On Mon, Jul 20, 2026 at 12:41 PM Jonathan Wakely <[email protected]> wrote:
> On Mon, 20 Jul 2026 at 11:16, Jonathan Wakely <[email protected]> wrote: > > > > On Mon, 20 Jul 2026 at 10:54 +0200, Tomasz Kamiński wrote: > > >From: Jonathan Wakely <[email protected]> > > > > > >This change allows the hardcoded list of leap seconds in <chrono> to be > > >used even when the program is executing after the hardcoded expiry date > > >in that header. > > > > > >For times after the hardcoded expiry, the inline __get_leap_second_info > > >function calls a new library function which compares the number of > > >hardcoded leap seconds in the header with the number of leap seconds > > >defined in the tzdata leapseconds file (usually provided by the OS). > > > > > >There are three leap second lists that are relevant here. The first is > > >the hardcoded list (and its expiry time) in the <chrono> header. That is > > >fixed when the user code is compiled, and might be out of date by the > > >time the application runs. The second list (and its expiry time) is > > >hardcoded in tzdb.cc in the libstdc++.so library. If the application > > >uses a newer libstdc++.so at runtime than the <chrono> header used at > > >compile time, we can still avoid going to the filesystem for dates > > >within the expiry time of the list in libstdc++.so. The third list is > > >the most up-to-date one which is read from the leapseconds file. > > > > > >The code added by this commit tries to avoid reading the file when > > >possible (because that's slower than using the in-memory lists), and if > > >it does have to go to the file system, it tries to avoid doing so again > > >next time the leap seconds are needed. The later is handled by storing > > > > "by storing the number" > > > > >of recently know leaps seconds in num_leap_seconds of struct > > >NumLeapSeconds, which decides whether to use std::atomic_ref<unsigned> > > >or perform all accesses while holding a lock on the pre-existing mutex > > >used for the tzdb_list singleton. To set_locked/set functions are used > > > > "Two" > > > > >to differentiate #if/#else branches of _Node::_S_replace_head that > > >already held corresponding mutext and use atomic respectivelly. > > > > "mutex" > > "atomics" > > "respectively" > > > > > > > >libstdc++-v3/ChangeLog: > > > > > > PR libstdc++/123165 > > > * acinclude.m4 (libtool_VERSION): Bump version. > > > * config/abi/pre/gnu.ver (GLIBCXX_3.4.36): Add new symbol > > > version and export new symbol. > > > * configure: Regenerate. > > > * include/std/chrono (__detail::__recent_leap_second_info): > > > Declare new function and make it a friend of varous classes. > > > (leap_second): Make private constructor constexpr. Remove friend > > > declaration for get_leap_second_info. > > > (__detail::__get_leap_second_info): Use new function for times > > > past the hardcoded expiry. > > > * src/c++20/tzdb.cc (tzdb_list::_Node::fixed_leaps): Move array > > > of leap seconds here from _S_read_leap_seconds. > > > (_Node::NumLeapSeconds): New class. > > > (_Node::num_leap_seconds): New static variable. > > > (__detail::__recent_leap_second_info): Define new function. > > > (tzdb_list::_Node::_S_read_leap_seconds): Populate vector from > > > _Node::fixed_leaps. Rename bool variable to clarify meaning. > > > (tzdb_list::_Node::_S_replace_head): Update num_leap_seconds > > > when updating the tzdb_list. > > > * testsuite/util/testsuite_abi.cc: Update known_versions and > > > latestp. > > > * testsuite/std/time/clock/utc/leap_second_info-2.cc: New test. > > > > > >Co-authored-by: Tomasz Kamiński <[email protected]> > > >Signed-off-by: Tomasz Kamiński <[email protected]> > > >(cherry picked from commit e79f0f818c0e42d0d84c90a54684dfb269ac388c) > > >(cherry picked from commit b12fdd952511786bf8d285e7080e94deeb32aa1d) > > >(cherry picked from commit adb4f4a064c009cd616106fa4c648182c18f96d9) > > >(cherry picked from commit a7ad4bee6fe7cd77aceb6e86380dcaeb6da82791) > > >--- > > >As suggested by cherry-pick lines this squashes the original and > > >tree follow-up patches. Please double check if I missed something. > > > > Thanks for squashing these, you got all the relevant commits. > > > > > > > >I am landing this first as this does introduce > > >6.36 version that my format patches uses. > > > > > >I have updated the commit description a bit, please check if you > > >have any suggestions. > > > > > >Testing on x86_64-linux.. OK for gcc-16 when all test passes? > > > > > > libstdc++-v3/acinclude.m4 | 2 +- > > > libstdc++-v3/config/abi/pre/gnu.ver | 7 + > > > libstdc++-v3/configure | 2 +- > > > libstdc++-v3/include/std/chrono | 104 +++---- > > > libstdc++-v3/src/c++20/tzdb.cc | 294 +++++++++++++++--- > > > .../std/time/clock/utc/leap_second_info-2.cc | 108 +++++++ > > > libstdc++-v3/testsuite/util/testsuite_abi.cc | 3 +- > > > 7 files changed, 420 insertions(+), 100 deletions(-) > > > create mode 100644 > libstdc++-v3/testsuite/std/time/clock/utc/leap_second_info-2.cc > > > > > >diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4 > > >index e6e4f7b394a..a615692e7be 100644 > > >--- a/libstdc++-v3/acinclude.m4 > > >+++ b/libstdc++-v3/acinclude.m4 > > >@@ -4096,7 +4096,7 @@ changequote([,])dnl > > > fi > > > > > > # For libtool versioning info, format is CURRENT:REVISION:AGE > > >-libtool_VERSION=6:35:0 > > >+libtool_VERSION=6:36:0 > > > > > > # Everything parsed; figure out what files and settings to use. > > > case $enable_symvers in > > >diff --git a/libstdc++-v3/config/abi/pre/gnu.ver > b/libstdc++-v3/config/abi/pre/gnu.ver > > >index bd4da641829..06892cd2d18 100644 > > >--- a/libstdc++-v3/config/abi/pre/gnu.ver > > >+++ b/libstdc++-v3/config/abi/pre/gnu.ver > > >@@ -2623,6 +2623,13 @@ GLIBCXX_3.4.35 { > > > > > > } GLIBCXX_3.4.34; > > > > > >+# GCC 17.1.0 > > > > This needs to be 16.2.0 (I see you've fixed this locally now). > > > > And we need a follow-up patch on trunk to bump the version to 3.4.37 > > and move the newer symbols (allocate_at_least etc.) to the new > > version. Maybe that should happen first, so that when the gcc-16 > > branch is changed, it matches what's already on trunk. > > I've just approved your patch to do exactly that on trunk, so this one > is OK for gcc-16 now (with the commit msg typos fixed), thanks. > OK, will merge the trunk patch first. Then this patch to GCC-16 (after the full test suite finishes), and after that my format changes. If this change allows them to apply cleanly, I will not send new revision. > > > > > > > > >+GLIBCXX_3.4.36 { > > >+ > > >+ > _ZNSt6chrono8__detail25__recent_leap_second_infoERNS_16leap_second_infoEj; > > >+ > > >+} GLIBCXX_3.4.35; > > >+ > > > # Symbols in the support library (libsupc++) have their own tag. > > > CXXABI_1.3 { > > > > > >diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure > > >index 359545c4bce..bc9dce5e288 100755 > > >--- a/libstdc++-v3/configure > > >+++ b/libstdc++-v3/configure > > >@@ -51429,7 +51429,7 @@ $as_echo "$as_me: WARNING: === Symbol > versioning will be disabled." >&2;} > > > fi > > > > > > # For libtool versioning info, format is CURRENT:REVISION:AGE > > >-libtool_VERSION=6:35:0 > > >+libtool_VERSION=6:36:0 > > > > > > # Everything parsed; figure out what files and settings to use. > > > case $enable_symvers in > > >diff --git a/libstdc++-v3/include/std/chrono > b/libstdc++-v3/include/std/chrono > > >index 674f867dcdc..692fd6025e7 100644 > > >--- a/libstdc++-v3/include/std/chrono > > >+++ b/libstdc++-v3/include/std/chrono > > >@@ -131,6 +131,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > leap_second_info > > > get_leap_second_info(const utc_time<_Duration>& __ut); > > > > > >+ /// @cond undocumented > > >+ namespace __detail > > >+ { > > >+ bool __recent_leap_second_info(leap_second_info&, unsigned); > > >+ } > > >+ /// @endcond > > >+ > > > /** A clock that measures Universal Coordinated Time (UTC). > > > * > > > * The epoch is 1970-01-01 00:00:00. > > >@@ -2818,6 +2825,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > friend class leap_second; > > > friend struct time_zone::_Impl; > > > friend class time_zone_link; > > >+ > > >+ friend bool > > >+ __detail::__recent_leap_second_info(leap_second_info&, unsigned); > > > }; > > > > > > class time_zone_link > > >@@ -2943,16 +2953,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > { return __x.date() <=> __y; } > > > > > > private: > > >- explicit leap_second(seconds::rep __s) : _M_s(__s) { } > > >+ constexpr explicit leap_second(seconds::rep __s) : _M_s(__s) { } > > > > > > friend struct tzdb_list::_Node; > > > > > > friend const tzdb& reload_tzdb(); > > > > > >- template<typename _Duration> > > >- friend leap_second_info > > >- get_leap_second_info(const utc_time<_Duration>&); > > >- > > > seconds _M_s; // == date().time_since_epoch() * value().count() > > > }; > > > > > >@@ -3217,6 +3223,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > > > > namespace __detail > > > { > > >+ // This function is inline to support fast conversions between > utc_time > > >+ // and sys_time when possible, without requiring a chrono::tzdb > object > > >+ // to be constructed. > > > inline leap_second_info > > > __get_leap_second_info(sys_seconds __ss, bool __is_utc) > > > { > > >@@ -3252,65 +3261,56 @@ namespace __detail > > > 1435708800, // 1 Jul 2015 > > > 1483228800, // 1 Jan 2017 > > > }; > > >+ > > >+ // The default result for times after the last leap year. > > >+ constexpr leap_second_info __after_last{ > > >+ .is_leap_second = false, > > >+ .elapsed = seconds(std::size(__leaps)) > > >+ }; > > >+ > > > // The list above is known to be valid until (at least) this date > > > // and only contains positive leap seconds. > > > constexpr sys_seconds __expires(1798416000s); // 2026-12-28 > 00:00:00 UTC > > > > > >-#if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI > > > if (__ss > __expires) > > > { > > >- // Use updated leap_seconds from tzdb. > > >- size_t __n = std::size(__leaps); > > >- > > >- auto __db = get_tzdb_list().begin(); > > >- auto __first = __db->leap_seconds.begin() + __n; > > >- auto __last = __db->leap_seconds.end(); > > >- auto __pos = std::upper_bound(__first, __last, __ss); > > >- seconds __elapsed(__n); > > >- for (auto __i = __first; __i != __pos; ++__i) > > >- __elapsed += __i->value(); > > >- > > >- if (__is_utc) > > >- { > > >- // Convert utc_time to sys_time: > > >- __ss -= __elapsed; > > >- // See if that sys_time is before (or during) previous > leap sec: > > >- if (__pos != __first && __ss < __pos[-1]) > > >- { > > >- if ((__ss + 1s) >= __pos[-1]) > > >- return {true, __elapsed}; > > >- __elapsed -= __pos[-1].value(); > > >- } > > >- } > > >- return {false, __elapsed}; > > >- } > > >- else > > >+#if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI // use > chrono::tzdb > > >+ // Call into the library because it might have knowledge of new > > >+ // leap seconds loaded at runtime from the tzdata files. > > >+ > > >+ // We misuse leap_second_info here to pass {bool, seconds} > inputs: > > >+ leap_second_info __info{ .is_leap_second = __is_utc, > > >+ .elapsed = __ss.time_since_epoch() }; > > >+ // If this returns true, then __info holds the output result: > > >+ if (__detail::__recent_leap_second_info(__info, > std::size(__leaps))) > > >+ return __info; > > > #endif > > >- { > > >- seconds::rep __s = __ss.time_since_epoch().count(); > > >- const seconds::rep* __first = std::begin(__leaps); > > >- const seconds::rep* __last = std::end(__leaps); > > >+ return __after_last; > > >+ } > > > > > >- // Don't bother searching the list if we're after the last one. > > >- if (__s > (__last[-1] + (__last - __first) + 1)) > > >- return { false, seconds(__last - __first) }; > > >+ seconds::rep __s = __ss.time_since_epoch().count(); > > >+ const seconds::rep* __first = std::begin(__leaps); > > >+ const seconds::rep* __last = std::end(__leaps); > > > > > >- auto __pos = std::upper_bound(__first, __last, __s); > > >- seconds __elapsed{__pos - __first}; > > >- if (__is_utc) > > >+ // Don't bother searching the list if we're after the last one. > > >+ if (__s > (__last[-1] + (__last - __first) + 1)) > > >+ return __after_last; > > >+ > > >+ auto __pos = std::upper_bound(__first, __last, __s); > > >+ seconds __elapsed{__pos - __first}; > > >+ if (__is_utc) > > >+ { > > >+ // Convert utc_time to sys_time: > > >+ __s -= __elapsed.count(); > > >+ // See if that sys_time is before (or during) previous leap > sec: > > >+ if (__pos != __first && __s < __pos[-1]) > > > { > > >- // Convert utc_time to sys_time: > > >- __s -= __elapsed.count(); > > >- // See if that sys_time is before (or during) previous > leap sec: > > >- if (__pos != __first && __s < __pos[-1]) > > >- { > > >- if ((__s + 1) >= __pos[-1]) > > >- return {true, __elapsed}; > > >- --__elapsed; > > >- } > > >+ if ((__s + 1) >= __pos[-1]) > > >+ return {true, __elapsed}; > > >+ --__elapsed; > > > } > > >- return {false, __elapsed}; > > > } > > >+ return {false, __elapsed}; > > > } > > > } // namespace __detail > > > > > >diff --git a/libstdc++-v3/src/c++20/tzdb.cc > b/libstdc++-v3/src/c++20/tzdb.cc > > >index b0fbfc46a6d..0013ad1877c 100644 > > >--- a/libstdc++-v3/src/c++20/tzdb.cc > > >+++ b/libstdc++-v3/src/c++20/tzdb.cc > > >@@ -36,6 +36,7 @@ > > > #include <memory> // atomic<shared_ptr<T>> > > > #include <mutex> // mutex > > > #include <iomanip> // quoted > > >+#include <span> > > > #if defined __GTHREADS && ! defined _GLIBCXX_HAS_GTHREADS > > > # include <ext/concurrence.h> // __gnu_cxx::__mutex > > > #endif > > >@@ -66,6 +67,7 @@ > > > #endif > > > > > > #if USE_ATOMIC_SHARED_PTR && ! USE_ATOMIC_LIST_HEAD > > >+// Cannot use atomic<shared_ptr<T>> without lock-free atomic<T*>. > > > # error Unsupported combination > > > #endif > > > > > >@@ -196,6 +198,13 @@ namespace std::chrono > > > static const tzdb& _S_replace_head(shared_ptr<_Node>, > shared_ptr<_Node>); > > > > > > static pair<vector<leap_second>, bool> _S_read_leap_seconds(); > > >+ > > >+ // This is here because _Node is a friend so can call private > constructor. > > >+ static const leap_second fixed_leaps[]; > > >+ > > >+ // This is a member so that it can access fixed_leaps. > > >+ struct NumLeapSeconds; > > >+ static NumLeapSeconds num_leap_seconds; > > > }; > > > > > > // Implementation of the private constructor used for the singleton > object. > > >@@ -1251,56 +1260,240 @@ namespace std::chrono > > > } > > > #endif // TZDB_DISABLED > > > > > >+// These are the same values as the array in the <chrono> header, but > might > > >+// contain additional leap seconds if the libstdc++.so used at runtime > is > > >+// newer than the <chrono> header used to compile parts of the > application. > > >+constexpr leap_second tzdb_list::_Node::fixed_leaps[] { > > >+#define LS leap_second > > >+ LS( 78796800), // 1 Jul 1972 > > >+ LS( 94694400), // 1 Jan 1973 > > >+ LS( 126230400), // 1 Jan 1974 > > >+ LS( 157766400), // 1 Jan 1975 > > >+ LS( 189302400), // 1 Jan 1976 > > >+ LS( 220924800), // 1 Jan 1977 > > >+ LS( 252460800), // 1 Jan 1978 > > >+ LS( 283996800), // 1 Jan 1979 > > >+ LS( 315532800), // 1 Jan 1980 > > >+ LS( 362793600), // 1 Jul 1981 > > >+ LS( 394329600), // 1 Jul 1982 > > >+ LS( 425865600), // 1 Jul 1983 > > >+ LS( 489024000), // 1 Jul 1985 > > >+ LS( 567993600), // 1 Jan 1988 > > >+ LS( 631152000), // 1 Jan 1990 > > >+ LS( 662688000), // 1 Jan 1991 > > >+ LS( 709948800), // 1 Jul 1992 > > >+ LS( 741484800), // 1 Jul 1993 > > >+ LS( 773020800), // 1 Jul 1994 > > >+ LS( 820454400), // 1 Jan 1996 > > >+ LS( 867715200), // 1 Jul 1997 > > >+ LS( 915148800), // 1 Jan 1999 > > >+ LS(1136073600), // 1 Jan 2006 > > >+ LS(1230768000), // 1 Jan 2009 > > >+ LS(1341100800), // 1 Jul 2012 > > >+ LS(1435708800), // 1 Jul 2015 > > >+ LS(1483228800), // 1 Jan 2017 > > >+ // If new leap seconds get defined they should be added here. > > >+ // Negative leap seconds are represented as -1 * timestamp. > > >+#undef LS > > >+}; > > >+ > > >+namespace > > >+{ > > >+ // The expiry date corresponding to the list above. > > >+ // tzdata 2026a leapseconds list expires at 2026-12-28 00:00:00 UTC > > >+ constexpr seconds fixed_expiry{1798416000u}; > > >+} > > >+ > > >+// This holds the most up-to-date number of leap seconds known at > runtime. > > >+// Initially zero, updated when _S_read_leap_seconds() is called. > > >+struct tzdb_list::_Node::NumLeapSeconds > > >+{ > > >+ // Called by __recent_leap_second_info to read num_leap_seconds. > > >+ unsigned > > >+ get() > > >+ { > > >+#if ATOMIC_INT_LOCK_FREE == 2 > > >+ atomic_ref<unsigned> ref(count); > > >+ auto num = ref.load(memory_order::relaxed); > > >+ > > >+ if (num == std::size(_Node::fixed_leaps)) > > >+ // A leapseconds file has been read and has no new leap seconds. > > >+ return num; > > >+ > > >+ if (num == 0) > > >+ // No leapseconds file has been read yet. > > >+ return 0; > > >+ > > >+ // The tzdb_list has been initialized and contains a tzdb object > with > > >+ // new leap seconds, which the caller is going to use. > > >+ // The relaxed load above does not synchronize with anything, so to > > >+ // ensure that the get_tzdb_list() in the caller will see a tzdb > object > > >+ // set by _S_replace_head, we load num_leap_seconds again with > acquire > > >+ // ordering: > > >+ return ref.load(memory_order::acquire); > > >+#else > > >+ lock_guard<mutex> l(list_mutex()); // This ensures acquire > ordering. > > >+ return count; > > >+#endif > > >+ } > > >+ > > >+ // Called by __recent_leap_second_info to set num_leap_seconds when > > >+ // we have determined there are no new leap seconds in a leapseconds > file. > > >+ void > > >+ set_to_fixed_size() > > >+ { > > >+#if ATOMIC_INT_LOCK_FREE == 2 > > >+ atomic_ref<unsigned> ref(count); > > >+ unsigned expected = 0; > > >+ ref.compare_exchange_strong(expected, > std::size(_Node::fixed_leaps), > > >+ memory_order::relaxed); > > >+#else > > >+ lock_guard<mutex> l(list_mutex()); > > >+ if (count == 0) > > >+ count = std::size(_Node::fixed_leaps); > > >+#endif > > >+ } > > >+ > > >+ // Called by _Node::_S_replace_head > > >+ // The two versions are named differently so that caller has to be > explicit > > >+ // about which version it calls, based on whether the mutex is held. > > >+ void > > >+ set(unsigned val) > > >+ { > > >+#if ATOMIC_INT_LOCK_FREE == 2 > > >+ atomic_ref<unsigned> ref(count); > > >+ // The release op here synchronizes with the acquire op in get(). > > >+ ref.store(val, memory_order::release); > > >+#else > > >+ lock_guard<mutex> l(list_mutex()); > > >+ count = val; > > >+#endif > > >+ } > > >+ > > >+ void > > >+ set_locked(unsigned val, const lock_guard<mutex>&) > > >+ { > > >+#if ATOMIC_INT_LOCK_FREE == 2 > > >+ // Even though the caller locked the mutex, we still need to use an > > >+ // atomic store in this case, because there could be concurrent > loads. > > >+ set(val); > > >+#else > > >+ // The only caller of this function locks list_mutex() so we would > > >+ // deadlock if we locked it again here. > > >+ count = val; > > >+#endif > > >+ } > > >+ > > >+private: > > >+ unsigned count = 0; > > >+}; > > >+ > > >+constinit tzdb_list::_Node::NumLeapSeconds > tzdb_list::_Node::num_leap_seconds; > > >+ > > >+ namespace __detail > > >+ { > > >+ // Called by chrono::__detail::__get_leap_second_info in <chrono> > > >+ // to get leap_second_info for times after the expiry date in the > header. > > >+ // The caller provides the time being queried in `info.elapsed` and > > >+ // whether that is a UTC time in `info.is_leap_second`. > > >+ // If it returns true, this function did the lookup and updated > `info`. > > >+ // If this returns false, it means the hardcoded list of leap > seconds > > >+ // in the header should be used for the lookup. > > >+ bool > > >+ __recent_leap_second_info(leap_second_info& info, > > >+ unsigned num_positive_leaps) > > >+ { > > >+ // Extract the input args from info: > > >+ const auto [is_utc, secs] = info; > > >+ // And then reuse info for the output result: > > >+ info.is_leap_second = false; > > >+ info.elapsed = seconds(num_positive_leaps); > > >+ > > >+ auto update_info = [&](span<const leap_second> leaps) > > >+ { > > >+ if (leaps.size() == num_positive_leaps) > > >+ return false; // No new leap seconds, use the array in the > header. > > >+ > > >+ // info.elapsed already contains the first N leap seconds, > > >+ // so we only search the end of the span. > > >+ auto first = leaps.begin() + num_positive_leaps; > > >+ auto pos = std::upper_bound(first, leaps.end(), > sys_seconds(secs)); > > >+ for (auto i = first; i != pos; ++i) > > >+ info.elapsed += i->value(); > > >+ > > >+ if (is_utc) > > >+ { > > >+ // This should never happen, but check it so that pos[-1] is > valid: > > >+ if (num_positive_leaps == 0) [[unlikely]] > > >+ return false; > > >+ > > >+ // Convert utc_time to sys_time: > > >+ sys_seconds ss(secs - info.elapsed); > > >+ // See if that sys_time is before (or during) previous leap > sec: > > >+ if (ss < pos[-1]) > > >+ { > > >+ if ((ss + 1s) >= pos[-1]) > > >+ info.is_leap_second = true; > > >+ else > > >+ info.elapsed -= pos[-1].value(); > > >+ } > > >+ } > > >+ return true; > > >+ }; > > >+ > > >+ using _Node = tzdb_list::_Node; > > >+ > > >+ // If the caller was compiled using an older GCC with an older > expiry > > >+ // time in the header than the `fixed_expiry` defined above, we > might > > >+ // be able to answer the query easily using the static > `fixed_leaps`. > > >+ if (secs <= fixed_expiry) > > >+ return update_info(_Node::fixed_leaps); > > >+ > > >+ constexpr auto num_fixed_leaps = std::size(_Node::fixed_leaps); > > >+ > > >+ auto num_leaps = _Node::num_leap_seconds.get(); > > >+ if (num_leaps == num_fixed_leaps) > > >+ // A leapseconds file has been read and has no new leap seconds: > > >+ return update_info(_Node::fixed_leaps); > > >+ else if (num_leaps == 0) > > >+ { > > >+ // The tzdb_list has not been initialized yet, so we don't know > > >+ // the correct number of leap seconds. > > >+ // We use _S_read_leap_seconds() to read the leapseconds file. > > >+ // If that tells us there are no new leapseconds, we don't need > > >+ // to parse all of tzdata.zi and initialize a whole tzdb > object. > > >+ if (_Node::_S_read_leap_seconds().first.size() == > num_fixed_leaps) > > >+ { > > >+ // There are no new leap seconds. Remember that so that > the next > > >+ // call to this function can just use fixed_leaps. > > >+ _Node::num_leap_seconds.set_to_fixed_size(); > > >+ return update_info(_Node::fixed_leaps); > > >+ } > > >+ // else there are new leap seconds. We init tzdb_list so that > the > > >+ // new leap seconds are persisted in a tzdb object. > > >+ } > > >+ > > >+ // Use updated leap_seconds from tzdb. > > >+ return update_info(get_tzdb_list().begin()->leap_seconds); > > >+ } > > >+ } > > >+ > > > // Return leap_second values, and a bool indicating whether the > values are > > > // current (true), or potentially out of date (false). > > > pair<vector<leap_second>, bool> > > > tzdb_list::_Node::_S_read_leap_seconds() > > > { > > >- // This list is valid until at least 2026-12-28 00:00:00 UTC. > > >- constexpr auto expires = sys_days{2026y/12/28}; > > >- vector<leap_second> leaps > > >- { > > >- (leap_second) 78796800, // 1 Jul 1972 > > >- (leap_second) 94694400, // 1 Jan 1973 > > >- (leap_second) 126230400, // 1 Jan 1974 > > >- (leap_second) 157766400, // 1 Jan 1975 > > >- (leap_second) 189302400, // 1 Jan 1976 > > >- (leap_second) 220924800, // 1 Jan 1977 > > >- (leap_second) 252460800, // 1 Jan 1978 > > >- (leap_second) 283996800, // 1 Jan 1979 > > >- (leap_second) 315532800, // 1 Jan 1980 > > >- (leap_second) 362793600, // 1 Jul 1981 > > >- (leap_second) 394329600, // 1 Jul 1982 > > >- (leap_second) 425865600, // 1 Jul 1983 > > >- (leap_second) 489024000, // 1 Jul 1985 > > >- (leap_second) 567993600, // 1 Jan 1988 > > >- (leap_second) 631152000, // 1 Jan 1990 > > >- (leap_second) 662688000, // 1 Jan 1991 > > >- (leap_second) 709948800, // 1 Jul 1992 > > >- (leap_second) 741484800, // 1 Jul 1993 > > >- (leap_second) 773020800, // 1 Jul 1994 > > >- (leap_second) 820454400, // 1 Jan 1996 > > >- (leap_second) 867715200, // 1 Jul 1997 > > >- (leap_second) 915148800, // 1 Jan 1999 > > >- (leap_second)1136073600, // 1 Jan 2006 > > >- (leap_second)1230768000, // 1 Jan 2009 > > >- (leap_second)1341100800, // 1 Jul 2012 > > >- (leap_second)1435708800, // 1 Jul 2015 > > >- (leap_second)1483228800, // 1 Jan 2017 > > >- }; > > >+ // Populate the vector with the leap seconds we already know about: > > >+ vector<leap_second> leaps(fixed_leaps, std::end(fixed_leaps)); > > > > > >-#if 0 > > >- // This optimization isn't valid if the file has additional leap > seconds > > >- // defined since the library was compiled, but the system clock > has been > > >- // set to a time before the hardcoded expiration date. > > >- if (system_clock::now() < expires) > > >- return {std::move(leaps), true}; > > >-#endif > > >+ bool read_leaps_file = false; > > > > > > #ifndef TZDB_DISABLED > > > if (ifstream ls{zoneinfo_file(leaps_file)}) > > > { > > >- auto exp_year = year_month_day(expires).year(); > > >+ constexpr year exp_year > > >+ = > year_month_day(sys_days(duration_cast<days>(fixed_expiry))).year(); > > >+ > > > std::string s, w; > > > s.reserve(80); // Avoid later reallocations. > > > while (std::getline(ls, s)) > > >@@ -1309,6 +1502,7 @@ namespace std::chrono > > > > > > if (!s.starts_with("Leap")) > > > continue; > > >+ > > > istringstream li(std::move(s)); > > > li.exceptions(ios::failbit); > > > li.ignore(4); > > >@@ -1339,12 +1533,14 @@ namespace std::chrono > > > leaps.push_back(ls); > > > } > > > } > > >- s = std::move(li).str(); // return storage to s > > >+ s = std::move(li).str(); // give allocated storage back to s > > > } > > >- return {std::move(leaps), true}; > > >+ > > >+ read_leaps_file = true; > > > } > > > #endif > > >- return {std::move(leaps), false}; > > >+ > > >+ return {std::move(leaps), read_leaps_file}; > > > } > > > > > > #ifndef TZDB_DISABLED > > >@@ -1402,8 +1598,13 @@ namespace std::chrono > > > new_head_ptr->next = curr; > > > } > > > // XXX small window here where _S_head_cache still points to > previous tzdb. > > >+ _S_cache_list_head(new_head_ptr); > > >+ > > >+ // This allows __recent_leap_second_info() to know that it can use > > >+ // get_tzdb_list()->begin()->leap_seconds to get new leap seconds. > > >+ num_leap_seconds.set(new_head_ptr->db.leap_seconds.size()); > > > #else > > >- lock_guard<mutex> l(list_mutex()); > > >+ lock_guard<mutex> lock(list_mutex()); > > > if (const _Node* h = _S_head_owner.get()) > > > { > > > if (h->db.version == new_head_ptr->db.version) > > >@@ -1411,8 +1612,11 @@ namespace std::chrono > > > new_head_ptr->next = _S_head_owner; > > > } > > > _S_head_owner = std::move(new_head); > > >-#endif > > > _S_cache_list_head(new_head_ptr); > > >+ > > >+ num_leap_seconds.set_locked(new_head_ptr->db.leap_seconds.size(), > lock); > > >+#endif > > >+ > > > return new_head_ptr->db; > > > } > > > > > >diff --git > a/libstdc++-v3/testsuite/std/time/clock/utc/leap_second_info-2.cc > b/libstdc++-v3/testsuite/std/time/clock/utc/leap_second_info-2.cc > > >new file mode 100644 > > >index 00000000000..090a28291c8 > > >--- /dev/null > > >+++ b/libstdc++-v3/testsuite/std/time/clock/utc/leap_second_info-2.cc > > >@@ -0,0 +1,108 @@ > > >+// { dg-do run { target c++20 } } > > >+// { dg-require-effective-target tzdb } > > >+// { dg-require-effective-target cxx11_abi } > > >+// { dg-xfail-run-if "no weak override on AIX" { powerpc-ibm-aix* } } > > >+ > > >+#include <chrono> > > >+#include <fstream> > > >+#include <testsuite_hooks.h> > > >+ > > >+using namespace std::chrono_literals; > > >+ > > >+static bool override_used = false; > > >+ > > >+namespace __gnu_cxx > > >+{ > > >+ const char* zoneinfo_dir_override() { > > >+ override_used = true; > > >+ return "./"; > > >+ } > > >+} > > >+ > > >+void > > >+test_known_leaps() > > >+{ > > >+ // Test some values within the list of known leap seconds. > > >+ auto s = std::chrono::utc_seconds(-1s); > > >+ auto lsi = get_leap_second_info(s); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == 0s ); > > >+ > > >+ s = std::chrono::utc_seconds(126230402s); // 1 Jan 1974 > > >+ lsi = get_leap_second_info(s); > > >+ VERIFY( lsi.is_leap_second == true ); > > >+ VERIFY( lsi.elapsed == 3s ); > > >+ > > >+ s = std::chrono::utc_seconds(1483228826s); // 1 Jan 2017 > > >+ lsi = get_leap_second_info(s); > > >+ VERIFY( lsi.is_leap_second == true ); > > >+ VERIFY( lsi.elapsed == 27s ); > > >+ > > >+ // We should not have checked the filesystem for the times above. > > >+ VERIFY( ! override_used ); > > >+} > > >+ > > >+void > > >+test_future_leaps() > > >+{ > > >+ // XXX adjust this if real leap seconds are added to the hardcoded > lists: > > >+ const auto hardcoded_count = 27s; > > >+ > > >+ // Make sure there's no old file from a previous test run. > > >+ std::ofstream("leapseconds") << ""; > > >+ > > >+ using std::chrono::years; > > >+ auto s = std::chrono::utc_seconds(1483228826s + years(100)); // 1 > Jan 2117 > > >+ auto lsi = get_leap_second_info(s); > > >+ VERIFY( override_used ); // If this fails then XFAIL for the target. > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count ); > > >+ lsi = get_leap_second_info(s + years(10)); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count ); > > >+ > > >+ std::ofstream("leapseconds") << R"( > > >+# No need to repeat the real leap seconds here, they're hardcoded in > the lib. > > >+# These are fake new leap seconds for testing purposes: > > >+Leap 2099 Dec 31 23:59:60 + S > > >+Leap 2120 Jun 30 23:59:59 - S > > >+Leap 2120 Dec 30 23:59:59 - S > > >+)"; > > >+ > > >+ override_used = false; > > >+ std::chrono::reload_tzdb(); > > >+ VERIFY( override_used ); > > >+ > > >+ // Check the same dates again using the custom leapseconds file: > > >+ lsi = get_leap_second_info(s); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count + 1s ); // One positive leap > second. > > >+ lsi = get_leap_second_info(s + years(10)); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count - 1s ); // Two negative leap > seconds. > > >+ > > >+ // Overwrite the custom file again: > > >+ override_used = false; > > >+ std::ofstream("leapseconds") << ""; > > >+ > > >+ // This should not re-read the custom file, the head of the tzdb_list > > >+ // should already have been populated by calling > get_leap_second_info(s): > > >+ auto& tzdb = std::chrono::get_tzdb(); > > >+ // The file was not read again: > > >+ VERIFY( ! override_used ); > > >+ // The list in the tzdb contains the three fake leap seconds: > > >+ VERIFY( tzdb.leap_seconds.size() == hardcoded_count.count() + 3 ); > > >+ // And repeating the queries above gives the same results: > > >+ lsi = get_leap_second_info(s); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count + 1s ); // One positive leap > second. > > >+ lsi = get_leap_second_info(s + years(10)); > > >+ VERIFY( lsi.is_leap_second == false ); > > >+ VERIFY( lsi.elapsed == hardcoded_count - 1s ); // Two negative leap > seconds. > > >+} > > >+ > > >+int main() > > >+{ > > >+ test_known_leaps(); > > >+ test_future_leaps(); > > >+} > > >diff --git a/libstdc++-v3/testsuite/util/testsuite_abi.cc > b/libstdc++-v3/testsuite/util/testsuite_abi.cc > > >index 8fb38355cad..4e80c5f184a 100644 > > >--- a/libstdc++-v3/testsuite/util/testsuite_abi.cc > > >+++ b/libstdc++-v3/testsuite/util/testsuite_abi.cc > > >@@ -217,6 +217,7 @@ check_version(symbol& test, bool added) > > > known_versions.push_back("GLIBCXX_3.4.33"); > > > known_versions.push_back("GLIBCXX_3.4.34"); > > > known_versions.push_back("GLIBCXX_3.4.35"); > > >+ known_versions.push_back("GLIBCXX_3.4.36"); > > > known_versions.push_back("GLIBCXX_LDBL_3.4.31"); > > > known_versions.push_back("GLIBCXX_IEEE128_3.4.29"); > > > known_versions.push_back("GLIBCXX_IEEE128_3.4.30"); > > >@@ -260,7 +261,7 @@ check_version(symbol& test, bool added) > > > test.version_status = symbol::incompatible; > > > > > > // Check that added symbols are added in the latest pre-release > version. > > >- bool latestp = (test.version_name == "GLIBCXX_3.4.35" > > >+ bool latestp = (test.version_name == "GLIBCXX_3.4.36" > > > || test.version_name == "CXXABI_1.3.17" > > > || test.version_name == "CXXABI_FLOAT128" > > > || test.version_name == "CXXABI_TM_1"); > > >-- > > >2.55.0 > > > > > > > > > >
