8 Commits
Author SHA1 Message Date
Jakub Jelinek 62c126db6b libstdc++: Implement C++26 P3378R2 - constexpr exception types
The following patch attempts to implement the C++26 P3378R2 - constexpr
exception types paper.

This is quite complicated, because most of these classes which should
be constexpr-ized use solely or mostly out of line definitions in
libstdc++, both for historical, code size and dual ABI reasons, so that
one can throw these as exceptions between TUs with old vs. new (or vice
versa) ABIs.
For this reason, logic_error/runtime_error and classes derived from it
have the old ABI std::string object inside of them and the exported
APIs from libstdc++.so.6 ensure the right thing.

Now, because new invoked during constant evaluation needs to be deleted
during the same constant evaluation and can't leak into the constant
expressions, I think we don't have to use COW strings under the hood
(which aren't constexpr I guess because of reference counting/COW) and
we can use something else, the patch uses heap allocated std::string
object (where __cow_constexpr_string class has just a pointer to that).
As I think we still want to hide the ugly details if !consteval in the
library, the patch exports 8 __cow_string class symbols (6 existing which
were previously just not exported and 2 new ones) and if !consteval
calls those through extern "C" _Zmangled_name symbols.  The functions
are always_inline.

And then logic_error etc. have for C++26 (precisely for
__cpp_lib_constexpr_exceptions >= 202502L) constexpr definitions of
cdtors/methods.  This results in slightly larger code (a few insns at most)
at runtime for C++26, e.g. instead of calling say some logic error
cdtor/method with 2 arguments it calls some __cow_string one with 2
arguments but + 8 bytes pointer additions on both.

The patch also removes the __throw_format_error forward declaration
which apparently wasn't needed for anything as all __throw_format_error
users were either in <format> or included <format> before the uses,
reverts the
https://gcc.gnu.org/pipermail/libstdc++/2025-July/062598.html
patch and makes sure __throw_* functions (only those for exception types
which the P3378R2 or P3068R5 papers made constexpr usable and there are
actually constexpr/consteval uses of those) are constexpr for C++26
constexpr exceptions.

The patch does that by splitting the bits/functexcept.h header:
1) bits/functexcept.h stays for the __throw_* functions which are (at
least for now) never constexpr (the <ios>, <system_error>, <future>
and <functional> std::exception derived classes) or are never used
or never used in constexpr/consteval contexts (<exception>, <typeinfo>
std::exception derived classes and std::range_error).
2) bits/new_{throw,except}.h for __throw_bad_alloc/__throw_bad_array_new_length
and std::bad_alloc/std::bad_array_new_length (where <new> includes
<bits/new_except.h> and <bits/new_throw.h> as well for the C++26 constexpr
exceptions case)
3) for the most complicated <stdexcept> stuff, one header
addition to bits/stdexcept.h one header for the __throw_logic_error etc.
forward declarations, one header for the __throw_logic_error etc.
definitions and one header without header guards which will
depending on __glibcxx_exc_in_string include one or the other because
<string> vs. <string_view> vs. <stdexcept> have heavy interdependencies

2025-12-11  Jakub Jelinek  <jakub@redhat.com>

	PR libstdc++/121114
libstdc++-v3/
	* include/bits/version.def: Implement C++26 P3378R2 - constexpr
	exception types.
	(constexpr_exceptions): Change value from 1 to 202502, remove
	no_stdname and TODO comments.
	* include/bits/version.h: Regenerate.
	* src/c++11/cow-stdexcept.cc (__cow_string(const char*)): New
	ctor.
	(__cow_string::c_str()): New method.
	* config/abi/pre/gnu.ver (GLIBCXX_3.4.35): Export 8 __cow_string
	symbols.
	* include/bits/new_except.h: New file.
	* include/bits/new_throw.h: New file.
	* include/bits/stdexcept_throw.h: New file.
	* include/bits/stdexcept_throwdef.h: New file.
	* include/bits/stdexcept_throwfwd.h: New file.
	* include/std/stdexcept: Include bits/stdexcept_except.h and move
	everything after <string> include except for std::range_error into
	include/bits/stdexcept_except.h.
	(std::range_error): If __cpp_lib_constexpr_exceptions >= 202502L
	make all cdtors and methods constexpr.
	* include/bits/stdexcept_except.h: New file.
	* include/std/optional (__glibcxx_want_constexpr_exceptions): Define
	before including bits/version.h.
	(bad_optional_access::what): Make constexpr for
	__cpp_lib_constexpr_exceptions >= 202502L.
	(__throw_bad_optional_access): Likewise.
	* include/std/expected (__glibcxx_want_constexpr_exceptions): Define
	before including bits/version.h.
	(bad_expected_access): Make cdtors and all methods constexpr for
	__cpp_lib_constexpr_exceptions >= 202502L.
	* include/std/format (__glibcxx_want_constexpr_exceptions): Define
	before including bits/version.h.
	(_GLIBCXX_CONSTEXPR_FORMAT_ERROR): Define and undef later.
	(format_error): Use _GLIBCXX_CONSTEXPR_FORMAT_ERROR on ctors.
	* include/std/variant (__glibcxx_want_constexpr_exceptions): Define
	before including bits/version.h.
	(_GLIBCXX_CONSTEXPR_BAD_VARIANT_ACCESS): Define and undef later.
	(bad_variant_access): Use it on ctors and what() method.
	(__throw_bad_variant_access): Use it here too.
	* testsuite/18_support/exception/version.cc: Adjust expected
	__cpp_lib_constexpr_exceptions value.
	* testsuite/19_diagnostics/runtime_error/constexpr.cc: New test.
	* testsuite/19_diagnostics/headers/stdexcept/version.cc: New test.
	* testsuite/19_diagnostics/logic_error/constexpr.cc: New test.
	* testsuite/20_util/expected/observers.cc (test_value_throw): Change
	return type to bool from void, return true at the end, add test
	to dereference what() first character.  Make it constexpr for
	__cpp_lib_constexpr_exceptions >= 202502L and add static_assert.
	* testsuite/20_util/expected/version.cc: Add tests for
	__cpp_lib_constexpr_exceptions value.
	* testsuite/20_util/variant/constexpr.cc: For
	__cpp_lib_constexpr_exceptions >= 202502L include <string>.
	(test_get): New function if __cpp_lib_constexpr_exceptions >= 202502L,
	assert calling it is true.
	* testsuite/20_util/variant/version.cc: Add tests for
	__cpp_lib_constexpr_exceptions value.
	* testsuite/20_util/optional/constexpr/observers/3.cc: Include
	testsuite_hooks.h.
	(eat, test01): New functions.  Assert test01() is true.
	* testsuite/20_util/optional/version.cc: Add tests for
	__cpp_lib_constexpr_exceptions value.
	* include/std/future: Add #include <bits/functexcept.h>.
	* include/std/shared_mutex: Include <bits/new_throw.h>.
	* include/std/flat_map: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/std/syncstream: Remove <bits/functexcept.h> include.
	* include/std/flat_set: Likewise.
	* include/std/bitset: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/std/string_view: Don't include <bits/functexcept.h>, include
	<bits/stdexcept_throw.h> early if __glibcxx_exc_in_string is not
	defined and include <bits/stdexcept_throw.h> at the end of
	the header again if __glibcxx_exc_in_string is 2 and C++26 constexpr
	exceptions are enabled.
	(__glibcxx_exc_in_string): Define if __glibcxx_exc_in_string wasn't
	defined before including <bits/stdexcept_throw.h>.
	* include/std/array: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/std/inplace_vector: Likewise.
	* include/std/string: Include <bits/stdexcept_except.h> and
	<bits/stdexcept_throw.h> after bits/basic_string.tcc include if
	C++26 constexpr exceptions are enabled and include
	<bits/stdexcept_throw.h> instead of <bits/functexcept.h> early.
	(__glibcxx_exc_in_string): Define early to 1, undefine at the end.
	* include/std/deque: Include <bits/stdexcept_throw.h>.
	* include/bits/new_allocator.h: Include <bits/new_throw.h> instead
	of <bits/functexcept.h>.
	* include/bits/stl_algobase.h: Remove <bits/functexcept.h> include.
	* include/bits/stl_vector.h: Include <bits/stdexcept_throw.h> instead
	of <bits/functexcept.h>.
	* include/bits/memory_resource.h: Include <bits/new_throw.h> instead
	of <bits/functexcept.h>.
	* include/bits/functexcept.h: Guard everything after includes with
	#if _GLIBCXX_HOSTED.
	(__throw_bad_alloc, __throw_bad_array_new_length,  __throw_logic_error,
	__throw_domain_error, __throw_invalid_argument, __throw_length_error,
	__throw_out_of_range, __throw_out_of_range_fmt, __throw_runtime_error,
	__throw_overflow_error, __throw_underflow_error): Move declarations to
	other headers - <bits/new_throw.h> and <bits/stdexcept_throwfwd.h>.
	* include/bits/stl_map.h: Include <bits/stdexcept_throw.h> instead
	of <bits/functexcept.h>.
	* include/bits/hashtable_policy.h: Include <bits/stdexcept_throw.h>
	instead of <bits/functexcept.h>.
	* include/bits/formatfwd.h (std::__throw_format_error): Remove
	declaration.
	* include/bits/specfun.h: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/bits/basic_ios.h: Include <bits/functexcept.h>.
	* include/bits/locale_classes.h: Likewise.
	* include/tr1/cmath: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/tr1/memory: Remove <bits/functexcept.h> include.
	* include/tr1/array: Include <bits/stdexcept_throw.h>.
	* include/ext/vstring_util.h: Include <bits/stdexcept_throw.h> instead
	of <bits/functexcept.h>.
	* include/ext/bitmap_allocator.h: Include <bits/new_throw.h> instead
	of <bits/functexcept.h>.
	* include/ext/mt_allocator.h: Likewise.
	* include/ext/malloc_allocator.h: Likewise.
	* include/ext/debug_allocator.h: Include <bits/stdexcept_throw.h>
	instead of <bits/functexcept.h>.
	* include/ext/concurrence.h: Include <bits/exception_defines.h>
	instead of <bits/functexcept.h>.
	* include/ext/throw_allocator.h: Include <bits/new_throw.h> and
	<bits/stdexcept_throw.h> instead of <bits/functexcept.h>.
	* include/ext/string_conversions.h: Include <bits/stdexcept_throw.h>
	instead of <bits/functexcept.h>.
	* include/ext/pool_allocator.h: Include <bits/new_throw.h> instead
	of <bits/functexcept.h>.
	* include/ext/ropeimpl.h: Include <bits/stdexcept_throw.h> instead of
	<bits/functexcept.h>.
	* include/tr2/dynamic_bitset: Likewise.
	* include/experimental/optional: Include <bits/exception_defines.h>
	instead of <bits/functexcept.h>.
	* include/Makefile.am (bits_freestanding): Add
	${bits_srcdir}/{new,stdexcept}_{except,throw}.h
	and ${bits_srcdir}/stdexcept_throw{fwd,def}.h.
	* include/Makefile.in: Regenerate.
	* src/c++17/floating_from_chars.cc: Remove <bits/functexcept.h>
	include.
	* src/c++11/regex.cc: Likewise.
	* src/c++11/functexcept.cc: Likewise.
	* src/c++11/snprintf_lite.cc: Include <bits/stdexcept_throw.h> instead
	of <bits/functexcept.h>.
	* src/c++11/thread.cc: Include <bits/functexcept.h>.
	* testsuite/util/testsuite_hooks.h: Include <bits/stdexcept_throw.h>
	instead of <bits/functexcept.h>.
	* testsuite/util/io/verified_cmd_line_input.cc: Include
	<bits/exception_defines.h> instead of <bits/functexcept.h>.
	* testsuite/20_util/allocator/105975.cc: Expect different diagnostics
	for C++26.
	* testsuite/23_containers/inplace_vector/access/capacity.cc: Remove
	#error, guard if consteval { return; } with
	#ifndef __cpp_lib_constexpr_exceptions.
	* testsuite/23_containers/inplace_vector/access/elem.cc: Likewise.
	* testsuite/23_containers/inplace_vector/cons/1.cc: Likewise.
	* testsuite/23_containers/inplace_vector/cons/from_range.cc: Likewise.
	* testsuite/23_containers/inplace_vector/modifiers/single_insert.cc:
	Likewise.
	* testsuite/23_containers/inplace_vector/modifiers/assign.cc:
	Likewise.
	* testsuite/23_containers/inplace_vector/modifiers/multi_insert.cc:
	Likewise.
	* libsupc++/new: Include <bits/new_except.h>.
	(std::bad_alloc, std::bad_array_new_length): Move defintion to
	<bits/new_except.h>.
libgomp/
	* omp.h.in: Include <bits/new_throw.h> instead of
	<bits/functexcept.h>.
gcc/testsuite/
	* g++.dg/tree-ssa/pr110819.C: Guard scan-tree-dump-not delete on
	c++23_down and add comment explaining why C++26 fails that.
	* g++.dg/tree-ssa/pr96945.C: Likewise.
	* g++.dg/tree-ssa/pr109442.C: Likewise.
	* g++.dg/tree-ssa/pr116868.C: Likewise.
	* g++.dg/tree-ssa/pr58483.C: Likewise.
2025-12-11 19:54:44 +01:00
Yuao Ma bf9dd44a97 libstdc++: constexpr flat_set and flat_multiset
This patch makes flat_set and flat_multiset constexpr as part of P3372R3.

libstdc++-v3/ChangeLog:

	* include/bits/version.def: Add FTM.
	* include/bits/version.h: Regenerate.
	* include/std/flat_set: Add constexpr.
	* testsuite/23_containers/flat_multiset/1.cc: Add constexpr test.
	* testsuite/23_containers/flat_set/1.cc: Add constexpr test.
2025-12-11 22:24:42 +08:00
Patrick Palka aa93272cfd libstdc++: Fix availability of std::erase_if(std::flat_foo) [PR119427]
These std::erase_if overloads were wrongly implemented as hidden
friends, visible only via ADL, so erase_if(x) would work but not
std::erase_if(x).

	PR libstdc++/119427

libstdc++-v3/ChangeLog:

	* include/std/flat_map (_Flat_map_impl::erase_if): Replace
	this hidden friend with ...
	(_Flat_map_impl::_M_erase_if): ... this member function.
	(flat_map): Export _Flat_map_impl::_M_erase_if.
	(erase_if(flat_map)): Define.
	(flat_multimap): Export _Flat_map_impl::_M_erase_if.
	(erase_if(flat_multimap)): Define.
	* include/std/flat_set (_Flat_set_impl::erase_if): Replace
	with ...
	(_Flat_set_impl::_M_erase_if): ... this member function.
	(flat_set): Export _Flat_set_impl::_M_erase_if.
	(erase_if(flat_set)): Define.
	(flat_multiset): Export _Flat_set_impl::_M_erase_if.
	(erase_if(flat_multiset)): Define.
	* testsuite/23_containers/flat_map/1.cc (test07): New test.
	* testsuite/23_containers/flat_multimap/1.cc (test07): New test.
	* testsuite/23_containers/flat_multiset/1.cc (test09): New test.
	* testsuite/23_containers/flat_set/1.cc (test09): New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
2025-04-29 08:21:35 -04:00
Patrick Palka 2a36d22ab5 libstdc++: Avoid redundant value_type object in flat_set::emplace [PR119620]
flat_set::emplace (and flat_multiset's) currently unconditionally
constructs an object outside of the container, but if we're passed
a value_type object we can and should avoid that.

	PR libstdc++/119620

libstdc++-v3/ChangeLog:

	* include/std/flat_set (_Flat_set_impl::_M_try_emplace): Split
	out into two overloads, one taking at least one argument and one
	taking zero arguments.  Turn __k into an auto&& reference bound
	to __arg if it's already a value_type and otherwise bound to a
	lifetime-extended value_type temporary.
	* testsuite/23_containers/flat_multiset/1.cc (test08): New test.
	* testsuite/23_containers/flat_set/1.cc (test08): New test.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
2025-04-04 15:05:09 -04:00
Tomasz Kamiński 272d26d519 libstdc++: Check presence of iterator_category for flat_sets insert_range [PR119415]
As pointed out by Hewill Kang (reporter) in the issue, checking if iterator
of the incoming range satisfies __cpp17_input_iterator, may still lead
to hard errors inside of insert_range for iterators that satisfies
that concept, but specialize iterator_traits without iterator_category
typedef (std::common_iterator specialize iterator_traits without
iterator_category in some cases).

To address that we instead check if the iterator_traits<It>::iterator_category
is present and denote at least input_iterator_tag, using existing __has_input_iter_cat.

	PR libstdc++/119415

libstdc++-v3/ChangeLog:

	* include/std/flat_set (_Flat_set_impl:insert_range):
	Replace __detail::__cpp17_input_iterator with __has_input_iter_cat.
	* testsuite/23_containers/flat_multiset/1.cc: New tests
	* testsuite/23_containers/flat_set/1.cc: New tests

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>
2025-03-26 11:53:26 +01:00
Tomasz Kamiński 4d1b196956 libstdc++: Fix handling of common cpp20-only ranges for flat sets [PR119415]
These patch add check to verify if common range iterators satisfies
Cpp17LegacyIterator requirements (__detail::__cpp17_input_iterator),
before invoking overloads of insert that accepts two iterators.
As such overloads existed before c++20 iterators were introduced,
they commonly assume existence of iterator_traits<..>::iterator_category,
and passing a cpp20-only iterators, leads to hard errors.

In case if user-defined container wants to support more efficient
insertion in such cases, it should provided insert_range method,
as in the case of standard containers.

	PR libstdc++/119415

libstdc++-v3/ChangeLog:

	* include/std/flat_set (_Flat_set_impl:insert_range):
	Add __detail::__cpp17_input_iterator check.
	* testsuite/23_containers/flat_multiset/1.cc: New tests
	* testsuite/23_containers/flat_set/1.cc: New tests

Reviewed-by: Patrick Palka <ppalka@redhat.com>, Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>
2025-03-25 10:24:58 +01:00
Patrick Palka a9172b107a libstdc++: Fix flat_foo::insert_range for non-common ranges [PR118156]
This fixes flat_map/multimap::insert_range by just generalizing the
insert implementation to handle heterogenous iterator/sentinel pair.
I'm not sure we can do better than this, e.g. we can't implement it in
terms of the adapted containers' insert_range because that'd require two
passes over the range.

For flat_set/multiset, we can implement insert_range directly in terms
of the adapted container's insert_range.  A fallback implementation
is also provided if insert_range isn't available, as is the case for
std::deque currently.

	PR libstdc++/118156

libstdc++-v3/ChangeLog:

	* include/std/flat_map (_Flat_map_impl::_M_insert): Generalized
	version of insert taking heterogenous iterator/sentinel pair.
	(_Flat_map_impl::insert): Dispatch to _M_insert.
	(_Flat_map_impl::insert_range): Likewise.
	(flat_map): Export _Flat_map_impl::insert_range.
	(flat_multimap): Likewise.
	* include/std/flat_set (_Flat_set_impl::insert_range):
	Reimplement directly, not in terms of insert.
	(flat_set): Export _Flat_set_impl::insert_range.
	(flat_multiset): Likewise.
	* testsuite/23_containers/flat_map/1.cc (test06): New test.
	* testsuite/23_containers/flat_multimap/1.cc (test06): New test.
	* testsuite/23_containers/flat_multiset/1.cc (test06): New test.
	* testsuite/23_containers/flat_set/1.cc (test06): New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
2025-01-31 15:53:12 -05:00
Patrick PalkaandJonathan Wakely e3fab34506 libstdc++: Implement C++23 <flat_set> (P1222R4)
This implements the C++23 container adaptors std::flat_set and
std::flat_multiset from P1222R4.  The implementation is essentially
an simpler and pared down version of std::flat_map.

libstdc++-v3/ChangeLog:

	* include/Makefile.am: Add new header <flat_set>.
	* include/Makefile.in: Regenerate.
	* include/bits/version.def (__cpp_flat_set): Define.
	* include/bits/version.h: Regenerate
	* include/precompiled/stdc++.h: Include <flat_set>.
	* include/std/flat_set: New file.
	* src/c++23/std.cc.in: Export <flat_set>.
	* testsuite/23_containers/flat_multiset/1.cc: New test.
	* testsuite/23_containers/flat_set/1.cc: New test.

Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
2024-12-19 11:31:19 -05:00