On 14/01/23 18:24 +0000, Jonathan Wakely wrote:
On 23/12/22 17:06 +0000, Iain Sandoe wrote:
This is a patch for comment on the approach - tested on x86_64-darwi21
thoughts?
Iain
--- 8< ---
Testing on Darwin revealed that the GLIBCXX_ZONEINFO_DIR was not doing quite
the right thing (we ended up with ${withval} in the config.h file).
This patch proposes revising the behaviour of the configure flag thus:
--with-libstdcxx-zoneinfo-dir=
unspecified : Set _GLIBCXX_ZONEINFO_DIR to a default suitable for $host
yes : Set _GLIBCXX_ZONEINFO_DIR to a default suitable for $host
no : Do not set _GLIBCXX_ZONEINFO_DIR
/some/path : set _GLIBCXX_ZONEINFO_DIR = "/some/path"
Here's what I've pushed to trunk now, after discussion with Iain.
This is a small follow-up to elide most of the code in
src/c++20/tzdb.cc when the library is configured with
--with-libstdcxx-zoneinfo=no
Tested x86_64-linux and powerpc64le-linux. Pushed to trunk.
-- >8 --
commit c47dcb95666ce0b48f0ff09aa99483fd12df8714
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Sat Jan 14 13:39:48 2023
libstdc++: Disable unwanted code for --with-libstdcxx-zoneinfo=no
This allows most of the tzdb functionality to be disabled by
configuring with --with-libstdcxx-zoneinfo=no. This might be desirable
for small targets that don't need the time zone support.
libstdc++-v3/ChangeLog:
* src/c++20/tzdb.cc (TZDB_DISABLED): Disable all code for
loading tzdb.
* testsuite/std/time/tzdb/leap_seconds.cc: Require tzdb
effective target.
* testsuite/std/time/tzdb_list/1.cc: Likewise.
diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
index 94fb0436091..a37859dffdb 100644
--- a/libstdc++-v3/src/c++20/tzdb.cc
+++ b/libstdc++-v3/src/c++20/tzdb.cc
@@ -82,6 +82,14 @@ namespace __gnu_cxx
#endif
}
+#if ! defined _GLIBCXX_ZONEINFO_DIR && ! defined _GLIBCXX_STATIC_TZDATA
+# define TZDB_DISABLED
+ [[noreturn]] void __throw_disabled()
+ {
+ std::__throw_runtime_error("tzdb: support for loading tzdata is disabled");
+ }
+#endif
+
namespace std::chrono
{
namespace
@@ -105,7 +113,9 @@ namespace std::chrono
{
shared_ptr<_Node> next;
tzdb db;
+#ifndef TZDB_DISABLED
vector<Rule> rules;
+#endif
// The following static members are here because making them members
// of this type gives them access to the private members of time_zone
@@ -175,6 +185,7 @@ namespace std::chrono
// assume that setting failbit will throw an exception, so individual
// input operations are not always checked for success.
+#ifndef TZDB_DISABLED
namespace
{
// Used for reading a possibly-quoted string from a stream.
@@ -582,6 +593,7 @@ namespace std::chrono
#endif
};
} // namespace
+#endif // TZDB_DISABLED
// Private constructor used by reload_tzdb() to create time_zone objects.
time_zone::time_zone(unique_ptr<_Impl> __p) : _M_impl(std::move(__p)) { }
@@ -591,6 +603,7 @@ namespace std::chrono
// The opaque pimpl class stored in a time_zone object.
struct time_zone::_Impl
{
+#ifndef TZDB_DISABLED
explicit
_Impl(weak_ptr<tzdb_list::_Node> node) : node(std::move(node)) { }
@@ -677,11 +690,19 @@ namespace std::chrono
}
}
};
-#endif
+#endif // __GTHREADS && __cpp_lib_atomic_wait
RulesCounter<atomic_signed_lock_free> rules_counter;
+#else // TZDB_DISABLED
+ _Impl(weak_ptr<tzdb_list::_Node>) { }
+ struct {
+ sys_info info;
+ void push_back(sys_info i) { info = std::move(i); }
+ } infos;
+#endif // TZDB_DISABLED
};
+#ifndef TZDB_DISABLED
namespace
{
bool
@@ -731,11 +752,13 @@ namespace std::chrono
select_std_or_dst_abbrev(info.abbrev, info.save);
}
}
+#endif // TZDB_DISABLED
// Implementation of std::chrono::time_zone::get_info(const sys_time<D>&)
sys_info
time_zone::_M_get_sys_info(sys_seconds tp) const
{
+#ifndef TZDB_DISABLED
// This gives us access to the node->rules vector, but also ensures
// that the tzdb node won't get erased while we're still using it.
const auto node = _M_impl->node.lock();
@@ -934,17 +957,20 @@ namespace std::chrono
// Decrement count of rule-based infos (might also release lock).
_M_impl->rules_counter.decrement();
}
-
return info;
+#else
+ return _M_impl->infos.info;
+#endif // TZDB_DISABLED
}
// Implementation of std::chrono::time_zone::get_info(const local_time<D>&)
local_info
time_zone::_M_get_local_info(local_seconds tp) const
{
+ local_info info{};
+#ifndef TZDB_DISABLED
const auto node = _M_impl->node.lock();
- local_info info{};
// Get sys_info assuming no offset between local time and UTC:
info.first = _M_get_sys_info(sys_seconds(tp.time_since_epoch()));
@@ -1007,9 +1033,13 @@ namespace std::chrono
}
// else tp is a unique local time, info.first is the correct sys_info.
}
+#else
+ info.first = _M_impl->infos.info;
+#endif // TZDB_DISABLED
return info;
}
+#ifndef TZDB_DISABLED
namespace
{
// If a zoneinfo directory is defined (either when the library was built,
@@ -1088,14 +1118,13 @@ namespace std::chrono
bool using_static_data() const { return this->rdbuf() == &sb; }
};
}
+#endif // TZDB_DISABLED
// 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()
{
- const string filename = zoneinfo_file(leaps_file);
-
// This list is valid until at least 2023-06-28 00:00:00 UTC.
auto expires = sys_days{2023y/6/28};
vector<leap_second> leaps
@@ -1137,10 +1166,10 @@ namespace std::chrono
return {std::move(leaps), true};
#endif
- auto exp_year = year_month_day(expires).year();
-
- if (ifstream ls{filename})
+#ifndef TZDB_DISABLED
+ if (ifstream ls{zoneinfo_file(leaps_file)})
{
+ auto exp_year = year_month_day(expires).year();
std::string s, w;
s.reserve(80); // Avoid later reallocations.
while (std::getline(ls, s))
@@ -1183,10 +1212,11 @@ namespace std::chrono
}
return {std::move(leaps), true};
}
- else
- return {std::move(leaps), false};
+#endif
+ return {std::move(leaps), false};
}
+#ifndef TZDB_DISABLED
namespace
{
// Read the version number from a tzdata.zi file.
@@ -1213,12 +1243,17 @@ namespace std::chrono
__throw_runtime_error("tzdb: no version found in tzdata.zi");
}
}
+#endif
// Definition of std::chrono::remote_version()
string remote_version()
{
+#ifndef TZDB_DISABLED
tzdata_stream zif;
return remote_version(zif);
+#else
+ __throw_disabled();
+#endif
}
// Used by chrono::reload_tzdb() to add a new node to the front of the list.
@@ -1255,11 +1290,13 @@ namespace std::chrono
const tzdb&
tzdb_list::_Node::_S_init_tzdb()
{
+#ifndef TZDB_DISABLED
__try
{
return reload_tzdb();
}
__catch (const std::exception&)
+#endif
{
auto [leaps, ok] = _S_read_leap_seconds();
@@ -1349,6 +1386,7 @@ namespace std::chrono
const tzdb&
reload_tzdb()
{
+#ifndef TZDB_DISABLED
using Node = tzdb_list::_Node;
tzdata_stream zif;
@@ -1458,6 +1496,9 @@ namespace std::chrono
shared_ptr<Node> head;
#endif
return Node::_S_replace_head(std::move(head), std::move(node));
+#else
+ __throw_disabled();
+#endif // TZDB_DISABLED
}
// Any call to tzdb_list::front() or tzdb_list::begin() must follow
@@ -1641,6 +1682,7 @@ namespace std::chrono
return get_tzdb_list().begin()->current_zone();
}
+#ifndef TZDB_DISABLED
namespace
{
istream& operator>>(istream& in, abbrev_month& am)
@@ -1933,5 +1975,5 @@ namespace std::chrono
return in;
}
} // namespace
-
+#endif // TZDB_DISABLED
} // namespace std::chrono
diff --git a/libstdc++-v3/testsuite/std/time/tzdb/leap_seconds.cc
b/libstdc++-v3/testsuite/std/time/tzdb/leap_seconds.cc
index 2b289436583..d27038225c8 100644
--- a/libstdc++-v3/testsuite/std/time/tzdb/leap_seconds.cc
+++ b/libstdc++-v3/testsuite/std/time/tzdb/leap_seconds.cc
@@ -1,5 +1,6 @@
// { dg-options "-std=gnu++20" }
// { 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* } }
diff --git a/libstdc++-v3/testsuite/std/time/tzdb_list/1.cc b/libstdc++-v3/testsuite/std/time/tzdb_list/1.cc
index 4cbd656efbd..2b121ff219d 100644
--- a/libstdc++-v3/testsuite/std/time/tzdb_list/1.cc
+++ b/libstdc++-v3/testsuite/std/time/tzdb_list/1.cc
@@ -1,5 +1,6 @@
// { dg-options "-std=gnu++20" }
// { 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* } }
