The compiler doesn't know about the invariant that the _S_empty_rep()
object is immutable and so _M_length and _M_refcount are always zero.
This means that we get warnings about writing possibly-non-zero length
strings into buffers that can't hold them. If we teach the compiler that
the empty rep is always zero length, it knows it can be copied into any
buffer.
For Stage 1 we might want to also consider adding this to capacity():
if (_S_empty_rep()._M_capacity != 0)
__builtin_unreachable();
And this to _Rep::_M_is_leaked() and _Rep::_M_is_shared():
if (_S_empty_rep()._M_refcount != 0)
__builtin_unreachable();
libstdc++-v3/ChangeLog:
PR tree-optimization/107087
* include/bits/cow_string.h (basic_string::size()): Add
optimizer hint that _S_empty_rep()._M_length is always zero.
(basic_string::length()): Call size().
We pass a const-reference to *this before it's constructed, and GCC
assumes that all const-references are accessed. Add the access attribute
to say it's not accessed.
libstdc++-v3/ChangeLog:
PR libstdc++/109339
* include/std/stop_token (_Stop_state_ptr(const stop_source&)):
Add attribute access with access-mode 'none'.
* testsuite/30_threads/stop_token/stop_source/109339.cc: New test.
As pointed out in P2641R1, we can use GCC's __builtin_constant_p to
emulate the proposed std::is_active_member. This allows us to detect
which of the union members is active during constant evaluation, so we
don't need the extra bool data member. We still can't support constexpr
until C++20 though, as we need to change the active member during
constant evaluation.
libstdc++-v3/ChangeLog:
* include/experimental/internet (ip::basic_endpoint::_M_if_v6):
Revert change from member function to data member. Fix for
constant evaluation by detecting which union member is active.
(ip::basic_endpoint::resize): Revert changes to update _M_is_v6
flag.
Change ip::basic_endpoint to work in constant expressions, but only for
C++20 and later (due to the use of a union, which cannot change active
member in constexpr evaluation until C++20).
During constant evaluation we cannot inspect the common initial sequence
of basic_endpoint's union members to check whether sin_family == AF_INET
or AF_INET6. This means we need to store an additional boolean member
that remembers whether we have a v4 or v6 address. The address type can
change behind our backs if a user copies an address to the data()
pointer and then calls resize(n), so we need to inspect the sa_family_t
member in the union after a resize and update the boolean. POSIX only
guarantees that the sa_family_t member of each protocol-specific address
structure is at the same offset and of the same type, not that there is
a common initial sequence. The check in resize is done using memcmp, so
that we avoid accessing an inactive member of the union if the
sockaddr_in and sockaddr_in6 structures do not have a common initial
sequence that includes the sa_family_t member.
libstdc++-v3/ChangeLog:
* include/experimental/internet (ip::make_address): Implement
missing overload.
(ip::address_v4::broadcast()): Avoid undefined shift.
(ip::basic_endpoint): Fix member functions for constexpr.
(ip::basic_endpoint::_M_is_v6): Replace member function with
data member, adjust member functions using it.
(ip::basic_endpoint::resize): Update _M_is_v6 based on sockaddr
content.
* testsuite/experimental/net/internet/address/v4/cons.cc: Fix
constexpr checks to work in C++14.
* testsuite/experimental/net/internet/address/v4/creation.cc:
Likewise.
* testsuite/experimental/net/internet/endpoint/cons.cc:
Likewise.
* testsuite/experimental/net/internet/network/v4/cons.cc:
Likewise.
* testsuite/experimental/net/internet/network/v4/members.cc:
Likewise.
* testsuite/experimental/net/internet/endpoint/extensible.cc: New test.
LWG 3843 adds some type requirements to std::expected::value to ensure
that it can correctly copy the error value if it needs to throw an
exception. We don't need to do anything to enforce that, because it will
already be ill-formed if the type can't be copied. The issue also makes
a small drive-by fix to ensure that a const E& is copied from the
non-const value()& overload, which this change implements.
libstdc++-v3/ChangeLog:
* include/std/expected (expected::value() &): Use const lvalue
for unex member passed to bad_expected_access constructor, as
per LWG 3843.
We need to strip cv-qualifiers from the result of the callable passed to
std::optional::transform.
For std::expected::transform and std::expected::transform_error I
noticed we were stripping cv-qualifiers but were also incorrectly
stripping references.
libstdc++-v3/ChangeLog:
PR libstdc++/109340
* include/std/expected (expected::transform): Use
std::remove_cv_t instead of std::remove_cvref_t.
(expected::transform_error): Likewise.
(expected<cv void, E>::transform): Likewise.
(expected<cv void, E>::transform_error): Likewise.
* include/std/optional (transform): Use std::remove_cv_t.
* testsuite/20_util/optional/monadic/pr109340.cc: New test.
The standard does not allow std::optional<T&>, std::optional<T[1]>,
std::optional<T()> etc. and although we do give errors, they come from
down inside the internals of std::optional. We could improve the static
assertions at the top of the class so that users get a more precise
diagnostic:
optional:721:21: error: static assertion failed
721 | static_assert(is_object_v<_Tp> && !is_array_v<_Tp>);
libstdc++-v3/ChangeLog:
* include/std/optional (optional): Adjust static assertion to
reject arrays and functions as well as references.
* testsuite/20_util/optional/requirements_neg.cc: New test.
For the powerpc64le build with two different long double
representations, we cannot use the ios_base::_M_num_put and
ios_base::_M_num_get pointers, because they might have been initialized
in a translation unit using the other long double type. With the changes
to add __try_use_facet to GCC 13 the cache isn't really needed now, we
can just access the right facet in the locale directly, without needing
RTTI checks.
libstdc++-v3/ChangeLog:
PR libstdc++/103387
* include/bits/istream.tcc (istream::_M_extract(ValueT&)): Use
std::use_facet instead of cached _M_num_get facet.
(istream::operator>>(short&)): Likewise.
(istream::operator>>(int&)): Likewise.
* include/bits/ostream.tcc (ostream::_M_insert(ValueT)): Use
std::use_facet instead of cached _M_num_put facet.
The std::char_traits member functions require that [p,p+n) is a valid
range, which is true for p==nullptr iff n==0. But we must not call
memcpy, memset etc, in that case, as they require non-null pointers even
when n==0.
This std::char_traits<char> and std::char_traits<wchar_t> explicit
specializations are already correct, but the primary template has some
bugs.
libstdc++-v3/ChangeLog:
* include/bits/char_traits.h (char_traits::copy): Return without
using memcpy if n==0.
(char_traits::assign): Likewise for memset.
This avoids a bogus warning about overflowing a buffer, because GCC
can't tell that we don't copy into the buffer unless it fits. By adding
a __builtin_unreachable() hint we inform the compiler about the
invariant that the buffer is only used when it's big enough.
This can also improve codegen, by eliminating dead code that GCC
couldn't tell was unreachable.
libstdc++-v3/ChangeLog:
PR libstdc++/109299
* include/bits/basic_string.h (basic_string::_M_is_local()): Add
hint for compiler that local strings fit in the local buffer.
Import the new 2023a tzdata.zi file and update the expiry dates of the
hardcoded lists of leapseconds to 2023-12-28.
With the new data, Africa/Egypt no longer has a single unbroken sys_info
from 2014-09-25 to chrono::year::max(). Only check up to 2014-09-01 so
that the test isn't sensitive to differences between 2022g and 2023a
data.
libstdc++-v3/ChangeLog:
PR libstdc++/109288
* include/std/chrono (__detail::__get_leap_second_info): Update
expiry date of hardcoded leapseconds list.
* src/c++20/tzdb.cc (tzdb_list::_Node::_S_read_leap_seconds()):
Likewise.
* src/c++20/tzdata.zi: Import new file from 2023a release.
* testsuite/std/time/time_zone/get_info_local.cc: Only check
transitions for Egypt up to 2014.
This resolves a regression of my previous fix where Clang would ICE on
_S_divides.
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
* include/experimental/bits/simd_x86.h (_SimdImplX86): Use
_Base::_S_divides if the optimized _S_divides function is hidden
via the preprocessor.
LWG voted this to Tentatively Ready recently.
libstdc++-v3/ChangeLog:
* include/bits/shared_ptr_atomic.h (atomic::operator=(nullptr_t)):
Add overload, as per LWG 3893.
* testsuite/20_util/shared_ptr/atomic/atomic_shared_ptr.cc:
Check assignment from nullptr.
This was approved in Issaquah as LWG 3833.
libstdc++-v3/ChangeLog:
* include/std/format (formatter<const charT[N], charT>): Do not
define partial speclialization, as per LWG 3833.
* testsuite/std/format/formatter/requirements.cc: Check it.
We actually defined this macro in <utility> at one point, but I removed
it in r10-7901-g2025db692e9ed1.
libstdc++-v3/ChangeLog:
* include/std/utility (__cpp_lib_constexpr_algorithms): Define,
as per LWG 3792.
* testsuite/20_util/exchange/constexpr.cc: Check for it.
Previously the C++23 draft required that the callback arguments were
lvalues, which was overvable by the callback. LWG 3645 removes that
overspecification, so we can pass rvalues and the user can't modify
our local variables. I've used auto(p) to produce rvalues, which is only
supported since Clang 15, but I think that's OK for a C++23 feature.
While making this change I noticed that we weren't correctly enforcing
the requirement that the callback returns an integer-like type. Add
better assertions for the type and value.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.tcc (basic_string::resize_and_overwrite):
Pass rvalues to the callback, as now allowed by LWG 3645.
Enforce preconditions on the return value.
* testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc:
Adjust.
This was approved in Issaquah last month.
libstdc++-v3/ChangeLog:
* include/bits/regex.h (match_results): Add allocator-extended
copy and move constructors, as per LWG 2195.
* testsuite/28_regex/match_results/ctors/char/alloc.cc: New test.
As explained in LWG 3600, we never implemented a C++0x change that made
the copy constructor of std::istream_iterator defined as defaulted. That
would be an ABI break, so the resolution of LWG 3600 is to not require
it to be trivial, but just constexpr and conditionally noexcept. This
applies that resolution.
libstdc++-v3/ChangeLog:
* include/bits/stream_iterator.h (istream_iterator): Add
constexpr to copy constructor, as per LWG 3600.
* testsuite/24_iterators/istream_iterator/cons/constexpr.cc:
Check copy construction.
Clang ICEs on _SimdImplX86::_S_divides. The function is only working
around a missed optimization and not necessary for correctness.
Therefore, don't use it for Clang.
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
* include/experimental/bits/simd_detail.h: Don't define
_GLIBCXX_SIMD_WORKAROUND_PR90993 for Clang.
* include/experimental/bits/simd_x86.h (_S_divides): Remove
check for __clang__.
Clang fails to compile some constant expressions involving simd.
Therefore, just disable this non-conforming extension for clang.
Fix AVX512 blend implementation for Clang. It was converting the bitmask
to bool before, which is obviously wrong. Instead use a Clang builtin to
convert the bitmask to vector-mask before using a vector blend ?:. A
similar change is required for the masked unary implementation, because
the GCC builtins do not exist on Clang.
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
* include/experimental/bits/simd_detail.h: Don't declare the
simd API as constexpr with Clang.
* include/experimental/bits/simd_x86.h (__movm): New.
(_S_blend_avx512): Resolve FIXME. Implement blend using __movm
and ?:.
(_SimdImplX86::_S_masked_unary): Clang does not implement the
same builtins. Implement the function using __movm, ?:, and -
operators on vector_size types instead.
The presence of a template-head on this constructor is a copy & paste
error from the primary template.
libstdc++-v3/ChangeLog:
PR libstdc++/109182
* include/std/expected (expected<void>::expected(in_place_t)):
Remove template-head.
libstdc++-v3/ChangeLog:
* include/bits/stl_iterator.h (move_iterator::_S_iter_concept):
Define.
(__cpp_lib_move_iterator_concept): Define for C++20.
(move_iterator::iterator_concept): Strengthen as per P2520R0.
* include/std/version (__cpp_lib_move_iterator_concept): Define
for C++20.
* testsuite/24_iterators/move_iterator/p2520r0.cc: New test.
libstdc++-v3/ChangeLog:
* include/bits/ranges_util.h (view_interface::empty): Add
preferred overloads that use ranges::size when the range is
sized as per LWG 3715.
* testsuite/std/ranges/adaptors/lwg3715.cc: New test.
Although variable templates are valid in C++14, inline ones aren't.
These are only used in C++17 (or later) code, so they don't need to be
defined for C++14.
libstdc++-v3/ChangeLog:
* include/bits/chrono.h (__is_duration_v, __is_time_point_v):
Only define for C++17 and later.
Add assertions to diagnose incorrect uses of valarray masks.
The assignment operators of std::mask_array do not have any explicit
preconditions in the standard, but the assignment operator
valarray<T>::operator=(const mask_array<T>&) requires the lengths to
match, so it seems consistent to also require that when the operands are
reversed. In support of that interpretation, libstdc++ has undefined
behaviour if the right-hand operand has more elements than are selected
by the mask, and libc++ has undefined behaviour if it has fewer
elements. Our std::mask_array stores the number of selected elements as
_M_sz so it's easy to add an assertion that checks it.
For the valarray::operator[] that takes a valarray<bool> mask,
[valarray.sub] in the standard says: "In each case the selected
element(s) shall exist." This makes it undefined to have a mask that
refers to out-of-range elements. We can easily check this too.
libstdc++-v3/ChangeLog:
PR libstdc++/62196
* include/bits/mask_array.h (mask_array): Add assertions to
assignment operators.
* include/std/valarray (valarray::operator[](valarray<bool>)):
Add assertions.
* testsuite/26_numerics/valarray/mask-1_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-2_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-3_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-4_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-5_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-6_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-7_neg.cc: New test.
* testsuite/26_numerics/valarray/mask-8_neg.cc: New test.
* testsuite/26_numerics/valarray/mask.cc: New test.
The LWG 3820 testcase revealed a bug in _M_advance, which this patch
also fixes.
libstdc++-v3/ChangeLog:
* include/std/ranges
(cartesian_product_view::_Iterator::_Iterator): Remove
constraint on default constructor as per LWG 3849.
(cartesian_product_view::_Iterator::_M_prev): Adjust position
of _Nm > 0 test as per LWG 3820.
(cartesian_product_view::_Iterator::_M_advance): Perform bounds
checking only on sized cartesian products.
* testsuite/std/ranges/cartesian_product/1.cc (test08): New test.
PR libstdc++/108362
libstdc++-v3/ChangeLog:
* include/std/ranges (__detail::__can_single_view): New concept.
(_Single::operator()): Constrain it. Move [[nodiscard]] to the
end of the function declarator.
(__detail::__can_iota_view): New concept.
(_Iota::operator()): Constrain it. Move [[nodiscard]] to the
end of the function declarator.
(__detail::__can_istream_view): New concept.
(_Istream::operator()): Constrain it. Move [[nodiscard]] to the
end of the function declarator.
* testsuite/std/ranges/iota/iota_view.cc (test07): New test.
* testsuite/std/ranges/istream_view.cc (test08): New test.
* testsuite/std/ranges/single_view.cc (test07): New test.
ranges::begin() isn't guaranteed to be equality-preserving for non-forward
ranges, so in cartesian_product_view::end we need to avoid needlessly
calling begin() on the first range (which could be non-forward) in the
case where __empty_tail is false as per its specification.
Since we're already using a variadic lambda to compute __empty_tail, we
might as well use that same lambda to build up the tuple of iterators
instead of building it separately via e.g. std::apply or __tuple_transform.
PR libstdc++/107572
libstdc++-v3/ChangeLog:
* include/std/ranges (cartesian_product_view::end): When
building the tuple of iterators, avoid calling ranges::begin on
the first range if __empty_tail is false.
* testsuite/std/ranges/cartesian_product/1.cc (test07): New test.
Like pthread_create, pthread_join may fail to be statically linked in
absent strong uses, so add to user code strong references to both when
std::thread objects are created.
for libstdc++-v3/ChangeLog
PR libstdc++/104852
PR libstdc++/95989
PR libstdc++/52590
* include/bits/std_thread.h (thread::_M_thread_deps): New
static implicitly-inline member function.
(std::thread template ctor): Pass it to _M_start_thread.
* src/c++11/thread.cc (thread::_M_start_thread): Name depend
parameter, force it live on entry.
This implements LWG 3527 which fixes the handling of pair<T&&, U&&> in
std::uses_allocator_construction_args.
libstdc++-v3/ChangeLog:
PR libstdc++/108952
* include/bits/uses_allocator_args.h
(uses_allocator_construction_args): Implement LWG 3527.
* testsuite/20_util/pair/astuple/get-2.cc: New test.
* testsuite/20_util/scoped_allocator/108952.cc: New test.
* testsuite/20_util/uses_allocator/lwg3527.cc: New test.
This avoids overwriting tail padding when algorithms like std::copy are
used to write a single value through a pointer to a base subobject.
The pointer arithmetic on a Base* is valid for N==1, but the copy/move
operation needs to be done using assignment, not a memmove or memcpy of
sizeof(Base) bytes.
Instead of putting a check for N==1 in all of copy, copy_n, move etc.
this adds it to the __copy_move and __copy_move_backward partial
specializations used for trivially copyable types. When N==1 those
partial specializations dispatch to new static member functions of the
partial specializations for non-trivial types, so that a copy/move
assignment is done appropriately for the _IsMove constant.
libstdc++-v3/ChangeLog:
PR libstdc++/108846
* include/bits/stl_algobase.h (__copy_move<false, false, RA>)
Add __assign_one static member function.
(__copy_move<true, false, RA>): Likewise.
(__copy_move<IsMove, true, RA>): Do not use memmove for a single
value.
(__copy_move_backward<IsMove, true, RA>): Likewise.
* testsuite/25_algorithms/copy/108846.cc: New test.
* testsuite/25_algorithms/copy_backward/108846.cc: New test.
* testsuite/25_algorithms/copy_n/108846.cc: New test.
* testsuite/25_algorithms/move/108846.cc: New test.
* testsuite/25_algorithms/move_backward/108846.cc: New test.
This is a complicated API that should be clearly documented.
Also improve the comment on basic_ios::_M_setstate.
libstdc++-v3/ChangeLog:
* include/bits/basic_ios.h (basic_ios::_M_setstate): Add
caveat to comment.
* include/bits/basic_string.h (resize_and_overwrite): Add
doxygen comment.
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
PR libstdc++/108856
* include/experimental/bits/simd_builtin.h
(_SimdImplBuiltin::_S_masked_unary): More efficient
implementation of masked inc-/decrement for integers and floats
without AVX2.
* include/experimental/bits/simd_x86.h
(_SimdImplX86::_S_masked_unary): New. Use AVX512 masked subtract
builtins for masked inc-/decrement.
The TS says the arguments to these constructors shall meet the Executor
requirements, so it's undefined if they don't. Constraining on a subset
of those requirements won't affect valid cases, but prevents the
majority of invalid cases from trying to instantiate the constructor.
This prevents the non-explicit executor(Executor) constructor being a
candidate anywhere that a net::executor could be constructed e.g.
comparing ip::tcp::v4() == ip::udp::v4() would try to convert both
operands to executor using that constructor, then compare then using
operator==(const executor&, const executor&).
libstdc++-v3/ChangeLog:
* include/experimental/executor (executor): Constrain template
constructors.
I messed up the endianness of the address_v4::bytes_type array, which
should always be in network byte order. We can just use bit_cast to
convert the _M_addr member to/from bytes_type.
libstdc++-v3/ChangeLog:
* include/experimental/internet (address_4(const bytes_type&)):
Use __builtin_bit_cast if available, otherwise convert to
network byte order.
(address_v4::to_bytes()): Likewise, but convert from network
byte order.
* testsuite/experimental/net/internet/address/v4/cons.cc: Fix
incorrect tests. Check for constexpr too.
* testsuite/experimental/net/internet/address/v4/creation.cc:
Likewise.
* testsuite/experimental/net/internet/address/v4/members.cc:
Check that bytes_type is a standard-layout type.
This is an order of magnitude faster than calling inet_ntop (and not
only because we now avoid allocating a string that is one byte larger
than the SSO buffer).
libstdc++-v3/ChangeLog:
* include/experimental/internet (address_v4::to_string):
Optimize.
* testsuite/experimental/net/internet/address/v4/members.cc:
Check more addresses.
Jonathan Wakely
Matthias Kretz
Patrick Palka
Alexandre Oliva