Implement LWG 3912, approved in Varna, June 2023.

libstdc++-v3/ChangeLog:

	* include/std/ranges (enumerate_view::_Iterator::operator-):
	Add noexcept, as per LWG 3912.
	* testsuite/std/ranges/adaptors/enumerate/1.cc: Check iterator
	difference is noexcept.

I notice std::timespec and std::timespec_get are used in preprocessor
condition _GLIBCXX_HAVE_TIMESPEC_GET. So in module std, it should be
the same.

libstdc++-v3:

	* src/c++23/std-clib.cc.in (timespec): Move within preprocessor
	group guarded by _GLIBCXX_HAVE_TIMESPEC_GET.

The new test functions I added in r15-7765-g3866ca796d5281 are causing
those tests to FAIL on Solaris and arm-thumb due to the linker
complaining about undefined functions.  The new test functions are not
called, so it shouldn't matter that they call undefined member
functions, but it does.

Move those functions to separate { dg-do compile } files so the linker
isn't used and won't complain.

libstdc++-v3/ChangeLog:

	PR libstdc++/119110
	* testsuite/25_algorithms/move/constrained.cc: Move test06
	function to ...
	* testsuite/25_algorithms/move/105609.cc: New test.
	* testsuite/25_algorithms/move_backward/constrained.cc: Move
	test04 function to ...
	* testsuite/25_algorithms/move_backward/105609.cc: New test.

libstdc++-v3/ChangeLog:

	* include/bits/version.def (ranges_cache_latest): Define.
	* include/bits/version.h: Regenerate.
	* include/std/ranges (__detail::__non_propagating_cache::_M_reset):
	Export from base class _Optional_base.
	(cache_latest_view): Define for C++26.
	(cache_latest_view::_Iterator): Likewise.
	(cache_latest_view::_Sentinel): Likewise.
	(views::__detail::__can_cache_latest): Likewise.
	(views::_CacheLatest, views::cache_latest): Likewise.
	* testsuite/std/ranges/adaptors/cache_latest/1.cc: New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

This is a C++ >= 26 codepath for supporting constexpr stable_sort, so we
know that we have if consteval available; it just needs protection with
the feature-testing macro. Also merge the return in the same statement.
Amends r15-7708-gff43f9853d3b10.

libstdc++-v3/ChangeLog:

	* include/bits/stl_algo.h (__stable_sort): Use if consteval
	instead of is_constant_evaluated.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

- Use __builtin_unreachable to suppress a false-positive "control
  reaches end of non-void function" warning in the recursive lambda
  (which the existing tests failed to notice since test01 wasn't
  being called at runtime)
- Relax the constraints on views::concat in the single-argument case
  as per PR115215
- Add an input_range requirement to that same case as per LWG 4082
- In the const-converting constructor of concat_view's iterator,
  don't require the first iterator to be default constructible

	PR libstdc++/115215
	PR libstdc++/115218

libstdc++-v3/ChangeLog:

	* include/std/ranges
	(concat_view::iterator::_S_invoke_with_runtime_index): Use
	__builtin_unreachable in recursive lambda to certify it always
	exits via 'return'.
	(concat_view::iterator::iterator): In the const-converting
	constructor, direct initialize _M_it.
	(views::_Concat::operator()): Adjust constraints in the
	single-argument case as per LWG 4082.
	* testsuite/std/ranges/concat/1.cc (test01): Call it at runtime
	too.
	(test04): New test.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Fix regression introduced by r14-8710-g65b4cba9d6a9ff

	PR libstdc++/119121

libstdc++-v3/ChangeLog:

	* include/bits/ranges_util.h (__detail::__pair_like_convertible_from):
	Use `_Tp` in `is_reference_v` check
	* testsuite/std/ranges/subrange/tuple_like.cc: New tests for
	pair-like conversion

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

This commit adds support for C++26's constexpr specialized memory
algorithms, introduced by P2283R2, P3508R0, P3369R0.

The uninitialized_default, value, copy, move and fill algorithms are
affected, in all of their variants (iterator-based, range-based and _n
versions.)

The changes are mostly mechanical -- add `constexpr` to a number of
signatures when compiling in C++26 and above modes. The internal helper
guard class for range algorithms instead can be marked unconditionally.

uninitialized_default_construct is implemented in terms of the
_Construct_novalue helper, which requires support for C++26's constexpr
placement new from the compiler (P2747R2, which GCC implements). We can
simply mark it as constexpr in C++26 language modes, even if the
compiler does not support P2747R2 (e.g. Clang 17/18), because C++23's
P2448R2 makes it OK to mark functions as constexpr even if they never
qualify, and other compilers implement this.

The only "real" change to the implementation of the algorithms is that
during constant evaluation I need to dispatch to a constexpr-friendly
version of them.

For each algorithm family I've added only one test to cover it and its
variants; the idea is to avoid too much repetition and simplify future
maintenance.

libstdc++-v3/ChangeLog:

	* include/bits/ranges_uninitialized.h: Mark the specialized
	memory algorithms as constexpr in C++26. Also mark the members
	of the _DestroyGuard helper class.
	* include/bits/stl_uninitialized.h: Ditto.
	* include/bits/stl_construct.h: (_Construct_novalue) Mark it
	as constexpr in C++26.
	* include/bits/version.def (raw_memory_algorithms): Bump the
	feature-testing macro for C++26.
	* include/bits/version.h: Regenerate.
	* testsuite/20_util/headers/memory/synopsis.cc: Add constexpr to
	the uninitialized_* algorithms (when in C++26) in the test.
	* testsuite/20_util/specialized_algorithms/feature_test_macro.cc:
	New test.
	* testsuite/20_util/specialized_algorithms/uninitialized_copy/constexpr.cc:
	New test.
	* testsuite/20_util/specialized_algorithms/uninitialized_default_construct/constexpr.cc:
	New test.
	* testsuite/20_util/specialized_algorithms/uninitialized_fill/constexpr.cc:
	New test.
	* testsuite/20_util/specialized_algorithms/uninitialized_move/constexpr.cc:
	New test.
	* testsuite/20_util/specialized_algorithms/uninitialized_value_construct/constexpr.cc:
	New test.

Reviewed-by: Patrick Palka <ppalka@redhat.com>

libstdc++-v3/ChangeLog:

	* doc/xml/manual/test.xml: Remove stray comma.
	* doc/html/manual/test.html: Regenerate.

The specification for std::ranges::iter_move apparently requires us to
handle types which do not satisfy std::indirectly_readable, for example
with overloaded operator* which behaves differently for different value
categories.

libstdc++-v3/ChangeLog:

	PR libstdc++/106612
	* include/bits/iterator_concepts.h (_IterMove::__iter_ref_t):
	New alias template.
	(_IterMove::__result): Use __iter_ref_t instead of
	std::iter_reference_t.
	(_IterMove::__type): Remove incorrect __dereferenceable
	constraint.
	(_IterMove::operator()): Likewise. Add correct constraints. Use
	__iter_ref_t instead of std::iter_reference_t. Forward parameter
	as correct value category.
	(iter_swap): Add comments.
	* testsuite/24_iterators/customization_points/iter_move.cc: Test
	that iter_move is found by ADL and that rvalue arguments are
	handled correctly.

Reviewed-by: Patrick Palka <ppalka@redhat.com>

The ranges::move and ranges::move_backward algorithms are supposed to
use ranges::iter_move(iter) instead of std::move(*iter), which matters
for an iterator type with an iter_move overload findable by ADL.

Currently those algorithms use std::__assign_one which uses std::move,
so define a new ranges::__detail::__assign_one helper function that uses
ranges::iter_move.

libstdc++-v3/ChangeLog:

	PR libstdc++/105609
	* include/bits/ranges_algobase.h (__detail::__assign_one): New
	helper function.
	(__copy_or_move, __copy_or_move_backward): Use new function
	instead of std::__assign_one.
	* testsuite/25_algorithms/move/constrained.cc: Check that
	ADL iter_move is used in preference to std::move.
	* testsuite/25_algorithms/move_backward/constrained.cc:
	Likewise.

The standard requires that we reject attempts to create a ranges::to
adaptor for cv-qualified types and non-class types. Currently we only
diagnose it once the adaptor is used in a pipeline.

This adds static assertions to diagnose it immediately.

libstdc++-v3/ChangeLog:

	PR libstdc++/112803
	* include/std/ranges (ranges::to): Add static assertions to
	enforce Mandates conditions.
	* testsuite/std/ranges/conv/112803.cc: New test.

It turns out the reason the behavior of this testcase changed after CWG
2369 is because validity of the substituted return type is now checked
later, after constraints.  So a more reliable workaround for this issue
is to add a constraint to check the validity of the return type earlier,
matching the pre-CWG 2369 semantics.

	PR libstdc++/104606

libstdc++-v3/ChangeLog:

	* include/std/optional (operator<=>): Revert r14-9771 change.
	Add constraint checking the validity of the return type
	compare_three_way_result_t before the three_way_comparable_with
	constraint.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Here for

  using RCI = reverse_iterator<basic_const_iterator<vector<int>::iterator>>
  static_assert(std::totally_ordered<RCI>);

we effectively need to check the requirement

  requires (RCI x) { x RELOP x; }  for each RELOP in {<, >, <=, >=}

which we expect to be straightforwardly satisfied by reverse_iterator's
namespace-scope relops.  But due to ADL we find ourselves also
considering the basic_const_iterator relop friends, which before CWG
2369 would be quickly discarded since RCI clearly isn't convertible to
basic_const_iterator.  After CWG 2369 though we must first check these
relops' constraints (with _It = vector<int>::iterator and _It2 = RCI),
which entails checking totally_ordered<RCI> recursively.

This patch fixes this by turning the problematic non-dependent function
parameters of type basic_const_iterator<_It> into dependent ones of
type basic_const_iterator<_It3> where _It3 is constrained to match _It.
Thus the basic_const_iterator relop friends now get quickly discarded
during deduction and before the constraint check if the second operand
isn't a specialization of basic_const_iterator (or derived from one)
like before CWG 2369.

	PR libstdc++/112490

libstdc++-v3/ChangeLog:

	* include/bits/stl_iterator.h (basic_const_iterator::operator<):
	Replace non-dependent basic_const_iterator function parameter with
	a dependent one of type basic_const_iterator<_It3> where _It3
	matches _It.
	(basic_const_iterator::operator>): Likewise.
	(basic_const_iterator::operator<=): Likewise.
	(basic_const_iterator::operator>=): Likewise.
	* testsuite/24_iterators/const_iterator/112490.cc: New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

My r15-998-g2a83084ce55363 change replaced the use of nothrow
operator new with a call to __get_temporary_buffer, so update the
comment to match.

libstdc++-v3/ChangeLog:

	* include/std/stacktrace (_Impl::_M_allocate): Fix outdated
	comment.

	PR libstdc++/118083

libstdc++-v3/ChangeLog:

	* include/bits/ranges_base.h
	(ranges::__access::__possibly_const_range): Mention LWG 4027.

stable_sort has been made constexpr in C++26. Apart from plastering a
few functions with constexpr, there's an implementation challenge, that
is: stable_sort takes different codepaths in case extra memory can be
allocated. Rather than doing some major refactorings, simply use the
non-allocating path during constant evaluation. That's the same codepath
used when extra memory could not be allocated, as well as by
freestanding.

libstdc++-v3/ChangeLog:

	* include/bits/algorithmfwd.h (stable_sort): Add constexpr.
	* include/bits/ranges_algo.h (__stable_sort_fn): Add constexpr
	to the function call operators.
	* include/bits/stl_algo.h (__stable_sort): Add constexpr.
	During constant evaluation, always use the non-allocating path.
	(stable_sort): Add constexpr.
	(__inplace_stable_sort): Likewise.
	(__merge_without_buffer): Likewise.
	* include/bits/version.def (constexpr_algorithms): Bump value
	for C++26.
	* include/bits/version.h: Regnerate.
	* testsuite/25_algorithms/cpp_lib_constexpr.cc: Test the bumped
	feature-testing macro.
	* testsuite/25_algorithms/headers/algorithm/synopsis.cc: Adapt
	the test to constexpr stable_sort.
	* testsuite/25_algorithms/stable_sort/constexpr.cc: New test.

Signed-off-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

Following the precedent of _GLIBCXX20_CONSTEXPR.

It will be used to decorate some functions which have been made
constexpr in C++26 (for instance P2562R1, and maybe P3508R0, P3369R0,
...).

libstdc++-v3/ChangeLog:

	* include/bits/c++config (_GLIBCXX26_CONSTEXPR): New macro.

Signed-off-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

The r15-4321-gd8ef4471cb9c9f change incorrectly used __value as the
member of the __memcpyable_integer trait, but it should have been
__width. That meant this overload was not being used for _Tp != _Up.

Also return after doing the loop for the consteval case. The missing
return wasn't causing incorrect behaviour because the consteval loop
increments the iterator until it equals the end of the range, so the
memset isn't done.  But it's still better to return and not even try
to do the memset.

libstdc++-v3/ChangeLog:

	PR libstdc++/93059
	* include/bits/stl_algobase.h (__fill_a1): Fix typo in SFINAE
	constraint.

It is wrong to reuse a cached hash code from another container when this code depends
on the state of the container's Hash functor.

Add checks that Hash functor is stateless before reusing the cached hash code.

libstdc++-v3/ChangeLog:

	* include/bits/hashtable_policy.h
	(_Hash_code_base::_M_copy_code, _Hash_code_base::_M_store_code): Remove.
	* include/bits/hashtable.h (_M_hash_code_ext): New.
	(_M_merge_multi(_Hashtable&)): Use latter.
	(_M_copy_code): New.
	(_M_assign): Use latter.
	(_M_bucket_index_ex): New.
	(_M_equals): Use latter.
	(_M_store_code): New.
	(_M_src_hash_code): Remove key_type parameter.
	* testsuite/23_containers/unordered_map/modifiers/merge.cc (test10): New
	test case.

LWG 4027 effectively makes the const range access CPOs ranges::cfoo behave
more consistently across C++23 and C++20 (pre-P2278R4) and also more
consistently with the std::cfoo range accessors, as the below testcase
adjustments demonstrate (which mostly consist of reverting workarounds
added by r14-3771-gf12e26f3496275 and r13-7186-g0d94c6df183375).

In passing fix PR118083 which reports that the input_range constraint on
possibly-const-range is missing in our implementation.  A consequence of
this is that the const range access CPOs now consistently reject a non-range
argument, and so in some our of tests we need to introduce otherwise
unused begin/end members.

	PR libstdc++/118083

libstdc++-v3/ChangeLog:

	* include/bits/ranges_base.h
	(ranges::__access::__possibly_const_range): Adjust logic as per
	LWG 4027.  Add missing input_range constraint.
	* testsuite/std/ranges/access/cbegin.cc (test05): Verify LWG
	4027 testcases.
	* testsuite/std/ranges/access/cdata.cc: Adjust, simplify and
	consolidate some tests after the above.
	* testsuite/std/ranges/access/cend.cc: Likewise.
	* testsuite/std/ranges/access/crbegin.cc: Likewise.
	* testsuite/std/ranges/access/crend.cc: Likewise.
	* testsuite/std/ranges/adaptors/join.cc: Likewise.
	* testsuite/std/ranges/adaptors/take_while.cc: Likewise.
	* testsuite/std/ranges/adaptors/transform.cc: Likewise.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

The compiler emits code with init_priority(99) for -fvtable-verify=std
and that creates a section conflict with the uses of init_priority(99)
that I recently added to src/c++20/tzdb.cc.

Change tzdb.cc to use a different priority to avoid the conflict.

libstdc++-v3/ChangeLog:

	PR c++/118981
	* src/c++20/tzdb.cc: Use init_priority(98) instead of
	init_priority(99).

Turn test cases into UNSUPPORTED if running into 'sorry, unimplemented: dynamic stack allocation not supported'

In Subversion r217296 (Git commit e2acc079)
"Testsuite alloca fixes for ptx", effective-target 'alloca' was added to mark
up test cases that run into the nvptx back end's non-support of dynamic stack
allocation.  (Later, nvptx gained conditional support for that in
commit 3861d362
"nvptx: PTX 'alloca' for '-mptx=7.3'+, '-march=sm_52'+ [PR65181]", but on the
other hand, in commit f93a612f
"bpf: liberate R9 for general register allocation", the BPF back end joined
"the list of targets that do not support alloca in target-support.exp".

Manually maintaining the list of test cases requiring effective-target 'alloca'
is notoriously hard, gets out of date quickly: new test cases added to the test
suite may need to be analyzed and annotated, and over time annotations also may
need to be removed, in cases where the compiler learns to optimize out
'alloca'/VLA usage, for example.  This commit replaces (99 % of) the manual
annotations with an automatic scheme: turn test cases into UNSUPPORTED if
running into 'sorry, unimplemented: dynamic stack allocation not supported'.

	gcc/testsuite/
	* lib/target-supports.exp (check_effective_target_alloca):
	Gracefully handle the case that we've not be called (indirectly)
	from 'dg-test'.
	* lib/gcc-dg.exp (proc gcc-dg-prune): Turn
	'sorry, unimplemented: dynamic stack allocation not supported' into
	UNSUPPORTED.
	* c-c++-common/Walloca-larger-than.c: Don't
	'dg-require-effective-target alloca'.
	* c-c++-common/Warray-bounds-9.c: Likewise.
	* c-c++-common/Warray-bounds.c: Likewise.
	* c-c++-common/Wdangling-pointer-2.c: Likewise.
	* c-c++-common/Wdangling-pointer-4.c: Likewise.
	* c-c++-common/Wdangling-pointer-5.c: Likewise.
	* c-c++-common/Wdangling-pointer.c: Likewise.
	* c-c++-common/Wimplicit-fallthrough-7.c: Likewise.
	* c-c++-common/Wsizeof-pointer-memaccess1.c: Likewise.
	* c-c++-common/Wsizeof-pointer-memaccess2.c: Likewise.
	* c-c++-common/Wstringop-truncation.c: Likewise.
	* c-c++-common/Wunused-var-6.c: Likewise.
	* c-c++-common/Wunused-var-8.c: Likewise.
	* c-c++-common/analyzer/alloca-leak.c: Likewise.
	* c-c++-common/analyzer/allocation-size-multiline-2.c: Likewise.
	* c-c++-common/analyzer/allocation-size-multiline-3.c: Likewise.
	* c-c++-common/analyzer/capacity-1.c: Likewise.
	* c-c++-common/analyzer/capacity-3.c: Likewise.
	* c-c++-common/analyzer/imprecise-floating-point-1.c: Likewise.
	* c-c++-common/analyzer/infinite-recursion-alloca.c: Likewise.
	* c-c++-common/analyzer/malloc-callbacks.c: Likewise.
	* c-c++-common/analyzer/malloc-paths-8.c: Likewise.
	* c-c++-common/analyzer/out-of-bounds-5.c: Likewise.
	* c-c++-common/analyzer/out-of-bounds-diagram-11.c: Likewise.
	* c-c++-common/analyzer/uninit-alloca.c: Likewise.
	* c-c++-common/analyzer/write-to-string-literal-5.c: Likewise.
	* c-c++-common/asan/alloca_loop_unpoisoning.c: Likewise.
	* c-c++-common/auto-init-11.c: Likewise.
	* c-c++-common/auto-init-12.c: Likewise.
	* c-c++-common/auto-init-15.c: Likewise.
	* c-c++-common/auto-init-16.c: Likewise.
	* c-c++-common/builtins.c: Likewise.
	* c-c++-common/dwarf2/vla1.c: Likewise.
	* c-c++-common/gomp/pr61486-2.c: Likewise.
	* c-c++-common/torture/builtin-clear-padding-4.c: Likewise.
	* c-c++-common/torture/strub-run3.c: Likewise.
	* c-c++-common/torture/strub-run4.c: Likewise.
	* c-c++-common/torture/strub-run4c.c: Likewise.
	* c-c++-common/torture/strub-run4d.c: Likewise.
	* c-c++-common/torture/strub-run4i.c: Likewise.
	* g++.dg/Walloca1.C: Likewise.
	* g++.dg/Walloca2.C: Likewise.
	* g++.dg/cpp0x/pr70338.C: Likewise.
	* g++.dg/cpp1y/lambda-generic-vla1.C: Likewise.
	* g++.dg/cpp1y/vla10.C: Likewise.
	* g++.dg/cpp1y/vla2.C: Likewise.
	* g++.dg/cpp1y/vla6.C: Likewise.
	* g++.dg/cpp1y/vla8.C: Likewise.
	* g++.dg/debug/debug5.C: Likewise.
	* g++.dg/debug/debug6.C: Likewise.
	* g++.dg/debug/pr54828.C: Likewise.
	* g++.dg/diagnostic/pr70105.C: Likewise.
	* g++.dg/eh/cleanup5.C: Likewise.
	* g++.dg/eh/spbp.C: Likewise.
	* g++.dg/ext/builtin_alloca.C: Likewise.
	* g++.dg/ext/tmplattr9.C: Likewise.
	* g++.dg/ext/vla10.C: Likewise.
	* g++.dg/ext/vla11.C: Likewise.
	* g++.dg/ext/vla12.C: Likewise.
	* g++.dg/ext/vla15.C: Likewise.
	* g++.dg/ext/vla16.C: Likewise.
	* g++.dg/ext/vla17.C: Likewise.
	* g++.dg/ext/vla23.C: Likewise.
	* g++.dg/ext/vla3.C: Likewise.
	* g++.dg/ext/vla6.C: Likewise.
	* g++.dg/ext/vla7.C: Likewise.
	* g++.dg/init/array24.C: Likewise.
	* g++.dg/init/new47.C: Likewise.
	* g++.dg/init/pr55497.C: Likewise.
	* g++.dg/opt/pr78201.C: Likewise.
	* g++.dg/template/vla2.C: Likewise.
	* g++.dg/torture/Wsizeof-pointer-memaccess1.C: Likewise.
	* g++.dg/torture/Wsizeof-pointer-memaccess2.C: Likewise.
	* g++.dg/torture/pr62127.C: Likewise.
	* g++.dg/torture/pr67055.C: Likewise.
	* g++.dg/torture/stackalign/eh-alloca-1.C: Likewise.
	* g++.dg/torture/stackalign/eh-inline-2.C: Likewise.
	* g++.dg/torture/stackalign/eh-vararg-1.C: Likewise.
	* g++.dg/torture/stackalign/eh-vararg-2.C: Likewise.
	* g++.dg/warn/Wplacement-new-size-5.C: Likewise.
	* g++.dg/warn/Wsizeof-pointer-memaccess-1.C: Likewise.
	* g++.dg/warn/Wvla-1.C: Likewise.
	* g++.dg/warn/Wvla-3.C: Likewise.
	* g++.old-deja/g++.ext/array2.C: Likewise.
	* g++.old-deja/g++.ext/constructor.C: Likewise.
	* g++.old-deja/g++.law/builtin1.C: Likewise.
	* g++.old-deja/g++.other/crash12.C: Likewise.
	* g++.old-deja/g++.other/eh3.C: Likewise.
	* g++.old-deja/g++.pt/array6.C: Likewise.
	* g++.old-deja/g++.pt/dynarray.C: Likewise.
	* gcc.c-torture/compile/20000923-1.c: Likewise.
	* gcc.c-torture/compile/20030224-1.c: Likewise.
	* gcc.c-torture/compile/20071108-1.c: Likewise.
	* gcc.c-torture/compile/20071117-1.c: Likewise.
	* gcc.c-torture/compile/900313-1.c: Likewise.
	* gcc.c-torture/compile/parms.c: Likewise.
	* gcc.c-torture/compile/pr17397.c: Likewise.
	* gcc.c-torture/compile/pr35006.c: Likewise.
	* gcc.c-torture/compile/pr42956.c: Likewise.
	* gcc.c-torture/compile/pr51354.c: Likewise.
	* gcc.c-torture/compile/pr52714.c: Likewise.
	* gcc.c-torture/compile/pr55851.c: Likewise.
	* gcc.c-torture/compile/pr77754-1.c: Likewise.
	* gcc.c-torture/compile/pr77754-2.c: Likewise.
	* gcc.c-torture/compile/pr77754-3.c: Likewise.
	* gcc.c-torture/compile/pr77754-4.c: Likewise.
	* gcc.c-torture/compile/pr77754-5.c: Likewise.
	* gcc.c-torture/compile/pr77754-6.c: Likewise.
	* gcc.c-torture/compile/pr78439.c: Likewise.
	* gcc.c-torture/compile/pr79413.c: Likewise.
	* gcc.c-torture/compile/pr82564.c: Likewise.
	* gcc.c-torture/compile/pr87110.c: Likewise.
	* gcc.c-torture/compile/pr99787-1.c: Likewise.
	* gcc.c-torture/compile/vla-const-1.c: Likewise.
	* gcc.c-torture/compile/vla-const-2.c: Likewise.
	* gcc.c-torture/execute/20010209-1.c: Likewise.
	* gcc.c-torture/execute/20020314-1.c: Likewise.
	* gcc.c-torture/execute/20020412-1.c: Likewise.
	* gcc.c-torture/execute/20021113-1.c: Likewise.
	* gcc.c-torture/execute/20040223-1.c: Likewise.
	* gcc.c-torture/execute/20040308-1.c: Likewise.
	* gcc.c-torture/execute/20040811-1.c: Likewise.
	* gcc.c-torture/execute/20070824-1.c: Likewise.
	* gcc.c-torture/execute/20070919-1.c: Likewise.
	* gcc.c-torture/execute/built-in-setjmp.c: Likewise.
	* gcc.c-torture/execute/pr22061-1.c: Likewise.
	* gcc.c-torture/execute/pr43220.c: Likewise.
	* gcc.c-torture/execute/pr82210.c: Likewise.
	* gcc.c-torture/execute/pr86528.c: Likewise.
	* gcc.c-torture/execute/vla-dealloc-1.c: Likewise.
	* gcc.dg/20001012-2.c: Likewise.
	* gcc.dg/20020415-1.c: Likewise.
	* gcc.dg/20030331-2.c: Likewise.
	* gcc.dg/20101010-1.c: Likewise.
	* gcc.dg/Walloca-1.c: Likewise.
	* gcc.dg/Walloca-10.c: Likewise.
	* gcc.dg/Walloca-11.c: Likewise.
	* gcc.dg/Walloca-12.c: Likewise.
	* gcc.dg/Walloca-13.c: Likewise.
	* gcc.dg/Walloca-14.c: Likewise.
	* gcc.dg/Walloca-15.c: Likewise.
	* gcc.dg/Walloca-2.c: Likewise.
	* gcc.dg/Walloca-3.c: Likewise.
	* gcc.dg/Walloca-4.c: Likewise.
	* gcc.dg/Walloca-5.c: Likewise.
	* gcc.dg/Walloca-6.c: Likewise.
	* gcc.dg/Walloca-7.c: Likewise.
	* gcc.dg/Walloca-8.c: Likewise.
	* gcc.dg/Walloca-9.c: Likewise.
	* gcc.dg/Walloca-larger-than-2.c: Likewise.
	* gcc.dg/Walloca-larger-than-3.c: Likewise.
	* gcc.dg/Walloca-larger-than-4.c: Likewise.
	* gcc.dg/Walloca-larger-than.c: Likewise.
	* gcc.dg/Warray-bounds-22.c: Likewise.
	* gcc.dg/Warray-bounds-41.c: Likewise.
	* gcc.dg/Warray-bounds-46.c: Likewise.
	* gcc.dg/Warray-bounds-48-novec.c: Likewise.
	* gcc.dg/Warray-bounds-48.c: Likewise.
	* gcc.dg/Warray-bounds-50.c: Likewise.
	* gcc.dg/Warray-bounds-63.c: Likewise.
	* gcc.dg/Warray-bounds-66.c: Likewise.
	* gcc.dg/Wdangling-pointer.c: Likewise.
	* gcc.dg/Wfree-nonheap-object-2.c: Likewise.
	* gcc.dg/Wfree-nonheap-object.c: Likewise.
	* gcc.dg/Wrestrict-17.c: Likewise.
	* gcc.dg/Wrestrict.c: Likewise.
	* gcc.dg/Wreturn-local-addr-2.c: Likewise.
	* gcc.dg/Wreturn-local-addr-3.c: Likewise.
	* gcc.dg/Wreturn-local-addr-4.c: Likewise.
	* gcc.dg/Wreturn-local-addr-6.c: Likewise.
	* gcc.dg/Wsizeof-pointer-memaccess1.c: Likewise.
	* gcc.dg/Wstack-usage.c: Likewise.
	* gcc.dg/Wstrict-aliasing-bogus-vla-1.c: Likewise.
	* gcc.dg/Wstrict-overflow-27.c: Likewise.
	* gcc.dg/Wstringop-overflow-15.c: Likewise.
	* gcc.dg/Wstringop-overflow-23.c: Likewise.
	* gcc.dg/Wstringop-overflow-25.c: Likewise.
	* gcc.dg/Wstringop-overflow-27.c: Likewise.
	* gcc.dg/Wstringop-overflow-3.c: Likewise.
	* gcc.dg/Wstringop-overflow-39.c: Likewise.
	* gcc.dg/Wstringop-overflow-56.c: Likewise.
	* gcc.dg/Wstringop-overflow-57.c: Likewise.
	* gcc.dg/Wstringop-overflow-67.c: Likewise.
	* gcc.dg/Wstringop-overflow-71.c: Likewise.
	* gcc.dg/Wstringop-truncation-3.c: Likewise.
	* gcc.dg/Wvla-larger-than-1.c: Likewise.
	* gcc.dg/Wvla-larger-than-2.c: Likewise.
	* gcc.dg/Wvla-larger-than-3.c: Likewise.
	* gcc.dg/Wvla-larger-than-4.c: Likewise.
	* gcc.dg/Wvla-larger-than-5.c: Likewise.
	* gcc.dg/analyzer/boxed-malloc-1.c: Likewise.
	* gcc.dg/analyzer/call-summaries-2.c: Likewise.
	* gcc.dg/analyzer/malloc-1.c: Likewise.
	* gcc.dg/analyzer/malloc-reuse.c: Likewise.
	* gcc.dg/analyzer/out-of-bounds-diagram-12.c: Likewise.
	* gcc.dg/analyzer/pr93355-localealias.c: Likewise.
	* gcc.dg/analyzer/putenv-1.c: Likewise.
	* gcc.dg/analyzer/taint-alloc-1.c: Likewise.
	* gcc.dg/analyzer/torture/pr93373.c: Likewise.
	* gcc.dg/analyzer/torture/ubsan-1.c: Likewise.
	* gcc.dg/analyzer/vla-1.c: Likewise.
	* gcc.dg/atomic/stdatomic-vm.c: Likewise.
	* gcc.dg/attr-alloc_size-6.c: Likewise.
	* gcc.dg/attr-alloc_size-7.c: Likewise.
	* gcc.dg/attr-alloc_size-8.c: Likewise.
	* gcc.dg/attr-alloc_size-9.c: Likewise.
	* gcc.dg/attr-noipa.c: Likewise.
	* gcc.dg/auto-init-uninit-36.c: Likewise.
	* gcc.dg/auto-init-uninit-9.c: Likewise.
	* gcc.dg/auto-type-1.c: Likewise.
	* gcc.dg/builtin-alloc-size.c: Likewise.
	* gcc.dg/builtin-dynamic-alloc-size.c: Likewise.
	* gcc.dg/builtin-dynamic-object-size-1.c: Likewise.
	* gcc.dg/builtin-dynamic-object-size-2.c: Likewise.
	* gcc.dg/builtin-dynamic-object-size-3.c: Likewise.
	* gcc.dg/builtin-dynamic-object-size-4.c: Likewise.
	* gcc.dg/builtin-object-size-1.c: Likewise.
	* gcc.dg/builtin-object-size-2.c: Likewise.
	* gcc.dg/builtin-object-size-3.c: Likewise.
	* gcc.dg/builtin-object-size-4.c: Likewise.
	* gcc.dg/builtins-64.c: Likewise.
	* gcc.dg/builtins-68.c: Likewise.
	* gcc.dg/c23-auto-2.c: Likewise.
	* gcc.dg/c99-const-expr-13.c: Likewise.
	* gcc.dg/c99-vla-1.c: Likewise.
	* gcc.dg/fold-alloca-1.c: Likewise.
	* gcc.dg/gomp/pr30494.c: Likewise.
	* gcc.dg/gomp/vla-2.c: Likewise.
	* gcc.dg/gomp/vla-3.c: Likewise.
	* gcc.dg/gomp/vla-4.c: Likewise.
	* gcc.dg/gomp/vla-5.c: Likewise.
	* gcc.dg/graphite/pr99085.c: Likewise.
	* gcc.dg/guality/guality.c: Likewise.
	* gcc.dg/lto/pr80778_0.c: Likewise.
	* gcc.dg/nested-func-10.c: Likewise.
	* gcc.dg/nested-func-12.c: Likewise.
	* gcc.dg/nested-func-13.c: Likewise.
	* gcc.dg/nested-func-14.c: Likewise.
	* gcc.dg/nested-func-15.c: Likewise.
	* gcc.dg/nested-func-16.c: Likewise.
	* gcc.dg/nested-func-17.c: Likewise.
	* gcc.dg/nested-func-9.c: Likewise.
	* gcc.dg/packed-vla.c: Likewise.
	* gcc.dg/pr100225.c: Likewise.
	* gcc.dg/pr25682.c: Likewise.
	* gcc.dg/pr27301.c: Likewise.
	* gcc.dg/pr31507-1.c: Likewise.
	* gcc.dg/pr33238.c: Likewise.
	* gcc.dg/pr41470.c: Likewise.
	* gcc.dg/pr49120.c: Likewise.
	* gcc.dg/pr50764.c: Likewise.
	* gcc.dg/pr51491-2.c: Likewise.
	* gcc.dg/pr51990-2.c: Likewise.
	* gcc.dg/pr51990.c: Likewise.
	* gcc.dg/pr59011.c: Likewise.
	* gcc.dg/pr59523.c: Likewise.
	* gcc.dg/pr61561.c: Likewise.
	* gcc.dg/pr78468.c: Likewise.
	* gcc.dg/pr78902.c: Likewise.
	* gcc.dg/pr79972.c: Likewise.
	* gcc.dg/pr82875.c: Likewise.
	* gcc.dg/pr83844.c: Likewise.
	* gcc.dg/pr84131.c: Likewise.
	* gcc.dg/pr87099.c: Likewise.
	* gcc.dg/pr87320.c: Likewise.
	* gcc.dg/pr89045.c: Likewise.
	* gcc.dg/pr91014.c: Likewise.
	* gcc.dg/pr93986.c: Likewise.
	* gcc.dg/pr98721-1.c: Likewise.
	* gcc.dg/pr99122-2.c: Likewise.
	* gcc.dg/shrink-wrap-alloca.c: Likewise.
	* gcc.dg/sso-14.c: Likewise.
	* gcc.dg/strlenopt-62.c: Likewise.
	* gcc.dg/strlenopt-83.c: Likewise.
	* gcc.dg/strlenopt-84.c: Likewise.
	* gcc.dg/strlenopt-91.c: Likewise.
	* gcc.dg/torture/Wsizeof-pointer-memaccess1.c: Likewise.
	* gcc.dg/torture/calleesave-sse.c: Likewise.
	* gcc.dg/torture/pr48953.c: Likewise.
	* gcc.dg/torture/pr71881.c: Likewise.
	* gcc.dg/torture/pr71901.c: Likewise.
	* gcc.dg/torture/pr78742.c: Likewise.
	* gcc.dg/torture/pr92088-1.c: Likewise.
	* gcc.dg/torture/pr92088-2.c: Likewise.
	* gcc.dg/torture/pr93124.c: Likewise.
	* gcc.dg/torture/pr94479.c: Likewise.
	* gcc.dg/torture/stackalign/alloca-1.c: Likewise.
	* gcc.dg/torture/stackalign/inline-2.c: Likewise.
	* gcc.dg/torture/stackalign/nested-3.c: Likewise.
	* gcc.dg/torture/stackalign/vararg-1.c: Likewise.
	* gcc.dg/torture/stackalign/vararg-2.c: Likewise.
	* gcc.dg/tree-ssa/20030807-2.c: Likewise.
	* gcc.dg/tree-ssa/20080530.c: Likewise.
	* gcc.dg/tree-ssa/alias-37.c: Likewise.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-22.c: Likewise.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-25.c: Likewise.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-3.c: Likewise.
	* gcc.dg/tree-ssa/loop-interchange-15.c: Likewise.
	* gcc.dg/tree-ssa/pr23848-1.c: Likewise.
	* gcc.dg/tree-ssa/pr23848-2.c: Likewise.
	* gcc.dg/tree-ssa/pr23848-3.c: Likewise.
	* gcc.dg/tree-ssa/pr23848-4.c: Likewise.
	* gcc.dg/uninit-32.c: Likewise.
	* gcc.dg/uninit-36.c: Likewise.
	* gcc.dg/uninit-39.c: Likewise.
	* gcc.dg/uninit-41.c: Likewise.
	* gcc.dg/uninit-9-O0.c: Likewise.
	* gcc.dg/uninit-9.c: Likewise.
	* gcc.dg/uninit-pr100250.c: Likewise.
	* gcc.dg/uninit-pr101300.c: Likewise.
	* gcc.dg/uninit-pr101494.c: Likewise.
	* gcc.dg/uninit-pr98583.c: Likewise.
	* gcc.dg/vla-2.c: Likewise.
	* gcc.dg/vla-22.c: Likewise.
	* gcc.dg/vla-24.c: Likewise.
	* gcc.dg/vla-3.c: Likewise.
	* gcc.dg/vla-4.c: Likewise.
	* gcc.dg/vla-stexp-1.c: Likewise.
	* gcc.dg/vla-stexp-2.c: Likewise.
	* gcc.dg/vla-stexp-4.c: Likewise.
	* gcc.dg/vla-stexp-5.c: Likewise.
	* gcc.dg/winline-7.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-1.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-10.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-2.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-3.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-4.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-5.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-6.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-7.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-8.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-9.c: Likewise.
	* gcc.target/arc/interrupt-6.c: Likewise.
	* gcc.target/i386/pr80969-3.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-1.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-2.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-3.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-4.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-5.c: Likewise.
	* gcc.target/loongarch/stack-check-alloca-6.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-1.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-10.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-2.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-3.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-4.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-5.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-6.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-7.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-8.c: Likewise.
	* gcc.target/riscv/stack-check-alloca-9.c: Likewise.
	* gcc.target/sparc/setjmp-1.c: Likewise.
	* gcc.target/x86_64/abi/ms-sysv/ms-sysv.c: Likewise.
	* gcc.c-torture/compile/20001221-1.c: Don't 'dg-skip-if'
	for '! alloca'.
	* gcc.c-torture/compile/20020807-1.c: Likewise.
	* gcc.c-torture/compile/20050801-2.c: Likewise.
	* gcc.c-torture/compile/920428-4.c: Likewise.
	* gcc.c-torture/compile/debugvlafunction-1.c: Likewise.
	* gcc.c-torture/compile/pr41469.c: Likewise.
	* gcc.c-torture/execute/920721-2.c: Likewise.
	* gcc.c-torture/execute/920929-1.c: Likewise.
	* gcc.c-torture/execute/921017-1.c: Likewise.
	* gcc.c-torture/execute/941202-1.c: Likewise.
	* gcc.c-torture/execute/align-nest.c: Likewise.
	* gcc.c-torture/execute/alloca-1.c: Likewise.
	* gcc.c-torture/execute/pr22061-4.c: Likewise.
	* gcc.c-torture/execute/pr36321.c: Likewise.
	* gcc.dg/torture/pr8081.c: Likewise.
	* gcc.dg/analyzer/data-model-1.c: Don't
	'dg-require-effective-target alloca'.  XFAIL relevant
	'dg-warning's for '! alloca'.
	* gcc.dg/uninit-38.c: Likewise.
	* gcc.dg/uninit-pr98578.c: Likewise.
	* gcc.dg/compat/struct-by-value-22_main.c: Comment on
	'dg-require-effective-target alloca'.
	libstdc++-v3/
	* testsuite/lib/prune.exp (proc libstdc++-dg-prune): Turn
	'sorry, unimplemented: dynamic stack allocation not supported' into
	UNSUPPORTED.

No conversion is needed because the type of _M_i is __int_type anyway.

libstdc++-v3/ChangeLog:

	* include/bits/atomic_base.h (__atomic_base<_ITp>): Remove
	misleading comment.

In r15-7647-g32457bc25fea80 I added a cast and also changed the type of
the variable, making the cast redundant. This removes the cast.

libstdc++-v3/ChangeLog:

	* src/c++17/floating_from_chars.cc (__floating_from_chars_hex):
	Remove redundant cast.

We started using the __array_rank built-in with r15-1252-g6f0dfa6f1acdf7
but that built-in is buggy in versions of Clang up to and including 19.

libstdc++-v3/ChangeLog:

	PR libstdc++/118559
	* include/std/type_traits (rank, rank_v): Do not use
	__array_rank for Clang 19 and older.

This allows _GLIBCXX_HAS_BUILTIN (or _GLIBCXX_USE_BUILTIN_TRAIT) to be
used as part of a larger logical expression.

libstdc++-v3/ChangeLog:

	* include/bits/c++config (_GLIBCXX_HAS_BUILTIN): Add parentheses.

This makes several functions in <bit> faster to compile, with fewer
expressions to parse and fewer instantiations of __numeric_traits
required.

libstdc++-v3/ChangeLog:

	PR libstdc++/118855
	* include/std/bit (__count_lzero, __count_rzero, __popcount):
	Use type-generic built-ins when available.

These should have been unsigned, but the static assertions are only in
the public std::bit_ceil and std::bit_width functions, not the internal
__bit_ceil and __bit_width ones.

libstdc++-v3/ChangeLog:

	* include/experimental/bits/simd.h (__find_next_valid_abi): Cast
	__bit_ceil argument to unsigned.
	* src/c++17/floating_from_chars.cc (__floating_from_chars_hex):
	Cast __bit_ceil argument to unsigned.
	* src/c++17/memory_resource.cc (big_block): Cast __bit_width
	argument to unsigned.

Since r15-7511-g4e7f74225116e7 we can disable the warnings for using a
reserved priority using a diagnostic pragma. That means we no longer
need to put globals using that attribute into separate files that get
included.

This replaces the two uses of such separate files by moving the variable
definition into the source file and adding the diagnostic pragma.

libstdc++-v3/ChangeLog:

	* src/c++17/memory_resource.cc (default_res): Define here
	instead of including default_resource.h.
	* src/c++98/globals_io.cc (__ioinit): Define here instead of
	including ios_base_init.h.
	* src/c++17/default_resource.h: Removed.
	* src/c++98/ios_base_init.h: Removed.

When linking statically to libstdc++.a (or to libstdc++_nonshared.a in
the RHEL devtoolset compiler) there's a static initialization order
problem where user code might be constructed before the
std::chrono::tzdb_list globals, and so might try to use them after
they've already been destroyed.

Use the init_priority attribute on those globals so that they are
initialized early. Since r15-7511-g4e7f74225116e7 we can disable the
warnings for using a reserved priority using a diagnostic pragma.

libstdc++-v3/ChangeLog:

	PR libstdc++/118811
	* src/c++20/tzdb.cc (tzdb_list::_Node): Use init_priority
	attribute on static data members.
	* testsuite/std/time/tzdb_list/pr118811.cc: New test.

Even though 'iterator' is a reserved macro name, we can't use it as the
name of this implementation detail type since it could introduce name
lookup ambiguity in valid code, e.g.

  struct A { using iterator = void; }
  struct B : concat_view<...>, A { using type = iterator; };

libstdc++-v3/ChangeLog:

	* include/std/ranges (concat_view::iterator): Rename to ...
	(concat_view::_Iterator): ... this throughout.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Our concat_view implementation is accidentally based off of an older
revision of the paper, P2542R7 instead of R8.  As far as I can tell the
only semantic change in the final revision is the relaxed constraints on
the iterator's iter/sent operator- overloads, which this patch updates.

This patch also simplifies the concat_view::end wording via C++26 pack
indexing as per the final revision.  In turn we make the availability of
this library feature conditional on __cpp_pack_indexing.  (Note pack
indexing is implemented in GCC 15 and Clang 19).

	PR libstdc++/115209

libstdc++-v3/ChangeLog:

	* include/bits/version.def (ranges_concat): Depend on
	__cpp_pack_indexing.
	* include/bits/version.h: Regenerate.
	* include/std/ranges (__detail::__last_is_common): Remove.
	(__detail::__all_but_first_sized): New.
	(concat_view::end): Use C++26 pack indexing instead of
	__last_is_common as per R8 of P2542.
	(concat_view::iterator::operator-): Update constraints on
	iter/sent overloads as per R8 of P2542.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>