Undefine various macros unexpectedly defined by VxWorks headers.
for libstdc++-v3/ChangeLog
* testsuite/17_intro/names.cc: Account for VxWorks headers.
This patch conditionally disables the floating-point std::to_chars
implementation on targets whose float and double aren't IEEE binary32
and binary64, until a proper fallback can be added for such targets.
This fixes a bootstrap failure on non-IEEE-754 FP targets such as
vax-netbsdelf.
The new preprocessor tests in c++config that detect the binary32 and
binary64 formats were copied from gcc/testsuite/gcc.dg/float-exact-1.c.
libstdc++-v3/ChangeLog:
* include/bits/c++config (_GLIBCXX_FLOAT_IS_IEEE_BINARY_32):
Define this macro.
(_GLIBCXX_DOUBLE_IS_IEEE_BINARY_64): Likewise.
* include/std/charconv (to_chars): Use these macros to
conditionally hide the overloads for floating-point types.
* src/c++17/floating_to_chars.cc: Use the macros to
conditionally disable this file.
(floating_type_traits<float>): Remove redundant static assert.
(floating_type_traits<double>): Likewise.
* testsuite/20_util/to_chars/double.cc: Run this test only on
ieee-floats effective targets.
* testsuite/20_util/to_chars/float.cc: Likewise.
* testsuite/20_util/to_chars/long_double.cc: Likewise.
* testsuite/lib/libstdc++.exp
(check_effective_target_ieee-floats): Define new proc for
detecting whether float and double have the IEEE binary32 and
binary64 formats.
The #ifdef RADIXCHAR directive should be moved one line up so that it
also guards the outer if statement, or else when RADIXCHAR is not
defined the outer if statement will end up nonsensically guarding the
declaration of output_length_upper_bound a few lines below it.
libstdc++-v3/ChangeLog:
PR libstdc++/98377
* src/c++17/floating_to_chars.cc (__floating_to_chars_precision):
Fix mistake.
This should fix a build failure on AArch64 ILP32 due to int32_t mapping
to long int instead of int on this platform, which causes type deduction
to fail in the below call to std::max as reported in the PR.
libstdc++-v3/ChangeLog:
PR libstdc++/98370
* src/c++17/floating_to_chars.cc (__floating_to_chars_shortest):
Provide explicit template arguments to the call to std::max.
This should fix a build failure on Windows which lacks <langinfo.h>,
from which we use nl_langinfo() to obtain the radix character of the
current locale. (We can't use the more portable localeconv() from
<clocale> to obtain the radix character of the current locale here
because it's not thread-safe, unfortunately.)
This change means that on Windows and other such platforms, we'll just
always assume the radix character used by printf is '.' when formatting
a long double through it.
libstdc++-v3/ChangeLog:
PR libstdc++/98374
* src/c++17/floating_to_chars.cc: Guard include of <langinfo.h>
with __has_include.
(__floating_to_chars_precision) [!defined(RADIXCHAR)]: Don't
attempt to obtain the radix character of the current locale,
just assume it's '.'.
We need to test that FE_TONEAREST is defined before we may use it along
with fegetround/fesetround to adjust the floating-point rounding mode.
This fixes a build failure with older versions of newlib.
libstdc++-v3/ChangeLog:
* src/c++17/floating_from_chars.cc (from_chars_impl)
[!defined(FE_TONEAREST)]: Don't adjust the rounding mode.
* src/c++17/floating_to_chars.cc (__floating_to_chars_precision):
Likewise.
The testcases are imported almost verbatim, with the only change being
to the -double_nan and -float_nan testcases. We expect these values to
be formatted as "-nan" instead of "-nan(ind)".
libstdc++-v3/ChangeLog:
* testsuite/20_util/to_chars/double.cc: New test, consisting of
testcases imported from the MSVC STL testsuite.
* testsuite/20_util/to_chars/float.cc: Likewise.
This implements the floating-point std::to_chars overloads for float,
double and long double. We use the Ryu library to compute the shortest
round-trippable fixed and scientific forms for float, double and long
double. We also use Ryu for performing explicit-precision fixed and
scientific formatting for float and double. For explicit-precision
formatting for long double we fall back to using printf. Hexadecimal
formatting for float, double and long double is implemented from
scratch.
The supported long double binary formats are binary64, binary80 (x86
80-bit extended precision), binary128 and ibm128.
Much of the complexity of the implementation is in computing the exact
output length before handing it off to Ryu (which doesn't do bounds
checking). In some cases it's hard to compute the output length
beforehand, so in these cases we instead compute an upper bound on the
output length and use a sufficiently-sized intermediate buffer only if
necessary.
Another source of complexity is in the general-with-precision formatting
mode, where we need to do zero-trimming of the string returned by Ryu,
and where we also take care to avoid having to format the number through
Ryu a second time when the general formatting mode resolves to fixed
(which we determine by doing a scientific formatting first and
inspecting the scientific exponent). We avoid going through Ryu twice
by instead transforming the scientific form to the corresponding fixed
form via in-place string manipulation.
This implementation is non-conforming in a couple of ways:
1. For the shortest hexadecimal formatting, we currently follow the
Microsoft implementation's decision to be consistent with the
output of printf's '%a' specifier at the expense of sometimes not
printing the shortest representation. For example, the shortest hex
form for the number 1.08p+0 is 2.1p-1, but we output the former
instead of the latter, as does printf.
2. The Ryu routine generic_binary_to_decimal that we use for performing
shortest formatting for large floating point types is implemented
using the __int128 type, but some targets with a large long double
type lack __int128 (e.g. i686), so we can't perform shortest
formatting of long double on such targets through Ryu. As a
temporary stopgap this patch makes the long double to_chars overloads
just dispatch to the double overloads on these targets, which means
we lose precision in the output. (We could potentially fix this by
writing a specialized version of Ryu's generic_binary_to_decimal
routine that uses uint64_t instead of __int128.) [Though I wonder if
there's a better way to work around the lack of __int128 on i686
specifically?]
3. Our shortest formatting for __ibm128 doesn't guarantee the round-trip
property if the difference between the high- and low-order exponent
is large. This is because we treat __ibm128 as if it has a
contiguous 105-bit mantissa by merging the mantissas of the high-
and low-order parts (using code extracted from glibc), so we
potentially lose precision from the low-order part. This seems to be
consistent with how glibc printf formats __ibm128.
libstdc++-v3/ChangeLog:
* config/abi/pre/gnu.ver: Add new exports.
* include/std/charconv (to_chars): Declare the floating-point
overloads for float, double and long double.
* src/c++17/Makefile.am (sources): Add floating_to_chars.cc.
* src/c++17/Makefile.in: Regenerate.
* src/c++17/floating_to_chars.cc: New file.
(to_chars): Define for float, double and long double.
* testsuite/20_util/to_chars/long_double.cc: New test.
This performs the following modifications to our local copy of Ryu in
order to make it more readily usable for our std::to_chars
implementation:
* Remove all #includes
* Remove copy_special_str routines
* Adjust the exponent formatting to match printf
* Remove some functions we're not going to use
* Add an out-parameter to d2exp_buffered_n for the scientific exponent
* Store the sign bit inside struct floating_decimal_[32|64]
* Rename [df]2s_buffered_n and change their return type
* Make generic_binary_to_decimal take the bit representation in parts
libstdc++-v3/ChangeLog:
* src/c++17/ryu/common.h, src/c++17/ryu/d2fixed.c,
src/c++17/ryu/d2fixed_full_table.h, src/c++17/ryu/d2s.c,
src/c++17/ryu/d2s_intrinsics.h, src/c++17/ryu/f2s.c,
src/c++17/ryu/f2s_intrinsics.h, src/c++17/ryu/generic_128.c:
Apply local modifications.
This imports the source files from the Ryu library that define
d2s_buffered_n, f2s_buffered_n, d2fixed_buffered_n, d2exp_buffered_n and
generic_binary_to_decimal, which we're going to use as the base of our
std::to_chars implementation.
libstdc++-v3/ChangeLog:
* src/c++17/ryu/MERGE: New file.
* src/c++17/ryu/common.h, src/c++17/ryu/d2fixed.c,
src/c++17/ryu/d2fixed_full_table.h, src/c++17/ryu/d2s.c,
src/c++17/ryu/d2s_full_table.h, src/c++17/ryu/d2s_intrinsics.h,
src/c++17/ryu/digit_table.h, src/c++17/ryu/f2s.c,
src/c++17/ryu/f2s_intrinsics.h, src/c++17/ryu/generic_128.c,
src/c++17/ryu/generic_128.h, src/c++17/ryu/ryu_generic_128.h:
Import these files from the Ryu library.
This applies the same changes to the djgpp and mingw versions of
error_constants.h as r11-6137 did for the generic version.
All of these constants are defined as macros by <errno.h> on these
targets, so we can just test the macro directly instead of checking for
it at configure time.
libstdc++-v3/ChangeLog:
* config/os/djgpp/error_constants.h: Test POSIX errno macros
directly, instead of corresponding _GLIBCXX_HAVE_EXXX macros.
* config/os/mingw32-w64/error_constants.h: Likewise.
* config/os/mingw32/error_constants.h: Likewise.
The refactoring in r11-5500 altered the condition for the gthreads-timed
test from #if to #ifdef. For some reason that macro is always defined,
rather than being defined to 1 or undefined like most of our autoconf
macros. That means the test always passes now, even for targets where
the macro is defined to 0 (specifically, Darwin). That causes some tests
to FAIL when they should have been UNSUPPORTED.
This restores the previous behaviour.
libstdc++-v3/ChangeLog:
* testsuite/lib/libstdc++.exp (check_v3_target_gthreads_timed):
Fix condition for _GTHREAD_USE_MUTEX_TIMEDLOCK test.
As noted in PR 66146 comment 35, there is a new warning in the new
std::call_once implementation.
libstdc++-v3/ChangeLog:
* src/c++11/mutex.cc (std::once_flag::_M_finish): Add
maybe_unused attribute to variable used in assertion.
This makes the hash function available without including the whole of
<thread>, which is needed for <barrier>.
libstdc++-v3/ChangeLog:
* include/bits/std_thread.h (hash<thread::id>): Move here,
from ...
* include/std/thread (hash<thread::id>): ... here.
This adds support for the new __ieee128 long double format on
powerpc64le targets.
Most of the complexity comes from wanting a single libstdc++.so library
that contains the symbols needed by code compiled with both
-mabi=ibmlongdouble and -mabi=ieeelongdouble (and not forgetting
-mlong-double-64 as well!)
In a few places this just requires an extra overload, for example
std::from_chars has to be overloaded for both forms of long double.
That can be done in a single translation unit that defines overloads
for 'long double' and also '__ieee128', so that user code including
<charconv> will be able to link to a definition for either type of long
double. Those are the easy cases.
The difficult parts are (as for the std::string ABI transition) the I/O
and locale facets. In order to be able to write either form of long
double to an ostream such as std::cout we need the locale to contain a
std::num_put facet that can handle both forms. The same approach is
taken as was already done for supporting 64-bit long double and 128-bit
long double: adding extra overloads of do_put to the facet class. On
targets where the new long double code is enabled, the facets that are
registered in the locale at program startup have additional overloads so
that they can work with any long double type. Where this fails to work
is if user code installs its own facet, which will probably not have the
additional overloads and so will only be able to output one or the other
type. In practice the number of users expecting to be able to use their
own locale facets in code using a mix of -mabi=ibmlongdouble and
-mabi=ieeelongdouble is probably close to zero.
libstdc++-v3/ChangeLog:
* Makefile.in: Regenerate.
* config.h.in: Regenerate.
* config/abi/pre/gnu.ver: Make patterns less greedy.
* config/os/gnu-linux/ldbl-ieee128-extra.ver: New file with patterns
for IEEE128 long double symbols.
* configure: Regenerate.
* configure.ac: Enable alternative 128-bit long double format on
powerpc64*-*-linux*.
* doc/Makefile.in: Regenerate.
* fragment.am: Regenerate.
* include/Makefile.am: Set _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT.
* include/Makefile.in: Regenerate.
* include/bits/c++config: Define inline namespace for new long
double symbols. Don't define _GLIBCXX_USE_FLOAT128 when it's the
same type as long double.
* include/bits/locale_classes.h [_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT]
(locale::_Impl::_M_init_extra_ldbl128): Declare new member function.
* include/bits/locale_facets.h (_GLIBCXX_NUM_FACETS): Simplify by
only counting narrow character facets.
(_GLIBCXX_NUM_CXX11_FACETS): Likewise.
(_GLIBCXX_NUM_LBDL_ALT128_FACETS): New.
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT] (num_get::__do_get): Define
vtable placeholder for __ibm128 long double type.
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(num_get::__do_get): Declare vtable placeholder for __ibm128 long
double type.
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(num_put::__do_put): Likewise.
* include/bits/locale_facets.tcc
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(num_get::__do_get, num_put::__do_put): Define.
* include/bits/locale_facets_nonio.h
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(money_get::__do_get): Declare vtable placeholder for __ibm128 long
double type.
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(money_put::__do_put): Likewise.
* include/bits/locale_facets_nonio.tcc
[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
(money_get::__do_get, money_put::__do_put): Define.
* include/ext/numeric_traits.h [_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT]
(__numeric_traits<__ibm128>, __numeric_traits<__ieee128>): Define.
* libsupc++/Makefile.in: Regenerate.
* po/Makefile.in: Regenerate.
* python/Makefile.in: Regenerate.
* src/Makefile.am: Add compatibility-ldbl-alt128.cc and
compatibility-ldbl-alt128-cxx11.cc sources and recipes for objects.
* src/Makefile.in: Regenerate.
* src/c++11/Makefile.in: Regenerate.
* src/c++11/compatibility-ldbl-alt128-cxx11.cc: New file defining
symbols using the old 128-bit long double format, for the cxx11 ABI.
* src/c++11/compatibility-ldbl-alt128.cc: Likewise, for the
gcc4-compatible ABI.
* src/c++11/compatibility-ldbl-facets-aliases.h: New header for long
double compat aliases.
* src/c++11/cow-locale_init.cc: Add comment.
* src/c++11/cxx11-locale-inst.cc: Define C and C_is_char
unconditionally.
* src/c++11/cxx11-wlocale-inst.cc: Add sanity check. Include
locale-inst.cc directly, not via cxx11-locale-inst.cc.
* src/c++11/locale-inst-monetary.h: New header for monetary
category instantiations.
* src/c++11/locale-inst-numeric.h: New header for numeric category
instantiations.
* src/c++11/locale-inst.cc: Include new headers for monetary,
numeric, and long double definitions.
* src/c++11/wlocale-inst.cc: Remove long double compat aliases that
are defined in new header now.
* src/c++17/Makefile.am: Use -mabi=ibmlongdouble for
floating_from_chars.cc.
* src/c++17/Makefile.in: Regenerate.
* src/c++17/floating_from_chars.cc (from_chars_impl): Add
if-constexpr branch for __ieee128.
(from_chars): Overload for __ieee128.
* src/c++20/Makefile.in: Regenerate.
* src/c++98/Makefile.in: Regenerate.
* src/c++98/locale_init.cc (num_facets): Adjust calculation.
(locale::_Impl::_Impl(size_t)): Call _M_init_extra_ldbl128.
* src/c++98/localename.cc (num_facets): Adjust calculation.
(locale::_Impl::_Impl(const char*, size_t)): Call
_M_init_extra_ldbl128.
* src/filesystem/Makefile.in: Regenerate.
* testsuite/Makefile.in: Regenerate.
* testsuite/util/testsuite_abi.cc: Add new symbol versions.
Allow new symbols to be added to GLIBCXX_IEEE128_3.4.29 and
CXXABI_IEEE128_1.3.13 too.
* testsuite/26_numerics/complex/abi_tag.cc: Add u9__ieee128 to
regex matching expected symbols.
Now that GCC supports __has_builtin there is no need to test whether
it's defined, we can just use it unconditionally.
libstdc++-v3/ChangeLog:
* include/std/utility: Use __has_builtin without checking if
it's defined.
Recent changes to use __int128 as an integer-like type in <ranges> and
to optimize std::uniform_int_distribution mean that the library relies
on __int128 more heavily than in the past.
The library expects that if __int128 is supported then either
__GLIBCXX_TYPE_INT_N_0 is defined (and we treat is like the standard
integer types), or __STRICT_ANSI__ is defined (and we need to add
special handling for __int128 as a non-standard integer type).
If users compile with -std=c++NN -U__STRICT_ANSI__ then it puts the
library into a broken and inconsistent state, where the compiler doesn't
define the __GLIBCXX_TYPE_INT_N_0 macro, but the library thinks it
doesn't need special handling for __int128. What the user should do is
compile with -std=gnu++NN instead.
This adds a warning if it appears that __int128 is supported but neither
__GLIBCXX_TYPE_INT_N_0 nor __STRICT_ANSI__ is defined.
libstdc++-v3/ChangeLog:
* include/bits/c++config: Warn if __STRICT_ANSI__ state is
inconsistent with __GLIBCXX_TYPE_INT_N_0.
Clang doesn't support __builtin_sprintf, so use std::sprintf instead.
libstdc++-v3/ChangeLog:
PR libstdc++/96083
* include/ext/throw_allocator.h: Use __has_builtin to check for
__builtin_sprintf support, and use std::sprtinf if necessary.
Currently the <experimental/random>, <experimental/source_location> and
<experimental/utility> headers can be included in C++98 and C++11 modes,
but gives errors. With this change they can be included, but define
nothing.
libstdc++-v3/ChangeLog:
PR libstdc++/98319
* include/experimental/random: Only define contents for C++14
and later.
* include/experimental/source_location: Likewise.
* include/experimental/utility: Likewise.
* testsuite/experimental/feat-lib-fund.cc: Include all LFTS
headers that are present. Allow test to run for all modes.
This adds a test to compare the performance of std::atomic_flag with
similar operations on std::atomic_uchar and std::atomic_int.
libstdc++-v3/ChangeLog:
PR libstdc++/46447
* testsuite/performance/29_atomics/atomic_flag.cc: New test.
This fixes a bug caused by a mismatch between the macros defined by
<errno.h> when GCC is built and the macros defined by <errno.h> when
users include <system_error>. If the user code is compiled with
_XOPEN_SOURCE defined to 500 or 600, Darwin suppresses the
ENOTRECOVERABLE and EOWNERDEAD macros, which are not defined by SUSv3
(aka POSIX.1-2001).
Since POSIX requires the errno macros to be macros (and not variables or
enumerators) we can just test for them directly using the preprocessor.
That means that <system_error> will match what is actuallydefined when
it's included, not what was defined when GCC was built. With that change
there is no need for the GLIBCXX_CHECK_SYSTEM_ERROR configure checks and
they can be removed.
libstdc++-v3/ChangeLog:
PR libstdc++/93151
* acinclude.m4 (GLIBCXX_CHECK_SYSTEM_ERROR): Remove.
* configure.ac: Regenerate.
* config/os/generic/error_constants.h: Test POSIX errno macros
directly, instead of corresponding _GLIBCXX_HAVE_EXXX macros.
* testsuite/19_diagnostics/headers/system_error/errc_std_c++0x.cc:
Likewise.
* testsuite/19_diagnostics/headers/system_error/93151.cc: New
test.
The current libstdc++ basic_file_stdio.cc code assumes a POSIX API
underneath the stdio implementation provided by the host libc. This
means that the host must provide a fairly broad POSIX file API,
including read, write, open, close, lseek and ioctl.
This patch changes basic_file_stdio.cc to only use basic ANSI-C stdio
functions, allowing it to be used with libc implementations like
picolibc which may not have a POSIX operating system underneath.
This is enabled by a new --enable-cstdio=stdio_pure configure option.
Aided-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_CSTDIO): Allow "stdio_pure"
option and define _GLIBCXX_USE_PURE_STDIO when it is used. Also
add "stdio_posix" option as an alias for "stdio".
* config/io/basic_file_stdio.cc [_GLIBCXX_USE_PURE_STDIO]: Only
use defined stdio entry points for all I/O operations, without
direct calls to underlying POSIX functions.
* config.h.in: Regenerate.
* configure: Regenerate.
These tests FAIL when testing debug mode with a small tool_timeout
value. Give them a longer relative timeout.
libstdc++-v3/ChangeLog:
* testsuite/25_algorithms/lexicographical_compare/deque_iterators/1.cc:
Add dg-timeout-factor directive.
* testsuite/ext/pb_ds/regression/tree_map_rand_debug.cc:
Increase timeout factor from 2.0 to 3.0.
* testsuite/ext/pb_ds/regression/tree_set_rand_debug.cc:
Likewise.
* testsuite/lib/libstdc++.exp (check_effective_target_debug-mode):
Define "debug-mode" as an effective-target keyword.
There's no point even checking is_constant_evaluated() in C++11 mode,
because the 'if' statement used for the assertion wouldn't be valid in a
C++11 constexpr function anyway.
libstdc++-v3/ChangeLog:
* include/bits/c++config (__glibcxx_assert_1): Define as empty
for C++11.
The testsuite for libstdc++ aims to skips test cases for which not all
required locales are installed. This patch adds missing directives about
required locales to one test case to avoid false positive test failures
on systems that have a partial set of locales installed.
Verified by test suite runs that this patch changes the test case from
FAIL to UNSUPPORTED when not all required locales are available and that
the test case will run and PASS when the necessary locales have been
added.
libstdc++-v3/ChangeLog:
* testsuite/22_locale/locale/cons/5.cc: Add missing directives
for required locales.
Now that the G++ bug is fixed we no longer need to protect this partial
specialization from complaining about subtracting void pointers.
libstdc++-v3/ChangeLog:
* include/bits/iterator_concepts.h (incrementable_traits<Tp>):
Remove workaround for PR c++/78173.
The AC_LIBTOOL_DLOPEN checks were previously disabled for newlib targets.
The patch applies similar logic to avr-libc based builds.
libstdc++-v3/ChangeLog:
* configure.ac: Skip AC_LIBTOOL_DLOPEN check if avr-libc is used.
* configure: Regenerate.
This causes the global objects that run the <iostream> initialization
code to be constructed earlier, which avoids some bugs in user code due
to incorrectly relying on static initialization order.
libstdc++-v3/ChangeLog:
PR libstdc++/98108
* include/std/iostream (__ioinit): Add init_priority attribute.
libstdc++-v3/ChangeLog:
* testsuite/23_containers/array/debug/back2_neg.cc: target c++14 because assertion
for constexpr is disabled in C++11.
* testsuite/23_containers/array/debug/front2_neg.cc: Likewise.
* testsuite/23_containers/array/debug/square_brackets_operator2_neg.cc: Likewise.
* testsuite/23_containers/vector/debug/multithreaded_swap.cc: Include <memory>
for shared_ptr.
The __glibcxx_check_can_[increment|decrement]_range macros are using the
_GLIBCXX_DEBUG_VERIFY_COND_AT macro which is not constexpr compliant and will produce nasty
diagnostics rather than the std::__failed_assertion dedicated to constexpr. Replace it with
correct _GLIBCXX_DEBUG_VERIFY_AT_F.
libstdc++-v3/ChangeLog:
* include/debug/macros.h (__glibcxx_check_can_increment_range): Replace
_GLIBCXX_DEBUG_VERIFY_COND_AT usage with _GLIBCXX_DEBUG_VERIFY_AT_F.
(__glibcxx_check_can_decrement_range): Likewise.
* testsuite/25_algorithms/copy_backward/constexpr.cc (test03): New.
* testsuite/25_algorithms/copy/debug/constexpr_neg.cc: New test.
* testsuite/25_algorithms/copy_backward/debug/constexpr_neg.cc: New test.
* testsuite/25_algorithms/equal/constexpr_neg.cc: New test.
* testsuite/25_algorithms/equal/debug/constexpr_neg.cc: New test.
There's no need to explicitly check for the maximum value, because the
function we call handles it correctly anyway.
libstdc++-v3/ChangeLog:
PR libstdc++/98226
* include/std/bit (__countl_one, __countr_one): Remove redundant
branches.
