Synchronize v2.x With Changes from v1.x (#3581)

* docs(tasks): v1.x inventory, triage template, merge report; update task checklist

- Record merge-base and export v1-only commits (v2..v1)
- Document failed merge attempt: v2 file tree diverges from v1
- Mark completed checklist items 0.x, 1.x, merge report draft (5.2)

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* fix(pattern): %z with UTC pattern time shows +00:00 (port v1 09a674b7)

- z_formatter takes pattern_time_type; emit +00:00 when pattern uses UTC
- Track port in tasks/commits-ported.txt and merge-report; update checklist

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* fix(os): Windows utc_minutes_offset via mktime/_mkgmtime (port v1 b656d1ce)

- Replace GetTimeZoneInformation-based offset with v1.x mktime/_mkgmtime approach
- Add tests/test_timezone.cpp and extend pattern_formatter tests; update os.h comment

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* test(timezone): POSIX TZ with DST rules; include fcntl in tcp_client_unix (v1 ports)

- 0f7562a0: EST5EDT / IST-2IDT macros for POSIX vs Windows
- d2100d5d: fcntl.h for Unix tcp client header (v2 path)

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* feat(tcp): connect timeouts and socket IO timeouts; ci: checkout@v6 (v1 ports)

- 9ecdf5c8: connect_socket_with_timeout on Unix/Windows; tcp_sink timeout_ms
- 3c61b051: actions/checkout@v6 on all workflows
- tcp_sink: remove duplicate #pragma once

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* feat(dup_filter_sink): ctor with sink list (v1 45b67eee); add full v1 SHA triage table

- tasks/v1-triage-complete.md: 245 commits PORTED/PENDING/N/A for PRD 3A tracking
- Merge report and task checklist updated

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* feat(level): case-insensitive level_from_str; cmake: BUILD_TYPE only if top-level (v1 ports)

- 566b2d14: common.cpp + test_misc (SUPERSEDED note for d5af52d9 in triage)
- dd3ca04a: guard default CMAKE_BUILD_TYPE for add_subdirectory consumers
- Update v1-triage-complete.md counts and statuses

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* v1 parity: MSVC UTF-8, ansicolor/syslog/os, getenv, triage docs

- CMake: SPDLOG_MSVC_UTF8 + /utf-8 for real MSVC only
- ansicolor: protected target_file_; fix set_color_mode_ lock nesting
- os: drop redundant fileapi.h; spdlog::details::os::getenv via std::getenv
- tests: stopwatch waits 500ms; includes/triage/commits-ported/merge-report updates
- Reclassify superseded v1 SHAs (Sep, syslog, stopwatch ms, utf8 tests, etc.)

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* parity: ringbuffer zero capacity, utf8 assert; v1 triage sync

- ringbuffer_sink: throw if n_items==0 (#3436); test expects spdlog_ex
- utf8_to_wstrbuf: assert compares int to static_cast<int>(target.size()) (#3479)
- Triage: PORTED ad725d34 getenv, 677a2d93 stopwatch, 3f7e5028, a6215527;
  SUPERSEDED a45c9390, eeb22c13, 5673e9e5, fe4f9952, 287333ee
- tasks: 27 PORTED / 26 SUPERSEDED / 78 PENDING; merge-report + commits-ported

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* docs(tasks): note regular commits and push after parity ports

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* parity: dup_filter_sink notification level from last duplicate (#3390)

- Remove notification_level ctor arg; track skipped_msg_log_level_ on duplicate skips
- Test: skipped summary line uses same short level as duplicated messages
- Triage: 847db337 PORTED; 28/26/77 counts; merge-report + commits-ported

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* parity: UWP getenv (WINAPI_FAMILY); triage fmt/cfg/no-except

- os_windows: detect non-desktop/UWP for empty getenv (#3489)
- Triage: PORTED 8806ca65; SUPERSEDED e3f5a4fe e655dbb6; N/A ae1de0dc 548b2642
- Counts 29/28/116/72; merge-report + commits-ported

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* parity: qt_sinks sign casts (#3487); triage 9c582574 superseded

- qt_color_sink: qsizetype for UTF-8 color range lengths; index colors_ with size_t
- SUPERSEDED: 9c582574 — os_unix utc_minutes_offset already matches #3366
- Counts 30/29/70; merge-report + commits-ported

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* parity: SPDLOG_NO_TZ_OFFSET (#3483); triage #3360 superseded

- CMake: option SPDLOG_NO_TZ_OFFSET; PUBLIC compile definition when ON
- z_formatter: +??:?? when macro; else keep UTC +00:00 and local offset
- utc_minutes_offset: stub on Unix/Windows when macro
- test_pattern_formatter: %z UTC case matches placeholder when NO_TZ
- SUPERSEDED 10320184 (ScopedPadder / %D already in v2)
- Triage 31/30/68; merge-report + commits-ported

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* triage: supersede 5931a3d6 ba508057 47b7e7c7 (already on v2 tree)

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* tasks: sync 5.1 triage counts (33 superseded, 65 pending)

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* parity: MSVC/clang hygiene #3515–#3519 #3521; triage batch

- dup_filter_sink: filter_ const, const filter_duration (#3515)
- logger: should_flush uses flush_level() (#3516)
- daily_file_sink: new_filename locals (#3516)
- spdlog::should_log(level log_level) (#3519)
- example my_type value_ / ctor param (#3521)
- Triage: PORTED 1774e700 309204d5 f2a9dec0 472945ba; N/A d299603e 57505989;
  SUPERSEDED 1ef8d3ce 8cfd4a7e; fix ba508057 row

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* parity: udp_sink const udp_sink_config& (#3520); triage fc7e9c87 1685e694

- dist_sink already used std::move(sinks)
- SUPERSEDED: no common-inl.h on v2; log_with_format_ avoids fmt copy path (#3541)

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* parity: README fmt::format_to (#3259); triage 2670f47d d276069a 951c5b99

- Document ambiguous format_to fix in README user-defined type example
- SUPERSEDED: z_formatter warning, fmt11 const formatter, rotate_now + test

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* parity: lock rotate_now mutex (#3281); triage a2b42620 f355b3d5 d276069a

- rotating_file_sink::rotate_now matches #3281 (sync with sink_it_)
- SUPERSEDED: CMake 3.10..3.21 (v2 uses 3.23); daily test fmt::format; fmt11 const row

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* parity: basic_file_sink::truncate (#3280); triage fwrite/fmt/test batch

- truncate(): lock + file_helper::reopen(true)
- test basic_file_sink_truncate
- SUPERSEDED: b7e0e2c2 71925ca3 fa6605dc 885b5473 96c9a62b 1e6250e1 d7155530

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* parity: test_sink/callback iterator cast (#3315); triage Catch2 #3038

- difference_type cast for formatted.end() - eol_len (ad0f31c0)
- SUPERSEDED: c1569a3d Catch2 v3.5.0, 73e2e02b wstr_to_utf8buf bounds

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* parity: SPDLOG_WCHAR_CONSOLE WriteConsoleW path (#3092); triage b6da5944

- WIN32 option SPDLOG_WCHAR_CONSOLE; SPDLOG_UTF8_TO_WCHAR_CONSOLE in private defs
- wincolor print_range_: utf8_to_wstrbuf + WriteConsoleW when defined
- N/A: async_msg flush_callback move-assign (no v1 shape on v2)

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* triage: v1 async_logger/thread_pool + fmt 11.1 batch (15 SHAs)

- N/A: fe79bfcc 6725584e async tests 16e0d2e7 63d18842 d8e0ad46 1e7d7e07 3c23c27d
- SUPERSEDED: faa0a7a9 85bdab0c 276ee5f5 7f8060d5 96a8f625
- Counts: 58 SUPERSEDED, 129 N/A, 17 PENDING; merge-report subsection

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* Port v1 TSAN CMake (#3237); close 3A triage (MDC N/A, fmt 5A)

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* docs(triage): note 3A table complete

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* 5A: bundle fmt 12.1.0 (match v1.x), FMT_INSTALL, MSVC /wd4834, find_dependency(fmt 12)

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* docs(5.4): migration and release notes for v1 parity integration branch

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* docs: cross-link migration notes; refresh PRD/tasks/merge-report for completed 5A/3A

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* revert: remove README and PRD cross-links to migration notes

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* docs(merge-report): audit — add 9fe79692 to ports table; fix 6004e3d1 paths

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* Remove tasks

* PR comment fixes

* Fix small random issues

* Fix PR comments - un-remove the comment and allow any fmt library version

---------

Co-authored-by: Jan Moravec <jan.moravec@hidglobal.com>

src/details/os_unix.cpp

@@ -127,8 +127,12 @@ size_t filesize(FILE *f) {
     return 0;  // will not be reached.
 }
 
-// Return utc offset in minutes or throw spdlog_ex on failure
+// Return utc offset in minutes (0 on failure to compute offset)
 int utc_minutes_offset(const std::tm &tm) {
+#if defined(SPDLOG_NO_TZ_OFFSET)
+    (void)tm;
+    return 0;
+#else
     #if defined(sun) || defined(__sun) || defined(_AIX) || \
        (defined(__NEWLIB__) && !defined(__TM_GMTOFF)) ||  \
        (!defined(__APPLE__) && !defined(_BSD_SOURCE) && !defined(_GNU_SOURCE) && \
@@ -165,6 +169,7 @@ int utc_minutes_offset(const std::tm &tm) {
     auto offset_seconds = tm.tm_gmtoff;
 #endif
     return static_cast<int>(offset_seconds / 60);
+#endif  // SPDLOG_NO_TZ_OFFSET
 }
 
 // Return current thread id as size_t
@@ -269,8 +274,8 @@ bool is_color_terminal() noexcept {
 bool in_terminal(FILE *file) noexcept { return ::isatty(fileno(file)) != 0; }
 
 std::string getenv(const char *field) {
-    char *buf = ::getenv(field);
-    return buf != nullptr ? buf : std::string{};
+    char *buf = std::getenv(field);
+    return buf != nullptr ? std::string(buf) : std::string{};
 }
 
 // Do fsync by FILE pointer

src/details/os_windows.cpp

@@ -6,10 +6,9 @@
 #endif
 
 // clang-format off
-#include "spdlog/details/windows_include.h" // must be included before fileapi.h etc.
+#include "spdlog/details/windows_include.h" // must be first; provides FlushFileBuffers via Windows headers
 // clang-format on
 
-#include <fileapi.h>  // for FlushFileBuffers
 #include <io.h>       // for _get_osfhandle, _isatty, _fileno
 #include <process.h>  // for _get_pid
 #include <sys/stat.h>
@@ -107,24 +106,27 @@ size_t filesize(FILE *f) {
     #pragma warning(pop)
 #endif
 
-// Return utc offset in minutes or throw spdlog_ex on failure
+// Compare the timestamp as local (mktime) vs UTC (_mkgmtime) to get the offset.
+// Matches v1.x behavior: better historical DST handling than GetTimeZoneInformation alone.
 int utc_minutes_offset(const std::tm &tm) {
-#if _WIN32_WINNT < _WIN32_WINNT_WS08
-    TIME_ZONE_INFORMATION tzinfo;
-    auto rv = ::GetTimeZoneInformation(&tzinfo);
+#if defined(SPDLOG_NO_TZ_OFFSET)
+    (void)tm;
+    return 0;
 #else
-    DYNAMIC_TIME_ZONE_INFORMATION tzinfo;
-    auto rv = ::GetDynamicTimeZoneInformation(&tzinfo);
-#endif
-    if (rv == TIME_ZONE_ID_INVALID) throw_spdlog_ex("Failed getting timezone info. ", errno);
-
-    int offset = -tzinfo.Bias;
-    if (tm.tm_isdst) {
-        offset -= tzinfo.DaylightBias;
-    } else {
-        offset -= tzinfo.StandardBias;
+    std::tm local_tm = tm;  // copy since mktime might adjust it (normalize dates, set tm_isdst)
+    std::time_t local_time_t = std::mktime(&local_tm);
+    if (local_time_t == static_cast<std::time_t>(-1)) {
+        return 0;  // fallback
     }
-    return offset;
+
+    std::time_t utc_time_t = _mkgmtime(&local_tm);
+    if (utc_time_t == static_cast<std::time_t>(-1)) {
+        return 0;  // fallback
+    }
+
+    const auto offset_seconds = utc_time_t - local_time_t;
+    return static_cast<int>(offset_seconds / 60);
+#endif
 }
 
 // Return current thread id as size_t
@@ -212,7 +214,7 @@ void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target) {
         target.resize(result_size);
         result_size = ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(), result_size);
         if (result_size > 0) {
-            assert(result_size == target.size());
+            assert(result_size == static_cast<int>(target.size()));
             return;
         }
     }
@@ -220,21 +222,22 @@ void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target) {
     throw_spdlog_ex(fmt_lib::format("MultiByteToWideChar failed. Last error: {}", ::GetLastError()));
 }
 
+#ifdef _MSC_VER
+    #pragma warning(push)
+    #pragma warning(disable : 4996)
+#endif
 std::string getenv(const char *field) {
-#if defined(_MSC_VER)
-    #if defined(__cplusplus_winrt)
-    return std::string{};  // not supported under uwp
-    #else
-    size_t len = 0;
-    char buf[128];
-    bool ok = ::getenv_s(&len, buf, sizeof(buf), field) == 0;
-    return ok ? buf : std::string{};
-    #endif
-#else  // revert to getenv
-    char *buf = ::getenv(field);
-    return buf != nullptr ? buf : std::string{};
+#if defined(_MSC_VER) && defined(WINAPI_FAMILY) && defined(WINAPI_FAMILY_DESKTOP_APP) && \
+    (WINAPI_FAMILY != WINAPI_FAMILY_DESKTOP_APP)
+    return std::string{};  // not supported on UWP / non-desktop WinRT targets (#3489)
+#else
+    char *buf = std::getenv(field);
+    return buf != nullptr ? std::string(buf) : std::string{};
 #endif
 }
+#ifdef _MSC_VER
+    #pragma warning(pop)
+#endif
 
 // Do fsync by FILE handlerpointer
 // Return true on success