& os, buffer<Char>& buf) {
+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;
  unsigned_streamsize size = buf.size();
@@ -101,16 +111,17 @@ void format_value(buffer<Char>& buf, const T& value,
 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
  if (loc) output.imbue(loc.get<std::locale>());
 #endif
-  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
  output << value;
-  buf.resize(buf.size());
+  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
+  buf.try_resize(buf.size());
 }

 // Formats an object of type T that has an overloaded ostream operator<<.
 template <typename T, typename Char>
 struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
    : private formatter<basic_string_view<Char>, Char> {
-  auto parse(basic_format_parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
    return formatter<basic_string_view<Char>, Char>::parse(ctx);
  }
  template <typename ParseCtx,
@@ -136,14 +147,14 @@ struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
    return std::copy(buffer.begin(), buffer.end(), ctx.out());
  }
 };
-}  // namespace internal
+}  // namespace detail

 template <typename Char>
 void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
            basic_format_args<buffer_context<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buffer;
-  internal::vformat_to(buffer, format_str, args);
-  internal::write(os, buffer);
+  detail::vformat_to(buffer, format_str, args);
+  detail::write_buffer(os, buffer);
 }

 /**
@@ -156,10 +167,10 @@ void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
  \endrst
 */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 void print(std::basic_ostream<Char>& os, const S& format_str, Args&&... args) {
  vprint(os, to_string_view(format_str),
-         internal::make_args_checked<Args...>(format_str, args...));
+         fmt::make_args_checked<Args...>(format_str, args...));
 }
 FMT_END_NAMESPACE

--- a/include/spdlog/fmt/bundled/printf.h
+++ b/include/spdlog/fmt/bundled/printf.h
@@ -14,7 +14,7 @@
 #include "ostream.h"

 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {

 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
@@ -90,11 +90,11 @@ template <typename T, typename Context> class arg_converter {
    if (const_check(sizeof(target_type) <= sizeof(int))) {
      // Extra casts are used to silence warnings.
      if (is_signed) {
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
            static_cast<int>(static_cast<target_type>(value)));
      } else {
        using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
            static_cast<unsigned>(static_cast<unsigned_type>(value)));
      }
    } else {
@@ -102,9 +102,9 @@ template <typename T, typename Context> class arg_converter {
        // 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.
-        arg_ = internal::make_arg<Context>(static_cast<long long>(value));
+        arg_ = detail::make_arg<Context>(static_cast<long long>(value));
      } else {
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
            static_cast<typename make_unsigned_or_bool<U>::type>(value));
      }
    }
@@ -133,7 +133,7 @@ template <typename Context> class char_converter {

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

@@ -141,6 +141,13 @@ template <typename Context> class char_converter {
  void operator()(T) {}  // No conversion needed for non-integral types.
 };

+// An argument visitor that return a pointer to a C string if argument is a
+// string or null otherwise.
+template <typename Char> struct get_cstring {
+  template <typename T> const Char* operator()(T) { return nullptr; }
+  const Char* operator()(const Char* s) { return s; }
+};
+
 // Checks if an argument is a valid printf width specifier and sets
 // left alignment if it is negative.
 template <typename Char> class printf_width_handler {
@@ -155,7 +162,7 @@ template <typename Char> class printf_width_handler {
  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  unsigned operator()(T value) {
    auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
-    if (internal::is_negative(value)) {
+    if (detail::is_negative(value)) {
      specs_.align = align::left;
      width = 0 - width;
    }
@@ -172,22 +179,20 @@ template <typename Char> class printf_width_handler {
 };

 template <typename Char, typename Context>
-void printf(buffer<Char>& buf, basic_string_view<Char> format,
+void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
             basic_format_args<Context> args) {
-  Context(std::back_inserter(buf), format, args).format();
+  Context(buffer_appender<Char>(buf), format, args).format();
 }
+}  // namespace detail

-template <typename OutputIt, typename Char, typename Context>
-internal::truncating_iterator<OutputIt> printf(
-    internal::truncating_iterator<OutputIt> it, basic_string_view<Char> format,
+// For printing into memory_buffer.
+template <typename Char, typename Context>
+FMT_DEPRECATED void printf(detail::buffer<Char>& buf,
+                           basic_string_view<Char> format,
                           basic_format_args<Context> args) {
-  return Context(it, format, args).format();
+  return detail::vprintf(buf, format, args);
 }
-}  // namespace internal
-
-using internal::printf;  // For printing into memory_buffer.
-
-template <typename Range> class printf_arg_formatter;
+using detail::vprintf;

 template <typename Char>
 class basic_printf_parse_context : public basic_format_parse_context<Char> {
@@ -200,15 +205,15 @@ template <typename OutputIt, typename Char> class basic_printf_context;
  The ``printf`` argument formatter.
  \endrst
 */
-template <typename Range>
-class printf_arg_formatter : public internal::arg_formatter_base<Range> {
+template <typename OutputIt, typename Char>
+class printf_arg_formatter : public detail::arg_formatter_base<OutputIt, Char> {
 public:
-  using iterator = typename Range::iterator;
+  using iterator = OutputIt;

 private:
-  using char_type = typename Range::value_type;
-  using base = internal::arg_formatter_base<Range>;
-  using context_type = basic_printf_context<iterator, char_type>;
+  using char_type = Char;
+  using base = detail::arg_formatter_base<OutputIt, Char>;
+  using context_type = basic_printf_context<OutputIt, Char>;

  context_type& context_;

@@ -233,9 +238,9 @@ class printf_arg_formatter : public internal::arg_formatter_base<Range> {
    \endrst
   */
  printf_arg_formatter(iterator iter, format_specs& specs, context_type& ctx)
-      : base(Range(iter), &specs, internal::locale_ref()), context_(ctx) {}
+      : base(iter, &specs, detail::locale_ref()), context_(ctx) {}

-  template <typename T, FMT_ENABLE_IF(fmt::internal::is_integral<T>::value)>
+  template <typename T, FMT_ENABLE_IF(fmt::detail::is_integral<T>::value)>
  iterator operator()(T value) {
    // MSVC2013 fails to compile separate overloads for bool and char_type so
    // use std::is_same instead.
@@ -250,6 +255,10 @@ class printf_arg_formatter : public internal::arg_formatter_base<Range> {
        return (*this)(static_cast<int>(value));
      fmt_specs.sign = sign::none;
      fmt_specs.alt = false;
+      fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
+      // align::numeric needs to be overwritten here since the '0' flag is
+      // ignored for non-numeric types
+      if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
        fmt_specs.align = align::right;
      return base::operator()(value);
    } else {
@@ -316,12 +325,14 @@ template <typename T> struct printf_formatter {

  template <typename FormatContext>
  auto format(const T& value, FormatContext& ctx) -> decltype(ctx.out()) {
-    internal::format_value(internal::get_container(ctx.out()), value);
+    detail::format_value(detail::get_container(ctx.out()), value);
    return ctx.out();
  }
 };

-/** This template formats data and writes the output to a writer. */
+/**
+ This template formats data and writes the output through an output iterator.
+ */
 template <typename OutputIt, typename Char> class basic_printf_context {
 public:
  /** The character type for the output. */
@@ -351,9 +362,8 @@ template <typename OutputIt, typename Char> class basic_printf_context {
 public:
  /**
   \rst
-   Constructs a ``printf_context`` object. References to the arguments and
-   the writer are stored in the context object so make sure they have
-   appropriate lifetimes.
+   Constructs a ``printf_context`` object. References to the arguments are
+   stored in the context object so make sure they have appropriate lifetimes.
   \endrst
   */
  basic_printf_context(OutputIt out, basic_string_view<char_type> format_str,
@@ -363,7 +373,7 @@ template <typename OutputIt, typename Char> class basic_printf_context {
  OutputIt out() { return out_; }
  void advance_to(OutputIt it) { out_ = it; }

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

  format_arg arg(int id) const { return args_.get(id); }

@@ -374,7 +384,7 @@ template <typename OutputIt, typename Char> class basic_printf_context {
  }

  /** Formats stored arguments and writes the output to the range. */
-  template <typename ArgFormatter = printf_arg_formatter<buffer_range<Char>>>
+  template <typename ArgFormatter = printf_arg_formatter<OutputIt, Char>>
  OutputIt format();
 };

@@ -394,7 +404,9 @@ void basic_printf_context<OutputIt, Char>::parse_flags(format_specs& specs,
      specs.fill[0] = '0';
      break;
    case ' ':
+      if (specs.sign != sign::plus) {
        specs.sign = sign::space;
+      }
      break;
    case '#':
      specs.alt = true;
@@ -412,7 +424,7 @@ basic_printf_context<OutputIt, Char>::get_arg(int arg_index) {
    arg_index = parse_ctx_.next_arg_id();
  else
    parse_ctx_.check_arg_id(--arg_index);
-  return internal::get_arg(*this, arg_index);
+  return detail::get_arg(*this, arg_index);
 }

 template <typename OutputIt, typename Char>
@@ -424,7 +436,7 @@ int basic_printf_context<OutputIt, Char>::parse_header(const Char*& it,
  if (c >= '0' && c <= '9') {
    // Parse an argument index (if followed by '$') or a width possibly
    // preceded with '0' flag(s).
-    internal::error_handler eh;
+    detail::error_handler eh;
    int value = parse_nonnegative_int(it, end, eh);
    if (it != end && *it == '$') {  // value is an argument index
      ++it;
@@ -443,12 +455,12 @@ int basic_printf_context<OutputIt, Char>::parse_header(const Char*& it,
  // Parse width.
  if (it != end) {
    if (*it >= '0' && *it <= '9') {
-      internal::error_handler eh;
+      detail::error_handler eh;
      specs.width = parse_nonnegative_int(it, end, eh);
    } else if (*it == '*') {
      ++it;
      specs.width = static_cast<int>(visit_format_arg(
-          internal::printf_width_handler<char_type>(specs), get_arg()));
+          detail::printf_width_handler<char_type>(specs), get_arg()));
    }
  }
  return arg_index;
@@ -476,38 +488,52 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {

    // Parse argument index, flags and width.
    int arg_index = parse_header(it, end, specs);
-    if (arg_index == 0) on_error("argument index out of range");
+    if (arg_index == 0) on_error("argument not found");

    // Parse precision.
    if (it != end && *it == '.') {
      ++it;
      c = it != end ? *it : 0;
      if ('0' <= c && c <= '9') {
-        internal::error_handler eh;
+        detail::error_handler eh;
        specs.precision = parse_nonnegative_int(it, end, eh);
      } else if (c == '*') {
        ++it;
        specs.precision = static_cast<int>(
-            visit_format_arg(internal::printf_precision_handler(), get_arg()));
+            visit_format_arg(detail::printf_precision_handler(), get_arg()));
      } else {
        specs.precision = 0;
      }
    }

    format_arg arg = get_arg(arg_index);
-    if (specs.alt && visit_format_arg(internal::is_zero_int(), arg))
+    // 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())
+      specs.fill[0] =
+          ' ';  // Ignore '0' flag for non-numeric types or if '-' present.
+    if (specs.precision >= 0 && arg.type() == detail::type::cstring_type) {
+      auto str = visit_format_arg(detail::get_cstring<Char>(), arg);
+      auto str_end = str + specs.precision;
+      auto nul = std::find(str, str_end, Char());
+      arg = detail::make_arg<basic_printf_context>(basic_string_view<Char>(
+          str,
+          detail::to_unsigned(nul != str_end ? nul - str : specs.precision)));
+    }
+    if (specs.alt && visit_format_arg(detail::is_zero_int(), arg))
      specs.alt = false;
    if (specs.fill[0] == '0') {
-      if (arg.is_arithmetic())
+      if (arg.is_arithmetic() && specs.align != align::left)
        specs.align = align::numeric;
      else
-        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types.
+        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
+                              // flag is also present.
    }

    // Parse length and convert the argument to the required type.
    c = it != end ? *it++ : 0;
    char_type t = it != end ? *it : 0;
-    using internal::convert_arg;
+    using detail::convert_arg;
    switch (c) {
    case 'h':
      if (t == 'h') {
@@ -531,7 +557,7 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
      convert_arg<intmax_t>(arg, t);
      break;
    case 'z':
-      convert_arg<std::size_t>(arg, t);
+      convert_arg<size_t>(arg, t);
      break;
    case 't':
      convert_arg<std::ptrdiff_t>(arg, t);
@@ -556,7 +582,7 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
        specs.type = 'd';
        break;
      case 'c':
-        visit_format_arg(internal::char_converter<basic_printf_context>(arg),
+        visit_format_arg(detail::char_converter<basic_printf_context>(arg),
                         arg);
        break;
      }
@@ -565,15 +591,14 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
    start = it;

    // Format argument.
-    visit_format_arg(ArgFormatter(out, specs, *this), arg);
+    out = visit_format_arg(ArgFormatter(out, specs, *this), arg);
  }
  return std::copy(start, it, out);
 }

 template <typename Char>
 using basic_printf_context_t =
-    basic_printf_context<std::back_insert_iterator<internal::buffer<Char>>,
-                         Char>;
+    basic_printf_context<detail::buffer_appender<Char>, Char>;

 using printf_context = basic_printf_context_t<char>;
 using wprintf_context = basic_printf_context_t<wchar_t>;
@@ -610,7 +635,7 @@ inline std::basic_string<Char> vsprintf(
    const S& format,
    basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
+  vprintf(buffer, to_string_view(format), args);
  return to_string(buffer);
 }

@@ -624,7 +649,7 @@ inline std::basic_string<Char> vsprintf(
  \endrst
 */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 inline std::basic_string<Char> sprintf(const S& format, const Args&... args) {
  using context = basic_printf_context_t<Char>;
  return vsprintf(to_string_view(format), make_format_args<context>(args...));
@@ -635,8 +660,8 @@ inline int vfprintf(
    std::FILE* f, const S& format,
    basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
-  std::size_t size = buffer.size();
+  vprintf(buffer, to_string_view(format), args);
+  size_t size = buffer.size();
  return std::fwrite(buffer.data(), sizeof(Char), size, f) < size
             ? -1
             : static_cast<int>(size);
@@ -652,7 +677,7 @@ inline int vfprintf(
  \endrst
 */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 inline int fprintf(std::FILE* f, const S& format, const Args&... args) {
  using context = basic_printf_context_t<Char>;
  return vfprintf(f, to_string_view(format),
@@ -676,7 +701,7 @@ inline int vprintf(
  \endrst
 */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 inline int printf(const S& format_str, const Args&... args) {
  using context = basic_printf_context_t<char_t<S>>;
  return vprintf(to_string_view(format_str),
@@ -688,8 +713,8 @@ inline int vfprintf(
    std::basic_ostream<Char>& os, const S& format,
    basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
  basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
-  internal::write(os, buffer);
+  vprintf(buffer, to_string_view(format), args);
+  detail::write_buffer(os, buffer);
  return static_cast<int>(buffer.size());
 }

@@ -698,7 +723,7 @@ template <typename ArgFormatter, typename Char,
          typename Context =
              basic_printf_context<typename ArgFormatter::iterator, Char>>
 typename ArgFormatter::iterator vprintf(
-    internal::buffer<Char>& out, basic_string_view<Char> format_str,
+    detail::buffer<Char>& out, basic_string_view<Char> format_str,
    basic_format_args<type_identity_t<Context>> args) {
  typename ArgFormatter::iterator iter(out);
  Context(iter, format_str, args).template format<ArgFormatter>();
--- a/include/spdlog/fmt/bundled/ranges.h
+++ b/include/spdlog/fmt/bundled/ranges.h
@@ -33,7 +33,7 @@ template <typename Char> struct formatting_base {

 template <typename Char, typename Enable = void>
 struct formatting_range : formatting_base<Char> {
-  static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
+  static FMT_CONSTEXPR_DECL const size_t range_length_limit =
      FMT_RANGE_OUTPUT_LENGTH_LIMIT;  // output only up to N items from the
                                      // range.
  Char prefix;
@@ -54,7 +54,7 @@ struct formatting_tuple : formatting_base<Char> {
  static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
 };

-namespace internal {
+namespace detail {

 template <typename RangeT, typename OutputIterator>
 OutputIterator copy(const RangeT& range, OutputIterator out) {
@@ -118,26 +118,24 @@ template <typename T> class is_tuple_like_ {
 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
 template <typename T, T... N>
 using integer_sequence = std::integer_sequence<T, N...>;
-template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
-template <std::size_t N>
-using make_index_sequence = std::make_index_sequence<N>;
+template <size_t... N> using index_sequence = std::index_sequence<N...>;
+template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 #else
 template <typename T, T... N> struct integer_sequence {
  using value_type = T;

-  static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
+  static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
 };

-template <std::size_t... N>
-using index_sequence = integer_sequence<std::size_t, N...>;
+template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;

-template <typename T, std::size_t N, T... Ns>
+template <typename T, size_t N, T... Ns>
 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 template <typename T, T... Ns>
 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};

-template <std::size_t N>
-using make_index_sequence = make_integer_sequence<std::size_t, N>;
+template <size_t N>
+using make_index_sequence = make_integer_sequence<size_t, N>;
 #endif

 template <class Tuple, class F, size_t... Is>
@@ -159,6 +157,9 @@ template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
  for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
 }

+template <typename Range>
+using value_type = remove_cvref_t<decltype(*std::declval<Range>().begin())>;
+
 template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
                                      typename std::decay<Arg>::type>::value)>
 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
@@ -184,12 +185,11 @@ FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
  return add_space ? L" '{}'" : L"'{}'";
 }
-
-}  // namespace internal
+}  // namespace detail

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

 template <typename TupleT, typename Char>
@@ -202,17 +202,17 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
        if (formatting.add_prepostfix_space) {
          *out++ = ' ';
        }
-        out = internal::copy(formatting.delimiter, out);
+        out = detail::copy(formatting.delimiter, out);
      }
      out = format_to(out,
-                      internal::format_str_quoted(
+                      detail::format_str_quoted(
                          (formatting.add_delimiter_spaces && i > 0), v),
                      v);
      ++i;
    }

    formatting_tuple<Char>& formatting;
-    std::size_t& i;
+    size_t& i;
    typename std::add_lvalue_reference<decltype(
        std::declval<FormatContext>().out())>::type out;
  };
@@ -228,14 +228,14 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
  template <typename FormatContext = format_context>
  auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
    auto out = ctx.out();
-    std::size_t i = 0;
-    internal::copy(formatting.prefix, out);
+    size_t i = 0;
+    detail::copy(formatting.prefix, out);

-    internal::for_each(values, format_each<FormatContext>{formatting, i, out});
+    detail::for_each(values, format_each<FormatContext>{formatting, i, out});
    if (formatting.add_prepostfix_space) {
      *out++ = ' ';
    }
-    internal::copy(formatting.postfix, out);
+    detail::copy(formatting.postfix, out);

    return ctx.out();
  }
@@ -243,15 +243,23 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {

 template <typename T, typename Char> struct is_range {
  static FMT_CONSTEXPR_DECL const bool value =
-      internal::is_range_<T>::value &&
-      !internal::is_like_std_string<T>::value &&
+      detail::is_range_<T>::value && !detail::is_like_std_string<T>::value &&
      !std::is_convertible<T, std::basic_string<Char>>::value &&
-      !std::is_constructible<internal::std_string_view<Char>, T>::value;
+      !std::is_constructible<detail::std_string_view<Char>, T>::value;
 };

-template <typename RangeT, typename Char>
-struct formatter<RangeT, Char,
-                 enable_if_t<fmt::is_range<RangeT, Char>::value>> {
+template <typename T, typename Char>
+struct formatter<
+    T, Char,
+    enable_if_t<fmt::is_range<T, Char>::value
+// Workaround a bug in MSVC 2017 and earlier.
+#if !FMT_MSC_VER || FMT_MSC_VER >= 1927
+                &&
+                (has_formatter<detail::value_type<T>, format_context>::value ||
+                 detail::has_fallback_formatter<detail::value_type<T>,
+                                                format_context>::value)
+#endif
+                >> {
  formatting_range<Char> formatting;

  template <typename ParseContext>
@@ -260,17 +268,18 @@ struct formatter<RangeT, Char,
  }

  template <typename FormatContext>
-  typename FormatContext::iterator format(const RangeT& values,
-                                          FormatContext& ctx) {
-    auto out = internal::copy(formatting.prefix, ctx.out());
-    std::size_t i = 0;
-    for (auto it = values.begin(), end = values.end(); it != end; ++it) {
+  typename FormatContext::iterator format(const T& values, FormatContext& ctx) {
+    auto out = detail::copy(formatting.prefix, ctx.out());
+    size_t i = 0;
+    auto it = values.begin();
+    auto end = values.end();
+    for (; it != end; ++it) {
      if (i > 0) {
        if (formatting.add_prepostfix_space) *out++ = ' ';
-        out = internal::copy(formatting.delimiter, out);
+        out = detail::copy(formatting.delimiter, out);
      }
      out = format_to(out,
-                      internal::format_str_quoted(
+                      detail::format_str_quoted(
                          (formatting.add_delimiter_spaces && i > 0), *it),
                      *it);
      if (++i > formatting.range_length_limit) {
@@ -279,11 +288,11 @@ struct formatter<RangeT, Char,
      }
    }
    if (formatting.add_prepostfix_space) *out++ = ' ';
-    return internal::copy(formatting.postfix, out);
+    return detail::copy(formatting.postfix, out);
  }
 };

-template <typename Char, typename... T> struct tuple_arg_join : internal::view {
+template <typename Char, typename... T> struct tuple_arg_join : detail::view {
  const std::tuple<T...>& tuple;
  basic_string_view<Char> sep;

@@ -301,14 +310,14 @@ struct formatter<tuple_arg_join<Char, T...>, Char> {
  template <typename FormatContext>
  typename FormatContext::iterator format(
      const tuple_arg_join<Char, T...>& value, FormatContext& ctx) {
-    return format(value, ctx, internal::make_index_sequence<sizeof...(T)>{});
+    return format(value, ctx, detail::make_index_sequence<sizeof...(T)>{});
  }

 private:
  template <typename FormatContext, size_t... N>
  typename FormatContext::iterator format(
      const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
-      internal::index_sequence<N...>) {
+      detail::index_sequence<N...>) {
    return format_args(value, ctx, std::get<N>(value.tuple)...);
  }

@@ -371,14 +380,14 @@ FMT_CONSTEXPR tuple_arg_join<wchar_t, T...> join(const std::tuple<T...>& tuple,
  \endrst
 */
 template <typename T>
-arg_join<internal::iterator_t<const std::initializer_list<T>>, char> join(
-    std::initializer_list<T> list, string_view sep) {
+arg_join<const T*, const T*, char> join(std::initializer_list<T> list,
+                                        string_view sep) {
  return join(std::begin(list), std::end(list), sep);
 }

 template <typename T>
-arg_join<internal::iterator_t<const std::initializer_list<T>>, wchar_t> join(
-    std::initializer_list<T> list, wstring_view sep) {
+arg_join<const T*, const T*, wchar_t> join(std::initializer_list<T> list,
+                                           wstring_view sep) {
  return join(std::begin(list), std::end(list), sep);
 }

--- a/include/spdlog/fmt/chrono.h
+++ b/include/spdlog/fmt/chrono.h
@@ -0,0 +1,20 @@
+//
+// Copyright(c) 2016 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+#pragma once
+//
+// include bundled or external copy of fmtlib's chrono support
+//
+
+#if !defined(SPDLOG_FMT_EXTERNAL)
+#ifdef SPDLOG_HEADER_ONLY
+#ifndef FMT_HEADER_ONLY
+#define FMT_HEADER_ONLY
+#endif
+#endif
+#include <spdlog/fmt/bundled/chrono.h>
+#else
+#include <fmt/chrono.h>
+#endif
--- a/include/spdlog/fmt/fmt.h
+++ b/include/spdlog/fmt/fmt.h
@@ -17,6 +17,8 @@
 #ifndef FMT_USE_WINDOWS_H
 #define FMT_USE_WINDOWS_H 0
 #endif
+// enable the 'n' flag in for backward compatibility with fmt 6.x
+#define FMT_DEPRECATED_N_SPECIFIER
 #include <spdlog/fmt/bundled/core.h>
 #include <spdlog/fmt/bundled/format.h>
 #else // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
--- a/include/spdlog/logger-inl.h
+++ b/include/spdlog/logger-inl.h
@@ -247,7 +247,11 @@ SPDLOG_INLINE void logger::err_handler_(const std::string &msg)
        auto tm_time = details::os::localtime(system_clock::to_time_t(now));
        char date_buf[64];
        std::strftime(date_buf, sizeof(date_buf), "%Y-%m-%d %H:%M:%S", &tm_time);
-        fprintf(stderr, "[*** LOG ERROR #%04zu ***] [%s] [%s] {%s}\n", err_counter, date_buf, name().c_str(), msg.c_str());
+#if defined(USING_R) && defined(R_R_H) // if in R environment
+        REprintf("[*** LOG ERROR #%04zu ***] [%s] [%s] {%s}\n", err_counter, date_buf, name().c_str(), msg.c_str());
+#else
+        std::fprintf(stderr, "[*** LOG ERROR #%04zu ***] [%s] [%s] {%s}\n", err_counter, date_buf, name().c_str(), msg.c_str());
+#endif
    }
 }
 } // namespace spdlog
--- a/include/spdlog/logger.h
+++ b/include/spdlog/logger.h
@@ -75,58 +75,58 @@ public:

    // FormatString is a type derived from fmt::compile_string
    template<typename FormatString, typename std::enable_if<fmt::is_compile_string<FormatString>::value, int>::type = 0, typename... Args>
-    void log(source_loc loc, level::level_enum lvl, const FormatString &fmt, const Args &... args)
+    void log(source_loc loc, level::level_enum lvl, const FormatString &fmt, Args&&...args)
    {
-        log_(loc, lvl, fmt, args...);
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
    }

    // FormatString is NOT a type derived from fmt::compile_string but is a string_view_t or can be implicitly converted to one
    template<typename... Args>
-    void log(source_loc loc, level::level_enum lvl, string_view_t fmt, const Args &... args)
+    void log(source_loc loc, level::level_enum lvl, string_view_t fmt, Args&&...args)
    {
-        log_(loc, lvl, fmt, args...);
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void log(level::level_enum lvl, const FormatString &fmt, const Args &... args)
+    void log(level::level_enum lvl, const FormatString &fmt, Args&&...args)
    {
-        log(source_loc{}, lvl, fmt, args...);
+        log(source_loc{}, lvl, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void trace(const FormatString &fmt, const Args &... args)
+    void trace(const FormatString &fmt, Args&&...args)
    {
-        log(level::trace, fmt, args...);
+        log(level::trace, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void debug(const FormatString &fmt, const Args &... args)
+    void debug(const FormatString &fmt, Args&&...args)
    {
-        log(level::debug, fmt, args...);
+        log(level::debug, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void info(const FormatString &fmt, const Args &... args)
+    void info(const FormatString &fmt, Args&&...args)
    {
-        log(level::info, fmt, args...);
+        log(level::info, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void warn(const FormatString &fmt, const Args &... args)
+    void warn(const FormatString &fmt, Args&&...args)
    {
-        log(level::warn, fmt, args...);
+        log(level::warn, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void error(const FormatString &fmt, const Args &... args)
+    void error(const FormatString &fmt, Args&&...args)
    {
-        log(level::err, fmt, args...);
+        log(level::err, fmt, std::forward<Args>(args)...);
    }

    template<typename FormatString, typename... Args>
-    void critical(const FormatString &fmt, const Args &... args)
+    void critical(const FormatString &fmt, Args&&...args)
    {
-        log(level::critical, fmt, args...);
+        log(level::critical, fmt, std::forward<Args>(args)...);
    }

    template<typename T>
@@ -225,7 +225,7 @@ public:
 #else

    template<typename... Args>
-    void log(source_loc loc, level::level_enum lvl, wstring_view_t fmt, const Args &... args)
+    void log(source_loc loc, level::level_enum lvl, wstring_view_t fmt, Args&&...args)
    {
        bool log_enabled = should_log(lvl);
        bool traceback_enabled = tracer_.enabled();
@@ -237,7 +237,7 @@ public:
        {
            // format to wmemory_buffer and convert to utf8
            fmt::wmemory_buffer wbuf;
-            fmt::format_to(wbuf, fmt, args...);
+            fmt::format_to(wbuf, fmt, std::forward<Args>(args)...);

            memory_buf_t buf;
            details::os::wstr_to_utf8buf(wstring_view_t(wbuf.data(), wbuf.size()), buf);
@@ -326,7 +326,7 @@ protected:

    // common implementation for after templated public api has been resolved
    template<typename FormatString, typename... Args>
-    void log_(source_loc loc, level::level_enum lvl, const FormatString &fmt, const Args &... args)
+    void log_(source_loc loc, level::level_enum lvl, const FormatString &fmt, Args&&...args)
    {
        bool log_enabled = should_log(lvl);
        bool traceback_enabled = tracer_.enabled();
@@ -337,7 +337,7 @@ protected:
        SPDLOG_TRY
        {
            memory_buf_t buf;
-            fmt::format_to(buf, fmt, args...);
+            fmt::format_to(buf, fmt, std::forward<Args>(args)...);
            details::log_msg log_msg(loc, name_, lvl, string_view_t(buf.data(), buf.size()));
            log_it_(log_msg, log_enabled, traceback_enabled);
        }
--- a/include/spdlog/pattern_formatter-inl.h
+++ b/include/spdlog/pattern_formatter-inl.h
@@ -45,12 +45,12 @@ public:
            return;
        }

-        if (padinfo_.side_ == padding_info::left)
+        if (padinfo_.side_ == padding_info::pad_side::left)
        {
            pad_it(remaining_pad_);
            remaining_pad_ = 0;
        }
-        else if (padinfo_.side_ == padding_info::center)
+        else if (padinfo_.side_ == padding_info::pad_side::center)
        {
            auto half_pad = remaining_pad_ / 2;
            auto reminder = remaining_pad_ & 1;
@@ -1246,9 +1246,24 @@ SPDLOG_INLINE void pattern_formatter::handle_flag_(char flag, details::padding_i

    default: // Unknown flag appears as is
        auto unknown_flag = details::make_unique<details::aggregate_formatter>();
+
+        if (!padding.truncate_)
+        {
            unknown_flag->add_ch('%');
            unknown_flag->add_ch(flag);
            formatters_.push_back((std::move(unknown_flag)));
+        }
+        // fix issue #1617 (prev char was '!' and should have been treated as funcname flag instead of truncating flag)
+        // spdlog::set_pattern("[%10!] %v") => "[      main] some message"
+        // spdlog::set_pattern("[%3!!] %v") => "[mai] some message"
+        else
+        {
+            padding.truncate_ = false;
+            formatters_.push_back(details::make_unique<details::source_funcname_formatter<Padder>>(padding));
+            unknown_flag->add_ch(flag);
+            formatters_.push_back((std::move(unknown_flag)));
+        }
+
        break;
    }
 }
@@ -1270,15 +1285,15 @@ SPDLOG_INLINE details::padding_info pattern_formatter::handle_padspec_(std::stri
    switch (*it)
    {
    case '-':
-        side = padding_info::right;
+        side = padding_info::pad_side::right;
        ++it;
        break;
    case '=':
-        side = padding_info::center;
+        side = padding_info::pad_side::center;
        ++it;
        break;
    default:
-        side = details::padding_info::left;
+        side = details::padding_info::pad_side::left;
        break;
    }

--- a/include/spdlog/pattern_formatter.h
+++ b/include/spdlog/pattern_formatter.h
@@ -22,7 +22,7 @@ namespace details {
 // padding information.
 struct padding_info
 {
-    enum pad_side
+    enum class pad_side
    {
        left,
        right,
@@ -42,7 +42,7 @@ struct padding_info
        return enabled_;
    }
    size_t width_ = 0;
-    pad_side side_ = left;
+    pad_side side_ = pad_side::left;
    bool truncate_ = false;
    bool enabled_ = false;
 };
@@ -92,9 +92,9 @@ public:
    void format(const details::log_msg &msg, memory_buf_t &dest) override;

    template<typename T, typename... Args>
-    pattern_formatter &add_flag(char flag, const Args &... args)
+    pattern_formatter &add_flag(char flag, Args&&...args)
    {
-        custom_handlers_[flag] = details::make_unique<T>(args...);
+        custom_handlers_[flag] = details::make_unique<T>(std::forward<Args>(args)...);
        return *this;
    }
    void set_pattern(std::string pattern);
--- a/include/spdlog/sinks/dup_filter_sink.h
+++ b/include/spdlog/sinks/dup_filter_sink.h
@@ -64,7 +64,7 @@ protected:
        {
            memory_buf_t buf;
            fmt::format_to(buf, "Skipped {} duplicate messages..", skip_counter_);
-            details::log_msg skipped_msg{msg.logger_name, msg.level, string_view_t{buf.data(), buf.size()}};
+            details::log_msg skipped_msg{msg.logger_name, level::info, string_view_t{buf.data(), buf.size()}};
            dist_sink<Mutex>::sink_it_(skipped_msg);
        }

--- a/include/spdlog/sinks/msvc_sink.h
+++ b/include/spdlog/sinks/msvc_sink.h
@@ -8,12 +8,13 @@
 #include <spdlog/details/null_mutex.h>
 #include <spdlog/sinks/base_sink.h>

-#include <spdlog/details/windows_include.h>
-#include <winbase.h>
-
 #include <mutex>
 #include <string>

+
+// Avoid including windows.h (https://stackoverflow.com/a/30741042)
+extern "C" __declspec(dllimport) void __stdcall OutputDebugStringA(const char *lpOutputString);
+
 namespace spdlog {
 namespace sinks {
 /*
@@ -23,12 +24,11 @@ template<typename Mutex>
 class msvc_sink : public base_sink<Mutex>
 {
 public:
-    explicit msvc_sink() {}
+    msvc_sink() = default;

 protected:
    void sink_it_(const details::log_msg &msg) override
    {
-
        memory_buf_t formatted;
        base_sink<Mutex>::formatter_->format(msg, formatted);
        OutputDebugStringA(fmt::to_string(formatted).c_str());
--- a/include/spdlog/sinks/stdout_sinks-inl.h
+++ b/include/spdlog/sinks/stdout_sinks-inl.h
@@ -11,6 +11,15 @@
 #include <spdlog/pattern_formatter.h>
 #include <memory>

+#ifdef _WIN32
+// under windows using fwrite to non-binary stream results in \r\r\n (see issue #1675)
+// so instead we use ::FileWrite
+#include <spdlog/details/windows_include.h>
+#include <fileapi.h> // WriteFile (..)
+#include <io.h>      // _get_osfhandle(..)
+#include <stdio.h>   // _fileno(..)
+#endif               // WIN32
+
 namespace spdlog {

 namespace sinks {
@@ -20,7 +29,16 @@ SPDLOG_INLINE stdout_sink_base<ConsoleMutex>::stdout_sink_base(FILE *file)
    : mutex_(ConsoleMutex::mutex())
    , file_(file)
    , formatter_(details::make_unique<spdlog::pattern_formatter>())
-{}
+{
+#ifdef _WIN32
+    // get windows handle from the FILE* object
+    handle_ = (HANDLE)::_get_osfhandle(::_fileno(file_));
+    if (handle_ == INVALID_HANDLE_VALUE)
+    {
+        throw_spdlog_ex("spdlog::stdout_sink_base: _get_osfhandle() failed", errno);
+    }
+#endif // WIN32
+}

 template<typename ConsoleMutex>
 SPDLOG_INLINE void stdout_sink_base<ConsoleMutex>::log(const details::log_msg &msg)
@@ -28,8 +46,19 @@ 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_);
-    fflush(file_); // flush every line to terminal
+#ifdef _WIN32
+    ::fflush(file_); // flush in case there is somthing in this file_ already
+    auto size = static_cast<DWORD>(formatted.size());
+    DWORD bytes_written = 0;
+    bool ok = ::WriteFile(handle_, formatted.data(), size, &bytes_written, nullptr) != 0;
+    if (!ok)
+    {
+        throw_spdlog_ex("stdout_sink_base: WriteFile() failed. GetLastError(): " + std::to_string(::GetLastError()));
+    }
+#else
+    ::fwrite(formatted.data(), sizeof(char), formatted.size(), file_);
+    ::fflush(file_); // flush every line to terminal
+#endif // WIN32    
 }

 template<typename ConsoleMutex>
--- a/include/spdlog/sinks/stdout_sinks.h
+++ b/include/spdlog/sinks/stdout_sinks.h
@@ -8,6 +8,10 @@
 #include <spdlog/sinks/sink.h>
 #include <cstdio>

+#ifdef _WIN32
+#include <spdlog/details/windows_include.h>
+#endif
+
 namespace spdlog {

 namespace sinks {
@@ -36,6 +40,9 @@ protected:
    mutex_t &mutex_;
    FILE *file_;
    std::unique_ptr<spdlog::formatter> formatter_;
+#ifdef _WIN32
+    HANDLE handle_;    
+#endif // WIN32
 };

 template<typename ConsoleMutex>
--- a/include/spdlog/sinks/wincolor_sink-inl.h
+++ b/include/spdlog/sinks/wincolor_sink-inl.h
@@ -146,22 +146,12 @@ void SPDLOG_INLINE wincolor_sink<ConsoleMutex>::write_to_file_(const memory_buf_
        return;
    }
    auto size = static_cast<DWORD>(formatted.size());
-    if (size == 0)
-    {
-        return;
-    }
-
-    DWORD total_written = 0;
-    do
-    {
    DWORD bytes_written = 0;
-        bool ok = ::WriteFile(out_handle_, formatted.data() + total_written, size - total_written, &bytes_written, nullptr) != 0;
-        if (!ok || bytes_written == 0)
+    bool ok = ::WriteFile(out_handle_, formatted.data(), size, &bytes_written, nullptr) != 0;
+    if (!ok)
    {
-            throw_spdlog_ex("wincolor_sink: write_to_file_ failed. GetLastError(): " + std::to_string(::GetLastError()));
+        throw_spdlog_ex("wincolor_sink: ::WriteFile() failed. GetLastError(): " + std::to_string(::GetLastError()));
    }
-        total_written += bytes_written;
-    } while (total_written < size);
 }

 // wincolor_stdout_sink
--- a/include/spdlog/spdlog-inl.h
+++ b/include/spdlog/spdlog-inl.h
@@ -47,6 +47,16 @@ SPDLOG_INLINE void dump_backtrace()
    default_logger_raw()->dump_backtrace();
 }

+SPDLOG_INLINE level::level_enum get_level()
+{
+    return default_logger_raw()->level();
+}
+
+SPDLOG_INLINE bool should_log(level::level_enum log_level)
+{
+    return default_logger_raw()->should_log(log_level);
+}
+
 SPDLOG_INLINE void set_level(level::level_enum log_level)
 {
    details::registry::instance().set_level(log_level);
--- a/include/spdlog/spdlog.h
+++ b/include/spdlog/spdlog.h
@@ -67,9 +67,15 @@ SPDLOG_API void disable_backtrace();
 // call dump backtrace on default logger
 SPDLOG_API void dump_backtrace();

+// Get global logging level
+SPDLOG_API level::level_enum get_level();
+
 // Set global logging level
 SPDLOG_API void set_level(level::level_enum log_level);

+// Determine whether the default logger should log messages with a certain level
+SPDLOG_API bool should_log(level::level_enum lvl);
+
 // Set global flush level
 SPDLOG_API void flush_on(level::level_enum log_level);

@@ -105,7 +111,7 @@ SPDLOG_API void set_automatic_registration(bool automatic_registration);
 //
 // 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);
+// spdlog::default_logger()->sinks().push_back(some_sink);
 //
 // The default logger can replaced using spdlog::set_default_logger(new_logger).
 // For example, to replace it with a file logger.
@@ -122,51 +128,51 @@ SPDLOG_API spdlog::logger *default_logger_raw();
 SPDLOG_API void set_default_logger(std::shared_ptr<spdlog::logger> default_logger);

 template<typename FormatString, typename... Args>
-inline void log(source_loc source, level::level_enum lvl, const FormatString &fmt, const Args &... args)
+inline void log(source_loc source, level::level_enum lvl, const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->log(source, lvl, fmt, args...);
+    default_logger_raw()->log(source, lvl, fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void log(level::level_enum lvl, const FormatString &fmt, const Args &... args)
+inline void log(level::level_enum lvl, const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->log(source_loc{}, lvl, fmt, args...);
+    default_logger_raw()->log(source_loc{}, lvl, fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void trace(const FormatString &fmt, const Args &... args)
+inline void trace(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->trace(fmt, args...);
+    default_logger_raw()->trace(fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void debug(const FormatString &fmt, const Args &... args)
+inline void debug(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->debug(fmt, args...);
+    default_logger_raw()->debug(fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void info(const FormatString &fmt, const Args &... args)
+inline void info(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->info(fmt, args...);
+    default_logger_raw()->info(fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void warn(const FormatString &fmt, const Args &... args)
+inline void warn(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->warn(fmt, args...);
+    default_logger_raw()->warn(fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void error(const FormatString &fmt, const Args &... args)
+inline void error(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->error(fmt, args...);
+    default_logger_raw()->error(fmt, std::forward<Args>(args)...);
 }

 template<typename FormatString, typename... Args>
-inline void critical(const FormatString &fmt, const Args &... args)
+inline void critical(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->critical(fmt, args...);
+    default_logger_raw()->critical(fmt, std::forward<Args>(args)...);
 }

 template<typename T>
--- a/include/spdlog/stopwatch.h
+++ b/include/spdlog/stopwatch.h
@@ -0,0 +1,61 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include <spdlog/fmt/fmt.h>
+
+// Stopwatch support for spdlog  (using std::chrono::steady_clock).
+// Displays elapsed seconds since construction as double.
+//
+// Usage:
+//
+// spdlog::stopwatch sw;
+// ...
+// spdlog::debug("Elapsed: {} seconds", sw);    =>  "Elapsed 0.005116733 seconds"
+// spdlog::info("Elapsed: {:.6} seconds", sw);  =>  "Elapsed 0.005163 seconds"
+//
+//
+// If other units are needed (e.g. millis instead of double), include "fmt/chrono.h" and use "duration_cast<..>(sw.elapsed())":
+//
+// #include <spdlog/fmt/chrono.h>
+//..
+// using std::chrono::duration_cast;
+// using std::chrono::milliseconds;
+// spdlog::info("Elapsed {}", duration_cast<milliseconds>(sw.elapsed())); => "Elapsed 5ms"
+
+namespace spdlog {
+class stopwatch
+{
+    using clock = std::chrono::steady_clock;
+    std::chrono::time_point<clock> start_tp_;
+
+public:
+    stopwatch()
+        : start_tp_{clock::now()}
+    {}
+
+    std::chrono::duration<double> elapsed() const
+    {
+        return std::chrono::duration<double>(clock::now() - start_tp_);
+    }
+
+    void reset()
+    {
+        start_tp_ = clock ::now();
+    }
+};
+} // namespace spdlog
+
+// Support for fmt formatting  (e.g. "{:012.9}" or just "{}")
+namespace fmt {
+template<>
+struct formatter<spdlog::stopwatch> : formatter<double>
+{
+    template<typename FormatContext>
+    auto format(const spdlog::stopwatch &sw, FormatContext &ctx) -> decltype(ctx.out())
+    {
+        return formatter<double>::format(sw.elapsed().count(), ctx);
+    }
+};
+} // namespace fmt
--- 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 7
-#define SPDLOG_VER_PATCH 0
+#define SPDLOG_VER_MINOR 8
+#define SPDLOG_VER_PATCH 2

 #define SPDLOG_VERSION (SPDLOG_VER_MAJOR * 10000 + SPDLOG_VER_MINOR * 100 + SPDLOG_VER_PATCH)
--- a/src/fmt.cpp
+++ b/src/fmt.cpp
@@ -9,181 +9,95 @@
 #if !defined(SPDLOG_FMT_EXTERNAL)
 #include <spdlog/fmt/bundled/format-inl.h>

+
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {

 template <typename T>
-int format_float(char *buf, std::size_t size, const char *format, int precision, T value)
-{
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+int format_float(char* buf, std::size_t size, const char* format, int precision,
+                 T value) {
+#ifdef FMT_FUZZ
  if (precision > 100000)
-        throw std::runtime_error("fuzz mode - avoid large allocation inside snprintf");
+    throw std::runtime_error(
+        "fuzz mode - avoid large allocation inside snprintf");
 #endif
  // Suppress the warning about nonliteral format string.
  int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
-    return precision < 0 ? snprintf_ptr(buf, size, format, value) : snprintf_ptr(buf, size, format, precision, value);
+  return precision < 0 ? snprintf_ptr(buf, size, format, value)
+                       : snprintf_ptr(buf, size, format, precision, value);
 }
-struct sprintf_specs
-{
-    int precision;
-    char type;
-    bool alt : 1;

+template FMT_API dragonbox::decimal_fp<float> dragonbox::to_decimal(float x)
+    FMT_NOEXCEPT;
+template FMT_API dragonbox::decimal_fp<double> dragonbox::to_decimal(double x)
+    FMT_NOEXCEPT;
+
+// DEPRECATED! This function exists for ABI compatibility.
 template <typename Char>
-    constexpr sprintf_specs(basic_format_specs<Char> specs)
-        : precision(specs.precision)
-        , type(specs.type)
-        , alt(specs.alt)
-    {}
+typename basic_format_context<std::back_insert_iterator<buffer<Char>>,
+                              Char>::iterator
+vformat_to(buffer<Char>& buf, basic_string_view<Char> format_str,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+               type_identity_t<Char>>>
+               args) {
+  using iterator = std::back_insert_iterator<buffer<char>>;
+  using context = basic_format_context<
+      std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+      type_identity_t<Char>>;
+  auto out = iterator(buf);
+  format_handler<iterator, Char, context> h(out, format_str, args, {});
+  parse_format_string<false>(format_str, h);
+  return out;
+}
+template basic_format_context<std::back_insert_iterator<buffer<char>>,
+                              char>::iterator
+vformat_to(buffer<char>&, string_view,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<char>>>,
+               type_identity_t<char>>>);
+}  // namespace detail

-    constexpr bool has_precision() const
-    {
-        return precision >= 0;
-    }
-};
-
-// This is deprecated and is kept only to preserve ABI compatibility.
-template<typename Double>
-char *sprintf_format(Double value, internal::buffer<char> &buf, sprintf_specs specs)
-{
-    // Buffer capacity must be non-zero, otherwise MSVC's vsnprintf_s will fail.
-    FMT_ASSERT(buf.capacity() != 0, "empty buffer");
-
-    // Build format string.
-    enum
-    {
-        max_format_size = 10
-    }; // longest format: %#-*.*Lg
-    char format[max_format_size];
-    char *format_ptr = format;
-    *format_ptr++ = '%';
-    if (specs.alt || !specs.type)
-        *format_ptr++ = '#';
-    if (specs.precision >= 0)
-    {
-        *format_ptr++ = '.';
-        *format_ptr++ = '*';
-    }
-    if (std::is_same<Double, long double>::value)
-        *format_ptr++ = 'L';
-
-    char type = specs.type;
-
-    if (type == '%')
-        type = 'f';
-    else if (type == 0 || type == 'n')
-        type = 'g';
-#if FMT_MSC_VER
-    if (type == 'F')
-    {
-        // MSVC's printf doesn't support 'F'.
-        type = 'f';
-    }
-#endif
-    *format_ptr++ = type;
-    *format_ptr = '\0';
-
-    // Format using snprintf.
-    char *start = nullptr;
-    char *decimal_point_pos = nullptr;
-    for (;;)
-    {
-        std::size_t buffer_size = buf.capacity();
-        start = &buf[0];
-        int result = format_float(start, buffer_size, format, specs.precision, value);
-        if (result >= 0)
-        {
-            unsigned n = internal::to_unsigned(result);
-            if (n < buf.capacity())
-            {
-                // Find the decimal point.
-                auto p = buf.data(), end = p + n;
-                if (*p == '+' || *p == '-')
-                    ++p;
-                if (specs.type != 'a' && specs.type != 'A')
-                {
-                    while (p < end && *p >= '0' && *p <= '9')
-                        ++p;
-                    if (p < end && *p != 'e' && *p != 'E')
-                    {
-                        decimal_point_pos = p;
-                        if (!specs.type)
-                        {
-                            // Keep only one trailing zero after the decimal point.
-                            ++p;
-                            if (*p == '0')
-                                ++p;
-                            while (p != end && *p >= '1' && *p <= '9')
-                                ++p;
-                            char *where = p;
-                            while (p != end && *p == '0')
-                                ++p;
-                            if (p == end || *p < '0' || *p > '9')
-                            {
-                                if (p != end)
-                                    std::memmove(where, p, to_unsigned(end - p));
-                                n -= static_cast<unsigned>(p - where);
-                            }
-                        }
-                    }
-                }
-                buf.resize(n);
-                break; // The buffer is large enough - continue with formatting.
-            }
-            buf.reserve(n + 1);
-        }
-        else
-        {
-            // If result is negative we ask to increase the capacity by at least 1,
-            // but as std::vector, the buffer grows exponentially.
-            buf.reserve(buf.capacity() + 1);
-        }
-    }
-    return decimal_point_pos;
-}
-} // namespace internal
-
-template FMT_API char *internal::sprintf_format(double, internal::buffer<char> &, sprintf_specs);
-template FMT_API char *internal::sprintf_format(long double, internal::buffer<char> &, sprintf_specs);
-
-template struct FMT_INSTANTIATION_DEF_API internal::basic_data<void>;
+template struct FMT_INSTANTIATION_DEF_API detail::basic_data<void>;

 // Workaround a bug in MSVC2013 that prevents instantiation of format_float.
-int (*instantiate_format_float)(double, int, internal::float_specs, internal::buffer<char> &) = internal::format_float;
+int (*instantiate_format_float)(double, int, detail::float_specs,
+                                detail::buffer<char>&) = detail::format_float;

 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template FMT_API internal::locale_ref::locale_ref(const std::locale &loc);
-template FMT_API std::locale internal::locale_ref::get<std::locale>() const;
+template FMT_API detail::locale_ref::locale_ref(const std::locale& loc);
+template FMT_API std::locale detail::locale_ref::get<std::locale>() const;
 #endif

 // Explicit instantiations for char.

-template FMT_API std::string internal::grouping_impl<char>(locale_ref);
-template FMT_API char internal::thousands_sep_impl(locale_ref);
-template FMT_API char internal::decimal_point_impl(locale_ref);
+template FMT_API std::string detail::grouping_impl<char>(locale_ref);
+template FMT_API char detail::thousands_sep_impl(locale_ref);
+template FMT_API char detail::decimal_point_impl(locale_ref);

-template FMT_API void internal::buffer<char>::append(const char *, const char *);
+template FMT_API void detail::buffer<char>::append(const char*, const char*);

-template FMT_API void internal::arg_map<format_context>::init(const basic_format_args<format_context> &args);
+template FMT_API void detail::vformat_to(
+    detail::buffer<char>&, string_view,
+    basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);

-template FMT_API std::string internal::vformat<char>(string_view, basic_format_args<format_context>);
-
-template FMT_API format_context::iterator internal::vformat_to(internal::buffer<char> &, string_view, basic_format_args<format_context>);
-
-template FMT_API int internal::snprintf_float(double, int, internal::float_specs, internal::buffer<char> &);
-template FMT_API int internal::snprintf_float(long double, int, internal::float_specs, internal::buffer<char> &);
-template FMT_API int internal::format_float(double, int, internal::float_specs, internal::buffer<char> &);
-template FMT_API int internal::format_float(long double, int, internal::float_specs, internal::buffer<char> &);
+template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::snprintf_float(long double, int,
+                                            detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::format_float(double, int, detail::float_specs,
+                                          detail::buffer<char>&);
+template FMT_API int detail::format_float(long double, int, detail::float_specs,
+                                          detail::buffer<char>&);

 // Explicit instantiations for wchar_t.

-template FMT_API std::string internal::grouping_impl<wchar_t>(locale_ref);
-template FMT_API wchar_t internal::thousands_sep_impl(locale_ref);
-template FMT_API wchar_t internal::decimal_point_impl(locale_ref);
+template FMT_API std::string detail::grouping_impl<wchar_t>(locale_ref);
+template FMT_API wchar_t detail::thousands_sep_impl(locale_ref);
+template FMT_API wchar_t detail::decimal_point_impl(locale_ref);

-template FMT_API void internal::buffer<wchar_t>::append(const wchar_t *, const wchar_t *);
-
-template FMT_API std::wstring internal::vformat<wchar_t>(wstring_view, basic_format_args<wformat_context>);
+template FMT_API void detail::buffer<wchar_t>::append(const wchar_t*,
+                                                      const wchar_t*);
 FMT_END_NAMESPACE
-
 #endif // !SPDLOG_FMT_EXTERNAL
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,5 +1,4 @@
-cmake_minimum_required(VERSION 3.2)
-
+cmake_minimum_required(VERSION 3.10)
 project(spdlog_utests CXX)

 if(NOT TARGET spdlog)
@@ -33,7 +32,8 @@ set(SPDLOG_UTESTS_SOURCES
    test_backtrace.cpp
    test_create_dir.cpp
    test_cfg.cpp
-        test_time_point.cpp)
+    test_time_point.cpp
+    test_stopwatch.cpp)

 if(NOT SPDLOG_NO_EXCEPTIONS)
    list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
--- a/tests/test_async.cpp
+++ b/tests/test_async.cpp
@@ -87,7 +87,7 @@ TEST_CASE("async periodic flush", "[async]")
    auto test_sink = std::static_pointer_cast<spdlog::sinks::test_sink_mt>(logger->sinks()[0]);

    spdlog::flush_every(std::chrono::seconds(1));
-    std::this_thread::sleep_for(std::chrono::milliseconds(1100));
+    std::this_thread::sleep_for(std::chrono::milliseconds(1700));
    REQUIRE(test_sink->flush_counter() == 1);
    spdlog::flush_every(std::chrono::seconds(0));
    spdlog::drop_all();
--- a/tests/test_cfg.cpp
+++ b/tests/test_cfg.cpp
@@ -1,3 +1,4 @@
+
 #include "includes.h"
 #include "test_sink.h"

@@ -41,21 +42,23 @@ TEST_CASE("argv2", "[cfg]")
    auto l1 = spdlog::create<test_sink_st>("l1");
    REQUIRE(l1->level() == spdlog::level::warn);
    REQUIRE(spdlog::default_logger()->level() == spdlog::level::trace);
-    spdlog::set_level(spdlog::level::info);
 }

 TEST_CASE("argv3", "[cfg]")
 {
+    spdlog::set_level(spdlog::level::trace);
+
    spdlog::drop("l1");
-    const char *argv[] = {"ignore", "SPDLOG_LEVEL="};
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=junk_name=warn"};
    load_argv_levels(2, argv);
    auto l1 = spdlog::create<test_sink_st>("l1");
-    REQUIRE(l1->level() == spdlog::level::info);
-    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+    REQUIRE(l1->level() == spdlog::level::trace);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::trace);
 }

 TEST_CASE("argv4", "[cfg]")
 {
+    spdlog::set_level(spdlog::level::info);
    spdlog::drop("l1");
    const char *argv[] = {"ignore", "SPDLOG_LEVEL=junk"};
    load_argv_levels(2, argv);
@@ -65,6 +68,7 @@ TEST_CASE("argv4", "[cfg]")

 TEST_CASE("argv5", "[cfg]")
 {
+    spdlog::set_level(spdlog::level::info);
    spdlog::drop("l1");
    const char *argv[] = {"ignore", "ignore", "SPDLOG_LEVEL=l1=warn,trace"};
    load_argv_levels(3, argv);
@@ -91,3 +95,89 @@ TEST_CASE("argv7", "[cfg]")
    REQUIRE(spdlog::default_logger()->level() == spdlog::level::err);
    spdlog::set_level(spdlog::level::info);
 }
+
+TEST_CASE("level-not-set-test1", "[cfg]")
+{
+    spdlog::drop("l1");
+    const char *argv[] = {"ignore", ""};
+    load_argv_levels(2, argv);
+    auto l1 = spdlog::create<spdlog::sinks::test_sink_st>("l1");
+    l1->set_level(spdlog::level::trace);
+    REQUIRE(l1->level() == spdlog::level::trace);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+}
+
+TEST_CASE("level-not-set-test2", "[cfg]")
+{
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=l1=trace"};
+
+    auto l1 = spdlog::create<spdlog::sinks::test_sink_st>("l1");
+    l1->set_level(spdlog::level::warn);
+    auto l2 = spdlog::create<spdlog::sinks::test_sink_st>("l2");
+    l2->set_level(spdlog::level::warn);
+
+    load_argv_levels(2, argv);
+
+    REQUIRE(l1->level() == spdlog::level::trace);
+    REQUIRE(l2->level() == spdlog::level::warn);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+}
+
+TEST_CASE("level-not-set-test3", "[cfg]")
+{
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=l1=trace"};
+
+    load_argv_levels(2, argv);
+
+    auto l1 = spdlog::create<spdlog::sinks::test_sink_st>("l1");
+    auto l2 = spdlog::create<spdlog::sinks::test_sink_st>("l2");
+
+    REQUIRE(l1->level() == spdlog::level::trace);
+    REQUIRE(l2->level() == spdlog::level::info);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+}
+
+TEST_CASE("level-not-set-test4", "[cfg]")
+{
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=l1=trace,warn"};
+
+    load_argv_levels(2, argv);
+
+    auto l1 = spdlog::create<spdlog::sinks::test_sink_st>("l1");
+    auto l2 = spdlog::create<spdlog::sinks::test_sink_st>("l2");
+
+    REQUIRE(l1->level() == spdlog::level::trace);
+    REQUIRE(l2->level() == spdlog::level::warn);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::warn);
+}
+
+TEST_CASE("level-not-set-test5", "[cfg]")
+{
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=l1=junk,warn"};
+
+    load_argv_levels(2, argv);
+
+    auto l1 = spdlog::create<spdlog::sinks::test_sink_st>("l1");
+    auto l2 = spdlog::create<spdlog::sinks::test_sink_st>("l2");
+
+    REQUIRE(l1->level() == spdlog::level::warn);
+    REQUIRE(l2->level() == spdlog::level::warn);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::warn);
+}
+
+TEST_CASE("restore-to-default", "[cfg]")
+{
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=info"};
+    load_argv_levels(2, argv);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+}
--- a/tests/test_pattern_formatter.cpp
+++ b/tests/test_pattern_formatter.cpp
@@ -227,7 +227,7 @@ TEST_CASE("paddinng_truncate", "[pattern_formatter]")
    REQUIRE(log_to_str("123456", "%0!v", spdlog::pattern_time_type::local, "\n") == "\n");
 }

-TEST_CASE("paddinng_truncate_funcname", "[pattern_formatter]")
+TEST_CASE("padding_truncate_funcname", "[pattern_formatter]")
 {
    spdlog::sinks::test_sink_st test_sink;

@@ -237,13 +237,28 @@ TEST_CASE("paddinng_truncate_funcname", "[pattern_formatter]")

    spdlog::details::log_msg msg1{spdlog::source_loc{"ignored", 1, "func"}, "test_logger", spdlog::level::info, "message"};
    test_sink.log(msg1);
+    REQUIRE(test_sink.lines()[0] == "message [ func]");

    spdlog::details::log_msg msg2{spdlog::source_loc{"ignored", 1, "function"}, "test_logger", spdlog::level::info, "message"};
    test_sink.log(msg2);
+    REQUIRE(test_sink.lines()[1] == "message [funct]");
+}

-    auto lines = test_sink.lines();
-    REQUIRE(lines[0] == "message [ func]");
-    REQUIRE(lines[1] == "message [funct]");
+TEST_CASE("padding_funcname", "[pattern_formatter]")
+{
+    spdlog::sinks::test_sink_st test_sink;
+
+    const char *pattern = "%v [%10!]";
+    auto formatter = std::unique_ptr<spdlog::formatter>(new spdlog::pattern_formatter(pattern));
+    test_sink.set_formatter(std::move(formatter));
+
+    spdlog::details::log_msg msg1{spdlog::source_loc{"ignored", 1, "func"}, "test_logger", spdlog::level::info, "message"};
+    test_sink.log(msg1);
+    REQUIRE(test_sink.lines()[0] == "message [      func]");
+
+    spdlog::details::log_msg msg2{spdlog::source_loc{"ignored", 1, "func567890123"}, "test_logger", spdlog::level::info, "message"};
+    test_sink.log(msg2);
+    REQUIRE(test_sink.lines()[1] == "message [func567890123]");
 }

 TEST_CASE("clone-default-formatter", "[pattern_formatter]")
--- a/tests/test_stopwatch.cpp
+++ b/tests/test_stopwatch.cpp
@@ -0,0 +1,35 @@
+#include "includes.h"
+#include "test_sink.h"
+#include "spdlog/stopwatch.h"
+
+TEST_CASE("stopwatch1", "[stopwatch]")
+{
+    using std::chrono::milliseconds;
+    milliseconds wait_ms(250);
+    milliseconds tolerance_ms(250);
+
+    spdlog::stopwatch sw;
+    std::this_thread::sleep_for(wait_ms);
+    REQUIRE(sw.elapsed() >= wait_ms);
+    REQUIRE(sw.elapsed() <= wait_ms + tolerance_ms);
+}
+
+TEST_CASE("stopwatch2", "[stopwatch]")
+{
+    using spdlog::sinks::test_sink_st;
+
+    std::chrono::duration<double> wait_duration(0.250);
+    std::chrono::duration<double> tolerance_duration(0.250);
+
+    auto test_sink = std::make_shared<test_sink_st>();
+
+    spdlog::stopwatch sw;
+    spdlog::logger logger("test-stopwatch", test_sink);
+    logger.set_pattern("%v");
+    std::this_thread::sleep_for(wait_duration);
+    logger.info("{}", sw);
+    auto val = std::stod(test_sink->lines()[0]);
+
+    REQUIRE(val >= wait_duration.count());
+    REQUIRE(val <= (wait_duration + tolerance_duration).count());
+}
Author	SHA1	Message	Date
gabime	de0dbfa359	version 1.8.2	2020-12-11 16:40:52 +02:00
gabime	f93459579f	version 1.9.0	2020-12-11 16:37:37 +02:00
gabime	2b81c40b90	Bump fmt to version 7.1.3	2020-12-11 16:32:39 +02:00
Gabi Melman	233e97c5e4	Merge pull request #1749 from bluescarni/pr/async_test_fix Increase sleep time on a test case to avoid spurious failures	2020-11-26 11:03:46 +02:00
Francesco Biscani	fc1ce48dc7	Increase sleep time on a test case to avoid spurious failures.	2020-11-26 09:45:39 +01:00
Gabi Melman	fd5562eebe	Merge pull request #1744 from ArnaudBienner/ArnaudBienner-readme-patch 📝 README example: Add {:a} format flag to bin_to_hex example	2020-11-23 02:01:34 +02:00
ArnaudBienner	0695d9cb5f	📝 README example: Add {:a} format flag to bin_to_hex example Add {:a} format flag to bin_to_hex example	2020-11-22 20:54:28 +01:00
Gabi Melman	456b24134d	Merge pull request #1742 from jwittbrodt/v1.x Add missing include	2020-11-20 18:13:49 +02:00
Jonas Wittbrodt	f8ba24afee	add missing <algorithm> include	2020-11-19 14:09:33 +01:00
Gabi Melman	eebb921c9f	Merge pull request #1735 from o2gy84/v1.x Ability to get size of messages queue of async thread pool	2020-11-13 12:59:52 +02:00
Могилин Виктор	e17ee87f38	Ability to get size of messages queue of async thread pool	2020-11-13 13:12:32 +03:00
Gabi Melman	18e3f07f7d	Fix #1710	2020-11-05 18:27:31 +02:00
Gabi Melman	9ce39a470f	Merge pull request #1726 from dkavolis/v1.x Perfect forwarding for arguments	2020-11-02 04:02:38 +02:00
dkavolis	23572369fc	Perfect forwarding for arguments	2020-11-02 00:37:03 +00:00
Gabi Melman	01b350de96	Merge pull request #1712 from ChristofKaufmann/deb-package Add CPack debian package settings	2020-10-20 22:23:45 +03:00
Christof Kaufmann	365e470a32	Add CPack debian package settings	2020-10-20 19:57:56 +02:00
Gabi Melman	a42b40656c	Merge pull request #1711 from ChristofKaufmann/fix-typo Fix typo in comment	2020-10-20 10:00:43 +03:00
Christof Kaufmann	40160f2a57	Fix typo in comment	2020-10-20 02:49:09 +02:00
Gabi Melman	90b33b1552	Merge pull request #1709 from kitattyor/v1.x Download googlebenchmark if not found	2020-10-17 17:56:59 +03:00
kitattyor	5567ed01e5	Download googlebenchmark if not found; requires cmake 3.11	2020-10-17 21:08:36 +08:00
gabime	cbe9448650	version 1.8.1	2020-09-30 17:30:06 +03:00
gabime	5b345534dc	Minor change in ifdef for clarity	2020-09-30 17:29:44 +03:00
Gabi Melman	c8dc318fb3	Update logger-inl.h	2020-09-29 02:23:03 +03:00
Gabi Melman	23cb1a1080	Update logger-inl.h	2020-09-29 02:20:43 +03:00
Gabi Melman	21cf8d7d3c	Merge pull request #1685 from eddelbuettel/feature/r_use_of_reprintf let R header defines switch to REprintf over fprintf(stdderr)	2020-09-29 02:18:35 +03:00
Dirk Eddelbuettel	3cf4d34094	let R header defines switch to REprintf over fprintf(stdderr)	2020-09-28 17:13:09 -05:00
Gabi Melman	16d78ae5db	Update stdout_sinks-inl.h	2020-09-28 17:08:13 +03:00
gabime	62b4b7af83	Fix #1667	2020-09-28 13:39:31 +03:00
Gabi Melman	9799ecac6a	Remove redundant size check before calling WriteFile	2020-09-27 21:27:58 +03:00
Gabi Melman	dccb766095	Fix warning about enum usage	2020-09-27 19:08:24 +03:00
gabime	c97983a91c	Fix linux build	2020-09-27 18:42:27 +03:00
gabime	680fb07fd5	Updatd WriteFile usage	2020-09-27 18:34:01 +03:00
gabime	cfd0ea197c	Simplify WriteFile() usage under windows	2020-09-27 18:32:08 +03:00
gabime	48d4ed9bc0	Fix #1675	2020-09-27 18:27:41 +03:00
gabime	3bed78356e	Added cfg tests	2020-09-27 02:10:52 +03:00
gabime	8923922f30	Cleaned level loading from env var	2020-09-27 02:08:24 +03:00
gabime	7542e42e4f	removed extra parentheses	2020-09-27 01:05:55 +03:00
Gabi Melman	7a9b23e4f4	Update registry-inl.h	2020-09-26 16:09:43 +03:00
gabime	47253ba2a1	Updated comment	2020-09-26 15:56:57 +03:00
gabime	69b54dd9e4	Merge branch 'v1.x' of https://github.com/gabime/spdlog into v1.x	2020-09-26 15:49:21 +03:00
gabime	36138617fc	small readablilty update in registry	2020-09-26 15:36:57 +03:00
gabime	231ca50700	clang-format	2020-09-26 15:34:05 +03:00
gabime	c7613f3e91	Fixed #1680	2020-09-26 15:32:44 +03:00
gabime	05d5546eb1	Restore example	2020-09-26 15:30:45 +03:00
gabime	cefe67726e	wip fix #1680 again	2020-09-26 15:06:53 +03:00
gabime	1ac2dcc537	wip fix #1680 again	2020-09-26 14:41:33 +03:00
gabime	3a68eecb28	Fix issue #1680	2020-09-25 18:19:50 +03:00
gabime	54a8259b42	Fix #1680	2020-09-25 15:03:13 +03:00
gabime	32b6f1619f	Added tests for issue #1680	2020-09-25 14:44:01 +03:00
Gabi Melman	99b8c5d379	Update bin_to_hex.h	2020-09-24 10:04:07 +03:00
Gabi Melman	5deb7c55e1	Fix #1676	2020-09-21 03:31:19 +03:00
gabime	9cd25dd216	Remove un needed hasher declaration	2020-09-01 23:49:54 +03:00
gabime	4a9ccf7e38	Fixed chrono wrapper	2020-09-01 12:34:59 +03:00
gabime	2963b9f07f	Updated comment	2020-09-01 12:24:11 +03:00
gabime	a4a9bc4d8e	version 1.8.0	2020-09-01 12:05:23 +03:00
gabime	a16a029790	Added bundled fmt os.h file	2020-09-01 12:04:36 +03:00
Gabi Melman	97fea81599	Update README.md	2020-08-31 03:51:17 +03:00
gabime	ccffb6ecd6	Fix #1581	2020-08-30 20:44:42 +03:00
gabime	63b5a1a4d8	Fix #1581	2020-08-30 20:44:04 +03:00
gabime	dfc777803a	enable the 'n' flag in for backward compatibility with fmt 6.x	2020-08-30 15:58:22 +03:00
gabime	934a9bb23e	Fix issue #1617	2020-08-30 15:18:33 +03:00
gabime	7097f7a894	Updated stopwatch example to README.md	2020-08-29 03:50:48 +03:00
gabime	537fd7c4ba	Added stopwatch example to README.md	2020-08-29 03:49:18 +03:00
gabime	d5048b8b0c	Added stopwatch example to README.md	2020-08-29 03:48:24 +03:00
gabime	0348556aac	Added stopwatch example to README.md	2020-08-29 03:46:29 +03:00
gabime	d6329b9dce	Added some stopwatch tests	2020-08-29 03:25:16 +03:00
gabime	34f3d29d93	Added stopwatch support	2020-08-29 02:48:43 +03:00
gabime	cd701761f9	clang-format	2020-08-26 00:10:05 +03:00
gabime	23c2c00d69	Bumb fmt version to 7.0.3	2020-08-26 00:02:09 +03:00
Gabi Melman	fa501b46cf	Merge pull request #1653 from gk6k6k/patch-1 Update README.md	2020-08-20 12:26:03 +03:00
gk6k6k	38dc0a5c5d	Update README.md Hi, fedora yum is obsolite log time ago... https://www.2daygeek.com/comparison-difference-between-dnf-vs-yum/ Works for fedora 31: [root@Galleon ~]# uname -a Linux Galleon 5.6.13-200.fc31.x86_64 #1 SMP Thu May 14 23:26:14 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux [root@Galleon ~]#	2020-08-20 11:01:49 +02:00
Gabi Melman	685cc4edbc	Revert last commit	2020-08-20 00:00:54 +03:00
Gabi Melman	78369375e3	Update helpers-inl.h	2020-08-19 23:57:47 +03:00
Gabi Melman	6587058f74	Update argv.h	2020-08-19 23:56:56 +03:00
Gabi Melman	30f738e49a	Merge pull request #1651 from bareya/make_load_env_levels_inline Make load_env_levels inline function	2020-08-19 23:55:40 +03:00
Piotr Barejko	726ca01e5c	Make load_env_levels inline function	2020-08-19 12:43:41 -07:00
Gabi Melman	83b40b8cda	Merge pull request #1640 from dkruempe/v1.x tcp_client.h bugfix for macOS and add tcp example	2020-08-06 13:06:08 +03:00
Dominik Krümpelmann	db0d0438ff	tcp_client.h bugfix for macOS and add tcp example -> fix the issue that the head is not compilable bc. of missing declaration -> optimize if/else block in connection function. Else not needed bc. of break in if	2020-08-06 11:40:17 +02:00
Gabi Melman	3c527488e7	Update spdlog-inl.h	2020-07-24 13:06:29 +03:00
Gabi Melman	99abcf6ded	Merge pull request #1628 from eyalroz/issue-1627 Fix for issue #1627: Global get_level() and should_log()	2020-07-24 00:31:51 +03:00
Eyal Rozenberg	7009727559	Fix for issue #1627 : * Added: `spdlog::get_level()` API function - like `logger::level()`, except for the name change * Added: `spdlog::should_log()` API function - like `logger: should_log()`	2020-07-23 23:05:12 +03:00
Gabi Melman	ae02fba141	Merge pull request #1624 from tambry/cmake_range Bump CMake requirement to 3.10, don't enable C language	2020-07-21 14:28:42 +03:00
Raul Tambre	76cdeb62e3	Don't enable C language in CMake spdlog doesn't seem to actually require the C language. Not enabling it results in a significant initial configure time speedup.	2020-07-21 11:39:40 +03:00
Raul Tambre	ae9627c64c	Raise CMake requirement to 3.13 * Reduces the range of possible version we'd need to test with. * Enables newer policies reducing possible deprecation warnings from new policies. * Allows removing some code for compatibility with older versions. * Coincides with LLVM's bump to requiring CMake 3.13.	2020-07-20 22:03:50 +03:00
Gabi Melman	58875bdcd7	Update tcp_client-windows.h	2020-07-14 23:15:49 +03:00