Set C++ standard to 20 if not defined (#3583)

Why? to be able to use a greater c++ when using conan.

Because conan reports: Warning: Standard CMAKE_CXX_STANDARD value defined in conan_toolchain.cmake to 23 has been modified to 20 by .conan2/p/b/spdlo815dcec129526/b/src/CMakeLists.txt

.github/workflows/coverity_scan.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Coverity Scan
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install dependencies
         run: |

.github/workflows/linux.yml

@@ -28,7 +28,7 @@ jobs:
       image: ${{ matrix.config.compiler == 'clang' && 'teeks99/clang-ubuntu' || matrix.config.compiler }}:${{ matrix.config.version }}
     name: "${{ matrix.config.compiler}} ${{ matrix.config.version }} (C++${{ matrix.config.cppstd }} ${{ matrix.config.build_type }} ${{ matrix.config.asan == 'ON' && 'ASAN' || '' }}${{ matrix.config.tsan == 'ON' && 'TSAN' || '' }})"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup
         run: |
           apt-get update
@@ -68,7 +68,7 @@ jobs:
     runs-on: macOS-latest
     name: "OS X Clang (C++11, Release)"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build
         run: |
           mkdir -p build && cd build

.github/workflows/macos.yml

@@ -19,7 +19,7 @@ jobs:
               BUILD_EXAMPLE: 'ON'
               
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build
         run: |
           mkdir -p build && cd build

.github/workflows/windows.yml

@@ -42,7 +42,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: CMake ${{ matrix.config.GENERATOR }} CXX=${{matrix.config.CXX_STANDARD}} WCHAR=${{matrix.config.WCHAR_FILES}} STD_FORMAT=${{matrix.config.USE_STD_FORMAT}}
         shell: pwsh

CMakeLists.txt

@@ -30,7 +30,9 @@ endif()
 # Compiler config
 # ---------------------------------------------------------------------------------------
 if(SPDLOG_USE_STD_FORMAT)
+if(NOT DEFINED CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 20)
+endif()
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
 elseif(NOT CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 11)
@@ -199,7 +201,7 @@ spdlog_enable_warnings(spdlog)
 
 set_target_properties(spdlog PROPERTIES VERSION ${SPDLOG_VERSION} SOVERSION
                                                                   ${SPDLOG_VERSION_MAJOR}.${SPDLOG_VERSION_MINOR})
-set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX ${SPDLOG_DEBUG_POSTFIX})
+set_target_properties(spdlog PROPERTIES DEBUG_POSTFIX "${SPDLOG_DEBUG_POSTFIX}")
 
 if(COMMAND target_precompile_headers AND SPDLOG_ENABLE_PCH)
     configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/pch.h.in ${PROJECT_BINARY_DIR}/spdlog_pch.h @ONLY)

bench/CMakeLists.txt

@@ -19,7 +19,7 @@ if(NOT benchmark_FOUND)
     # disable tests
     set(BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "")
     # Do not build and run googlebenchmark tests
-    FetchContent_Declare(googlebenchmark GIT_REPOSITORY https://github.com/google/benchmark.git GIT_TAG v1.6.0)
+    FetchContent_Declare(googlebenchmark GIT_REPOSITORY https://github.com/google/benchmark.git GIT_TAG v1.8.4)
     FetchContent_MakeAvailable(googlebenchmark)
 endif()
 

example/example.cpp

@@ -267,16 +267,16 @@ void multi_sink_example() {
 
 // User defined types logging
 struct my_type {
-    int i = 0;
-    explicit my_type(int i)
-        : i(i) {}
+    int value_ = 0;
+    explicit my_type(int value)
+        : value_(value) {}
 };
 
 #ifndef SPDLOG_USE_STD_FORMAT  // when using fmtlib
 template <>
 struct fmt::formatter<my_type> : fmt::formatter<std::string> {
     auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
-        return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
+        return fmt::format_to(ctx.out(), "[my_type value={}]", my.value_);
     }
 };
 
@@ -284,7 +284,7 @@ struct fmt::formatter<my_type> : fmt::formatter<std::string> {
 template <>
 struct std::formatter<my_type> : std::formatter<std::string> {
     auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
-        return std::format_to(ctx.out(), "[my_type i={}]", my.i);
+        return std::format_to(ctx.out(), "[my_type value={}]", my.value_);
     }
 };
 #endif

include/spdlog/async_logger-inl.h

@@ -57,15 +57,15 @@ SPDLOG_LOGGER_CATCH(source_loc())
 //
 // backend functions - called from the thread pool to do the actual job
 //
-SPDLOG_INLINE void spdlog::async_logger::backend_sink_it_(const details::log_msg &msg) {
+SPDLOG_INLINE void spdlog::async_logger::backend_sink_it_(const details::log_msg &incoming_log_msg) {
     for (auto &sink : sinks_) {
-        if (sink->should_log(msg.level)) {
-            SPDLOG_TRY { sink->log(msg); }
-            SPDLOG_LOGGER_CATCH(msg.source)
+        if (sink->should_log(incoming_log_msg.level)) {
+            SPDLOG_TRY { sink->log(incoming_log_msg); }
+            SPDLOG_LOGGER_CATCH(incoming_log_msg.source)
         }
     }
 
-    if (should_flush_(msg)) {
+    if (should_flush_(incoming_log_msg)) {
         backend_flush_();
     }
 }

include/spdlog/cfg/argv.h

@@ -26,8 +26,8 @@ inline void load_argv_levels(int argc, const char **argv) {
     for (int i = 1; i < argc; i++) {
         std::string arg = argv[i];
         if (arg.find(spdlog_level_prefix) == 0) {
-            auto levels_string = arg.substr(spdlog_level_prefix.size());
-            helpers::load_levels(levels_string);
+            const auto levels_spec = arg.substr(spdlog_level_prefix.size());
+            helpers::load_levels(levels_spec);
         }
     }
 }

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:
@@ -26,9 +26,9 @@
 namespace spdlog {
 namespace cfg {
 inline void load_env_levels(const char* var = "SPDLOG_LEVEL") {
-    auto env_val = details::os::getenv(var);
-    if (!env_val.empty()) {
-        helpers::load_levels(env_val);
+    const auto levels_spec = details::os::getenv(var);
+    if (!levels_spec.empty()) {
+        helpers::load_levels(levels_spec);
     }
 }
 

include/spdlog/cfg/helpers-inl.h

@@ -70,12 +70,12 @@ inline std::unordered_map<std::string, std::string> extract_key_vals_(const std:
     return rv;
 }
 
-SPDLOG_INLINE void load_levels(const std::string &input) {
-    if (input.empty() || input.size() >= 32768) {
+SPDLOG_INLINE void load_levels(const std::string &levels_spec) {
+    if (levels_spec.empty() || levels_spec.size() >= 32768) {
         return;
     }
 
-    auto key_vals = extract_key_vals_(input);
+    auto key_vals = extract_key_vals_(levels_spec);
     std::unordered_map<std::string, level::level_enum> levels;
     level::level_enum global_level = level::info;
     bool global_level_found = false;
@@ -83,7 +83,7 @@ SPDLOG_INLINE void load_levels(const std::string &input) {
     for (auto &name_level : key_vals) {
         const auto &logger_name = name_level.first;
         const auto &level_name = to_lower_(name_level.second);
-        auto level = level::from_str(level_name);
+        const auto level = level::from_str(level_name);
         // ignore unrecognized level names
         if (level == level::off && level_name != "off") {
             continue;

include/spdlog/cfg/helpers.h

@@ -18,7 +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 void load_levels(const std::string &txt);
+SPDLOG_API void load_levels(const std::string &levels_spec);
 }  // namespace helpers
 
 }  // namespace cfg

include/spdlog/common-inl.h

@@ -9,6 +9,7 @@
 
 #include <algorithm>
 #include <iterator>
+#include <cctype>
 
 namespace spdlog {
 namespace level {
@@ -29,15 +30,31 @@ SPDLOG_INLINE const char *to_short_c_str(spdlog::level::level_enum l) SPDLOG_NOE
 }
 
 SPDLOG_INLINE spdlog::level::level_enum from_str(const std::string &name) SPDLOG_NOEXCEPT {
-    auto it = std::find(std::begin(level_string_views), std::end(level_string_views), name);
+    auto it = std::find_if(std::begin(level_string_views), std::end(level_string_views),
+                           [&name](const string_view_t &level_name) {
+                               return level_name.size() == name.size() &&
+                                      std::equal(name.begin(), name.end(), level_name.begin(),
+                                                 [](char a, char b) {
+                                                     return std::tolower(static_cast<unsigned char>(a)) ==
+                                                            std::tolower(static_cast<unsigned char>(b));
+                                                 });
+                           });
     if (it != std::end(level_string_views))
         return static_cast<level::level_enum>(std::distance(std::begin(level_string_views), it));
 
     // check also for "warn" and "err" before giving up..
-    if (name == "warn") {
+    auto iequals = [](const std::string &a, const std::string &b) {
+        return a.size() == b.size() &&
+               std::equal(a.begin(), a.end(), b.begin(), [](char ac, char bc) {
+                   return std::tolower(static_cast<unsigned char>(ac)) ==
+                          std::tolower(static_cast<unsigned char>(bc));
+               });
+    };
+
+    if (iequals(name, "warn")) {
         return level::warn;
     }
-    if (name == "err") {
+    if (iequals(name, "err")) {
         return level::err;
     }
     return level::off;

include/spdlog/common.h

@@ -340,38 +340,6 @@ struct file_event_handlers {
 
 namespace details {
 
-// to_string_view
-
-SPDLOG_CONSTEXPR_FUNC spdlog::string_view_t to_string_view(const memory_buf_t &buf)
-    SPDLOG_NOEXCEPT {
-    return spdlog::string_view_t{buf.data(), buf.size()};
-}
-
-SPDLOG_CONSTEXPR_FUNC spdlog::string_view_t to_string_view(spdlog::string_view_t str)
-    SPDLOG_NOEXCEPT {
-    return str;
-}
-
-#if defined(SPDLOG_WCHAR_FILENAMES) || defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
-SPDLOG_CONSTEXPR_FUNC spdlog::wstring_view_t to_string_view(const wmemory_buf_t &buf)
-    SPDLOG_NOEXCEPT {
-    return spdlog::wstring_view_t{buf.data(), buf.size()};
-}
-
-SPDLOG_CONSTEXPR_FUNC spdlog::wstring_view_t to_string_view(spdlog::wstring_view_t str)
-    SPDLOG_NOEXCEPT {
-    return str;
-}
-#endif
-
-#if defined(SPDLOG_USE_STD_FORMAT) && __cpp_lib_format >= 202207L
-template <typename T, typename... Args>
-SPDLOG_CONSTEXPR_FUNC std::basic_string_view<T> to_string_view(
-    std::basic_format_string<T, Args...> fmt) SPDLOG_NOEXCEPT {
-    return fmt.get();
-}
-#endif
-
 // make_unique support for pre c++14
 #if __cplusplus >= 201402L  // C++14 and beyond
 using std::enable_if_t;

include/spdlog/details/null_mutex.h

@@ -15,7 +15,7 @@ struct null_mutex {
 };
 
 struct null_atomic_int {
-    int value;
+    int value{0};
     null_atomic_int() = default;
 
     explicit null_atomic_int(int new_value)

include/spdlog/details/registry-inl.h

@@ -257,7 +257,7 @@ SPDLOG_INLINE void registry::throw_if_exists_(const std::string &logger_name) {
 }
 
 SPDLOG_INLINE void registry::register_logger_(std::shared_ptr<logger> new_logger) {
-    auto &logger_name = new_logger->name();
+    const auto &logger_name = new_logger->name();
     throw_if_exists_(logger_name);
     loggers_[logger_name] = std::move(new_logger);
 }

include/spdlog/details/udp_client.h

@@ -69,10 +69,9 @@ public:
     // Send exactly n_bytes of the given data.
     // On error close the connection and throw.
     void send(const char *data, size_t n_bytes) {
-        ssize_t toslen = 0;
-        socklen_t tolen = sizeof(struct sockaddr);
-        if ((toslen = ::sendto(socket_, data, n_bytes, 0, (struct sockaddr *)&sockAddr_, tolen)) ==
-            -1) {
+        socklen_t tolen = sizeof(sockAddr_);
+        if (::sendto(socket_, data, n_bytes, 0, reinterpret_cast<const sockaddr *>(&sockAddr_),
+                     tolen) == -1) {
             throw_spdlog_ex("sendto(2) failed", errno);
         }
     }

include/spdlog/logger-inl.h

@@ -164,8 +164,7 @@ SPDLOG_INLINE void logger::dump_backtrace_() {
 }
 
 SPDLOG_INLINE bool logger::should_flush_(const details::log_msg &msg) const {
-    auto flush_level = flush_level_.load(std::memory_order_relaxed);
-    return (msg.level >= flush_level) && (msg.level != level::off);
+    return (msg.level >= flush_level()) && (msg.level != level::off);
 }
 
 SPDLOG_INLINE void logger::err_handler_(const std::string &msg) const {

include/spdlog/logger.h

@@ -77,7 +77,11 @@ public:
 
     template <typename... Args>
     void log(source_loc loc, level::level_enum lvl, format_string_t<Args...> fmt, Args &&...args) {
-        log_(loc, lvl, details::to_string_view(fmt), std::forward<Args>(args)...);
+#if defined(SPDLOG_USE_STD_FORMAT) && __cpp_lib_format < 202207L
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
+#else
+        log_(loc, lvl, fmt.get(), std::forward<Args>(args)...);
+#endif
     }
 
     template <typename... Args>
@@ -158,7 +162,11 @@ public:
 #ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
     template <typename... Args>
     void log(source_loc loc, level::level_enum lvl, wformat_string_t<Args...> fmt, Args &&...args) {
-        log_(loc, lvl, details::to_string_view(fmt), std::forward<Args>(args)...);
+#if defined(SPDLOG_USE_STD_FORMAT) && __cpp_lib_format < 202207L
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
+#else
+        log_(loc, lvl, fmt.get(), std::forward<Args>(args)...);
+#endif
     }
 
     template <typename... Args>
@@ -258,7 +266,7 @@ public:
         log(level::critical, msg);
     }
 
-    // return true logging is enabled for the given level.
+    // return true if logging is enabled for the given level.
     bool should_log(level::level_enum msg_level) const {
         return msg_level >= level_.load(std::memory_order_relaxed);
     }

include/spdlog/pattern_formatter-inl.h

@@ -813,7 +813,7 @@ public:
         : flag_formatter(padinfo) {}
 
     void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override {
-        auto &mdc_map = mdc::get_context();
+        const auto &mdc_map = mdc::get_context();
         if (mdc_map.empty()) {
             ScopedPadder p(0, padinfo_, dest);
             return;
@@ -823,11 +823,10 @@ public:
     }
 
     void format_mdc(const mdc::mdc_map_t &mdc_map, memory_buf_t &dest) {
-        auto last_element = --mdc_map.end();
+        const auto last_element = std::prev(mdc_map.end());
         for (auto it = mdc_map.begin(); it != mdc_map.end(); ++it) {
-            auto &pair = *it;
-            const auto &key = pair.first;
-            const auto &value = pair.second;
+            const auto &key = it->first;
+            const auto &value = it->second;
             size_t content_size = key.size() + value.size() + 1;  // 1 for ':'
 
             if (it != last_element) {
@@ -1012,7 +1011,7 @@ SPDLOG_INLINE void pattern_formatter::set_pattern(std::string pattern) {
 
 SPDLOG_INLINE void pattern_formatter::need_localtime(bool need) { need_localtime_ = need; }
 
-SPDLOG_INLINE std::tm pattern_formatter::get_time_(const details::log_msg &msg) {
+SPDLOG_INLINE std::tm pattern_formatter::get_time_(const details::log_msg &msg) const {
     if (pattern_time_type_ == pattern_time_type::local) {
         return details::os::localtime(log_clock::to_time_t(msg.time));
     }

include/spdlog/pattern_formatter.h

@@ -99,7 +99,7 @@ private:
     std::vector<std::unique_ptr<details::flag_formatter>> formatters_;
     custom_flags custom_handlers_;
 
-    std::tm get_time_(const details::log_msg &msg);
+    std::tm get_time_(const details::log_msg &msg) const;
     template <typename Padder>
     void handle_flag_(char flag, details::padding_info padding);
 

include/spdlog/sinks/daily_file_sink.h

@@ -88,8 +88,8 @@ public:
         }
 
         auto now = log_clock::now();
-        auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
-        file_helper_.open(filename, truncate_);
+        const auto new_filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
+        file_helper_.open(new_filename, truncate_);
         rotation_tp_ = next_rotation_tp_();
 
         if (max_files_ > 0) {
@@ -107,8 +107,8 @@ protected:
         auto time = msg.time;
         bool should_rotate = time >= rotation_tp_;
         if (should_rotate) {
-            auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(time));
-            file_helper_.open(filename, truncate_);
+            const auto new_filename = FileNameCalc::calc_filename(base_filename_, now_tm(time));
+            file_helper_.open(new_filename, truncate_);
             rotation_tp_ = next_rotation_tp_();
         }
         memory_buf_t formatted;
@@ -131,11 +131,11 @@ private:
         std::vector<filename_t> filenames;
         auto now = log_clock::now();
         while (filenames.size() < max_files_) {
-            auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
-            if (!path_exists(filename)) {
+            const auto new_filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
+            if (!path_exists(new_filename)) {
                 break;
             }
-            filenames.emplace_back(filename);
+            filenames.emplace_back(new_filename);
             now -= std::chrono::hours(24);
         }
         for (auto iter = filenames.rbegin(); iter != filenames.rend(); ++iter) {

include/spdlog/sinks/dist_sink.h

@@ -24,7 +24,7 @@ class dist_sink : public base_sink<Mutex> {
 public:
     dist_sink() = default;
     explicit dist_sink(std::vector<std::shared_ptr<sink>> sinks)
-        : sinks_(sinks) {}
+        : sinks_(std::move(sinks)) {}
 
     dist_sink(const dist_sink &) = delete;
     dist_sink &operator=(const dist_sink &) = delete;

include/spdlog/sinks/dup_filter_sink.h

@@ -43,6 +43,11 @@ public:
     explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration)
         : max_skip_duration_{max_skip_duration} {}
 
+    template <class Rep, class Period>
+    explicit dup_filter_sink(std::chrono::duration<Rep, Period> max_skip_duration, std::vector<std::shared_ptr<sink>> sinks)
+        : max_skip_duration_{max_skip_duration}
+        , dist_sink<Mutex>(std::move(sinks)) {}
+
 protected:
     std::chrono::microseconds max_skip_duration_;
     log_clock::time_point last_msg_time_;
@@ -78,8 +83,8 @@ protected:
     }
 
     // return whether the log msg should be displayed (true) or skipped (false)
-    bool filter_(const details::log_msg &msg) {
-        auto filter_duration = msg.time - last_msg_time_;
+    bool filter_(const details::log_msg &msg) const {
+        const auto filter_duration = msg.time - last_msg_time_;
         return (filter_duration > max_skip_duration_) || (msg.payload != last_msg_payload_);
     }
 };

include/spdlog/sinks/udp_sink.h

@@ -36,7 +36,7 @@ template <typename Mutex>
 class udp_sink : public spdlog::sinks::base_sink<Mutex> {
 public:
     // host can be hostname or ip address
-    explicit udp_sink(udp_sink_config sink_config)
+    explicit udp_sink(const udp_sink_config& sink_config)
         : client_{sink_config.server_host, sink_config.server_port} {}
 
     ~udp_sink() override = default;

include/spdlog/spdlog.h

@@ -75,7 +75,7 @@ SPDLOG_API level::level_enum get_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);
+SPDLOG_API bool should_log(level::level_enum log_level);
 
 // Set a global flush level
 SPDLOG_API void flush_on(level::level_enum log_level);

tests/test_cfg.cpp

@@ -176,3 +176,33 @@ TEST_CASE("restore-to-default", "[cfg]") {
     load_argv_levels(2, argv);
     REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
 }
+
+TEST_CASE("uppercase-level-names", "[cfg]") {
+    spdlog::drop("l1");
+    spdlog::drop("l2");
+    
+#ifdef CATCH_PLATFORM_WINDOWS
+    _putenv_s("SPDLOG_LEVEL", "l1=DEBUG,INFO");
+#else
+    setenv("SPDLOG_LEVEL", "l1=DEBUG,INFO", 1);
+#endif
+    load_env_levels();
+    auto l1 = spdlog::create<test_sink_st>("l1");
+    auto l2 = spdlog::create<test_sink_st>("l2");
+    
+    REQUIRE(l1->level() == spdlog::level::debug);
+    REQUIRE(l2->level() == spdlog::level::info);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::info);
+    
+    // Test with argv
+    spdlog::drop("l3");
+    const char *argv[] = {"ignore", "SPDLOG_LEVEL=l3=WARN,ERROR"};
+    load_argv_levels(2, argv);
+    auto l3 = spdlog::create<test_sink_st>("l3");
+    
+    REQUIRE(l3->level() == spdlog::level::warn);
+    REQUIRE(spdlog::default_logger()->level() == spdlog::level::err);
+    
+    // Reset to info
+    spdlog::set_level(spdlog::level::info);
+}

tests/test_fmt_helper.cpp

@@ -2,7 +2,11 @@
 #include "includes.h"
 
 using spdlog::memory_buf_t;
-using spdlog::details::to_string_view;
+
+SPDLOG_CONSTEXPR_FUNC spdlog::string_view_t to_string_view(const memory_buf_t &buf)
+    SPDLOG_NOEXCEPT {
+    return spdlog::string_view_t{buf.data(), buf.size()};
+}
 
 void test_pad2(int n, const char *expected) {
     memory_buf_t buf;

tests/test_misc.cpp

@@ -73,6 +73,17 @@ TEST_CASE("to_level_enum", "[convert_to_level_enum]") {
     REQUIRE(spdlog::level::from_str("critical") == spdlog::level::critical);
     REQUIRE(spdlog::level::from_str("off") == spdlog::level::off);
     REQUIRE(spdlog::level::from_str("null") == spdlog::level::off);
+    REQUIRE(spdlog::level::from_str("TRACE") == spdlog::level::trace);
+    REQUIRE(spdlog::level::from_str("DEBUG") == spdlog::level::debug);
+    REQUIRE(spdlog::level::from_str("INFO") == spdlog::level::info);
+    REQUIRE(spdlog::level::from_str("WARNING") == spdlog::level::warn);
+    REQUIRE(spdlog::level::from_str("WARN") == spdlog::level::warn);
+    REQUIRE(spdlog::level::from_str("ERROR") == spdlog::level::err);
+    REQUIRE(spdlog::level::from_str("ERR") == spdlog::level::err);
+    REQUIRE(spdlog::level::from_str("CRITICAL") == spdlog::level::critical);
+    REQUIRE(spdlog::level::from_str("OFF") == spdlog::level::off);
+    REQUIRE(spdlog::level::from_str("TrAcE") == spdlog::level::trace);
+    REQUIRE(spdlog::level::from_str("DeBuG") == spdlog::level::debug);
 }
 
 TEST_CASE("periodic flush", "[periodic_flush]") {

tests/test_pattern_formatter.cpp

@@ -4,7 +4,11 @@
 #include <chrono>
 
 using spdlog::memory_buf_t;
-using spdlog::details::to_string_view;
+
+SPDLOG_CONSTEXPR_FUNC spdlog::string_view_t to_string_view(const memory_buf_t &buf)
+    SPDLOG_NOEXCEPT {
+    return spdlog::string_view_t{buf.data(), buf.size()};
+}
 
 // log to str and return it
 template <typename... Args>

tests/test_timezone.cpp

@@ -76,9 +76,56 @@ public:
 
 using spdlog::details::os::utc_minutes_offset;
 
+/*
+ * POSIX 2024 defines three formats for the TZ environment variable,
+ *
+ * 1. Implementation defined format which always starts with a colon:
+ *    ":characters".
+ * 2. A specifier which fully describes the timezone rule in format
+ *    "stdoffset[dst[offset][,start[/time],end[/time]]]". Note the
+ *    offset and start/end part could be omitted, in which case one hour
+ *    is implied, or it's considered implementation-defined when changing
+ *    to and from Daylight Saving Time occurs.
+ * 3. Geographical or special timezone from an implementation-defined
+ *    timezone database.
+ *
+ * On POSIX-compilant systems, we prefer format 2, and explicitly specify the
+ * DST rules to avoid implementation-defined behavior.
+ *
+ * See also IEEE 1003.1-2024 8.3 Other Environment Variables.
+ */
+#ifndef _WIN32
+/*
+ * Standard time is UTC-5 ("EST"), DST time is UTC-4 ("EDT"). DST is active
+ * from 2:00 on the 2nd Sunday in March, to 2:00 on 1st Sunday in November.
+ */
+#define EST5EDT  "EST5EDT,M3.2.0,M11.1.0"
+/*
+ * Standard time is UTC+2 ("IST"), DST time is UTC+3 ("IDT"). DST is active
+ * from 2:00 on following day of the 4th Thursday in March, to 2:00 on the
+ * last Sunday in October.
+ */
+#define IST_MINUS2_IDT "IST-2IDT,M3.4.4/26,M10.5.0"
+#else
+/*
+ * However, Windows doesn't follow the POSIX rules and only accept a TZ
+ * environment variable in format
+ *
+ *   tzn [+|-]hh[:mm[:ss] ][dzn]
+ *
+ * thus we couldn't specify the DST rules. Luckily, Windows C runtime library
+ * assumes the United State's rules for implementing the calculation of DST,
+ * which is fine for our test cases.
+ *
+ * See also https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/tzset?view=msvc-170
+ */
+#define EST5EDT "EST5EDT"
+#define IST_MINUS2_IDT "IST-2IDT"
+#endif
+
 TEST_CASE("UTC Offset - Western Hemisphere (USA - Standard Time)", "[timezone][west]") {
     // EST5EDT: Eastern Standard Time (UTC-5)
-    ScopedTZ tz("EST5EDT");
+    ScopedTZ tz(EST5EDT);
 
     // Jan 15th (Winter)
     auto tm = make_tm(2023, 1, 15, 12, 0);
@@ -87,7 +134,7 @@ TEST_CASE("UTC Offset - Western Hemisphere (USA - Standard Time)", "[timezone][w
 
 TEST_CASE("UTC Offset - Eastern Hemisphere (Europe/Israel - Standard Time)", "[timezone][east]") {
     // IST-2IDT: Israel Standard Time (UTC+2)
-    ScopedTZ tz("IST-2IDT");
+    ScopedTZ tz(IST_MINUS2_IDT);
 
     // Jan 15th (Winter)
     auto tm = make_tm(2023, 1, 15, 12, 0);
@@ -115,14 +162,14 @@ TEST_CASE("UTC Offset - Non-Integer Hour Offsets (India)", "[timezone][partial]"
 }
 
 TEST_CASE("UTC Offset - Edge Case: Negative Offset Crossing Midnight", "[timezone][edge]") {
-    ScopedTZ tz("EST5EDT");
+    ScopedTZ tz(EST5EDT);
     // Late night Dec 31st, 2023
     auto tm = make_tm(2023, 12, 31, 23, 59);
     REQUIRE(utc_minutes_offset(tm) == -300);
 }
 
 TEST_CASE("UTC Offset - Edge Case: Leap Year", "[timezone][edge]") {
-    ScopedTZ tz("EST5EDT");
+    ScopedTZ tz(EST5EDT);
     // Feb 29, 2024 (Leap Day) - Winter
     auto tm = make_tm(2024, 2, 29, 12, 0);
     REQUIRE(utc_minutes_offset(tm) == -300);
@@ -137,10 +184,10 @@ TEST_CASE("UTC Offset - Edge Case: Invalid Date (Pre-Epoch)", "[timezone][edge]"
 #else
     // Unix mktime handles pre-1970 dates correctly.
     // We expect the actual historical offset (EST was UTC-5 in 1960).
-    ScopedTZ tz("EST5EDT");
+    ScopedTZ tz(EST5EDT);
     auto tm = make_tm(1960, 1, 1, 12, 0);
     REQUIRE(utc_minutes_offset(tm) == -300);
 #endif
 }
 
-#endif  // !SPDLOG_NO_TZ_OFFSET
+#endif  // !SPDLOG_NO_TZ_OFFSET