feat universal: remove utils::datetime::date namespace definition

Tests: протестировано CI
commit_hash:5f480953683c3526628566bbb6f3b629b4d562fb

Author: apolukhin

universal/include/userver/utils/datetime/cpp_20_calendar.hpp

@@ -14,22 +14,25 @@ USERVER_NAMESPACE_BEGIN
 namespace utils::datetime {
 
 // TODO: remove the following aliases
-namespace date = std::chrono;
 using Days = std::chrono::days;
 using DaysTimepoint = std::chrono::sys_days;
 
 /// @brief Calculates the number of days between January 1, 00:00 of two years accounting for leap years.
 constexpr std::chrono::days DaysBetweenYears(int from, int to) {
     return std::chrono::duration_cast<Days>(
-        DaysTimepoint{date::year_month_day(date::year(to), date::month(1), date::day(1))} -
-        DaysTimepoint{date::year_month_day(date::year(from), date::month(1), date::day(1))}
+        DaysTimepoint{std::chrono::year_month_day(std::chrono::year(to), std::chrono::month(1), std::chrono::day(1))} -
+        DaysTimepoint{std::chrono::year_month_day(std::chrono::year(from), std::chrono::month(1), std::chrono::day(1))}
     );
 }
 
 /// @brief Get the number of days in the given month of a given year.
 constexpr std::chrono::day DaysInMonth(int month, int year) {
     UINVARIANT(month >= 1 && month <= 12, "Month must be between 1 and 12");
-    return date::year_month_day_last(date::year(year), date::month_day_last(date::month(month))).day();
+    return std::chrono::year_month_day_last(
+               std::chrono::year(year),
+               std::chrono::month_day_last(std::chrono::month(month))
+    )
+        .day();
 }
 
 }  // namespace utils::datetime

universal/src/utils/datetime/cpp_20_calendar_test.cpp

@@ -6,7 +6,7 @@
 
 USERVER_NAMESPACE_BEGIN
 
-namespace date = utils::datetime::date;
+namespace date = std::chrono;
 
 TEST(DaysBetweenYears, LeapYear) { EXPECT_EQ(utils::datetime::DaysBetweenYears(2019, 2021).count(), 365 + 366); }
 TEST(DaysBetweenYears, YearOne) { EXPECT_EQ(utils::datetime::DaysBetweenYears(1, 1970).count(), 719162); }

universal/src/utils/datetime/date.cpp

@@ -14,12 +14,14 @@ namespace {
 const std::string kDateFormat = "%Y-%m-%d";
 const auto kUtcTz = cctz::utc_time_zone();
 
-// TODO: replace with C++20 std::chrono::days
-constexpr date::days ToDays(int year, int month, int day) noexcept {
-    const date::year_month_day
-        ymd{date::year{year}, date::month{static_cast<unsigned>(month)}, date::day{static_cast<unsigned>(day)}};
-
-    return date::sys_days{ymd}.time_since_epoch();
+constexpr std::chrono::days ToDays(int year, int month, int day) noexcept {
+    const std::chrono::year_month_day ymd{
+        std::chrono::year{year},
+        std::chrono::month{static_cast<unsigned>(month)},
+        std::chrono::day{static_cast<unsigned>(day)}
+    };
+
+    return std::chrono::sys_days{ymd}.time_since_epoch();
 }
 
 }  // namespace