With the STL containers, I didn't enable move operations in C++03 mode
because that would change the overload resolution for things that today
are copy operations. With iostreams, though, the copy operations aren't
present at all, and so I see no problem with enabling move operations
even in (Clang's greatly extended) C++03 mode.
Clang's C++03 mode does not support delegating constructors.
Differential Revision: https://reviews.llvm.org/D104310
In typeinfo there is a reinterpret_cast between a uintptr_t and size_t. These are two integer types and therefore a reinterpret_cast is not right for this situation. It looks like it may have been copied and pasted from above in the file. An implicit cast works in it's place.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D104814
Moves:
* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
`__utility/${FUNCTION_NAME}`.
* `std::swap_ranges` and `std::iter_swap` into
`__algorithm/${FUNCTION_NAME}`
Differential Revision: https://reviews.llvm.org/D103734
Under the as-if rule, we can directly implement the array overload for
`std::swap`. By removing this circular dependency where `swap` is
implemented in terms of `swap_ranges` and `swap_ranges` is defined in
terms of `swap`, we can split them into their own headers. This will:
* limit the surface area in which Hyrum's law can bite us;
* force users to include the correct headers;
* make finding the definitions trivial (`swap` is a utility;
`swap_ranges` is an algorithm).
Differential Revision: https://reviews.llvm.org/D104760
Since we now have modules-enabled CI, it is now redundant to have ad-hoc
tests that check arbitrary things about our modules support. Instead,
the whole test suite should pass with modules enabled, period.
This patch also removes the module cache path workaround: one would
expect that modules work properly without that workaround. If that
isn't the case and we do run into flaky test failures, we can re-enable
the workaround temporarily (but that would be very vexing and we should
fix Clang ASAP if that's the case).
Differential Revision: https://reviews.llvm.org/D104746
* `<type_traits>` depends on `std::forward`, so we replaced it with
`static_cast<T&&>`.
* `swap`'s return type is confusing, so it's been rearranged to improve
readabilitiy.
* indicates whether work has been started or completed
* consolidates content that was split for dependency reasons (iff
everything has been merged)
* makes things a lot more fine-grained
* turns sub-CSVs into lists
* puts links into description section and removes patch column
* adds links to c++draft on occasion
These changes heavily prioritise the the reader of the generated HTML
file, not the source.
Differential Revision: https://reviews.llvm.org/D103295
C++03 didn't support `explicit` conversion operators;
but Clang's C++03 mode does, as an extension, so we can use it.
This lets us make the conversion explicit in `std::function` (even in '03),
and remove some silly metaprogramming in `std::basic_ios`.
Drive-by improvements to the tests for these operators, in addition
to making sure all these tests also run in `c++03` mode.
Differential Revision: https://reviews.llvm.org/D104682
The current implementation of `std::forward_list::swap` uses
`propagate_on_container_move_assignment` for `noexcept` specification.
This patch changes it to use `propagate_on_container_swap`, as it should.
Fixes https://llvm.org/PR50224.
Differential Revision: https://reviews.llvm.org/D101899
This is a fairly mechanical change, it just moves each algorithm into
its own header. This is intended to be a NFC.
This commit re-applies 7ed7d4ccb8, which was reverted in 692d7166f7
because the Modules build got broken. The modules build has now been
fixed, so we're re-committing this.
Differential Revision: https://reviews.llvm.org/D103583
Attribution note
----------------
I'm only committing this. This commit is a mix of D103583, D103330 and
D104171 authored by:
Co-authored-by: Christopher Di Bella <cjdb@google.com>
Co-authored-by: zoecarver <z.zoelec2@gmail.com>
P1518 does the following in C++23 but we'll just do it in C++17 as well:
- Stop requiring `Alloc` to be an allocator on some container-adaptor deduction guides
- Stop deducing from `Allocator` on some sequence container constructors
- Stop deducing from `Allocator` on some other container constructors (libc++ already did this)
The affected constructors are the "allocator-extended" versions of
constructors where the non-allocator arguments are already sufficient
to deduce the allocator type. For example,
std::pmr::vector<int> v1;
std::vector v2(v1, std::pmr::new_delete_resource());
std::stack s2(v1, std::pmr::new_delete_resource());
Differential Revision: https://reviews.llvm.org/D97742
When we removed the allocator<void> specialization, the triviality of
std::allocator<void> changed because the primary template had a
non-trivial default constructor and the specialization didn't
(so std::allocator<void> went from trivial to non-trivial).
This commit fixes that oversight by giving a trivial constructor to
the primary template when instantiated on cv-void.
This was reported in https://llvm.org/PR50299.
Differential Revision: https://reviews.llvm.org/D104398
A few slipped through the cracks because D104175 and D104170 didn't
concern themselves with newer commits.
Differential Revision: https://reviews.llvm.org/D104414
While the std::allocator<void> specialization was deprecated by
https://wg21.link/p0174#2.2, the *use* of std::allocator<void> by users
was not. The intent was that std::allocator<void> could still be used
in C++17 and C++20, but starting with C++20 (with the removal of the
specialization), std::allocator<void> would use the primary template.
That intent was called out in wg21.link/p0619r4#3.9.
As a result of this patch, _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
will also not control whether the explicit specialization is provided or
not. It shouldn't matter, since in C++20, one can simply use the primary
template.
Fixes http://llvm.org/PR50299
Differential Revision: https://reviews.llvm.org/D104323
Also, fix the last issue that prevented GCC 11 from passing the test
suite. Thanks to everyone else who fixed issues.
Differential Revision: https://reviews.llvm.org/D104315
This has been broken out of D104170 since it should be merged whether or
not we go ahead with the module map changes.
Differential Revision: https://reviews.llvm.org/D104175
https://eel.is/c++draft/atomics.types.operations#23 says: ... the value of failure is order except that a value of `memory_order::acq_rel` shall be replaced by the value `memory_order::acquire` and a value of `memory_order::release` shall be replaced by the value `memory_order::relaxed`.
This failure mapping is only handled for `_LIBCPP_HAS_GCC_ATOMIC_IMP`. We are seeing bad code generation for `compare_exchange_strong(cmp, 1, std::memory_order_acq_rel)` when using libc++ in place of libstdc++: https://godbolt.org/z/v3onrrq4G.
This was caught by tsan tests after D99434, `[TSAN] Honor failure memory orders in AtomicCAS`, but appears to be an issue in non-tsan code.
Reviewed By: ldionne, dvyukov
Differential Revision: https://reviews.llvm.org/D103846
The runtimes build has assertions enabled, which is necessary to catch
some of the modules-related issues we've been seeing recently. This
patch enables testing with modules in the runtimes build so as to cover
those cases.
In the future, a better solution would be to systematically use versions
of Clang that have assertions enabled. However, the Clangs we release
currently don't have assertions enabled by default, which causes a
challenge for the CI (we could try to build our own Clang from ToT with
assertions in the CI, but that poses some problems).
Differential Revision: https://reviews.llvm.org/D104252
This started as an attempt to fix a GCC 11 warning of misplaced parentheses.
I then noticed that trying to fix the parentheses warning actually triggered
errors in the tests, showing that we were incorrectly assuming that the
implementation of ranges::advance was using operator+= or operator-=.
This commit fixes that issue and makes the tests easier to follow by
localizing the assertions it makes.
Differential Revision: https://reviews.llvm.org/D103272
The synchronization library was marked as disabled on Apple platforms
up to now because we were not 100% sure that it was going to be ABI
stable. However, it's been some time since we shipped it in upstream
libc++ now and there's been no changes so far. This patch enables the
synchronization library on Apple platforms, and hence commits the ABI
stability as far as that vendor is concerned.
Differential Revision: https://reviews.llvm.org/D96790
Instead, people should be using CMAKE_POSITION_INDEPENDENT_CODE to control
whether they want to use PIC or not. We should try to avoid reinventing
the wheel whenever CMake natively supports something.
This makes libc++abi consistent with libc++ and libunwind.
Differential Revision: https://reviews.llvm.org/D103973
Makes the following operations constexpr:
* `std::swap(optional, optional)`
* `optional(optional<U> const&)`
* `optional(optional<U>&&)`
* `~optional()`
* `operator=(nullopt_t)`
* `operator=(U&&)`
* `operator=(optional<U> const&)`
* `operator=(optional<U>&&)`
* `emplace(Args&&...)`
* `emplace(initializer_list<U>, Args&&...)`
* `swap(optional&)`
* `reset()`
P2231 has been accepted by plenary, with the committee recommending
implementers retroactively apply to C++20. It's necessary for us to
implement _`semiregular-box`_ and _`non-propagating-cache`_, both of
which are required for ranges (otherwise we'll need to reimplement
`std::optional` with these members `constexpr`ified).
Differential Revision: https://reviews.llvm.org/D102119
The post-conditions for the self move assignment of `std::unique_ptr`
were changed. This requires no implementation changes. A test was added
to validate the new post-conditions.
Addresses
- LWG-3455: Incorrect Postconditions on `unique_ptr` move assignment
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D103764
The buffer size (`__nbuf`) in `num_put::do_put` is currently not an
integral/core constant expression. As a result, `__nar` is a Variable Length
Array (VLA). VLAs are a GNU extension and not part of the base C++ standard, so
unless there is good reason to do so they probably shouldn't be used in any of
the standard library headers. The call to `__iob.flags()` is the only thing
keeping `__nbuf` from being a compile time constant, so the solution here is to
simply err on the side of caution and always allocate a buffer large enough to
fit the base prefix.
Note that, while the base prefix for hex (`0x`) is slightly longer than the
base prefix for octal (`0`), this isn't a concern. The difference in the space
needed for the value portion of the string is enough to make up for this.
(Unless we're working with small, oddly sized types such as a hypothetical
`uint9_t`, the space needed for the value portion in octal is at least 1 more
than the space needed for the value portion in hex).
This PR also adds `constexpr` to `__nbuf` to enforce compile time const-ness
going forward.
Reviewed By: Mordante, #libc, Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D103558
This commit finishes moving the <atomic> design documents to the RST
documentation and removes the old documentation. https://libcxx.llvm.org
is already pointing to the new documentation only now, so the removal of
the old documentation is really a NFC.
I went over the old documentation and I don't think we're leaving anything
important behind - I think everything important was mentionned in the RST
documentation anyway.
Several macros were guarded with a check along the lines of:
#ifndef MACRO
# define MACRO ...
#endif
However, some of these macros are never intended to be defined by users,
so it's pointless to make this check (i.e. the first #ifndef is always
true). This commit removes those checks.
The motivation for doing this cleanup is to remove the impression that
arbitrary configurations macros can be defined by users when including
libc++ headers, which doesn't work reliably and leads to macro spaghetti.
If one needs to be able to override a knob in the __config, that's fine,
but the proper way to do that is to document the macro as being a public
facing knob in the documentation, and most likely to migrate that macro
to __config_site (depending on the nature of the macro).
Differential Revision: https://reviews.llvm.org/D103705
The "root nodes" of the graph are displayed in bold. My intent here
was to bold just the public-API headers, e.g. <vector> and
<experimental/coroutine> and <stdlib.h>, but not helper headers
such as <__functional_base> and <__iterator/next.h>. However,
the recent mass helper-header-ification has exposed defects in
this logic: all the new helpers were ending up bolded! Fix this.
Also, add <__undef_macros> to the list of headers we don't display
by default (like <__config>); it's not interesting to see those edges.
Also, add a sample `dot` command line to the `--help` text.
The `operator[]` of `_UnaryOp` and `_BinaryOp` returns the result of
calling `__op_`, so its return type should be `__result_type`, not
e.g. `_A0::value_type`. However, `_UnaryOp::value_type` also should
never have been `_A0::value_type`; it needs to be the correct type
for the result of the unary op, e.g. `bool` when the op is `logical_not`.
This turns out to matter when multiple operators are nested, e.g.
`+(v == v)` needs to have a `value_type` of `bool`, not `int`,
even when `v` is of type `valarray<int>`.
Differential Revision: https://reviews.llvm.org/D103416
This is a fairly mechanical change, it just moves each algorithm into its own header. This is a NFC.
Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."
Differential Revision: https://reviews.llvm.org/D103583
As discussed on cfe-dev [1], use the using_if_exists Clang attribute when
the compiler supports it. This makes it easier to port libc++ on top of
new platforms that don't fully support the C Standard library.
Previously, libc++ would fail to build when trying to import a missing
declaration in a <cXXXX> header. With the attribute, the declaration will
simply not be imported into namespace std, and hence it won't be available
for libc++ to use. In many cases, the declarations were *not* actually
required for libc++ to work (they were only surfaced for users to use
them as std::XXXX), so not importing them into namespace std is acceptable.
The same thing could be achieved by conscious usage of `#ifdef` along
with platform detection, however that quickly creates a maintenance
problem as libc++ is ported to new platforms. Furthermore, this problem
is exacerbated when mixed with vendor internal-only platforms, which can
lead to difficulties maintaining a downstream fork of the library.
For the time being, we only use the using_if_exists attribute when it
is supported. At some point in the future, we will start removing #ifdef
paths that are unnecessary when the attribute is supported, and folks
who need those #ifdef paths will be required to use a compiler that
supports the attribute.
[1]: http://lists.llvm.org/pipermail/cfe-dev/2020-June/066038.html
Differential Revision: https://reviews.llvm.org/D90257
If building code like this:
unsigned long val = 1000;
snprintf(buf, sizeof(buf), "%+lu", val);
with clang, clang warns
warning: flag '+' results in undefined behavior with 'u' conversion specifier [-Wformat]
Therefore, don't construct such undefined format strings. (There's
no compiler warnings here, as the compiler can't inspect dynamically
assembled format strings.)
This fixes number formatting in mingw-w64 if built with
`__USE_MINGW_ANSI_STDIO` defined (there, the '+' flag causes a
leading plus to be printed when formatting unsigned numbers too,
while the '+' flag doesn't cause any extra leading plus in other
stdio implementations).
Differential Revision: https://reviews.llvm.org/D103444
Most of our private headers need to be treated as submodules so that
Clang modules can export things correctly. Previous commits that split
monolithic headers into smaller chunks were unaware of this requirement,
and so this is being addressed in one fell swoop. Moving forward, most
new headers will need to have their own submodule (anything that's
conditionally included is exempt from this rule, which means `__support`
headers aren't made into submodules).
This hasn't been marked NFC, since I'm not 100% sure that's the case.
Differential Revision: https://reviews.llvm.org/D103551
D101613 added some macros used by Microsofts SAL. D103425 uses `__pre`
and `__post`. They are also used by SAL and cause issues when used on
Windows. Add them to the blacklist making it easier to figure out what
the issue is.
Differential Revision: https://reviews.llvm.org/D103541
Since D100581, Clang started flagging this variable which is set but
never read. Based on comparing this function with __match_at_start_posix_nosubs
(which is very similar), I am pretty confident that `__j` was simply left
behind as an oversight in Howard's 6afe8b0a23.
Also workaround some unused variable warnings in the <random> tests.
It's pretty lame that we're not asserting the skew and kurtosis of
the binomial and negative binomial distributions, but that should be
tackled separately.
Differential Revision: https://reviews.llvm.org/D103533
This matches the fact that we build the experimental library by default.
Otherwise, by default we'd be building the library but not testing it,
which is inconsistent.
Differential Revision: https://reviews.llvm.org/D102109
This reverts commit 924ea3bb53 *again*, this time because it broke the
LLDB build with modules. We need to figure out what's up with the libc++
modules build once and for all.
Differential Revision: https://reviews.llvm.org/D103369
In 07ef8e6796 and 3ed9f6ebde, `__nbuf` started to diverge from the amount
of space that was actually needed for the buffer. For 32-bit longs for example,
we allocate a buffer that is one larger than needed. Moreover, it is no longer
clear exactly where the extra +1 or +2 comes from - they're just numbers pulled
from thin air. This PR cleans up how `__nbuf` is calculated, and adds comments
to further clarify where each part comes from.
Specifically, it corrects the underestimation of the max size buffer needed
that the above two commits had to compensate for. The root cause looks to be
the use of signed type parameters to numeric_limits<>::digits. Since digits
only counts non-sign bits, the calculation was acting as though (for a signed
64-bit type) the longest value we would print was 2^63 in octal. However,
printing in octal treats values as unsigned, so it is actually 2^64. Thus,
using unsigned types and changing the final +2 to a +1 is probably a better
option.
Reviewed By: #libc, ldionne, Mordante
Differential Revision: https://reviews.llvm.org/D103339
The compiler used on Apple bots doesn't know about -std=c++20 yet, so
we can't use that just yet.
Differential Revision: https://reviews.llvm.org/D103475
The pipes.quote function quotes using single quotes, the same goes
for the newer shlex.quote (which is the preferred form in Python 3).
This isn't suitable for quoting in command lines on Windows (and the
documentation for shlex.quote even says it's only usable for Unix
shells).
In general, the python subprocess.list2cmdline function should do
proper quoting for the platform's current shell. However, it doesn't
quote the ';' char, which we pass within some arguments to run.py.
Therefore use the custom reimplementation from lit.TestRunner which
is amended to quote ';' too.
The fact that arguemnts were quoted with single quotes didn't matter
for command lines that were executed by either bash or the lit internal
shell, but if executing things directly using subprocess.call, as in
_supportsVerify, the quoted path to %{cxx} fails to be resolved by the
Windows shell.
This unlocks 114 tests that previously were skipped on Windows.
Differential Revision: https://reviews.llvm.org/D103310
Avoid including a header that is known not to work with clang in MSVC
mode when compiling as C.
(Alternatively, this could be something like "XFAIL: clang && msvc",
but I think it's more useful to actually check the rest of the test
instead of expecting the whole test to fail.)
Differential Revision: https://reviews.llvm.org/D103400
This was added inconsistently in
19fd9039ca242f408493b5c662f9d908eab8555e; Windows doesn't have the
aligned_alloc function (neither MSVC nor MinGW toolchains) and we don't
define _LIBCPP_HAS_ALIGNED_ALLOC while building libcxx.
Differential Revision: https://reviews.llvm.org/D103399
This define was out of sync with the corresponding define in tests, it
was added inconsistently in 171c77b7da.
Modern MSVC environments do have these typedefs and functions.
Differential Revision: https://reviews.llvm.org/D103398
While the code uses the type name `std::mbstate_t`, the warning message
mentions the original underlying type, which is a C library internal
type name.
On Windows this type is called `_Mbstatet` instead of `__mbstate_t`. Use
expect-warning-re to avoid spelling out the literal name of the type.
Due to issues with the detection of the clang-verify feature, these
tests have been skipped in the Windows CI configuration so far.
Differential Revision: https://reviews.llvm.org/D103309
Make sure we provide the correct It::difference_type member and update
the tests and synopses to be accurate.
Supersedes D102657 and D103101 (thanks to the original authors).
Differential Revision: https://reviews.llvm.org/D103273
Give each of the relevant functional operators a `__result_type`
instead, so that we can keep using those typedefs in <valarray>
even when the public binder typedefs are removed in C++20.
Differential Revision: https://reviews.llvm.org/D103371
Due to issues with the detection of the clang-verify feature, these
tests have been skipped in the Windows CI configuration so far.
Differential Revision: https://reviews.llvm.org/D103308
It looks to me as if *every* helper header needs to be added to the modulemap,
actually; which is unfortunate since we keep proliferating them at such a
rapid pace.
This should have been done in D96385; thanks ldionne for the catch!
Also, make the back/front inserter behavior tests a little more thorough,
which incidentally caught a cut-and-paste-bug in `nasty_list`, so fix that.
Differential Revision: https://reviews.llvm.org/D103318
C++17 deprecated std::iterator and removed it as a base class for all
iterator adaptors. We implement that change, but we still provide a way
to inherit from std::iterator in the few cases where doing otherwise
would be an ABI break.
Supersedes D101729 and the std::iterator base parts of D103101 and D102657.
Differential Revision: https://reviews.llvm.org/D103171
Implements part of P0896 'The One Ranges Proposal'.
Implements [range.iter.op.prev].
Depends on D102563.
Differential Revision: https://reviews.llvm.org/D102564
Implements part of P0896 'The One Ranges Proposal'.
Implements [range.iter.op.next].
Depends on D101922.
Differential Revision: https://reviews.llvm.org/D102563
Ensures that `get_return_object`'s return type is the same as the return type for the function calling `co_return`. Otherwise, we try to construct an object, then free it, then return it.
Differential Revision: https://reviews.llvm.org/D103196
I'm adding the job as a soft-fail for now, but once all the tests have
been fixed to work on it, we'll switch over from GCC 10 to GCC 11 and
remove the soft-fail.
Differential Revision: https://reviews.llvm.org/D103116
This prevents std::format to be available until there's an ABI stable
version. (This only impacts the Apple platform.)
Depends on D102703
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D102705
This is a preparation to split the format header in smaller parts for the
upcoming patches.
Depends on D101723
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D102703
This also provides some of the scaffolding needed by D102992 and D101729, and mops up after D101730 etc.
Differential Revision: https://reviews.llvm.org/D103055
If the nested create_directory call fails, we'd still want to
re-report the errors with the create_directories function name,
which is what the caller called.
This fixes one aspect from MS STL's tests for std::filesystem.
Differential Revision: https://reviews.llvm.org/D102365
This particular test relies on internal details from the libc++
filesystem implementation header, and those details are structured
differently in the implementation for Windows.
Differential Revision: https://reviews.llvm.org/D102357
Use the same visiblity attributes as for all other template
specializations in the same file; declare the specialization itself
using _LIBCPP_TYPE_VIS, and don't use _LIBCPP_EXPORTED_FROM_ABI on
the destructor. Methods that are excluded from the ABI are marked
with _LIBCPP_INLINE_VISIBILITY.
This makes the vtable exported from DLL builds of libc++. Practically,
it doesn't make any difference for the CI configuration, but it
can make a difference in mingw setups.
Differential Revision: https://reviews.llvm.org/D102717
cxx20_iterator_traits.compile.pass.cpp actually depends on
implementation details of libc++, which is not great;
but I just left a comment and moved on.
Not only do we conscientiously avoid using `__wrap_iter` for non-contiguous
iterators (in vector, string, span...) but also we make the assumption
(in regex) that `__wrap_iter<_Iter>` is contiguous for all `_Iter`.
So `__wrap_iter<reverse_iterator<int*>>` should be considered IFNDR,
and every `__wrap_iter` should correctly advertise contiguity in C++20.
Drive-by simplify some type traits.
Reviewed as part of https://reviews.llvm.org/D102781
- Fixes paper number P1862 -> P1868. (The title was correct.)
- Marks P1868 as in progress.
- Marks P1892 as in progress.
- Marks LWG-3327 as nothing to do, since the wording change doesn't
impact the code. (Also updated on the general C++20 status page.)
This commit alphabetizes all includes in libcxx. This is a NFC.
This can also serve as a pseudo "announcement" for how we should order these headers going forward (note: double underscores go before other headers).
Differential Revision: https://reviews.llvm.org/D102941
This is the second to last one! Based on D101396. Depends on D100255. Refs D101079 and D101193.
Differential Revision: https://reviews.llvm.org/D101476
Eventually, this should become the default way of running the tests.
For now, only move a few CI nodes to it, and keep a node that runs the
legacy configuration.
Differential Revision: https://reviews.llvm.org/D97565
* adds `sized_range` and conformance tests
* moves `disable_sized_range` into namespace `std::ranges`
* removes explicit type parameter
Implements part of P0896 'The One Ranges Proposal'.
Differential Revision: https://reviews.llvm.org/D102434
Add this attribute to some types to ensure that they have
debug info.
The debug info for these classes are required for debuggers to display
some STL types. With constructor homing (a new debug info optimization)
their debug info isn't emitted because their constructors are never
called.
The list of types with the attribute added are __hash_value_type,
__value_type, __tree_node_base, __tree_node, __hash_node, __list_node,
and __forward_list_node.
Differential Revision: https://reviews.llvm.org/D98750
Fix __bitop_unsigned_integer and rename to __libcpp_is_unsigned_integer.
There are only five unsigned integer types, so we should just list them out.
Also provide `__libcpp_is_signed_integer`, even though the Standard doesn't
consume that trait anywhere yet.
Notice that `concept uniform_random_bit_generator` is specifically specified
to rely on `concept unsigned_integral` and *not* `__is_unsigned_integer`.
Instantiating `std::ranges::sample` with a type `U` satisfying
`uniform_random_bit_generator` where `unsigned_integral<U::result_type>`
and not `__is_unsigned_integer<U::result_type>` is simply IFNDR.
Orthogonally, fix an undefined behavior in std::countr_zero(__uint128_t).
Orthogonally, improve tests for the <bit> manipulation functions.
It was these new tests that detected the bug in countr_zero.
Differential Revision: https://reviews.llvm.org/D102328
The problem with debug mode tests is that it isn't known which particular
_LIBCPP_ASSERT causes the test to exit, and as shown by
https://reviews.llvm.org/D100029 and 2908eb20ba it might be not the
expected one.
The patch adds TEST_LIBCPP_ASSERT_FAILURE macro that allows checking
_LIBCPP_ASSERT message to ensure we caught an expected failure.
Reviewed By: Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D100595
Arthur O'Dwyer