There's no need to explicitly check for the maximum value, because the
function we call handles it correctly anyway.
libstdc++-v3/ChangeLog:
PR libstdc++/98226
* include/std/bit (__countl_one, __countr_one): Remove redundant
branches.
In previous releases the std::this_thread::sleep_for function was only
declared if the target supports multiple threads. I changed that
recently in r11-2649-g5bbb1f3000c57fd4d95969b30fa0e35be6d54ffb so that
sleep_for could be used single-threaded. But that means that targets
using --disable-threads are now required to provide some way to sleep.
This breaks the build for (at least) AVR when trying to build a hosted
library.
This patch adds a new autoconf macro that is defined when no way to
sleep is available, and uses that to suppress the sleeping functions in
std::this_thread.
The #error in src/c++11/thread.cc is retained for the case where there
is no sleep function available but multiple threads are supported. This
is consistent with previous releases, but that #error could probably be
removed without any consequences.
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_LIBSTDCXX_TIME): Define NO_SLEEP
if none of nanosleep, sleep and Sleep is available.
* config.h.in: Regenerate.
* configure: Regenerate.
* include/std/thread [_GLIBCXX_NO_SLEEP] (__sleep_for): Do
not declare.
[_GLIBCXX_NO_SLEEP] (sleep_for, sleep_until): Do not
define.
* src/c++11/thread.cc [_GLIBCXX_NO_SLEEP] (__sleep_for): Do
not define.
This doesn't define a new _GLIBCXX_HAVE_BUILTIN_SOURCE_LOCATION macro.
because using __has_builtin(__builtin_source_location) is sufficient.
Currently only GCC supports it, but if/when Clang and Intel add it the
__has_builtin check should for them too.
Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* doc/doxygen/user.cfg.in (INPUT): Add <source_location>.
* include/Makefile.am: Add <source_location>.
* include/Makefile.in: Regenerate.
* include/std/version (__cpp_lib_source_location): Define.
* include/std/source_location: New file.
* testsuite/18_support/source_location/1.cc: New test.
* testsuite/18_support/source_location/consteval.cc: New test.
* testsuite/18_support/source_location/srcloc.h: New test.
* testsuite/18_support/source_location/version.cc: New test.
Thanks to Jakub's addition of the built-in, we can add this to the
library now. The compiler tests for the built-in are quite extensive,
including verifying the constraints, so this only adds minimal tests to
the library testsuite.
This doesn't add a new _GLIBCXX_HAVE_BUILTIN_BIT_CAST because using
__has_builtin(__builtin_bit_cast) works for GCC and versions of Clang
that provide the built-in.
libstdc++-v3/ChangeLog:
PR libstdc++/93121
* include/std/bit (__cpp_lib_bit_cast, bit_cast): Define.
* include/std/version (__cpp_lib_bit_cast): Define.
* testsuite/26_numerics/bit/bit.cast/bit_cast.cc: New test.
* testsuite/26_numerics/bit/bit.cast/version.cc: New test.
The recent changes to add assertions to std::array broke the functions
that need to be constexpr in C++11, because of the restrictive rules for
constexpr functions in C++11.
This simply disables the assertions for C++11 mode, so the functions can
be constexpr again.
libstdc++-v3/ChangeLog:
* include/std/array (array::operator[](size_t) const, array::front() const)
(array::back() const) [__cplusplus == 201103]: Disable
assertions.
* testsuite/23_containers/array/element_access/constexpr_element_access.cc:
Check for correct values.
* testsuite/23_containers/array/tuple_interface/get_neg.cc:
Adjust dg-error line numbers.
* testsuite/23_containers/array/debug/constexpr_c++11.cc: New test.
This changes some #ifdef checks to use #if instead.
libstdc++-v3/ChangeLog:
* include/bits/atomic_timed_wait.h: Use #if instead of #ifdef.
* include/bits/semaphore_base.h: Likewise.
* include/std/version: Remove trailing whitespace.
Adds __cpp_lib_atomic_wait feature test macro which was overlooked in
the initial commit of this feature. Replaces uses of
_GLIBCXX_HAVE_ATOMIC_WAIT.
libstdc++-v3/ChangeLog:
* include/bits/atomic_base.h: Replace usage of
_GLIBCXX_HAVE_ATOMIC_WAIT with __cpp_lib_atomic_wait.
* include/bits/atomic_timed_wait.h: Likewise.
* include/bits/atomic_wait.h: Define __cpp_lib_atomic_wait
feature test macro.
* include/bits/semaphore_base.h: Replace usage of
_GLIBCXX_HAVE_ATOMIC_WAIT with __cpp_lib_atomic_wait.
* include/std/atomic: Likewise.
* include/std/latch: Likewise.
* include/std/semaphore: Likewise.
* include/std/version: Define __cpp_lib_atomic wait
feature test macro and replace usage of
_GLIBCXX_HAVE_ATOMIC_WAIT.
* testsuite/29_atomics/atomic/wait_notify/1.cc: New test.
* testsuite/29_atomics/atomic/wait_notify/2.cc: Likewise.
In order to simplify the preprocessor checks for whether __atomic_wait
is available, this commit does:
-#if defined _GLIBCXX_HAS_GTHREADS || _GLIBCXX_HAVE_LINUX_FUTEX
+#ifdef _GLIBCXX_HAVE_ATOMIC_WAIT
The original was wrong anyway, as it should have used 'defined' to check
_GLIBCXX_HAVE_LINUX_FUTEX (for consistency with how that's used
elsewhere).
The new macro is defined in <bits/atomic_wait.h> when the file is
defines __atomic_wait and related facilities. All other code that
depends on those features can just check the one macro.
libstdc++-v3/ChangeLog:
* include/bits/atomic_wait.h (_GLIBCXX_HAVE_ATOMIC_WAIT):
Define.
* include/bits/atomic_base.h: Check _GLIBCXX_HAVE_ATOMIC_WAIT.
* include/bits/atomic_timed_wait.h: Likewise.
* include/bits/semaphore_base.h: Likewise.
* include/std/atomic: Likewise.
* include/std/latch: Likewise.
* include/std/semaphore: Likewise.
This introduces a new internal utility, std::__condvar, which is a
simplified form of std::condition_variable. It has no dependency on
<chrono> or std::unique_lock, which allows it to be used in
<bits/atomic_wait.h>.
This avoids repeating the #ifdef __GTHREAD_COND_INIT preprocessor
conditions and associated logic for initializing a __gthread_cond_t
correctly. It also encapsulates most of the __gthread_cond_xxx functions
as member functions of __condvar.
libstdc++-v3/ChangeLog:
* include/bits/atomic_timed_wait.h (__cond_wait_until_impl):
Do not define when _GLIBCXX_HAVE_LINUX_FUTEX is defined. Use
__condvar and mutex instead of __gthread_cond_t and
unique_lock<mutex>.
(__cond_wait_until): Likewise. Fix test for return value of
__cond_wait_until_impl.
(__timed_waiters::_M_do_wait_until): Use __condvar instead
of __gthread_cond_t.
* include/bits/atomic_wait.h: Remove <bits/unique_lock.h>
include. Only include <bits/std_mutex.h> if not using futexes.
(__platform_wait_max_value): Remove unused variable.
(__waiters::lock_t): Use lock_guard instead of unique_lock.
(__waiters::_M_cv): Use __condvar instead of __gthread_cond_t.
(__waiters::_M_do_wait(__platform_wait_t)): Likewise.
(__waiters::_M_notify()): Likewise. Use notify_one() if not
asked to notify all.
* include/bits/std_mutex.h (__condvar): New type.
* include/std/condition_variable (condition_variable::_M_cond)
(condition_variable::wait_until): Use __condvar instead of
__gthread_cond_t.
* src/c++11/condition_variable.cc (condition_variable): Define
default constructor and destructor as defaulted.
(condition_variable::wait, condition_variable::notify_one)
(condition_variable::notify_all): Forward to corresponding
member function of __condvar.
Unlike the other headers that declare alias templates in namespace pmr,
<regex> includes <memory_resource>. That was done because the
pmr::string::const_iterator typedef requires pmr::string to be complete,
which requires pmr::polymorphic_allocator<char> to be complete.
By using __normal_iterator<const char*, pmr::string> instead of the
const_iterator typedef we can avoid the completeness requirement.
This makes <regex> smaller, by not requiring <memory_resource> and its
<shared_mutex> dependency, which depends on <chrono>. Backporting this
will also help with PR 97876, where <stop_token> ends up being needed by
<regex> via <memory_resource>.
libstdc++-v3/ChangeLog:
PR libstdc++/92546
* include/std/regex (pmr::smatch, pmr::wsmatch): Declare using
underlying __normal_iterator type, not nested typedef
basic_string::const_iterator.
This makes it possible to use std::thread without including the whole of
<thread>. It also makes this_thread::get_id() and this_thread::yield()
available even when there is no gthreads support (e.g. when GCC is built
with --disable-threads or --enable-threads=single).
In order for the std:🧵:id return type of this_thread::get_id() to
be defined, std:thread itself is defined unconditionally. However the
constructor that creates new threads is not defined for single-threaded
builds. The thread::join() and thread::detach() member functions are
defined inline for single-threaded builds and just throw an exception
(because we know the thread cannot be joinable if the constructor that
creates joinable threads doesn't exit).
The thread::hardware_concurrency() member function is also defined
inline and returns 0 (as suggested by the standard when the value "is
not computable or well-defined").
The main benefit for most targets is that other headers such as <future>
do not need to include the whole of <thread> just to be able to create a
std::thread. That avoids including <stop_token> and std::jthread where
not required. This is another partial fix for PR 92546.
This also means we can use this_thread::get_id() and this_thread::yield()
in <stop_token> instead of using the gthread functions directly. This
removes some preprocessor conditionals, simplifying the code.
libstdc++-v3/ChangeLog:
PR libstdc++/92546
* include/Makefile.am: Add new <bits/std_thread.h> header.
* include/Makefile.in: Regenerate.
* include/std/future: Include new header instead of <thread>.
* include/std/stop_token: Include new header instead of
<bits/gthr.h>.
(stop_token::_S_yield()): Use this_thread::yield().
(_Stop_state_t::_M_requester): Change type to std:🧵:id.
(_Stop_state_t::_M_request_stop()): Use this_thread::get_id().
(_Stop_state_t::_M_remove_callback(_Stop_cb*)): Likewise.
Use __is_single_threaded() to decide whether to synchronize.
* include/std/thread (thread, operator==, this_thread::get_id)
(this_thread::yield): Move to new header.
(operator<=>, operator!=, operator<, operator<=, operator>)
(operator>=, hash<thread::id>, operator<<): Define even when
gthreads not available.
* src/c++11/thread.cc: Include <memory>.
* include/bits/std_thread.h: New file.
(thread, operator==, this_thread::get_id, this_thread::yield):
Define even when gthreads not available.
[!_GLIBCXX_HAS_GTHREADS] (thread::join, thread::detach)
(thread::hardware_concurrency): Define inline.
This applies the proposed resolution of LWG 3500, which corrects the
return type and constraints of this member function to use the right
iterator type. Additionally, a nearby local variable is uglified.
libstdc++-v3/ChangeLog:
* include/std/ranges (join_view::_Iterator::_M_satisfy): Uglify
local variable inner.
(join_view::_Iterator::operator->): Use _Inner_iter instead of
_Outer_iter in the function signature as per LWG 3500.
* testsuite/std/ranges/adaptors/join.cc (test08): Test it.
The <span> header is empty unless Concepts are supported, but <version>
defines the __cpp_lib_span feature test macro unconditionally. It should
be guarded by the same conditions as in <span>.
libstdc++-v3/ChangeLog:
PR libstdc++/97869
* include/precompiled/stdc++.h: Include <coroutine>.
* include/std/version (__cpp_lib_span): Check __cpp_lib_concepts
before defining.
To poll a std::future to see if it's ready you have to call one of the
timed waiting functions. The most obvious way is wait_for(0s) but this
was previously very inefficient because it would turn the relative
timeout to an absolute one by calling system_clock::now(). When the
relative timeout is zero (or less) we're obviously going to get a time
that has already passed, but the overhead of obtaining the current time
can be dozens of microseconds. The alternative is to call wait_until
with an absolute timeout that is in the past. If you know the clock's
epoch is in the past you can use a default constructed time_point.
Alternatively, using some_clock::time_point::min() gives the earliest
time point supported by the clock, which should be safe to assume is in
the past. However, using a futex wait with an absolute timeout before
the UNIX epoch fails and sets errno=EINVAL. The new code using futex
waits with absolute timeouts was not checking for this case, which could
result in hangs (or killing the process if the libray is built with
assertions enabled).
This patch checks for times before the epoch before attempting to wait
on a futex with an absolute timeout, which fixes the hangs or crashes.
It also makes it very fast to poll using an absolute timeout before the
epoch (because we skip the futex syscall).
It also makes future::wait_for avoid waiting at all when the relative
timeout is zero or less, to avoid the unnecessary overhead of getting
the current time. This makes polling with wait_for(0s) take only a few
cycles instead of dozens of milliseconds.
libstdc++-v3/ChangeLog:
* include/std/future (future::wait_for): Do not wait for
durations less than or equal to zero.
* src/c++11/futex.cc (_M_futex_wait_until)
(_M_futex_wait_until_steady): Do not wait for timeouts before
the epoch.
* testsuite/30_threads/future/members/poll.cc: New test.
Move assigning to a std::jthread that represents a thread of execution
needs to send a stop request and join that running thread. Otherwise the
std::thread data member will terminate in its assignment operator.
Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/std/thread (jthread::operator=(jthread&&)): Transfer
any existing state to a temporary that will request a stop and
then join.
* testsuite/30_threads/jthread/jthread.cc: Test move assignment.
This encapsulates the storing and checking of the thread ID into a class
type, so that the macro _GLIBCXX_HAS_GTHREADS is only checked in one
place. The code doing the checks just calls member functions of the new
type, without caring whether that really does any work or not.
libstdc++-v3/ChangeLog:
* include/std/stop_token (_Stop_state_t::_M_requester): Define
new struct with members to store and check the thread ID.
(_Stop_state_t::_M_request_stop()): Use _M_requester._M_set().
(_Stop_state_t::_M_remove_callback(_Stop_cb*)): Use
_M_requester._M_is_current_thread().
This adds the manipulators for use with basic_osyncstream. In order to
detect when an arbitrary basic_ostream<C,T> is the base class of a
basic_syncbuf<C,T,A> object, introduce a new intermediate base class
that stores the data members. The new base class stores a pointer and
two bools, which wastes (sizeof(void*) - 2) bytes of padding. It would
be possible to use the two least significant bits of the pointer for the
two bools, at least for targets where alignof(basic_streambuf) > 2, but
that's left as a possible change for a future date.
Also define basic_syncbuf::overflow to override the virtual function in
the base class, so that single characters can be inserted into the
stream buffer. Previously the default basic_streambuf::overflow
implementation was used, which drops the character on the floor.
libstdc++-v3/ChangeLog:
* include/std/ostream (__syncbuf_base): New class template.
(emit_on_flush, noemit_on_flush, flush_emit): New manipulators.
* include/std/syncstream (basic_syncbuf): Derive from
__syncbuf_base instead of basic_streambuf.
(basic_syncbuf::operator=): Remove self-assignment check.
(basic_syncbuf::swap): Remove self-swap check.
(basic_syncbuf::emit): Do not skip pubsync() call if sequence
is empty.
(basic_syncbuf::sync): Remove no-op pubsync on stringbuf.
(basic_syncbuf::overflow): Define override.
* testsuite/27_io/basic_syncstream/basic_ops/1.cc: Test
basic_osyncstream::put(char_type).
* testsuite/27_io/basic_ostream/emit/1.cc: New test.
This groups all the constructors together, consistent with the synopses
in the C++20 standard.
libstdc++-v3/ChangeLog:
* include/std/sstream (basic_stringbug, basic_istringstream)
(basic_ostringstream, basic_stringstream): Reorder C++20
constructors to be declared next to other constructors.
This adds some more null checks to avoid a relational comparison with a
null pointer, similar to 78198b6021.
libstdc++-v3/ChangeLog:
PR libstdc++/97415
* include/std/sstream (basic_stringbuf::_M_update_egptr)
(basic_stringbuf::__xfer_bufptrs::__xfer_bufptrs): Check for
null before comparing pointers.
The popcount built-ins work fine for zero, so there's no need to check
for it.
libstdc++-v3/ChangeLog:
* include/std/bit (__popcount): Remove redundant check for zero.
The relational operators for std::optional were using the wrong types
in the declval expressions used to constrain them. Instead of using
const lvalues they were using non-const rvalues, which meant that a type
might satisfy the constraints but then give an error when the function
body was instantiated.
libstdc++-v3/ChangeLog:
PR libstdc++/96269
* include/std/optional (operator==, operator!=, operator<)
(operator>, operator<=, operator>=): Fix types used in
SFINAE constraints.
* testsuite/20_util/optional/relops/96269.cc: New test.
This fixes some multiple definition errors caused by the changes for
PR libstdc++/90295. The previous solution for inlining the members of
std::exception_ptr but still exporting them from the library was to
suppress the 'inline' keyword on those functions when compiling
libsupc++/eh_ptr.cc, so they get defined in that file. That produces ODR
violations though, because there are now both inline and non-inline
definitions in the library, due to the use of std::exception_ptr in
other files sucg as src/c++11/future.cc.
The new solution is to define all the relevant members as 'inline'
unconditionally, but use __attribute__((used)) to cause definitions to
be emitted in libsupc++/eh_ptr.cc as before. This doesn't quite work
however, because PR c++/67453 means the attribute is ignored on
constructors and destructors. As a workaround, the old solution
(conditionally inline) is still used for those members, but they are
given the always_inline attribute so that they aren't emitted in
src/c++11/future.o as inline definitions.
libstdc++-v3/ChangeLog:
PR libstdc++/97729
* include/std/future (__basic_future::_M_get_result): Use
nullptr for null pointer constant.
* libsupc++/eh_ptr.cc (operator==, operator!=): Remove
definitions.
* libsupc++/exception_ptr.h (_GLIBCXX_EH_PTR_USED): Define
macro to conditionally add __attribute__((__used__)).
(operator==, operator!=, exception_ptr::exception_ptr())
(exception_ptr::exception_ptr(const exception_ptr&))
(exception_ptr::~exception_ptr())
(exception_ptr::operator=(const exception_ptr&))
(exception_ptr::swap(exception_ptr&)): Always define as
inline. Add macro to be conditionally "used".
- Add a missing 'explicit' to a basic_stringbuf constructor.
- Set up the get/put area pointers in the constructor from strings using
different allocator types.
- Remove public basic_stringbuf::__sv_type alias.
- Do not construct temporary basic_string objects with a
default-constructed allocator.
Also, change which basic_string constructor is used, as a minor
compile-time optimization. Constructing from a basic_string_view
requires more work from the compiler, so just use a pointer and length.
libstdc++-v3/ChangeLog:
* include/std/sstream (basic_stringbuf(const allocator_type&):
Add explicit.
(basic_stringbuf(const basic_string<C,T,SA>&, openmode, const A&)):
Call _M_stringbuf_init. Construct _M_string from pointer and length
to avoid constraint checks for string view.
(basic_stringbuf::view()): Make __sv_type alias local to the
function.
(basic_istringstream(const basic_string<C,T,SA>&, openmode, const A&)):
Pass string to _M_streambuf instead of constructing a temporary
with the wrong allocator.
(basic_ostringstream(const basic_string<C,T,SA>&, openmode, const A&)):
Likewise.
(basic_stringstream(const basic_string<C,T,SA>&, openmode, const A&)):
Likewise.
* src/c++20/sstream-inst.cc: Use string_view and wstring_view
typedefs in explicit instantiations.
* testsuite/27_io/basic_istringstream/cons/char/1.cc: Add more
tests for constructors.
* testsuite/27_io/basic_ostringstream/cons/char/1.cc: Likewise.
* testsuite/27_io/basic_stringbuf/cons/char/1.cc: Likewise.
* testsuite/27_io/basic_stringbuf/cons/char/2.cc: Likewise.
* testsuite/27_io/basic_stringbuf/cons/wchar_t/1.cc: Likewise.
* testsuite/27_io/basic_stringbuf/cons/wchar_t/2.cc: Likewise.
* testsuite/27_io/basic_stringstream/cons/char/1.cc: Likewise.
The current implementation of std::call_once uses pthread_once, which
only meets the C++ requirements when compiled with support for
exceptions. For most glibc targets and all non-glibc targets,
pthread_once does not work correctly if the init_routine exits via an
exception. The pthread_once_t object is left in the "active" state, and
any later attempts to run another init_routine will block forever.
This change makes std::call_once work correctly for Linux targets, by
replacing the use of pthread_once with a futex, based on the code from
__cxa_guard_acquire. For both glibc and musl, the Linux implementation
of pthread_once is already based on futexes, and pthread_once_t is just
a typedef for int, so this change does not alter the layout of
std::once_flag. By choosing the values for the int appropriately, the
new code is even ABI compatible. Code that calls the old implementation
of std::call_once will use pthread_once to manipulate the int, while new
code will use the new std::once_flag members to manipulate it, but they
should interoperate correctly. In both cases, the int is initially zero,
has the lowest bit set when there is an active execution, and equals 2
after a successful returning execution. The difference with the new code
is that exceptional exceptions are correctly detected and the int is
reset to zero.
The __cxa_guard_acquire code (and musl's pthread_once) use an additional
state to say there are other threads waiting. This allows the futex wake
syscall to be skipped if there is no contention. Glibc doesn't use a
waiter bit, so we have to unconditionally issue the wake in order to be
compatible with code calling the old std::call_once that uses Glibc's
pthread_once. If we know that we're using musl (and musl's pthread_once
doesn't change) it would be possible to set a waiting state and check
for it in std::once_flag::_M_finish(bool), but this patch doesn't do
that.
This doesn't fix the bug for non-linux targets. A similar approach could
be used for targets where we know the definition of pthread_once_t is a
mutex and an integer. We could make once_flag._M_activate() use
pthread_mutex_lock on the mutex member within the pthread_once_t, and
then only set the integer if the execution finishes, and then unlock the
mutex. That would require careful study of each target's pthread_once
implementation and that work is left for a later date.
This also fixes PR 55394 because pthread_once is no longer needed, and
PR 84323 because the fast path is now just an atomic load.
As a consequence of the new implementation that doesn't use
pthread_once, we can also make std::call_once work for targets with no
gthreads support. The code for the single-threaded implementation
follows the same methods as on Linux, but with no need for atomics or
futexes.
libstdc++-v3/ChangeLog:
PR libstdc++/55394
PR libstdc++/66146
PR libstdc++/84323
* config/abi/pre/gnu.ver (GLIBCXX_3.4.29): Add new symbols.
* include/std/mutex [!_GLIBCXX_HAS_GTHREADS] (once_flag): Define
even when gthreads is not supported.
(once_flag::_M_once) [_GLIBCXX_HAVE_LINUX_FUTEX]: Change type
from __gthread_once_t to int.
(once_flag::_M_passive(), once_flag::_M_activate())
(once_flag::_M_finish(bool), once_flag::_Active_execution):
Define new members for futex and non-threaded implementation.
[_GLIBCXX_HAS_GTHREADS] (once_flag::_Prepare_execution): New
RAII helper type.
(call_once): Use new members of once_flag.
* src/c++11/mutex.cc (std::once_flag::_M_activate): Define.
(std::once_flag::_M_finish): Define.
* testsuite/30_threads/call_once/39909.cc: Do not require
gthreads.
* testsuite/30_threads/call_once/49668.cc: Likewise.
* testsuite/30_threads/call_once/60497.cc: Likewise.
* testsuite/30_threads/call_once/call_once1.cc: Likewise.
* testsuite/30_threads/call_once/dr2442.cc: Likewise.
* testsuite/30_threads/call_once/once_flag.cc: Add test for
constexpr constructor.
* testsuite/30_threads/call_once/66146.cc: New test.
* testsuite/30_threads/call_once/constexpr.cc: Removed.
* testsuite/30_threads/once_flag/cons/constexpr.cc: Removed.
This meets the requirement that std::is_integral_v<wchar_t> is true,
even when full library support for wchar_t via specializations of
char_traits etc. is not provided. This is done by checking
__WCHAR_TYPE__ to see if the compiler knows about the type, rather than
checking the library's own _GLIBCXX_USE_WCHAR_T autoconf macro.
This assumes that the C++ compiler correctly defines wchar_t as a
distinct type, not a typedef for one of the other integeral types. This
is always true for G++ and should be true for any supported non-GNU
compilers.
Similarly, the std::make_unsigned and std::make_signed traits and the
internal helpers std::__is_integer and std::__is_char are also changed
to depend on the same macro.
libstdc++-v3/ChangeLog:
* include/std/type_traits (is_integral<wchar_t>)
(make_unsigned<wchar_t>, make_signed<wchar_t>): Define based
on #ifdef __WCHAR_TYPE__ instead of _GLIBCXX_USE_WCHAR_T.
* include/bits/cpp_type_traits.h (__is_integer<wchar_t>)
(__is_char<wchar_t>): Likewise.
This works around a subtle issue where instantiating the begin()/end()
member of some views (as part of return type deduction) inadvertently
requires computing the satisfaction value of range<foo_view>.
This is problematic because the constraint range<foo_view> requires the
begin()/end() member to be callable. But it's not callable until we've
deduced its return type, so evaluation of range<foo_view> yields false
at this point. And if after both members are instantiated (and their
return types deduced) we evaluate range<foo_view> again, this time it
will yield true since the begin()/end() members are now both callable.
This makes the program ill-formed according to [temp.constr.atomic]/3:
If, at different points in the program, the satisfaction result is
different for identical atomic constraints and template arguments, the
program is ill-formed, no diagnostic required.
The views affected by this issue are those whose begin()/end() member
has a placeholder return type and that member initializes an _Iterator
or _Sentinel object from a reference to *this. The second condition is
relevant because it means explicit conversion functions are considered
during overload resolution (as per [over.match.copy], I think), and
therefore it causes g++ to check the constraints of the conversion
function view_interface<foo_view>::operator bool(). And this conversion
function's constraints indirectly require range<foo_view>.
This issue is observable on trunk only with basic_istream_view (as in
the testcase in the PR). But a pending patch that makes g++ memoize
constraint satisfaction values indefinitely (it currently invalidates
the satisfaction cache on various events) causes many existing tests for
the other affected views to fail, because range<foo_view> then remains
false for the whole compilation.
This patch works around this issue by adjusting the constructors of the
_Iterator and _Sentinel types of the affected views to take their
foo_view argument by pointer instead of by reference, so that g++ no
longer considers explicit conversion functions when resolving the
direct-initialization inside these views' begin()/end() members.
libstdc++-v3/ChangeLog:
PR libstdc++/97600
* include/std/ranges (basic_istream_view::begin): Initialize
_Iterator from 'this' instead of '*this'.
(basic_istream_view::_Iterator::_Iterator): Adjust constructor
accordingly.
(filter_view::_Iterator::_Iterator): Take a filter_view*
argument instead of a filter_view& argument.
(filter_view::_Sentinel::_Sentinel): Likewise.
(filter_view::begin): Initialize _Iterator from 'this' instead
of '*this'.
(filter_view::end): Likewise.
(transform_view::_Iterator::_Iterator): Take a _Parent* instead
of a _Parent&.
(filter_view::_Iterator::operator+): Adjust accordingly.
(filter_view::_Iterator::operator-): Likewise.
(filter_view::begin): Initialize _Iterator from 'this' instead
of '*this'.
(filter_view::end): Likewise.
(join_view::_Iterator): Take a _Parent* instead of a _Parent&.
(join_view::_Sentinel): Likewise.
(join_view::begin): Initialize _Iterator from 'this' instead of
'*this'.
(join_view::end): Initialize _Sentinel from 'this' instead of
'*this'.
(split_view::_OuterIter): Take a _Parent& instead of a _Parent*.
(split_view::begin): Initialize _OuterIter from 'this' instead
of '*this'.
(split_view::end): Likewise.
* testsuite/std/ranges/97600.cc: New test.
This makes some range adaptors model the borrowed_range concept if they
are adapting a borrowed range. This hasn't been added to the C++23
working paper yet, but it has been approved by LWG, and the
recommendation is to treat it as a defect report for C++20 as well.
libstdc++-v3/ChangeLog:
* include/std/ranges (enable_borrowed_view<take_view<T>>)
(enable_borrowed_view<drop_view<T>>)
(enable_borrowed_view<drop_while_view<T>>)
(enable_borrowed_view<reverse_view<T>>)
(enable_borrowed_view<common_view<T>>)
(enable_borrowed_view<elements_view<T>>): Add partial
specializations as per P2017R1.
* testsuite/std/ranges/adaptors/conditionally_borrowed.cc:
New test.
The class template semiregular-box<T> of [range.semi.wrap] is specified
to value-initialize the underlying object whenever its type is default
initializable. Our primary template for __detail::__box respects this
requirement, but the recently added partial specialization (for types
that are already semiregular) does not.
This patch fixes this issue, and additionally makes the corresponding in
place constructor explicit (as in the primary template).
libstdc++-v3/ChangeLog:
* include/std/ranges (__detail::__box): For the partial
specialization used by types that are already semiregular,
make the default constructor value-initialize the underlying
object instead of default-initializing it. Make its in place
constructor explicit.
* testsuite/std/ranges/adaptors/detail/semiregular_box.cc:
Augment test.
These are usually suppressed in system headers, but should be fixed
anyway.
libstdc++-v3/ChangeLog:
* include/bits/parse_numbers.h (_Select_int_base): Avoid
narrowing conversion in constant expression.
* include/experimental/buffer (buffer_copy): Avoid narrowing
conversion.
* include/experimental/internet (hash<>::operator()): Do not
use deprecated 'argument_type' member.
* include/std/variant (variant::emplace): Use cast instead
of implicit conversion from size_t to narrower unsigned type.
libstdc++-v3/ChangeLog:
* include/std/sstream (basic_stringbuf(__string_type&&, openmode)):
Call _M_init_syncbuf to set up get/put areas. Also qualify
std::move.
The conversion function year_month_weekday::operator sys_days computes
the offset in days from the first weekday of the month with:
days{(index()-1)*7}
^~~~~~~~~~~~~ type 'unsigned'
We want the above to yield -7d when index() is 0u, but our 'days' alias
is based on long instead of int, so the conversion from unsigned to the
underlying type of 'days' instead yields a large positive value.
This patch fixes this by casting the result of index() to int so that
the initializer is sign-extended in the conversion to long.
The added testcase also verifies we do the right thing when index() == 5.
libstdc++-v3/ChangeLog:
PR libstdc++/96713
* include/std/chrono (year_month_weekday::operator sys_days):
Cast the result of index() to int so that the initializer for
days{} is sign-extended when it's converted to the underlying
type.
* testsuite/std/time/year_month_weekday/3.cc: New test.
This replaces uses of BUFSIZ with a new _GLIBCXX_BUFSIZ macro that can
be overridden in target-specific config headers.
That allows the mingw and mingw-w64 targets to override it, because
BUFSIZ is apparently defined to 512, resulting in poor performance. The
MSVCRT stdio apparently uses 4096, so we use that too.
libstdc++-v3/ChangeLog:
PR libstdc++/94268
* config/os/mingw32-w64/os_defines.h (_GLIBCXX_BUFSIZ):
Define.
* config/os/mingw32/os_defines.h (_GLIBCXX_BUFSIZ):
Define.
* include/bits/fstream.tcc: Use _GLIBCXX_BUFSIZ instead
of BUFSIZ.
* include/ext/stdio_filebuf.h: Likewise.
* include/std/fstream (_GLIBCXX_BUFSIZ): Define.
This change reorders the data members of std::span so that span<byte> is
layout-compatible with common implementations of struct iovec. This will
allow span<byte> to be used directly in places that use a struct iovec
to do scatter-gather I/O.
It's important to note that POSIX doesn't specify the order of members
in iovec. Also the equivalent type on Windows has members in the other
order, and uses type ULONG (which is always 32-bit whereas size_t is
64-bit for Win64). So this change will only help for certain targets and
an indirection between std::span and I/O system calls will still be
needed for the general case.
libstdc++-v3/ChangeLog:
PR libstdc++/95609
* include/std/span (span): Reorder data members to match common
implementations of struct iovec.
* testsuite/23_containers/span/layout_compat.cc: New test.
The placeholders for std::tr1::bind are defined in an anonymous
namespace, which means they have internal linkage. This will cause ODR
violations when used in function templates (such as std::tr1::bind) from
multiple translation units. Although probably harmless (every definition
will generate identical code, even if technically ill-formed) we can
avoid the ODR violations by reusing the std::placeholder objects as the
std::tr1::placeholder objects.
To make this work, the std::_Placeholder type needs to be defined for
C++98 mode, so that <tr1/functional> can use it. The members of the
std::placeholder namespace must not be defined by <functional> in C++98
mode, because "placeholders", "_1", "_2" etc. are not reserved names in
C++98. Instead they can be declared in <tr1/functional>, because those
names *are* reserved in that header. With the std::placeholders objects
declared, a simple using-directive suffices to redeclare them in
namespace std::tr1::placeholders. This means any use of the TR1
placeholders actually refers to the C++11 placeholders, which are
defined with external linkage and exported from the library, so don't
cause ODR violations.
libstdc++-v3/ChangeLog:
* include/std/functional (std::_Placeholder): Define for C++98
as well as later standards.
* include/tr1/functional (std::placeholders::_1 etc): Declare
for C++98.
(tr1::_Placeholder): Replace with using-declaration for
std::_Placeholder.
(tr1::placeholders::_1 etc.): Replace with using-directive for
std::placeholders.
libstdc++-v3/ChangeLog:
* include/std/ranges (single_view::single_view): Mark the
in place constructor explicit as per LWG 3428.
(take_view): Remove the constraint on the deduction guide's
template parameter as per LWG 3447.
The recent changes to reduce includes in <memory_resource> went a bit
too far, and it's possible for std::forward_as_tuple to not be defined
when used.
While doing this, I noticed the problematic calls to forward_as_tuple
were not qualified, so performed unwanted ADL.
libstdc++-v3/ChangeLog:
* include/experimental/memory_resource: Include <tuple>.
(polymorphic_allocator::construct): Qualify forward_as_tuple.
* include/std/memory_resource: Likewise.
The <condition_variable> header is not small, so <shared_mutex> should
not include it unless it actually needs std::condition_variable, which
is only the case when we don't have pthread_rwlock_t and the POSIX
Timers option.
The <shared_mutex> header would be even smaller if we had a header for
std::condition_variable (separate from std::condition_variable_any).
That's already planned for a future change.
And <memory_resource> would be even smaller if it was possible to get
std::shared_mutex without std::shared_timed_mutex (which depends on
<chrono>). For that to be effective, the synchronized_pool_resource
would have to create its own simpler version of std::shared_lock without
the timed waiting functions. I have no plans to do that.
libstdc++-v3/ChangeLog:
* include/std/shared_mutex: Only include <condition_variable>
when pthread_rwlock_t and POSIX timers are not available.
(__cpp_lib_shared_mutex, __cpp_lib_shared_timed_mutex): Change
value to be type 'long'.
* include/std/version (__cpp_lib_shared_mutex)
(__cpp_lib_shared_timed_mutex): Likewise.
