For USE_OS_TZDB, look for leap seconds in the files

leapseconds and leap-seconds.list

include/date/tz.h

@@ -86,15 +86,6 @@ static_assert(HAS_REMOTE_API == 0 ? AUTO_DOWNLOAD == 0 : true,
 #  ifdef _WIN32
 #    error "USE_OS_TZDB can not be used on Windows"
 #  endif
-#  ifndef MISSING_LEAP_SECONDS
-#    ifdef __APPLE__
-#      define MISSING_LEAP_SECONDS 1
-#    else
-#      define MISSING_LEAP_SECONDS 0
-#    endif
-#  endif
-#else
-#  define MISSING_LEAP_SECONDS 0
 #endif
 
 #ifndef HAS_DEDUCTION_GUIDES
@@ -995,8 +986,6 @@ inline bool operator>=(const time_zone_link& x, const time_zone_link& y) {return
 
 #endif  // !USE_OS_TZDB
 
-#if !MISSING_LEAP_SECONDS
-
 class leap_second
 {
 private:
@@ -1120,8 +1109,6 @@ operator>=(const sys_time<Duration>& x, const leap_second& y)
 
 using leap = leap_second;
 
-#endif  // !MISSING_LEAP_SECONDS
-
 #ifdef _WIN32
 
 namespace detail
@@ -1167,9 +1154,7 @@ struct tzdb
 #if !USE_OS_TZDB
     std::vector<time_zone_link> links;
 #endif
-#if !MISSING_LEAP_SECONDS
     std::vector<leap_second>    leap_seconds;
-#endif
 #if !USE_OS_TZDB
     std::vector<detail::Rule>   rules;
 #endif
@@ -1864,8 +1849,6 @@ operator<<(std::basic_ostream<CharT, Traits>& os, const zoned_time<Duration, Tim
     return to_stream(os, fmt, t);
 }
 
-#if !MISSING_LEAP_SECONDS
-
 class utc_clock
 {
 public:
@@ -2804,8 +2787,6 @@ to_gps_time(const tai_time<Duration>& t)
     return gps_clock::from_utc(tai_clock::to_utc(t));
 }
 
-#endif  // !MISSING_LEAP_SECONDS
-
 }  // namespace date
 
 #endif  // TZ_H

src/tz.cpp

@@ -465,6 +465,32 @@ get_tzdb_list()
     return tz_db;
 }
 
+static
+std::string
+parse3(std::istream& in)
+{
+    std::string r(3, ' ');
+    ws(in);
+    r[0] = static_cast<char>(in.get());
+    r[1] = static_cast<char>(in.get());
+    r[2] = static_cast<char>(in.get());
+    return r;
+}
+
+static
+unsigned
+parse_month(std::istream& in)
+{
+    CONSTDATA char*const month_names[] =
+        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+    auto s = parse3(in);
+    auto m = std::find(std::begin(month_names), std::end(month_names), s) - month_names;
+    if (m >= std::end(month_names) - std::begin(month_names))
+        throw std::runtime_error("oops: bad month name: " + s);
+    return static_cast<unsigned>(++m);
+}
+
 #if !USE_OS_TZDB
 
 #ifdef _WIN32
@@ -679,18 +705,6 @@ load_timezone_mappings_from_xml_file(const std::string& input_path)
 
 // Parsing helpers
 
-static
-std::string
-parse3(std::istream& in)
-{
-    std::string r(3, ' ');
-    ws(in);
-    r[0] = static_cast<char>(in.get());
-    r[1] = static_cast<char>(in.get());
-    r[2] = static_cast<char>(in.get());
-    return r;
-}
-
 static
 unsigned
 parse_dow(std::istream& in)
@@ -704,20 +718,6 @@ parse_dow(std::istream& in)
     return static_cast<unsigned>(dow);
 }
 
-static
-unsigned
-parse_month(std::istream& in)
-{
-    CONSTDATA char*const month_names[] =
-        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
-         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
-    auto s = parse3(in);
-    auto m = std::find(std::begin(month_names), std::end(month_names), s) - month_names;
-    if (m >= std::end(month_names) - std::begin(month_names))
-        throw std::runtime_error("oops: bad month name: " + s);
-    return static_cast<unsigned>(++m);
-}
-
 static
 std::chrono::seconds
 parse_unsigned_time(std::istream& in)
@@ -2221,15 +2221,11 @@ operator<<(std::ostream& os, const time_zone& z)
     return os;
 }
 
-#if !MISSING_LEAP_SECONDS
-
 leap_second::leap_second(const sys_seconds& s, detail::undocumented)
     : date_(s)
 {
 }
 
-#endif  // !MISSING_LEAP_SECONDS
-
 #else  // !USE_OS_TZDB
 
 time_zone::time_zone(const std::string& s, detail::undocumented)
@@ -2626,8 +2622,6 @@ operator<<(std::ostream& os, const time_zone& z)
 
 #endif  // !USE_OS_TZDB
 
-#if !MISSING_LEAP_SECONDS
-
 std::ostream&
 operator<<(std::ostream& os, const leap_second& x)
 {
@@ -2635,8 +2629,6 @@ operator<<(std::ostream& os, const leap_second& x)
     return os << x.date_ << "  +";
 }
 
-#endif  // !MISSING_LEAP_SECONDS
-
 #if USE_OS_TZDB
 
 # ifdef __APPLE__
@@ -2655,6 +2647,85 @@ get_version()
 }
 # endif
 
+static
+std::vector<leap_second>
+find_read_and_leap_seconds()
+{
+    std::ifstream in(get_tz_dir() + std::string(1, folder_delimiter) + "leapseconds",
+                     std::ios_base::binary);
+    if (in)
+    {
+        std::vector<leap_second> leap_seconds;
+        std::string line;
+        while (in)
+        {
+            std::getline(in, line);
+            if (!line.empty() && line[0] != '#')
+            {
+                std::istringstream in(line);
+                in.exceptions(std::ios::failbit | std::ios::badbit);
+                std::string word;
+                in >> word;
+                if (word == "Leap")
+                {
+                    int y, m, d;
+                    in >> y;
+                    m = static_cast<int>(parse_month(in));
+                    in >> d;
+                    leap_seconds.push_back(leap_second(sys_days{year{y}/m/d} + days{1},
+                                                                 detail::undocumented{}));
+                }
+                else
+                {
+                    std::cerr << line << '\n';
+                }
+            }
+        }
+        return leap_seconds;
+    }
+    in.clear();
+    in.open(get_tz_dir() + std::string(1, folder_delimiter) + "leap-seconds.list",
+                     std::ios_base::binary);
+    if (in)
+    {
+        std::vector<leap_second> leap_seconds;
+        std::string line;
+        const auto offset = sys_days{1970_y/1/1}-sys_days{1900_y/1/1};
+        while (in)
+        {
+            std::getline(in, line);
+            if (!line.empty() && line[0] != '#')
+            {
+                std::istringstream in(line);
+                in.exceptions(std::ios::failbit | std::ios::badbit);
+                using seconds = std::chrono::seconds;
+                seconds::rep s;
+                in >> s;
+                if (s == 2272060800)
+                    continue;
+                leap_seconds.push_back(leap_second(sys_seconds{seconds{s}} - offset,
+                                                                 detail::undocumented{}));
+            }
+        }
+        return leap_seconds;
+    }
+    in.clear();
+    in.open(get_tz_dir() + std::string(1, folder_delimiter) + "right/UTC",
+                     std::ios_base::binary);
+    if (in)
+    {
+        return load_just_leaps(in);
+    }
+    in.clear();
+    in.open(get_tz_dir() + std::string(1, folder_delimiter) + "UTC",
+                     std::ios_base::binary);
+    if (in)
+    {
+        return load_just_leaps(in);
+    }
+    return {};
+}
+
 static
 std::unique_ptr<tzdb>
 init_tzdb()
@@ -2709,25 +2780,7 @@ init_tzdb()
     }
     db->zones.shrink_to_fit();
     std::sort(db->zones.begin(), db->zones.end());
-#  if !MISSING_LEAP_SECONDS
+    db->leap_seconds = find_read_and_leap_seconds();
-    std::ifstream in(get_tz_dir() + std::string(1, folder_delimiter) + "right/UTC",
-                     std::ios_base::binary);
-    if (in)
-    {
-        in.exceptions(std::ios::failbit | std::ios::badbit);
-        db->leap_seconds = load_just_leaps(in);
-    }
-    else
-    {
-        in.clear();
-        in.open(get_tz_dir() + std::string(1, folder_delimiter) +
-                "UTC", std::ios_base::binary);
-        if (!in)
-            throw std::runtime_error("Unable to extract leap second information");
-        in.exceptions(std::ios::failbit | std::ios::badbit);
-        db->leap_seconds = load_just_leaps(in);
-    }
-#  endif  // !MISSING_LEAP_SECONDS
 #  ifdef __APPLE__
     db->version = get_version();
 #  endif
@@ -3580,11 +3633,9 @@ operator<<(std::ostream& os, const tzdb& db)
     os << "Version: " << db.version << "\n\n";
     for (const auto& x : db.zones)
         os << x << '\n';
-#if !MISSING_LEAP_SECONDS
     os << '\n';
     for (const auto& x : db.leap_seconds)
         os << x << '\n';
-#endif  // !MISSING_LEAP_SECONDS
     return os;
 }