These compare overloads throw when the pos index is out of range, not
only when the const T& parameter throws on conversion to string_view.
Remove the incorrect conditional noexcept-specifier from the two
overloads that can throw.
libstdc++-v3/ChangeLog:
PR libstdc++/123991
* include/bits/basic_string.h (compare(size_type, size_type, T)):
Remove noexcept-specifier.
(compare(size_type, size_type, T, size_type, size_type)):
Likewise.
* include/bits/cow_string.h (compare(size_type, size_type, T)):
Remove noexcept-specifier.
(compare(size_type, size_type, T, size_type, size_type)):
Likewise.
* testsuite/21_strings/basic_string/operations/compare/char/123991.cc:
New test.
* testsuite/21_strings/basic_string/operations/compare/wchar_t/123991.cc:
New test.
Reviewed-by: Nathan Myers <nmyers@redhat.com>
My recent r15-9381-g648d5c26e25497 change assumes that a contiguous
iterator with the correct value_type can be converted to a const charT*
but that's not true for volatile charT*. The optimization should only be
done if it can be converted to the right pointer type.
Additionally, some generic loops for non-contiguous iterators need an
explicit cast to deal with iterator reference types that do not bind to
the const charT& parameter of traits_type::assign.
libstdc++-v3/ChangeLog:
PR libstdc++/119748
* include/bits/basic_string.h (_S_copy_chars): Only optimize for
contiguous iterators that are convertible to const charT*. Use
explicit conversion to charT after dereferencing iterator.
(_S_copy_range): Likewise for contiguous ranges.
* include/bits/basic_string.tcc (_M_construct): Use explicit
conversion to charT after dereferencing iterator.
* include/bits/cow_string.h (_S_copy_chars): Likewise.
(basic_string(from_range_t, R&&, const Allocator&)): Likewise.
Only optimize for contiguous iterators that are convertible to
const charT*.
* testsuite/21_strings/basic_string/cons/char/119748.cc: New
test.
* testsuite/21_strings/basic_string/cons/wchar_t/119748.cc:
New test.
Reviewed-by: Tomasz Kaminski <tkaminsk@redhat.com>
This is the last piece of P1206R7, adding new members to
std::basic_string.
libstdc++-v3/ChangeLog:
PR libstdc++/111055
* include/bits/basic_string.h (_S_copy_range): New function.
(basic_string(from_range_t, R%%, const Alloc&)): New
constructor.
(append_range, assign_range, insert_range, replace_with_range):
New functions.
* include/bits/cow_string.h: Likewise.
* testsuite/21_strings/basic_string/cons/from_range.cc: New
test.
* testsuite/21_strings/basic_string/modifiers/append/append_range.cc:
New test.
* testsuite/21_strings/basic_string/modifiers/assign/assign_range.cc:
New test.
* testsuite/21_strings/basic_string/modifiers/insert/insert_range.cc:
New test.
* testsuite/21_strings/basic_string/modifiers/replace/replace_with_range.cc:
New test.
Co-authored-by: Tomasz Kamiński <tkaminsk@redhat.com>
We can use the __glibcxx_string_view macro to guard the uses of
std::string_view in <string>, instead of just checking the value of
__cplusplus. It makes no practical difference because
__glibcxx_string_view is defined for C++17 and up, but it makes it clear
to readers that the lines guarded by that macro are features that depend
on string_view.
We could be more precise and check __glibcxx_string_view >= 201606L
which is the value for the P0254R2 paper that integrated
std::string_view with std::string, but I think just checking for the
macro being defined is clear enough.
We can also check __glibcxx_variant for the _Never_valueless_alt partial
specialization.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h: Check __glibcxx_string_view and
__glibcxx_variant instead of __cplusplus >= 2017L.
* include/bits/cow_string.h: Likewise.
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
This fixes a -Wattributes warning for the COW std::string which was
previously suppressed due to being in a system header.
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (__resize_for_overwrite): Add
inline keyword to function with always_inline attribute.
This is needed to avoid errors outside the immediate context when
evaluating is_default_constructible_v<basic_string<C, T, A>> when A is
not default constructible.
This change is not sufficient to solve the problem because there are a
large number of member functions which have a default argument that
constructs an allocator.
libstdc++-v3/ChangeLog:
PR libstdc++/113841
* include/bits/basic_string.h (basic_string::basic_string()):
Constrain so that it's only present if the allocator is default
constructible.
* include/bits/cow_string.h (basic_string::basic_string()):
Likewise.
* testsuite/21_strings/basic_string/cons/113841.cc: New test.
The C++17 non-const overload of data() allows modifying the string
contents directly, so for the COW string we must do a copy-on-write to
unshare it. That means allocating, which can throw, so it shouldn't be
noexcept.
libstdc++-v3/ChangeLog:
PR libstdc++/99942
* include/bits/cow_string.h (data()): Change to noexcept(false).
This change moves the definitions of feature test macros (or strictly
speaking, the requests for <bits/version.h> to define them) so that only
standard headers define them. For example, <bits/shared_ptr.h> will no
longer define macros related to std::shared_ptr, only <memory> and
<version> will define them. This means that __cpp_lib_shared_ptr_arrays
will not be defined by <future> or by other headers that include
<bits/shared_ptr.h>. It will only be defined when <memory> has been
included. This will discourage users from relying on transitive
includes.
As a result, internal headers that need to query the macros should use
the internal macros like __glibcxx_shared_ptr_arrays instead of
__cpp_lib_shared_ptr_arrays, as those internal macros are defined by the
internal headers after icluding <bits/version.h>. There are some
exceptions to this rule, because __cpp_lib_is_constant_evaluated is
defined by bits/c++config.h and so is available everywhere, and
__cpp_lib_three_way_comparison is defined by <compare> which several
headers are explicitly specified to include, so its macro is guaranteed
to be usable too.
N.B. not many internal headers actually need an explicit include of
<bits/version.h>, because most of them include <type_traits> and so get
all the __glibcxx_foo internal macros from there.
libstdc++-v3/ChangeLog:
* include/bits/algorithmfwd.h: Do not define standard feature
test macro here.
* include/bits/align.h: Likewise. Test internal macros instead
of standard macros.
* include/bits/alloc_traits.h: Likewise.
* include/bits/allocator.h: Likewise.
* include/bits/atomic_base.h: Likewise.
* include/bits/atomic_timed_wait.h: Likewise.
* include/bits/atomic_wait.h: Likewise.
* include/bits/basic_string.h: Likewise.
* include/bits/basic_string.tcc: Likewise.
* include/bits/char_traits.h: Likewise.
* include/bits/chrono.h: Likewise.
* include/bits/cow_string.h: Likewise.
* include/bits/forward_list.h: Likewise.
* include/bits/hashtable.h: Likewise.
* include/bits/ios_base.h: Likewise.
* include/bits/memory_resource.h: Likewise.
* include/bits/move.h: Likewise.
* include/bits/move_only_function.h: Likewise.
* include/bits/node_handle.h: Likewise.
* include/bits/ptr_traits.h: Likewise.
* include/bits/range_access.h: Likewise.
* include/bits/ranges_algo.h: Likewise.
* include/bits/ranges_cmp.h: Likewise.
* include/bits/ranges_util.h: Likewise.
* include/bits/semaphore_base.h: Likewise.
* include/bits/shared_ptr.h: Likewise.
* include/bits/shared_ptr_atomic.h: Likewise.
* include/bits/shared_ptr_base.h: Likewise.
* include/bits/stl_algo.h: Likewise.
* include/bits/stl_algobase.h: Likewise.
* include/bits/stl_function.h: Likewise.
* include/bits/stl_iterator.h: Likewise.
* include/bits/stl_list.h: Likewise.
* include/bits/stl_map.h: Likewise.
* include/bits/stl_pair.h: Likewise.
* include/bits/stl_queue.h: Likewise.
* include/bits/stl_stack.h: Likewise.
* include/bits/stl_tree.h: Likewise.
* include/bits/stl_uninitialized.h: Likewise.
* include/bits/stl_vector.h: Likewise.
* include/bits/unique_ptr.h: Likewise.
* include/bits/unordered_map.h: Likewise.
* include/bits/uses_allocator_args.h: Likewise.
* include/bits/utility.h: Likewise.
* include/bits/erase_if.h: Add comment.
* include/std/algorithm: Define standard feature test macros
here.
* include/std/atomic: Likewise.
* include/std/array: Likewise.
* include/std/chrono: Likewise.
* include/std/condition_variable: Likewise.
* include/std/deque: Likewise.
* include/std/format: Likewise.
* include/std/functional: Likewise.
* include/std/forward_list: Likewise.
* include/std/ios: Likewise.
* include/std/iterator: Likewise.
* include/std/list: Likewise.
* include/std/map: Likewise.
* include/std/memory: Likewise.
* include/std/numeric: Likewise.
* include/std/queue: Likewise.
* include/std/ranges: Likewise.
* include/std/regex: Likewise.
* include/std/set: Likewise.
* include/std/stack: Likewise.
* include/std/stop_token: Likewise.
* include/std/string: Likewise.
* include/std/string_view:
* include/std/tuple: Likewise.
* include/std/unordered_map:
* include/std/unordered_set:
* include/std/utility: Likewise.
* include/std/vector: Likewise.
* include/std/scoped_allocator: Query internal macros instead of
standard macros.
There are several places in the library where we can improve performance
using resize_and_overwrite so it's inconvenient only being able to use
it in C++23 mode, and only for cxx11 strings. This adds it for COW
strings, and also adds __resize_and_overwrite as an extension for C++11
mode.
The new __resize_and_overwrite is available for C++11 and later, so
within the library we can use that consistently even in C++23. In order
to avoid making a copy (which might not be possible for non-copyable,
non-movable types) the callable is passed to resize_and_overwrite as an
lvalue reference. Unlike wrapping it in std::ref(op) this ensures that
invoking it as std::move(op)(n, p) will use the correct value category.
It also avoids any overhead that would be added by wrapping it in a
lambda like [&op](auto p, auto n) { return std::move(op)(p, n); }.
Adjust std::format to use the new __resize_and_overwrite, which we can
assume exists because we only use std::basic_string<char> and
std::basic_string<wchar_t>, so no program-defined specializations.
The uses in <experimental/internet> cannot be replaced, because those
are type-dependent on an Allocator template parameter, which could mean
they use program-defined specializations of std::basic_string that don't
have the __resize_and_overwrite extension.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h (__resize_and_overwrite): New
function.
* include/bits/basic_string.tcc (__resize_and_overwrite): New
function.
(resize_and_overwrite): Simplify by using reserve instead of
growing the string manually. Adjust for C++11 compatibility.
* include/bits/cow_string.h (resize_and_overwrite): New
function.
(__resize_and_overwrite): New function.
* include/bits/version.def (__cpp_lib_string_resize_and_overwrite):
Do not depend on cxx11abi.
* include/bits/version.h: Regenerate.
* include/std/format (__formatter_fp::_S_resize_and_overwrite):
Remove.
(__formatter_fp::format, __formatter_fp::_M_localize): Use
__resize_and_overwrite instead of _S_resize_and_overwrite.
* testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc:
Adjust for C++11 compatibility when included by ...
* testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite_ext.cc:
New test.
The compiler doesn't know about the invariant that the _S_empty_rep()
object is immutable and so _M_length and _M_refcount are always zero.
This means that we get warnings about writing possibly-non-zero length
strings into buffers that can't hold them. If we teach the compiler that
the empty rep is always zero length, it knows it can be copied into any
buffer.
For Stage 1 we might want to also consider adding this to capacity():
if (_S_empty_rep()._M_capacity != 0)
__builtin_unreachable();
And this to _Rep::_M_is_leaked() and _Rep::_M_is_shared():
if (_S_empty_rep()._M_refcount != 0)
__builtin_unreachable();
libstdc++-v3/ChangeLog:
PR tree-optimization/107087
* include/bits/cow_string.h (basic_string::size()): Add
optimizer hint that _S_empty_rep()._M_length is always zero.
(basic_string::length()): Call size().
Ideally this wouldn't be needed, because eventually these pointers all
get passed to either the basic_string_view(const CharT*) constructor, or
to basic_string_view::find(const CharT*), both of which already have the
attribute. But for that to work requires optimization, so that the null
value gets propagated through the call chain.
Adding it explicitly to each member that requires a non-null pointer
makes the diagnostics more reliable even without optimization. It's
better to give a diagnostic earlier anyway, at the actual problematic
call in the user's code.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h (starts_with, ends_with, contains):
Add nonnull attribute.
* include/bits/cow_string.h (starts_with, ends_with, contains):
Likewise.
* include/std/string_view (starts_with, ends_with, contains):
Likewise.
* testsuite/21_strings/basic_string/operations/contains/nonnull.cc
* testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
* testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
* testsuite/21_strings/basic_string_view/operations/contains/nonnull.cc
* testsuite/21_strings/basic_string_view/operations/ends_with/nonnull.cc
* testsuite/21_strings/basic_string_view/operations/starts_with/nonnull.cc
Defining the compare member functions inline allows calls to
traits_type::length and std::min to be inlined, taking advantage of
constant expression arguments. When not inline, the compiler prefers to
use the explicit instantiation definitions in libstdc++.so and can't
take advantage of constant arguments.
libstdc++-v3/ChangeLog:
PR libstdc++/59048
* include/bits/basic_string.h (compare): Define inline.
* include/bits/basic_string.tcc (compare): Remove out-of-line
definitions.
* include/bits/cow_string.h (compare): Define inline.
* testsuite/21_strings/basic_string/operations/compare/char/3.cc:
New test.
Since the COW std::string was moved to its own header, we don't need the
atomic dispatch helpers in the definition of std::__cxx11::string. Move
the inclusion of the <ext/atomicity.h> header to <bits/cow_string.h>
where it's needed.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h: Do not include <ext/atomicity.h>
here.
* include/bits/cow_string.h: Include it here.
The new deleted constructors added by P2166R1 are a breaking change,
making previously valid code ill-formed in C++23. As a result, they
should only be defined for C++23 and not for C++11 and up.
libstdc++-v3/ChangeLog:
PR libstdc++/104099
* include/bits/basic_string.h (basic_string(nullptr_t)): Only
define for C++23.
(operator=(nullptr_t)): Likewise.
* include/bits/cow_string.h: Likewise.
* include/std/string_view (basic_string_view(nullptr_t)):
Likewise.
* testsuite/21_strings/basic_string/cons/char/nullptr.cc: Adjust
expected error. Add examples that become ill-formed in C++23.
* testsuite/21_strings/basic_string_view/cons/char/nonnull.cc:
Adjust expected errors.
* testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc:
Likewise.
The C++17 basic_string(const T&, size_t, size_t) constructor is
overconstrained, so it can't be used for a NTBS and a temporary string
gets constructed (potentially allocating memory). There is no
corresponding constructor taking an NTBS, so no need to disambiguate
from it. Accepting an NTBS avoids the temporary (and potential
allocation) and is what the standard requires.
libstdc++-v3/ChangeLog:
PR libstdc++/103919
* include/bits/basic_string.h (basic_string(const T&, size_t, size_t)):
Relax constraints on string_view parameter.
* include/bits/cow_string.h (basic_string(const T&, size_t, size_t)):
Likewise.
* testsuite/21_strings/basic_string/cons/char/103919.cc: New test.
When non-const references, pointers or iterators are obtained to the
contents of a COW std::basic_string, the implementation has to assume it
could result in a write to the contents. If the string was previously
shared, it does the "copy-on-write" step of creating a new copy of the
data that is not shared by another object. It also marks the string as
"leaked", so that no future copies of it will share ownership either.
However, if the string is empty then the only character in the sequence
is the terminating null, and modifying that is undefined behaviour. This
means that non-const references/pointers/iterators to an empty string
are effectively const. Since no direct modification is possible, there
is no need to "leak" the string, it can be safely shared with other
objects. This avoids unnecessary allocations to create new copies of
empty strings that can't be modified anyway.
We already did this optimization for strings that share ownership of the
static _S_empty_rep() object, but not for strings that have non-zero
capacity, and not for fully-dynamic-strings (where the _S_empty_rep()
object is never used).
With this change we avoid two allocations in the return statement:
std::string s;
s.reserve(1); // allocate
std::string s2 = s;
std::string s3 = s;
return s[0] + s2[0] + s3[0]; // leak+allocate twice
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (basic_string::_M_leak_hard): Do not
reallocate an empty string.
The relaxed load is already optimal, checking the __single_threaded
global before doing a non-atomic load isn't an optimization.
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (basic_string::_M_is_leaked()):
Revert change to check __is_single_threaded() before using
atomic load.
This adds std::__is_constant_evaluated() as a C++11 wrapper for
__builtin_is_constant_evaluated, but just returning false if the
built-in isn't supported by the compiler. This allows us to use it
throughout the library without checking __has_builtin every time.
Some uses in std::vector and std::string can only be constexpr when the
std::is_constant_evaluated() function actually works, so we might as
well guard them with a relevant macro and call that function directly,
rather than the built-in or std::__is_constant_evaluated().
The remaining checks of the __cpp_lib_is_constant_evaluated macro could
now be replaced by checking __cplusplus >= 202002 instead, but there's
no practical difference. We still need some kind of preprocessor check
there anyway.
libstdc++-v3/ChangeLog:
* doc/doxygen/user.cfg.in (PREDEFINED): Change macro name.
* include/bits/allocator.h (allocate, deallocate): Use
std::__is_constant_evaluated() unconditionally, instead of
checking whether std::is_constant_evaluated() (or the built-in)
can be used.
* include/bits/basic_string.h: Check new macro. call
std::is_constant_evaluated() directly in C++20-only code that is
guarded by a suitable macro.
* include/bits/basic_string.tcc: Likewise.
* include/bits/c++config (__is_constant_evaluated): Define.
(_GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED): Replace with ...
(_GLIBCXX_HAVE_IS_CONSTANT_EVALUATED): New macro.
* include/bits/char_traits.h (char_traits): Replace conditional
calls to std::is_constant_evaluated with unconditional calls to
std::__is_constant_evaluated.
* include/bits/cow_string.h: Use new macro.
* include/bits/ranges_algobase.h (__copy_or_move): Replace
conditional calls to std::is_constant_evaluated with unconditional
calls to std::__is_constant_evaluated.
(__copy_or_move_backward, __fill_n_fn): Likewise.
* include/bits/ranges_cmp.h (ranges::less): Likewise.
* include/bits/stl_algobase.h (lexicographical_compare_three_way):
Likewise.
* include/bits/stl_bvector.h: Call std::is_constant_evaluated
directly in C++20-only code that is guarded by a suitable macro.
* include/bits/stl_construct.h (_Construct, _Destroy, _Destroy_n):
Replace is_constant_evaluated with __is_constant_evaluated.
* include/bits/stl_function.h (greater, less, greater_equal)
(less_equal): Replace __builtin_is_constant_evaluated and
__builtin_constant_p with __is_constant_evaluated.
* include/bits/stl_vector.h: Call std::is_constant_evaluated()
in C++20-only code.
* include/debug/helper_functions.h (__check_singular): Use
__is_constant_evaluated instead of built-in, or remove check
entirely.
* include/std/array (operator<=>): Use __is_constant_evaluated
unconditionally.
* include/std/bit (__bit_ceil): Likewise.
* include/std/type_traits (is_constant_evaluated): Define using
'if consteval' if possible.
* include/std/version: Use new macro.
* libsupc++/compare: Use __is_constant_evaluated instead of
__builtin_is_constant_evaluated.
* testsuite/23_containers/array/tuple_interface/get_neg.cc:
Adjust dg-error lines.
Most ref-count updates in the COW string are done via the functions in
<ext/atomicity.h>, which will use non-atomic ops when the program is
known to be single-threaded. The _M_is_leaked() and _M_is_shared()
functions use __atomic_load_n directly, because <ext/atomicity.h>
doesn't provide a load operation. Those functions can check the
__is_single_threaded() predicate to avoid using __atomic_load_n when not
needed.
The move constructor for the fully-dynamic-string increments the
ref-count by either 2 or 1, for leaked or non-leaked strings
respectively. That can be changed to use a non-atomic store of 1 for all
non-shared strings. It can be non-atomic because even if the program is
multi-threaded, conflicting access to the rvalue object while it's being
moved from would be data race anyway. It can store 1 directly for all
non-shared strings because it doesn't matter whether the initial
refcount was -1 or 0, it should be 1 after the move constructor creates
a second owner.
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (basic_string::_M_is_leaked): Use
non-atomic load when __is_single_threaded() is true.
(basic_string::_M_is_shared): Likewise.
(basic_string::(basic_string&&)) [_GLIBCXX_FULLY_DYNAMIC_STRING]:
Use non-atomic store when rvalue is not shared.
My last change to the fully-dynamic-string actually broke it. This fixes
the move constructor so it builds, and simplifies it slightly so that
more code is common between the fully-dynamic enabled/disabled cases.
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (basic_string(basic_string&&)): Fix
mem-initializer for _GLIBCXX_FULLY_DYNAMIC_STRING==0 case.
* testsuite/21_strings/basic_string/cons/char/noexcept_move_construct.cc:
Remove outdated comment.
* testsuite/21_strings/basic_string/cons/wchar_t/noexcept_move_construct.cc:
Likewise.
This is only supported for the cxx11 ABI, not for COW strings.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h (basic_string, operator""s): Add
constexpr for C++20.
(basic_string::basic_string(basic_string&&)): Only copy
initialized portion of the buffer.
(basic_string::basic_string(basic_string&&, const Alloc&)):
Likewise.
* include/bits/basic_string.tcc (basic_string): Add constexpr
for C++20.
(basic_string::swap(basic_string&)): Only copy initialized
portions of the buffers.
(basic_string::_M_replace): Add constexpr implementation that
doesn't depend on pointer comparisons.
* include/bits/cow_string.h: Adjust comment.
* include/ext/type_traits.h (__is_null_pointer): Add constexpr.
* include/std/string (erase, erase_if): Add constexpr.
* include/std/version (__cpp_lib_constexpr_string): Update
value.
* testsuite/21_strings/basic_string/cons/char/constexpr.cc:
New test.
* testsuite/21_strings/basic_string/cons/wchar_t/constexpr.cc:
New test.
* testsuite/21_strings/basic_string/literals/constexpr.cc:
New test.
* testsuite/21_strings/basic_string/modifiers/constexpr.cc: New test.
* testsuite/21_strings/basic_string/modifiers/swap/char/constexpr.cc:
New test.
* testsuite/21_strings/basic_string/modifiers/swap/wchar_t/constexpr.cc:
New test.
* testsuite/21_strings/basic_string/version.cc: New test.
Implement this C++23 feature. Because construction from a null pointer
is undefined, we can implement it for C++11 and up, turning undefined
behaviour into a compilation error.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h (basic_string(nullptr_t)): Define
as deleted.
(operator=(nullptr_t)): Likewise.
* include/bits/cow_string.h (basic_string(nullptr_t)): Likewise.
(operator=(nullptr_t)): Likewise.
* include/std/string_view (basic_string_view(nullptr_t)):
Likewise.
* testsuite/21_strings/basic_string/cons/char/nullptr.cc: New test.
* testsuite/21_strings/basic_string_view/cons/char/nonnull.cc:
Change dg-warning to dg-error.
* testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc:
Likewise.
The move constructor for the "fully-dynamic" COW string is not noexcept,
because it allocates a new empty string rep for the moved-from string.
However, there is no need to do that, because the moved-from string does
not have to be left empty. Instead, implement move construction for the
fully-dynamic case as a reference count increment, so the string is
shared.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h [_GLIBCXX_FULLY_DYNAMIC_STRING]
(basic_string(basic_string&&)): Add noexcept and avoid
allocation, by sharing rep with the rvalue string.
The new contains member of the COW string is defined for non-strict
gnu++20 mode as well as for C++23 modes. I think that was left in the
committed patch unintentionally. It is inconsistent with the SSO string,
and doesn't actually compile because it uses the
basic_string_view::contains member which only defined for C++23.
This makes it only defined for C++23.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/cow_string.h (basic_string::contains): Do not
define for -std=gnu++20.
This moves the definitions of the COW string to a separate file, so that
they don't need to be preprocessed for the common case. We could also
move the SSO string definitions to a new file, so that they don't need
to be preprocessed for the old ABI case, but that would require more
shovel work because there are some parts of <bits/basic_string.h> and
<bits/basic_string.tcc> that are common to both definitions.
libstdc++-v3/ChangeLog:
* include/Makefile.am: Add new header.
* include/Makefile.in: Regenerate.
* include/bits/basic_string.h [!_GLIBCXX_USE_CXX11_ABI]
(basic_string): Move definition of Copy-on-Write string to
new file.
* include/bits/basic_string.tcc: Likewise.
* include/bits/cow_string.h: New file.
Jonathan Wakely