If the allocator-extended move constructor move-constructs each element
into the new container, the contents of the old container are left in
moved-from states. We cannot know if those states preserve the
container's ordering and uniqueness guarantees, so just erase all
moved-from elements.
libstdc++-v3/ChangeLog:
PR libstdc++/103501
* include/bits/stl_tree.h (_Rb_tree(_Rb_tree&&, false_type)):
Clear container if elements have been moved-from.
* testsuite/23_containers/map/allocator/move_cons.cc: Expect
moved-from container to be empty.
* testsuite/23_containers/multimap/allocator/move_cons.cc:
Likewise.
* testsuite/23_containers/multiset/allocator/103501.cc: New test.
* testsuite/23_containers/set/allocator/103501.cc: New test.
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.
When using COW strings, accessing _M_pathname[0] and similar non-const
accessors can cause the string to "leak", meaning it reallocates itself
if it shares ownership with another string object.
This causes test failures for --enable-fully-dynamic-string builds:
/home/jwakely/src/gcc/libstdc++-v3/testsuite/experimental/filesystem/path/construct/90634.cc:62: void test01(): Assertion 'bytes_allocated == 0' failed.
FAIL: experimental/filesystem/path/construct/90634.cc execution test
This FAIL happens because the fully-dynamic move constructor results in
shared ownership, so for path(std::move(std::string("foo"))) the
_M_pathname member shares ownership with the temporary, and the
non-const accesses in _M_split_cmpts() cause a new copy of the string to
be allocated. This un-sharing is wasteful, and entirely unnecessary when
sharing ownership with an rvalue that is about to release its ownership
anyway. Even for lvalues, sharing ownership is not a problem and
reallocating a unique copy of the string is wasteful.
This removes non-const accesses of _M_pathname in the
path::_M_split_cmpts() members.
libstdc++-v3/ChangeLog:
* src/c++17/fs_path.cc (path::_M_split_cmpts()): Remove
micro-optimization for "/" path.
* src/filesystem/path.cc (path::_M_split_cmpts()): Only access
the contents of _M_pathname using const member functions.
Fix some tests that assume that a moved-from string is empty, or that
default constructing a string doesn't allocate.
libstdc++-v3/ChangeLog:
* testsuite/21_strings/basic_string/cons/char/moveable.cc: Allow
moved-from string to be non-empty.
* testsuite/21_strings/basic_string/cons/char/moveable2.cc:
Likewise.
* testsuite/21_strings/basic_string/cons/char/moveable2_c++17.cc:
Likewise.
* testsuite/21_strings/basic_string/cons/wchar_t/moveable.cc:
Likewise.
* testsuite/21_strings/basic_string/cons/wchar_t/moveable2.cc:
Likewise.
* testsuite/21_strings/basic_string/cons/wchar_t/moveable2_c++17.cc:
Likewise.
* testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc:
Construct empty string before setting oom flag.
* testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc:
Likewise.
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.
The definitions of the new C++20 members of std::stringstream etc are
missing when --with-default-libstdcxx-abi=gcc4-compatible is used,
because all the explicit instantiations in src/c++20/sstream-inst.cc are
skipped.
This ensures the contents of that file are compiled with the new ABI, so
the same set of symbols are exported regardless of which ABI is active
by default.
libstdc++-v3/ChangeLog:
* src/c++20/sstream-inst.cc (_GLIBCXX_USE_CXX11_ABI): Define to
select new ABI.
In C++17 mode all callers of _S_relocate have already done:
if constexpr (_S_use_relocate())
so we don't need to repeat that check and use tag dispatching to avoid
ill-formed instantiations.
libstdc++-v3/ChangeLog:
* include/bits/stl_vector.h (vector::_S_do_relocate): Remove
C++20 constexpr specifier.
(vector::_S_relocate) [__cpp_if_constexpr]: Call __relocate_a
directly without tag dispatching.
Clang doesn't define __SANITIZE_ADDRESS__ so use its __has_feature check
to detect Asan instead.
libstdc++-v3/ChangeLog:
PR libstdc++/103453
* config/allocator/malloc_allocator_base.h
(_GLIBCXX_SANITIZE_STD_ALLOCATOR): Define for Clang.
* config/allocator/new_allocator_base.h
(_GLIBCXX_SANITIZE_STD_ALLOCATOR): Likewise.
This patch adds [[nodiscard]] to std::byteswap, because the function
template doesn't do anything useful if the result isn't used.
2021-11-30 Jakub Jelinek <jakub@redhat.com>
* include/std/bit (byteswap): Add [[nodiscard]].
This patch attempts to implement P1272R4 (except for the std::bit_cast
changes in there which seem quite unrelated to this and will need to be
fixed on the compiler side).
While at least for GCC __builtin_bswap{16,32,64,128} should work fine
in constant expressions, I wonder about other compilers, so I'm using
a fallback implementation for constexpr evaluation always.
If you think that is unnecessary, I can drop the
__cpp_if_consteval >= 202106L &&
if !consteval
{
and
}
and reformat.
The fallback implementation is an attempt to make it work even for integral
types that don't have number of bytes divisible by 2 or when __CHAR_BIT__
is e.g. 16.
2021-11-28 Jakub Jelinek <jakub@redhat.com>
* include/std/bit (__cpp_lib_byteswap, byteswap): Define.
* include/std/version (__cpp_lib_byteswap): Define.
* testsuite/26_numerics/bit/bit.byteswap/byteswap.cc: New test.
* testsuite/26_numerics/bit/bit.byteswap/version.cc: New test.
This test was written to verify that the LWG 3265 changes work. But
those changes were superseded by LWG 3435, and the test is now incorrect
according to the current draft. The assignment operator is now
constrained to also require convertibility, which makes the test fail.
Change the Iter type to be convertible from int*, but make it throw an
exception if that conversion is used. Change the test from compile-only
to run, so we verify that the exception isn't thrown.
libstdc++-v3/ChangeLog:
* testsuite/24_iterators/move_iterator/dr3265.cc: Fix test to
account for LWG 3435 resolution.
When implementing constexpr std::vector I added a check for constant
evaluation in vector::_S_use_relocate(), so that we would not try to relocate
trivial objects by using memmove. But I put it in the constexpr function
that decides whether to relocate or not, and calls to that function are
always constant evaluated. This had the effect of disabling relocation
entirely, even in non-constexpr vectors.
This removes the check in _S_use_relocate() and modifies the actual
relocation algorithm, __relocate_a_1, to use the non-trivial
implementation instead of memmove when called during constant
evaluation.
libstdc++-v3/ChangeLog:
* include/bits/stl_uninitialized.h (__relocate_a_1): Do not use
memmove during constant evaluation.
* include/bits/stl_vector.h (vector::_S_use_relocate()): Do not
check is_constant_evaluated in always-constexpr function.
The FE bug was fixed, so we don't need this workaround now.
libstdc++-v3/ChangeLog:
PR libstdc++/96592
* include/std/tuple (tuple::is_constructible): Remove.
An 'xfail' selector means the test is expected to fail at runtime, so is
ignored for a compile-only test. The way to mark a compile-only test as
failing is with dg-error (which these already do).
libstdc++-v3/ChangeLog:
* testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc:
Remove xfail selector.
* testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc:
Likewise.
Likewise.
* testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc:
Likewise.
* testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc:
Likewise.
* testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc:
Likewise.
* testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc:
Likewise.
* testsuite/23_containers/span/101411.cc: Likewise.
* testsuite/25_algorithms/copy/debug/constexpr_neg.cc: Likewise.
* testsuite/25_algorithms/copy_backward/debug/constexpr_neg.cc:
Likewise.
* testsuite/25_algorithms/equal/constexpr_neg.cc: Likewise.
* testsuite/25_algorithms/equal/debug/constexpr_neg.cc: Likewise.
* testsuite/25_algorithms/lower_bound/debug/constexpr_partitioned_neg.cc:
Likewise.
* testsuite/25_algorithms/lower_bound/debug/constexpr_partitioned_pred_neg.cc:
Likewise.
* testsuite/25_algorithms/lower_bound/debug/constexpr_valid_range_neg.cc:
Likewise.
* testsuite/25_algorithms/upper_bound/debug/constexpr_partitioned_neg.cc:
Likewise.
* testsuite/25_algorithms/upper_bound/debug/constexpr_partitioned_pred_neg.cc:
Likewise.
* testsuite/25_algorithms/upper_bound/debug/constexpr_valid_range_neg.cc:
Likewise.
Some of the checks in 20_util/pointer_traits/lwg3545.cc really belong in
20_util/to_address/lwg3545 instead.
This also fixes the ordering of the dg-options and dg-do directives.
libstdc++-v3/ChangeLog:
* testsuite/20_util/pointer_traits/lwg3545.cc: Move to_address
tests to ...
* testsuite/20_util/to_address/lwg3545.cc: ... here. Add -std
option before checking effective target.
There was a c++11_only dg-error in this testcase, for a "body of
constexpr function is not a return statement" diagnostic that was bogus,
but happened because the return statement was ill-formed. A change to
G++ earlier this month means that diagnostic is no longer emitted, so
remove the dg-error.
libstdc++-v3/ChangeLog:
* testsuite/20_util/tuple/comparison_operators/overloaded2.cc:
Remove dg-error for C++11_only error.
This implements the resolution I'm proposing for LWG 3545, to avoid hard
errors when using std::to_address for types that make pointer_traits
ill-formed.
Consistent with std::iterator_traits, instantiating std::pointer_traits
for a non-pointer type will be well-formed, but give an empty type with
no member types. This avoids the problematic cases for std::to_address.
Additionally, the pointer_to member is now only declared when the
element type is not cv void (and for C++20, when the function body would
be well-formed). The rebind member was already SFINAE-friendly in our
implementation.
libstdc++-v3/ChangeLog:
PR libstdc++/96416
* include/bits/ptr_traits.h (pointer_traits): Reimplement to be
SFINAE-friendly (LWG 3545).
* testsuite/20_util/pointer_traits/lwg3545.cc: New test.
* testsuite/20_util/to_address/1_neg.cc: Adjust dg-error line.
* testsuite/20_util/to_address/lwg3545.cc: New test.
libstdc++-v3/ChangeLog:
PR libstdc++/101608
* include/bits/ranges_algobase.h (__fill_n_fn): Check for
constant evaluation before using memset.
* testsuite/25_algorithms/fill_n/constrained.cc: Check
byte-sized values as well.
The type printers are not substituting std::string for
std::basic_string<char> in debug mode, mark some tests as xfail.
libstdc++-v3/ChangeLog:
* testsuite/libstdc++-prettyprinters/80276.cc: Add xfail for
debug mode.
* testsuite/libstdc++-prettyprinters/libfundts.cc: Likewise.
An effective target like foo-bar-baz will match a target selector of
*-*-* and cause problems in the testsuite. Several libstdc++ et keywords
are of the form foo-bar, which could still be a problem for *-*
selectors.
Replace hyphens with underscores in the et keywords "debug-mode",
"cxx11-abi", etc.
libstdc++-v3/ChangeLog:
* testsuite/lib/libstdc++.exp: Rename effective target keywords
to avoid dashes in the name.
* testsuite/*: Update effective targe keywords.
This allows tests to be skipped if the std::allocator implementation is
not __gnu_cxx::new_allocator.
The 20_util/allocator/overaligned.cc test requires either C++17 or
new_allocator, otherwise we can't guarantee to return overaligned
memory.
libstdc++-v3/ChangeLog:
* testsuite/18_support/50594.cc: Check effective target.
* testsuite/20_util/allocator/1.cc: Likewise.
* testsuite/20_util/allocator/overaligned.cc: Likewise.
* testsuite/23_containers/unordered_map/96088.cc: Likewise.
* testsuite/23_containers/unordered_multimap/96088.cc: Likewise.
* testsuite/23_containers/unordered_multiset/96088.cc: Likewise.
* testsuite/23_containers/unordered_set/96088.cc: Likewise.
* testsuite/ext/throw_allocator/check_delete.cc: Likewise.
* testsuite/ext/throw_allocator/check_new.cc: Likewise.
* testsuite/lib/libstdc++.exp (check_effective_target_std_allocator_new):
Define new proc.
<ext/bitmap_allocator.h> includes <function>, and since C++17 that
includes <unordered_map>. If std::allocator is defined in terms of
__gnu_cxx::bitmap_allocator then you get a circular reference and
bootstrap fails when compiling src/c++17/*.cc.
libstdc++-v3/ChangeLog:
PR libstdc++/103381
* include/ext/bitmap_allocator.h: Include <bits/stl_function.h>
instead of <functional>.
The check for C++14 was using the wrong date.
libstdc++-v3/ChangeLog:
* include/bits/c++config (_GLIBCXX14_DEPRECATED): Fix condition
checking for C++14.
This replaces a __gthread_active_p() check with __is_single_threaded()
so that std::locale initialization doesn't use __gthread_once if it
happens before the first thread is created.
This means that _S_initialize_once() might now be called twice instead
of only once, because if __is_single_threaded() changes to false then we
will do the __gthread_once call even if _S_initialize_once() was already
called. Add a check to _S_initialize_once() and return immediately if
it is the second call.
Also use __builtin_expect to _S_initialize, as the branch will be taken
at most once in the lifetime of the program.
libstdc++-v3/ChangeLog:
* src/c++98/locale_init.cc (_S_initialize_once): Check if
initialization has already been done.
(_S_initialize): Replace __gthread_active_p with
__is_single_threaded. Use __builtin_expect.
All writes into the allocated buffer need to be via traits_type::assign
to begin lifetimes.
libstdc++-v3/ChangeLog:
PR libstdc++/103295
* include/bits/basic_string.tcc (_M_construct): Use the
traits assign member to write into allcoated memory.
Depending on the permutation of CPU, OS version and shared/non-
shared library inclusion, we get can get warnings from the external
tools (ld64, dsymutil) which are not actually libstdc++ issues but
relate to the external tools themselves. This is already pruned
in the main testsuite, this adds it to the library.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
libstdc++-v3/ChangeLog:
* testsuite/lib/prune.exp: Prune dsymutil (ld64) warning.
Clang gives errors for constexpr std::string because the memory returned
by std::allocator<T>::allocate does not contain any objects yet, and
attempting to set them using char_traits::assign or char_traits::copy
fails with:
assignment to object outside its lifetime is not allowed in a constant expression
*__result = *__first;
^
This adds code to std::char_traits to use std::construct_at to begin
lifetimes when called during constant evaluation. To support
specializations of std::basic_string that don't use std::char_traits
there is now another layer of wrapper around the allocator_traits, so
that the lifetime of characters is begun as soon as the memory is
allocated. By doing it in the char traits and allocator traits, the rest
of basic_string can ignore the problem.
While modifying char_traits::copy and char_traits::assign to begin
lifetimes for the constexpr cases, I also replaced their uses of
std::copy and std::fill_n respectively. That means we don't need
<bits/stl_algobase.h> for char_traits.
libstdc++-v3/ChangeLog:
PR libstdc++/103295
* include/bits/basic_string.h (_Alloc_traits): Replace typedef
with struct for C++20 mode.
* include/bits/basic_string.tcc (_M_replace): Use _Alloc_traits
for allocation.
* include/bits/char_traits.h (__gnu_cxx::char_traits::assign):
Use std::_Construct during constant evaluation.
(__gnu_cxx::char_traits::assign(CharT*, const CharT*, size_t)):
Likewise. Replace std::fill_n with memset or manual loop.
(__gnu_cxx::char_traits::copy): Likewise, replacing std::copy
with memcpy.
* include/ext/vstring.h: Include <bits/stl_algobase.h> for
std::min.
* include/std/string_view: Likewise.
* testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc:
Add constexpr test.
Newlib changed ctype.h recently[1] by moving the short labels from ctype.h intro
the private namespace in ctype_.h. This broke embedded builds due to them no
longer being found. Instead they now expose the long names to match glibc.
This patch now uses the short or long names depending on is the short ones are
defined or not.
[1] 3ba1bd0d9d
libstdc++-v3/ChangeLog:
PR libstdc++/103305
* config/os/newlib/ctype_base.h (upper, lower, alpha, digit, xdigit,
space, print, graph, cntrl, punct, alnum, blank): Use short or long
names depending on if short ones are defined.
The constexpr branch in __gnu_cxx::char_traits::move compares the string
arguments to see if they overlap, but relational comparisons between
unrelated pointers are not core constant expressions.
I want to replace the comparisons with a loop using pointer equality to
determine whether the end of the source string is in the destination
string. However, that doesn't work with GCC, due to PR c++/89074 so
allocate a temporary buffer instead and copy out into that first, so
that overlapping source and destination don't matter. The allocation
isn't supported by the current Intel icc so use the loop as a fallback.
libstdc++-v3/ChangeLog:
* include/bits/char_traits.h (__gnu_cxx::char_traits::move):
Do not compare unrelated pointers during constant evaluation.
* testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc:
Improve tests for char_traits::move.
This replaces most uses of AC_CACHE_VAL with AC_CACHE_CHECK, which means
we don't need separate AC_MSG_CHECKING and AC_MSG_RESULT macros.
There are a few trivial bugs fixed as a side effect, where an
AC_MSG_RESULT was printed out even if the actual checks hadn't been
done. That didn't affect the results, only the content of config.log.
libstdc++-v3/ChangeLog:
* acinclude.m4: Replace AC_CACHE_VAL with AC_CACHE_CHECK.
* configure: Regenerate.
GCC Administrator
Jonathan Wakely
Jakub Jelinek
François Dumont
Iain Sandoe
Tamar Christina