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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-6396] libstdc++: Make std::chrono::current_zone() default to UTC Date: Wed, 1 Mar 2023 21:26:19 +0000 (GMT) [thread overview] Message-ID: <20230301212619.B2B5F3858D33@sourceware.org> (raw) https://gcc.gnu.org/g:4abd5bc600193e821fbc41995a0b8d9ea42b42c3 commit r13-6396-g4abd5bc600193e821fbc41995a0b8d9ea42b42c3 Author: Jonathan Wakely <jwakely@redhat.com> Date: Tue Feb 28 21:07:48 2023 +0000 libstdc++: Make std::chrono::current_zone() default to UTC This is consistent with the behaviour of glibc, which assumes UTC when /etc/localtime and TZ do not identify a valid time zone. The fallback tzdb used when no valid tzdata exists always contains the UTC zone, so this change means we have a valid tzdb and valid current zone even in the degenerate case. With this default we no longer need the AIX-specific kluge to try and identify TZ values specifying a 0-offset zone. We can just use the UTC default for those, as it has the same effect. It's still possible for chrono::current_zone() to fail, because the user could have provided a custom tzdata.zi file which doesn't contain the UTC time zone, so the "UTC" default would fail to find a valid zone, and throw an exception. That's just user error, they should not provide bad data and expect reasonable behaviour. libstdc++-v3/ChangeLog: * src/c++20/tzdb.cc (chrono::tzdb::current_zone()) Use "UTC" if current time zone cannot be determined. * testsuite/std/time/tzdb/1.cc: Remove conditions based on HAVE_TZDB macro and test all members unconditionally. Diff: --- libstdc++-v3/src/c++20/tzdb.cc | 15 ++++++--------- libstdc++-v3/testsuite/std/time/tzdb/1.cc | 22 +++++++++++----------- 2 files changed, 17 insertions(+), 20 deletions(-) diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc index 2e7e173f0ef..2b68888e3b9 100644 --- a/libstdc++-v3/src/c++20/tzdb.cc +++ b/libstdc++-v3/src/c++20/tzdb.cc @@ -1692,19 +1692,16 @@ namespace std::chrono // https://www.ibm.com/support/pages/managing-time-zone-variable-posix if (const char* env = std::getenv("TZ")) { - string_view s(env); - if (s == "GMT0") - s = "Etc/GMT"; - else if (s.size() == 4 && s[3] == '0') - s = "Etc/UTC"; - - // This will fail unless TZ contains an IANA time zone name, - // or one of the special cases above. - if (auto tz = do_locate_zone(this->zones, this->links, s)) + // This will fail unless TZ contains an IANA time zone name. + if (auto tz = do_locate_zone(this->zones, this->links, env)) return tz; } #endif + // Default to UTC. + if (auto tz = do_locate_zone(this->zones, this->links, "UTC")) + return tz; + __throw_runtime_error("tzdb: cannot determine current zone"); } diff --git a/libstdc++-v3/testsuite/std/time/tzdb/1.cc b/libstdc++-v3/testsuite/std/time/tzdb/1.cc index 64e42701d3b..877a55b8d31 100644 --- a/libstdc++-v3/testsuite/std/time/tzdb/1.cc +++ b/libstdc++-v3/testsuite/std/time/tzdb/1.cc @@ -1,7 +1,6 @@ // { dg-options "-std=gnu++20" } // { dg-do run { target c++20 } } // { dg-require-effective-target cxx11_abi } -// { dg-additional-options "-DHAVE_TZDB" { target tzdb } } #include <chrono> #include <testsuite_hooks.h> @@ -14,22 +13,25 @@ test_version() const tzdb& db = get_tzdb(); VERIFY( &db == &get_tzdb_list().front() ); -#ifdef HAVE_TZDB - VERIFY( db.version == remote_version() ); - const tzdb& reloaded = reload_tzdb(); - if (reloaded.version == db.version) - VERIFY( &reloaded == &db ); -#endif + const char* func; + try { + func = "remote_version"; + VERIFY( db.version == remote_version() ); + func = "reload_tzdb"; + const tzdb& reloaded = reload_tzdb(); + if (reloaded.version == db.version) + VERIFY( &reloaded == &db ); + } catch (const std::exception&) { + std::printf("std::chrono::%s() failed\n", func); + } } void test_current() { -#ifdef HAVE_TZDB const tzdb& db = get_tzdb(); const time_zone* tz = db.current_zone(); VERIFY( tz == std::chrono::current_zone() ); -#endif } void @@ -43,9 +45,7 @@ test_locate() VERIFY( tz == db.locate_zone("Etc/GMT") ); VERIFY( tz == db.locate_zone("Etc/GMT+0") ); -#ifdef HAVE_TZDB VERIFY( db.locate_zone(db.current_zone()->name()) == db.current_zone() ); -#endif } int main()
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