gcc.git/libstdc++-v3/include/std/tuple, branch master Unnamed repository; edit this file 'description' to name the repository. libstdc++: Implement const copy-assignment for tuple<> [PR119721] 2025-10-29T16:13:59+00:00 Tomasz Kamiński tkaminsk@redhat.com 2025-10-27T13:19:47+00:00 8728f60b9750ea10abd1a02db7972a6ff6ef2eae This patch completes the implementation of P2321R2, giving tuple proper proxy reference semantics. The assignment operator is implemented as a template constrained to accept only tuple<>. Consequently, the language does not consider it a copy assignment operator, which prevents tuple<> from losing its trivially copyable status. The _Tuple template parameter is defaulted, ensuring the operator remains a viable candidate for assignment with an empty brace-init list. PR libstdc++/119721 libstdc++-v3/ChangeLog: * include/std/tuple (tuple<>::operator=(const _Tuple&) const) [__cpp_lib_ranges_zip]: Define. * testsuite/23_containers/tuple/cons/119721.cc: Test const assignment. Reviewed-by: Jonathan Wakely <jwakely@redhat.com> Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com> 
This patch completes the implementation of P2321R2, giving tuple proper proxy
reference semantics.

The assignment operator is implemented as a template constrained to accept only
tuple<>. Consequently, the language does not consider it a copy assignment
operator, which prevents tuple<> from losing its trivially copyable status.

The _Tuple template parameter is defaulted, ensuring the operator remains
a viable candidate for assignment with an empty brace-init list.

	PR libstdc++/119721

libstdc++-v3/ChangeLog:

	* include/std/tuple (tuple<>::operator=(const _Tuple&) const)
	[__cpp_lib_ranges_zip]: Define.
	* testsuite/23_containers/tuple/cons/119721.cc: Test const
	assignment.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>
libstdc++: Add constructors and assignments for tuple<> with tuple-like types [PR119721] 2025-10-29T16:09:15+00:00 Osama Abdelkader osama.abdelkader@gmail.com 2025-10-25T17:25:42+00:00 52e300124d2eaad0f19ccc0a49f95fd605a1de69 This patch adds support for constructing and assigning tuple<> from other empty tuple-like types (e.g., array<T, 0>), completing the C++23 tuple-like interface for the zero-element tuple specialization. The implementation includes: - Constructor from forwarding reference to tuple-like types - Allocator-aware constructor from tuple-like types - Assignment operator from tuple-like types - Const assignment operator from tuple-like types PR libstdc++/119721 libstdc++-v3/ChangeLog: * include/std/tuple (tuple<>::tuple(const tuple&)) (tuple<>::operator=(const tuple&)): Define as defaulted. (tuple<>::swap): Moved the defintion after assignments. (tuple<>::tuple(_UTuple&&)) (tuple<>::tuple(allocator_arg_t, const _Alloc&, _UTuple&&)) (tuple<>::operator=(_UTuple&&)) [__cpp_lib_tuple_like]: Define. (tuple<>::operator==, tuple<>::opeator<=>): Parenthesize constrains individually. * testsuite/23_containers/tuple/cons/119721.cc: New test for constructors and assignments with empty tuple-like types. * testsuite/20_util/tuple/requirements/empty_trivial.cc: New test verifying tuple<> remains trivially copyable. Reviewed-by: Jonathan Wakely <jwakely@redhat.com> Co-authored-by: Tomasz Kamiński <tkaminsk@redhat.com> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com> Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com> 
This patch adds support for constructing and assigning tuple<> from
other empty tuple-like types (e.g., array<T, 0>), completing the C++23
tuple-like interface for the zero-element tuple specialization.

The implementation includes:
- Constructor from forwarding reference to tuple-like types
- Allocator-aware constructor from tuple-like types
- Assignment operator from tuple-like types
- Const assignment operator from tuple-like types

	PR libstdc++/119721

libstdc++-v3/ChangeLog:

	* include/std/tuple (tuple<>::tuple(const tuple&))
	(tuple<>::operator=(const tuple&)): Define as defaulted.
	(tuple<>::swap): Moved the defintion after assignments.
	(tuple<>::tuple(_UTuple&&))
	(tuple<>::tuple(allocator_arg_t, const _Alloc&, _UTuple&&))
	(tuple<>::operator=(_UTuple&&)) [__cpp_lib_tuple_like]: Define.
	(tuple<>::operator==, tuple<>::opeator<=>): Parenthesize
	constrains individually.
	* testsuite/23_containers/tuple/cons/119721.cc: New test for
	constructors and assignments with empty tuple-like types.
	* testsuite/20_util/tuple/requirements/empty_trivial.cc:
	New test verifying tuple<> remains trivially copyable.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Co-authored-by: Tomasz Kamiński <tkaminsk@redhat.com>
Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>
libstdc++: Add comparison operators between tuple<> and array<T, 0> [PR119721] 2025-10-22T07:02:18+00:00 Osama Abdelkader osama.abdelkader@gmail.com 2025-10-20T15:16:52+00:00 5a4f430006efeb58461402054e29b5ac5bd5ac5b This fixes the C++23 compliance issue where std::tuple<> cannot be compared with other empty tuple-like types such as std::array<T, 0>. The operators correctly allow comparison with array<T, 0> even when T is not comparable, because empty tuple-like types don't compare element values. PR libstdc++/119721 libstdc++-v3/ChangeLog: * include/std/tuple (tuple<>::operator==, tuple<>::operator<=>): Define. * testsuite/23_containers/tuple/comparison_operators/119721.cc: New test. Reviewed-by: Jonathan Wakely <jwakely@redhat.com> Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com> 
This fixes the C++23 compliance issue where std::tuple<> cannot be compared
with other empty tuple-like types such as std::array<T, 0>.

The operators correctly allow comparison with array<T, 0> even when T is not
comparable, because empty tuple-like types don't compare element values.

	PR libstdc++/119721

libstdc++-v3/ChangeLog:

	* include/std/tuple (tuple<>::operator==, tuple<>::operator<=>):
	Define.
	* testsuite/23_containers/tuple/comparison_operators/119721.cc:
	New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
libstdc++: Optimize determination of std::tuple_cat return type 2025-09-16T17:25:02+00:00 Jonathan Wakely jwakely@redhat.com 2025-09-16T11:00:19+00:00 5d774ec80bcb633a393790154c9969218b7c782f The std::tuple_cat function has to determine a std::tuple return type from zero or more tuple-like arguments. This uses the __make_tuple class template to transform a tuple-like type into a std::tuple, and the __combine_tuples class template to combine zero or more std::tuple types into a single std::tuple type. This change optimizes the __make_tuple class template to use an _Index_tuple and pack expansion instead of recursive instantiation, and optimizes __combine_tuples to use fewer levels of recursion. For ranges::adjacent_view's __detail::__repeated_tuple helper we can just use the __make_tuple class template directly, instead of doing overload resolution on std::tuple_cat to get its return type. libstdc++-v3/ChangeLog: * include/std/ranges (__detail::__repeated_tuple): Use __make_tuple helper alias directly, instead of doing overload resolution on std::tuple_cat. * include/std/tuple (__make_tuple_impl): Remove. (__do_make_tuple): Replace recursion with _Index_tuple and pack expansion. (__make_tuple): Adjust to new __do_make_tuple definition. (__combine_tuples<tuple<T1s...>, tuple<T2s...>, Rem...>): Replace with a partial specialization for exactly two tuples and a partial specialization for three or more tuples. Reviewed-by: Patrick Palka <ppalka@redhat.com> 
The std::tuple_cat function has to determine a std::tuple return type
from zero or more tuple-like arguments. This uses the __make_tuple class
template to transform a tuple-like type into a std::tuple, and the
__combine_tuples class template to combine zero or more std::tuple types
into a single std::tuple type.

This change optimizes the __make_tuple class template to use an
_Index_tuple and pack expansion instead of recursive instantiation, and
optimizes __combine_tuples to use fewer levels of recursion.

For ranges::adjacent_view's __detail::__repeated_tuple helper we can
just use the __make_tuple class template directly, instead of doing
overload resolution on std::tuple_cat to get its return type.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::__repeated_tuple): Use
	__make_tuple helper alias directly, instead of doing overload
	resolution on std::tuple_cat.
	* include/std/tuple (__make_tuple_impl): Remove.
	(__do_make_tuple): Replace recursion with _Index_tuple and pack
	expansion.
	(__make_tuple): Adjust to new __do_make_tuple definition.
	(__combine_tuples<tuple<T1s...>, tuple<T2s...>, Rem...>): Replace
	with a partial specialization for exactly two tuples and a
	partial specialization for three or more tuples.

Reviewed-by: Patrick Palka <ppalka@redhat.com>
libstdc++: Add comments to deleted std::swap overloads for LWG 2766 2025-07-14T20:41:37+00:00 Jonathan Wakely jwakely@redhat.com 2025-07-13T14:34:15+00:00 9840a1db02cb96011f90b8ee86ca2d23b41781db We pre-emptively implemented part of LWG 2766, which still hasn't been approved. Add comments to the deleted swap overloads saying why they're there, because the standard doesn't require them. libstdc++-v3/ChangeLog: * include/bits/stl_pair.h (swap): Add comment to deleted overload. * include/bits/unique_ptr.h (swap): Likewise. * include/std/array (swap): Likewise. * include/std/optional (swap): Likewise. * include/std/tuple (swap): Likewise. * include/std/variant (swap): Likewise. * testsuite/23_containers/array/tuple_interface/get_neg.cc: Adjust dg-error line numbers. 
We pre-emptively implemented part of LWG 2766, which still hasn't been
approved. Add comments to the deleted swap overloads saying why they're
there, because the standard doesn't require them.

libstdc++-v3/ChangeLog:

	* include/bits/stl_pair.h (swap): Add comment to deleted
	overload.
	* include/bits/unique_ptr.h (swap): Likewise.
	* include/std/array (swap): Likewise.
	* include/std/optional (swap): Likewise.
	* include/std/tuple (swap): Likewise.
	* include/std/variant (swap): Likewise.
	* testsuite/23_containers/array/tuple_interface/get_neg.cc:
	Adjust dg-error line numbers.
libstdc++: Implement LWG3528 make_from_tuple can perform (the equivalent of) a C-style cast 2025-06-10T13:28:55+00:00 Yihan Wang yronglin777@gmail.com 2025-06-09T10:07:51+00:00 73edc003c0a8f0badc7027e6deefd3a573300b03 Implement LWG3528 to make std::make_from_tuple SFINAE friendly. libstdc++-v3/ChangeLog: * include/std/tuple (__can_make_from_tuple): New variable template. (__make_from_tuple_impl): Add static_assert. (make_from_tuple): Constrain using __can_make_from_tuple. * testsuite/20_util/tuple/dr3528.cc: New test. Signed-off-by: Yihan Wang <yronglin777@gmail.com> Co-authored-by: Jonathan Wakely <jwakely@redhat.com> Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com> 
Implement LWG3528 to make std::make_from_tuple SFINAE friendly.

libstdc++-v3/ChangeLog:

	* include/std/tuple (__can_make_from_tuple): New variable
	template.
	(__make_from_tuple_impl): Add static_assert.
	(make_from_tuple): Constrain using __can_make_from_tuple.
	* testsuite/20_util/tuple/dr3528.cc: New test.

Signed-off-by: Yihan Wang <yronglin777@gmail.com>
Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
libstdc++: Make operator== for std::tuple convert to bool [PR119545] 2025-03-31T16:12:26+00:00 Jonathan Wakely jwakely@redhat.com 2025-03-31T11:17:02+00:00 b9adf3a4c8112df1d74440157f578a8344ebe166 The boolean-testable requirements don't require the type to be copyable, so we need to convert to bool before it might need to be copied. libstdc++-v3/ChangeLog: PR libstdc++/119545 * include/std/tuple (operator==): Convert comparison results to bool. * testsuite/20_util/tuple/comparison_operators/119545.cc: New test. Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com> 
The boolean-testable requirements don't require the type to be copyable,
so we need to convert to bool before it might need to be copied.

libstdc++-v3/ChangeLog:

	PR libstdc++/119545
	* include/std/tuple (operator==): Convert comparison results to
	bool.
	* testsuite/20_util/tuple/comparison_operators/119545.cc: New
	test.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
libstdc++: Work around C++20 tuple<tuple<any>> constraint recursion [PR116440] 2025-03-13T23:55:00+00:00 Patrick Palka ppalka@redhat.com 2025-03-13T23:55:00+00:00 6570fa6f2612a4e4ddd2fcfc119369a1a48656e4 The type tuple<tuple<any>> is clearly copy/move constructible, but for reasons that are not yet completely understood checking this triggers constraint recursion with our C++20 tuple implementation (but not the C++17 implementation). It turns out this recursion stems from considering the non-template tuple(const _Elements&) constructor during the copy/move constructibility check. Considering this constructor is ultimately redundant, since the defaulted copy/move constructors are better matches. GCC has a non-standard "perfect candidate" optimization[1] that causes overload resolution to shortcut considering template candidates if we find a (non-template) perfect candidate. So to work around this issue (and as a general compile-time optimization) this patch turns the problematic constructor into a template so that GCC doesn't consider it when checking for copy/move constructibility of this tuple type. Changing the template-ness of a constructor can affect overload resolution (since template-ness is a tiebreaker) so there's a risk this change could e.g. introduce overload resolution ambiguities. But the original C++17 implementation has long defined this constructor as a template (in order to constrain it etc), so doing the same thing in the C++20 mode should naturally be quite safe. The testcase still fails with Clang (in C++20 mode) since it doesn't implement said optimization. [1]: See r11-7287-g187d0d5871b1fa and https://isocpp.org/files/papers/P3606R0.html PR libstdc++/116440 libstdc++-v3/ChangeLog: * include/std/tuple (tuple::tuple(const _Elements&...)) [C++20]: Turn into a template. * testsuite/20_util/tuple/116440.C: New test. Reviewed-by: Jonathan Wakely <jwakely@redhat.com> 
The type tuple<tuple<any>> is clearly copy/move constructible, but for
reasons that are not yet completely understood checking this triggers
constraint recursion with our C++20 tuple implementation (but not the
C++17 implementation).

It turns out this recursion stems from considering the non-template
tuple(const _Elements&) constructor during the copy/move constructibility
check.  Considering this constructor is ultimately redundant, since the
defaulted copy/move constructors are better matches.

GCC has a non-standard "perfect candidate" optimization[1] that causes
overload resolution to shortcut considering template candidates if we
find a (non-template) perfect candidate.  So to work around this issue
(and as a general compile-time optimization) this patch turns the
problematic constructor into a template so that GCC doesn't consider it
when checking for copy/move constructibility of this tuple type.

Changing the template-ness of a constructor can affect overload
resolution (since template-ness is a tiebreaker) so there's a risk this
change could e.g. introduce overload resolution ambiguities.  But the
original C++17 implementation has long defined this constructor as a
template (in order to constrain it etc), so doing the same thing in the
C++20 mode should naturally be quite safe.

The testcase still fails with Clang (in C++20 mode) since it doesn't
implement said optimization.

[1]: See r11-7287-g187d0d5871b1fa and
https://isocpp.org/files/papers/P3606R0.html

	PR libstdc++/116440

libstdc++-v3/ChangeLog:

	* include/std/tuple (tuple::tuple(const _Elements&...))
	[C++20]: Turn into a template.
	* testsuite/20_util/tuple/116440.C: New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Update copyright years. 2025-01-02T10:59:57+00:00 Jakub Jelinek jakub@redhat.com 2025-01-02T10:59:57+00:00 6441eb6dc020faae0672ea724dfdb38c6a9bf6a1 






libstdc++: #ifdef out #pragma GCC system_header
2024-09-25T12:20:45+00:00

Jason Merrill
jason@redhat.com

2024-09-12T16:15:51+00:00

63a598deb0c9fcb8704af6ef90f0b905942b0276

In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build
flags to help catch problems in the library.  This patch takes a different
approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is
defined.  As a result, the testsuites will treat them as non-system-headers
to get better warning coverage during regression testing of both gcc and
libstdc++, not just when building the library.

My rationale for the #ifdef instead of just removing the #pragma is the
three G++ tests that want to test libstdc++ system header behavior, so we
need a way to select it.

This doesn't affect installed libraries, as they get their
system-header status from the lookup path.  But testsuite_flags
--build-includes gives -I directives rather than -isystem.

This patch doesn't change the headers in config/ because I'm not compiling
with most of them, so won't see any warnings that need fixing.  Adjusting
them could happen later, or we can not bother.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers.
	* configure: Regenerate.
	* include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header.
	* include/bits/atomic_base.h
	* include/bits/atomic_futex.h
	* include/bits/atomic_timed_wait.h
	* include/bits/atomic_wait.h
	* include/bits/basic_ios.h
	* include/bits/basic_string.h
	* include/bits/boost_concept_check.h
	* include/bits/char_traits.h
	* include/bits/charconv.h
	* include/bits/chrono.h
	* include/bits/chrono_io.h
	* include/bits/codecvt.h
	* include/bits/concept_check.h
	* include/bits/cpp_type_traits.h
	* include/bits/elements_of.h
	* include/bits/enable_special_members.h
	* include/bits/erase_if.h
	* include/bits/forward_list.h
	* include/bits/functional_hash.h
	* include/bits/gslice.h
	* include/bits/gslice_array.h
	* include/bits/hashtable.h
	* include/bits/indirect_array.h
	* include/bits/invoke.h
	* include/bits/ios_base.h
	* include/bits/iterator_concepts.h
	* include/bits/locale_classes.h
	* include/bits/locale_facets.h
	* include/bits/locale_facets_nonio.h
	* include/bits/localefwd.h
	* include/bits/mask_array.h
	* include/bits/max_size_type.h
	* include/bits/memory_resource.h
	* include/bits/memoryfwd.h
	* include/bits/move_only_function.h
	* include/bits/node_handle.h
	* include/bits/ostream_insert.h
	* include/bits/out_ptr.h
	* include/bits/parse_numbers.h
	* include/bits/postypes.h
	* include/bits/quoted_string.h
	* include/bits/range_access.h
	* include/bits/ranges_base.h
	* include/bits/refwrap.h
	* include/bits/sat_arith.h
	* include/bits/semaphore_base.h
	* include/bits/slice_array.h
	* include/bits/std_abs.h
	* include/bits/std_function.h
	* include/bits/std_mutex.h
	* include/bits/std_thread.h
	* include/bits/stl_iterator_base_funcs.h
	* include/bits/stl_iterator_base_types.h
	* include/bits/stl_tree.h
	* include/bits/stream_iterator.h
	* include/bits/streambuf_iterator.h
	* include/bits/stringfwd.h
	* include/bits/this_thread_sleep.h
	* include/bits/unique_lock.h
	* include/bits/uses_allocator_args.h
	* include/bits/utility.h
	* include/bits/valarray_after.h
	* include/bits/valarray_array.h
	* include/bits/valarray_before.h
	* include/bits/version.h
	* include/c_compatibility/fenv.h
	* include/c_compatibility/inttypes.h
	* include/c_compatibility/stdint.h
	* include/decimal/decimal.h
	* include/experimental/bits/net.h
	* include/experimental/bits/shared_ptr.h
	* include/ext/aligned_buffer.h
	* include/ext/alloc_traits.h
	* include/ext/atomicity.h
	* include/ext/concurrence.h
	* include/ext/numeric_traits.h
	* include/ext/pod_char_traits.h
	* include/ext/pointer.h
	* include/ext/stdio_filebuf.h
	* include/ext/stdio_sync_filebuf.h
	* include/ext/string_conversions.h
	* include/ext/type_traits.h
	* include/ext/vstring.h
	* include/ext/vstring_fwd.h
	* include/ext/vstring_util.h
	* include/parallel/algorithmfwd.h
	* include/parallel/numericfwd.h
	* include/tr1/functional_hash.h
	* include/tr1/hashtable.h
	* include/tr1/random.h
	* libsupc++/exception.h
	* libsupc++/hash_bytes.h
	* include/bits/basic_ios.tcc
	* include/bits/basic_string.tcc
	* include/bits/fstream.tcc
	* include/bits/istream.tcc
	* include/bits/locale_classes.tcc
	* include/bits/locale_facets.tcc
	* include/bits/locale_facets_nonio.tcc
	* include/bits/ostream.tcc
	* include/bits/sstream.tcc
	* include/bits/streambuf.tcc
	* include/bits/string_view.tcc
	* include/bits/version.tpl
	* include/experimental/bits/string_view.tcc
	* include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp
	* include/ext/random.tcc
	* include/ext/vstring.tcc
	* include/tr2/bool_set.tcc
	* include/tr2/dynamic_bitset.tcc
	* include/bits/c++config
	* include/c/cassert
	* include/c/cctype
	* include/c/cerrno
	* include/c/cfloat
	* include/c/ciso646
	* include/c/climits
	* include/c/clocale
	* include/c/cmath
	* include/c/csetjmp
	* include/c/csignal
	* include/c/cstdarg
	* include/c/cstddef
	* include/c/cstdio
	* include/c/cstdlib
	* include/c/cstring
	* include/c/ctime
	* include/c/cuchar
	* include/c/cwchar
	* include/c/cwctype
	* include/c_global/cassert
	* include/c_global/ccomplex
	* include/c_global/cctype
	* include/c_global/cerrno
	* include/c_global/cfenv
	* include/c_global/cfloat
	* include/c_global/cinttypes
	* include/c_global/ciso646
	* include/c_global/climits
	* include/c_global/clocale
	* include/c_global/cmath
	* include/c_global/csetjmp
	* include/c_global/csignal
	* include/c_global/cstdalign
	* include/c_global/cstdarg
	* include/c_global/cstdbool
	* include/c_global/cstddef
	* include/c_global/cstdint
	* include/c_global/cstdio
	* include/c_global/cstdlib
	* include/c_global/cstring
	* include/c_global/ctgmath
	* include/c_global/ctime
	* include/c_global/cuchar
	* include/c_global/cwchar
	* include/c_global/cwctype
	* include/c_std/cassert
	* include/c_std/cctype
	* include/c_std/cerrno
	* include/c_std/cfloat
	* include/c_std/ciso646
	* include/c_std/climits
	* include/c_std/clocale
	* include/c_std/cmath
	* include/c_std/csetjmp
	* include/c_std/csignal
	* include/c_std/cstdarg
	* include/c_std/cstddef
	* include/c_std/cstdio
	* include/c_std/cstdlib
	* include/c_std/cstring
	* include/c_std/ctime
	* include/c_std/cuchar
	* include/c_std/cwchar
	* include/c_std/cwctype
	* include/debug/array
	* include/debug/bitset
	* include/debug/deque
	* include/debug/forward_list
	* include/debug/list
	* include/debug/map
	* include/debug/set
	* include/debug/string
	* include/debug/unordered_map
	* include/debug/unordered_set
	* include/debug/vector
	* include/decimal/decimal
	* include/experimental/algorithm
	* include/experimental/any
	* include/experimental/array
	* include/experimental/buffer
	* include/experimental/chrono
	* include/experimental/contract
	* include/experimental/deque
	* include/experimental/executor
	* include/experimental/filesystem
	* include/experimental/forward_list
	* include/experimental/functional
	* include/experimental/internet
	* include/experimental/io_context
	* include/experimental/iterator
	* include/experimental/list
	* include/experimental/map
	* include/experimental/memory
	* include/experimental/memory_resource
	* include/experimental/net
	* include/experimental/netfwd
	* include/experimental/numeric
	* include/experimental/propagate_const
	* include/experimental/ratio
	* include/experimental/regex
	* include/experimental/scope
	* include/experimental/set
	* include/experimental/socket
	* include/experimental/string
	* include/experimental/string_view
	* include/experimental/synchronized_value
	* include/experimental/system_error
	* include/experimental/timer
	* include/experimental/tuple
	* include/experimental/type_traits
	* include/experimental/unordered_map
	* include/experimental/unordered_set
	* include/experimental/vector
	* include/ext/algorithm
	* include/ext/cmath
	* include/ext/functional
	* include/ext/iterator
	* include/ext/memory
	* include/ext/numeric
	* include/ext/random
	* include/ext/rb_tree
	* include/ext/rope
	* include/parallel/algorithm
	* include/std/algorithm
	* include/std/any
	* include/std/array
	* include/std/atomic
	* include/std/barrier
	* include/std/bit
	* include/std/bitset
	* include/std/charconv
	* include/std/chrono
	* include/std/codecvt
	* include/std/complex
	* include/std/concepts
	* include/std/condition_variable
	* include/std/coroutine
	* include/std/deque
	* include/std/execution
	* include/std/expected
	* include/std/filesystem
	* include/std/format
	* include/std/forward_list
	* include/std/fstream
	* include/std/functional
	* include/std/future
	* include/std/generator
	* include/std/iomanip
	* include/std/ios
	* include/std/iosfwd
	* include/std/iostream
	* include/std/istream
	* include/std/iterator
	* include/std/latch
	* include/std/limits
	* include/std/list
	* include/std/locale
	* include/std/map
	* include/std/memory
	* include/std/memory_resource
	* include/std/mutex
	* include/std/numbers
	* include/std/numeric
	* include/std/optional
	* include/std/ostream
	* include/std/print
	* include/std/queue
	* include/std/random
	* include/std/ranges
	* include/std/ratio
	* include/std/regex
	* include/std/scoped_allocator
	* include/std/semaphore
	* include/std/set
	* include/std/shared_mutex
	* include/std/span
	* include/std/spanstream
	* include/std/sstream
	* include/std/stack
	* include/std/stacktrace
	* include/std/stdexcept
	* include/std/streambuf
	* include/std/string
	* include/std/string_view
	* include/std/syncstream
	* include/std/system_error
	* include/std/text_encoding
	* include/std/thread
	* include/std/tuple
	* include/std/type_traits
	* include/std/typeindex
	* include/std/unordered_map
	* include/std/unordered_set
	* include/std/utility
	* include/std/valarray
	* include/std/variant
	* include/std/vector
	* include/std/version
	* include/tr1/array
	* include/tr1/cfenv
	* include/tr1/cinttypes
	* include/tr1/cmath
	* include/tr1/complex
	* include/tr1/cstdbool
	* include/tr1/cstdint
	* include/tr1/cstdio
	* include/tr1/cstdlib
	* include/tr1/cwchar
	* include/tr1/cwctype
	* include/tr1/functional
	* include/tr1/memory
	* include/tr1/random
	* include/tr1/regex
	* include/tr1/tuple
	* include/tr1/type_traits
	* include/tr1/unordered_map
	* include/tr1/unordered_set
	* include/tr1/utility
	* include/tr2/bool_set
	* include/tr2/dynamic_bitset
	* include/tr2/type_traits
	* libsupc++/atomic_lockfree_defines.h
	* libsupc++/compare
	* libsupc++/cxxabi.h
	* libsupc++/cxxabi_forced.h
	* libsupc++/cxxabi_init_exception.h
	* libsupc++/exception
	* libsupc++/initializer_list
	* libsupc++/new
	* libsupc++/typeinfo: Likewise.
	* testsuite/20_util/ratio/operations/ops_overflow_neg.cc
	* testsuite/23_containers/array/tuple_interface/get_neg.cc
	* testsuite/23_containers/vector/cons/destructible_debug_neg.cc
	* testsuite/24_iterators/operations/prev_neg.cc
	* testsuite/ext/type_traits/add_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/add_unsigned_integer_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust
	line numbers.

gcc/testsuite/ChangeLog

	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C
	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C
	* g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.





In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build
flags to help catch problems in the library.  This patch takes a different
approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is
defined.  As a result, the testsuites will treat them as non-system-headers
to get better warning coverage during regression testing of both gcc and
libstdc++, not just when building the library.

My rationale for the #ifdef instead of just removing the #pragma is the
three G++ tests that want to test libstdc++ system header behavior, so we
need a way to select it.

This doesn't affect installed libraries, as they get their
system-header status from the lookup path.  But testsuite_flags
--build-includes gives -I directives rather than -isystem.

This patch doesn't change the headers in config/ because I'm not compiling
with most of them, so won't see any warnings that need fixing.  Adjusting
them could happen later, or we can not bother.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers.
	* configure: Regenerate.
	* include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header.
	* include/bits/atomic_base.h
	* include/bits/atomic_futex.h
	* include/bits/atomic_timed_wait.h
	* include/bits/atomic_wait.h
	* include/bits/basic_ios.h
	* include/bits/basic_string.h
	* include/bits/boost_concept_check.h
	* include/bits/char_traits.h
	* include/bits/charconv.h
	* include/bits/chrono.h
	* include/bits/chrono_io.h
	* include/bits/codecvt.h
	* include/bits/concept_check.h
	* include/bits/cpp_type_traits.h
	* include/bits/elements_of.h
	* include/bits/enable_special_members.h
	* include/bits/erase_if.h
	* include/bits/forward_list.h
	* include/bits/functional_hash.h
	* include/bits/gslice.h
	* include/bits/gslice_array.h
	* include/bits/hashtable.h
	* include/bits/indirect_array.h
	* include/bits/invoke.h
	* include/bits/ios_base.h
	* include/bits/iterator_concepts.h
	* include/bits/locale_classes.h
	* include/bits/locale_facets.h
	* include/bits/locale_facets_nonio.h
	* include/bits/localefwd.h
	* include/bits/mask_array.h
	* include/bits/max_size_type.h
	* include/bits/memory_resource.h
	* include/bits/memoryfwd.h
	* include/bits/move_only_function.h
	* include/bits/node_handle.h
	* include/bits/ostream_insert.h
	* include/bits/out_ptr.h
	* include/bits/parse_numbers.h
	* include/bits/postypes.h
	* include/bits/quoted_string.h
	* include/bits/range_access.h
	* include/bits/ranges_base.h
	* include/bits/refwrap.h
	* include/bits/sat_arith.h
	* include/bits/semaphore_base.h
	* include/bits/slice_array.h
	* include/bits/std_abs.h
	* include/bits/std_function.h
	* include/bits/std_mutex.h
	* include/bits/std_thread.h
	* include/bits/stl_iterator_base_funcs.h
	* include/bits/stl_iterator_base_types.h
	* include/bits/stl_tree.h
	* include/bits/stream_iterator.h
	* include/bits/streambuf_iterator.h
	* include/bits/stringfwd.h
	* include/bits/this_thread_sleep.h
	* include/bits/unique_lock.h
	* include/bits/uses_allocator_args.h
	* include/bits/utility.h
	* include/bits/valarray_after.h
	* include/bits/valarray_array.h
	* include/bits/valarray_before.h
	* include/bits/version.h
	* include/c_compatibility/fenv.h
	* include/c_compatibility/inttypes.h
	* include/c_compatibility/stdint.h
	* include/decimal/decimal.h
	* include/experimental/bits/net.h
	* include/experimental/bits/shared_ptr.h
	* include/ext/aligned_buffer.h
	* include/ext/alloc_traits.h
	* include/ext/atomicity.h
	* include/ext/concurrence.h
	* include/ext/numeric_traits.h
	* include/ext/pod_char_traits.h
	* include/ext/pointer.h
	* include/ext/stdio_filebuf.h
	* include/ext/stdio_sync_filebuf.h
	* include/ext/string_conversions.h
	* include/ext/type_traits.h
	* include/ext/vstring.h
	* include/ext/vstring_fwd.h
	* include/ext/vstring_util.h
	* include/parallel/algorithmfwd.h
	* include/parallel/numericfwd.h
	* include/tr1/functional_hash.h
	* include/tr1/hashtable.h
	* include/tr1/random.h
	* libsupc++/exception.h
	* libsupc++/hash_bytes.h
	* include/bits/basic_ios.tcc
	* include/bits/basic_string.tcc
	* include/bits/fstream.tcc
	* include/bits/istream.tcc
	* include/bits/locale_classes.tcc
	* include/bits/locale_facets.tcc
	* include/bits/locale_facets_nonio.tcc
	* include/bits/ostream.tcc
	* include/bits/sstream.tcc
	* include/bits/streambuf.tcc
	* include/bits/string_view.tcc
	* include/bits/version.tpl
	* include/experimental/bits/string_view.tcc
	* include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp
	* include/ext/random.tcc
	* include/ext/vstring.tcc
	* include/tr2/bool_set.tcc
	* include/tr2/dynamic_bitset.tcc
	* include/bits/c++config
	* include/c/cassert
	* include/c/cctype
	* include/c/cerrno
	* include/c/cfloat
	* include/c/ciso646
	* include/c/climits
	* include/c/clocale
	* include/c/cmath
	* include/c/csetjmp
	* include/c/csignal
	* include/c/cstdarg
	* include/c/cstddef
	* include/c/cstdio
	* include/c/cstdlib
	* include/c/cstring
	* include/c/ctime
	* include/c/cuchar
	* include/c/cwchar
	* include/c/cwctype
	* include/c_global/cassert
	* include/c_global/ccomplex
	* include/c_global/cctype
	* include/c_global/cerrno
	* include/c_global/cfenv
	* include/c_global/cfloat
	* include/c_global/cinttypes
	* include/c_global/ciso646
	* include/c_global/climits
	* include/c_global/clocale
	* include/c_global/cmath
	* include/c_global/csetjmp
	* include/c_global/csignal
	* include/c_global/cstdalign
	* include/c_global/cstdarg
	* include/c_global/cstdbool
	* include/c_global/cstddef
	* include/c_global/cstdint
	* include/c_global/cstdio
	* include/c_global/cstdlib
	* include/c_global/cstring
	* include/c_global/ctgmath
	* include/c_global/ctime
	* include/c_global/cuchar
	* include/c_global/cwchar
	* include/c_global/cwctype
	* include/c_std/cassert
	* include/c_std/cctype
	* include/c_std/cerrno
	* include/c_std/cfloat
	* include/c_std/ciso646
	* include/c_std/climits
	* include/c_std/clocale
	* include/c_std/cmath
	* include/c_std/csetjmp
	* include/c_std/csignal
	* include/c_std/cstdarg
	* include/c_std/cstddef
	* include/c_std/cstdio
	* include/c_std/cstdlib
	* include/c_std/cstring
	* include/c_std/ctime
	* include/c_std/cuchar
	* include/c_std/cwchar
	* include/c_std/cwctype
	* include/debug/array
	* include/debug/bitset
	* include/debug/deque
	* include/debug/forward_list
	* include/debug/list
	* include/debug/map
	* include/debug/set
	* include/debug/string
	* include/debug/unordered_map
	* include/debug/unordered_set
	* include/debug/vector
	* include/decimal/decimal
	* include/experimental/algorithm
	* include/experimental/any
	* include/experimental/array
	* include/experimental/buffer
	* include/experimental/chrono
	* include/experimental/contract
	* include/experimental/deque
	* include/experimental/executor
	* include/experimental/filesystem
	* include/experimental/forward_list
	* include/experimental/functional
	* include/experimental/internet
	* include/experimental/io_context
	* include/experimental/iterator
	* include/experimental/list
	* include/experimental/map
	* include/experimental/memory
	* include/experimental/memory_resource
	* include/experimental/net
	* include/experimental/netfwd
	* include/experimental/numeric
	* include/experimental/propagate_const
	* include/experimental/ratio
	* include/experimental/regex
	* include/experimental/scope
	* include/experimental/set
	* include/experimental/socket
	* include/experimental/string
	* include/experimental/string_view
	* include/experimental/synchronized_value
	* include/experimental/system_error
	* include/experimental/timer
	* include/experimental/tuple
	* include/experimental/type_traits
	* include/experimental/unordered_map
	* include/experimental/unordered_set
	* include/experimental/vector
	* include/ext/algorithm
	* include/ext/cmath
	* include/ext/functional
	* include/ext/iterator
	* include/ext/memory
	* include/ext/numeric
	* include/ext/random
	* include/ext/rb_tree
	* include/ext/rope
	* include/parallel/algorithm
	* include/std/algorithm
	* include/std/any
	* include/std/array
	* include/std/atomic
	* include/std/barrier
	* include/std/bit
	* include/std/bitset
	* include/std/charconv
	* include/std/chrono
	* include/std/codecvt
	* include/std/complex
	* include/std/concepts
	* include/std/condition_variable
	* include/std/coroutine
	* include/std/deque
	* include/std/execution
	* include/std/expected
	* include/std/filesystem
	* include/std/format
	* include/std/forward_list
	* include/std/fstream
	* include/std/functional
	* include/std/future
	* include/std/generator
	* include/std/iomanip
	* include/std/ios
	* include/std/iosfwd
	* include/std/iostream
	* include/std/istream
	* include/std/iterator
	* include/std/latch
	* include/std/limits
	* include/std/list
	* include/std/locale
	* include/std/map
	* include/std/memory
	* include/std/memory_resource
	* include/std/mutex
	* include/std/numbers
	* include/std/numeric
	* include/std/optional
	* include/std/ostream
	* include/std/print
	* include/std/queue
	* include/std/random
	* include/std/ranges
	* include/std/ratio
	* include/std/regex
	* include/std/scoped_allocator
	* include/std/semaphore
	* include/std/set
	* include/std/shared_mutex
	* include/std/span
	* include/std/spanstream
	* include/std/sstream
	* include/std/stack
	* include/std/stacktrace
	* include/std/stdexcept
	* include/std/streambuf
	* include/std/string
	* include/std/string_view
	* include/std/syncstream
	* include/std/system_error
	* include/std/text_encoding
	* include/std/thread
	* include/std/tuple
	* include/std/type_traits
	* include/std/typeindex
	* include/std/unordered_map
	* include/std/unordered_set
	* include/std/utility
	* include/std/valarray
	* include/std/variant
	* include/std/vector
	* include/std/version
	* include/tr1/array
	* include/tr1/cfenv
	* include/tr1/cinttypes
	* include/tr1/cmath
	* include/tr1/complex
	* include/tr1/cstdbool
	* include/tr1/cstdint
	* include/tr1/cstdio
	* include/tr1/cstdlib
	* include/tr1/cwchar
	* include/tr1/cwctype
	* include/tr1/functional
	* include/tr1/memory
	* include/tr1/random
	* include/tr1/regex
	* include/tr1/tuple
	* include/tr1/type_traits
	* include/tr1/unordered_map
	* include/tr1/unordered_set
	* include/tr1/utility
	* include/tr2/bool_set
	* include/tr2/dynamic_bitset
	* include/tr2/type_traits
	* libsupc++/atomic_lockfree_defines.h
	* libsupc++/compare
	* libsupc++/cxxabi.h
	* libsupc++/cxxabi_forced.h
	* libsupc++/cxxabi_init_exception.h
	* libsupc++/exception
	* libsupc++/initializer_list
	* libsupc++/new
	* libsupc++/typeinfo: Likewise.
	* testsuite/20_util/ratio/operations/ops_overflow_neg.cc
	* testsuite/23_containers/array/tuple_interface/get_neg.cc
	* testsuite/23_containers/vector/cons/destructible_debug_neg.cc
	* testsuite/24_iterators/operations/prev_neg.cc
	* testsuite/ext/type_traits/add_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/add_unsigned_integer_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust
	line numbers.

gcc/testsuite/ChangeLog

	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C
	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C
	* g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.