This will allow simplifying executors by always just copying the whole
%T, and assuming that all file dependencies are contained in it.
Superseeds https://reviews.llvm.org/D78245, which tried to make %T unique
in Lit, but which encountered push back.
The test is failing on 32-bit targets in C++03 mode. Clang produces
the following warning: 'integer literal is too large to be represented
in type 'long' and is subject to undefined behavior under C++98,
interpreting as 'unsigned long'; this literal will have type 'long
long' in C++11 onwards [-Wc++11-compat]' which is promoted to an error
and causes the test to fail.
There have been no changes in the test itself since 2019, so it looks
like the diagnostic has been updated.
Differential Revision: https://reviews.llvm.org/D81559
Unlike parameters in litConfig.params, the config isn't shared across
all test suites. For example, if we want to enable exceptions in the
tests for libcxxabi, but not in the tests for libcxx, we can't set the
enable_exceptions parameter in the litConfig object, cause it will be
used by both. Instead, setting it inside the config object solves that
problem.
This reverts commit 0c148430cf, which added an assertion in day().
The Standard doesn't allow day() to crash -- instead it says that the
result is unspecified.
Differential Revision: https://reviews.llvm.org/D70346
All compilers supported by libc++ have rvalues in C++03 mode so, there is no need for this non-rvalue overload.
Differential Revision: https://reviews.llvm.org/D80881
Before this patch, we tried detecting whether small atomics were available
without linking against libatomic. However, that's not really what we want
to know -- instead, we want to know what's required in order to support
atomics fully, which is to link against libatomic when it's provided.
That is both much simpler, and it doesn't suffer the problem that we would
not link against libatomic when small atomics didn't require it, which
lead to non-lockfree atomics never working.
Furthermore, because we understand that some platforms might not want to
(or be able to) ship non-lockfree atomics, we add that notion to the test
suite, independently of a potential extern library.
After this patch, we therefore:
(1) Link against libatomic when it is provided
(2) Independently detect whether non-lockfree atomics are supported in
the test suite, regardless of whether that means we're linking against
an external library or not (which is an implementation detail).
Differential Revision: https://reviews.llvm.org/D81190
Libc++ provides support for <thread> in C++03 as an extension. Furthermore,
it does not support any compiler that doesn't have rvalue references. It
is hence possible to provide the move constructor and move assignment
operator in C++03.
C++98 and C++03 are effectively aliases as far as Clang is concerned.
As such, allowing both std=c++98 and std=c++03 as Lit parameters is
just slightly confusing, but provides no value. It's similar to allowing
both std=c++17 and std=c++1z, which we don't do.
This was discovered because we had an internal bot that ran the test
suite under both c++98 AND c++03 -- one of which is redundant.
Differential Revision: https://reviews.llvm.org/D80926
This test is arguably fatally flawed, at least as long as C++ condition
variables are just trivial wrappers around POSIX. I've added some notes
to the test for future authors to consider.
The Standard is currently unimplementable. We have to pick between:
1. Not implementing constexpr support properly in std::array<T, 0>
2. Making std::array<T, 0> non-trivial even when T is trivial
3. Returning nullptr from std::array<T, 0>::begin()
Libc++ initially picked (1). In 77b9abfc8e, we started implementing constexpr properly, but lost the guarantee of triviality. Since it seems like both (1) and (2) are really important, it seems like (3) is the only viable option for libc++, after all. This is also what other implementations are doing.
This patch moves libc++ from (1) to (3).
It also:
- Improves the test coverage for the various ways of initializing std::array
- Adds tests for the triviality of std::array
- Adds tests for the aggregate-ness of std::array
Reviewed By: #libc, miscco, EricWF, zoecarver
Differential Revision: https://reviews.llvm.org/D80821
When the __config_site header is generated, but LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
wasn't specified, _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT would be defined
to 0, which was the NonUnique RTTI comparison implementation. The intent
was to use the Unique RTTI comparison implementation in that case, which
caused https://llvm.org/PR45549.
Instead, use a proper "switch" to select the RTTI comparison implementation.
Note that 0 can't be used as a value, because that is treated the same
by CMake as a variable that is just not defined.
Differential Revision: https://reviews.llvm.org/D80037
This commit adds missing support for constexpr in std::array under all
standard modes up to and including C++20. It also transforms the <array>
tests to check for constexpr-friendliness under the right standard modes.
Fixes https://llvm.org/PR40124
Fixes rdar://57522096
Supersedes https://reviews.llvm.org/D60666
Differential Revision: https://reviews.llvm.org/D80452
Summary: Update status page and test synopsis. Add synopsis in <cmath>.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D80456
Summary: a4b8ee6 made all MoveOnly members constexpr but, some members and constructors contain expressions that are only valid in C++14 and later. This patch prefixes those methods and constructors with TEST_CONSTEXPR_CXX14.
Reviewers: ldionne, #libc!
Subscribers: dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D80482
Don't use std::filesystem APIs for CWDGuard, use POSIX functions
instead. This way the tests don't rely on the correctness of
the functionality they're testing.
Differential Revision: https://reviews.llvm.org/D78200
Summary:
As described in the bug report:
The commit a8b9f59e8caf378d56e8bfcecdb22184cdabf42d "Implement feature test macros using a script" added test features macros for libc++. Among others, it added `__cpp_lib_hardware_interference_size`. However, there is nothing like std::hardware_constructive_interference_size nor std::hardware_destructive_interference_size, that should be in header <new>.
* https://bugs.llvm.org/show_bug.cgi?id=41423
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D80431
The tests had copy-paste errors which started showing when an
unused-variable warning started being emitted after we made
the MoveOnly type constexpr (in a4b8ee6422).
Summary:
This LWG issue states that the result of `year_month_day_last::day()` is implementation defined if `ok()` is `false`.
However, from user perspective, calling `day()` in this situation will lead to a (possibly difficult to find) crash.
Hence, I have added an assertion to warn user at least when assertions are enabled.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D70346
Tests for `std::system_error` constructor marked as slightly non-portable.
One (but not the only one) reason for such non-portability is that these
tests assume the default locale to be set to "C" (or "POSIX").
However, the default locale for the process depends on OS and
environment. This patch adds explicit setting of the correct
locale expected by the tests.
Thanks to Andrey Maksimov for the patch.
Differential Revision: https://reviews.llvm.org/D72456
These two tests were clumsily using time measurements to determine
whether std::lock_guard was working correctly. In practice, this
approach merely verified that the underlying lock properly waits.
Now these two tests verify that lock is acquired, not dropped
prematurely, and finally, actually dropped at the end of the scope.
Like other uses of ALLOW_RETRIES, this test tried to verify that an API
returned "quickly" but quick is not safe to define given slow and/or
busy machines.
Instead, we now verify that these "wait" APIs actually wait, which the
old test did not.
* improve coverage in `span`'s "conversion from `std::array`" test, while eliminating MSVC diagnostics about `testConstructorArray<T>() && testConstructorArray<const T, T>()` being redundant when `T` is already `const`.
* Remove use of `is_assignable` that triggers UB due to an insufficiently-complete type argument in `std::function`'s assignment operator test.
* Don't test that `shared_ptr` initialization from an rvalue triggers the lvalue aliasing constructor on non-libc++; this is not the case for Standard Libraries that implement LWG-2996. (Ditto, I'd simply remove this but it's your library ;).)
Differential Revision: https://reviews.llvm.org/D80030
This implements the relaxed requirements on the std::array constructors of span,
where the type only needs to be convertible to the element type of the span.
Note that the previous tests were not sufficient, as the const array<T, n> constructor
was only tested for compile time and the array<T, N> only during runtime.
Restructure the tests so that we can test conversions as well as both constructors.
Differential Revision: https://reviews.llvm.org/D75706
The default constructor of a static span requires _Extent == 0 so
SFINAE it out rather than using a static_assert
Differential Revision: https://reviews.llvm.org/D71994
These two tests do not use the "thread sleeps X milliseconds" pattern
that other libcxx tests use, so all we can do in order to remove
ALLOW_RETRIES workaround is remove the assumption that measuring the
"quick" return of `wait()` is possible (it is not). Let the test harness
verify overall that `wait()` does not hang.
As a bonus, have the spin-waiting threads `yield()`, which is what well
behaved code should do.
This test tried to verify that "wait()" returned quickly but "quick" is
impossible to define given a busy and/or slow system.
Instead, I've refactored the test to verify that `wait()` actually
waits which the old test did not verify.
Implements P0414R2:
* Adds support for array types in std::shared_ptr.
* Adds reinterpret_pointer_cast for shared_ptr.
Re-committing now that the leaking tests are fixed.
Differential Revision: https://reviews.llvm.org/D62259
Operating systems are best effort by default, so we cannot assume that
sleep-like APIs return as soon as we'd like.
Even if a sleep-like API returns when we want it to, the potential for
preemption means that attempts to measure time are subject to delays.
Implements P0414R2:
* Adds support for array types in std::shared_ptr.
* Adds reinterpret_pointer_cast for shared_ptr.
Differential Revision: https://reviews.llvm.org/D62259
Operating systems are best effort by default, so we cannot assume that
sleep-like APIs return as soon as we'd like.
Even if a sleep-like API returns when we want it to, the potential for
preemption means that attempts to measure time are subject to delays.
The challenge with measuring time in tests is that slow and/or busy
machines can cause tests to fail in unexpected ways. After this change,
three tests should be much more robust. The only remaining and tiny race
that I can think of is preemption after `--countDown`. That being said,
the race isn't fixable because the standard library doesn't provide a
way to count threads that are waiting to acquire a lock.
Reviewers: ldionne, EricWF, howard.hinnant, mclow.lists, #libc
Reviewed By: ldionne, #libc
Subscribers: dexonsmith, jfb, broadwaylamb, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D79406
This change adds test coverage for the `codecvt<char16_t, char8_t, mbstate_t>` and `codecvt<char32_t, char8_t, mbstate_t>` ctype facets added to the C++20 WD by [P0482R6](https://wg21.link/P0428R6). Note that libc++ does not implement these facets despite implementing the remainder of P0482, presumably for ABI reasons, so these tests are marked `UNSUPPORTED: libc++`.
The ostream operator<< is currently broken for std::complex with
specified field widths.
This patch a partial revert of c3478eff7a (reviewed as D71214),
restoring the correct behavior.
Differential Revision: https://reviews.llvm.org/D78816
These tests fail due to a couple of changes to `move_iterator` for C++20:
* `move_iterator<I>::operator++(int)` returns `void` in C++20 if `I` doesn't model `forward_iterator`.
* `move_iterator<I>::reference` is calculated in C++20, so `I` must actually have an `operator*() const`.
Differential Revision: https://reviews.llvm.org/D79343
This patch adds deduction guides to <memory> to allow deducing
construction of shared_ptrs from unique_ptrs, and from weak_ptrs
and vice versa, as specified by C++17.
Differential Revision: https://reviews.llvm.org/D69603
This patch adds `_VSTD::` to some calls to `make_pair` inside the
implementations of searchers, to prevent things exploding if there is
a make_pair in an associated namespace of a user-defined type.
https://godbolt.org/z/xAFG98
Differential Revision: https://reviews.llvm.org/D72640
When running on remote hosts, we need the whole `echo 123 | %t.exe` command
to run on the remote host. Thus, we need to escape the pipe to make sure
the command is treated as `{ echo 123 | %t.exe } > %t.out` instead of
`{ echo 123 } | %t.exe > %t.out`m where only `echo 123` is run on the
remote host.
Since c0cd106fcc, we add __config_site macro defines to the compiler
command line whether we are building with modules or not. This means
that the modules tests are expected to fail on single-threaded systems
whether we build with modules or not.
Summary:
Instead of storing `static_test_env` (with all the symlinks) in the repo, we create it on the fly to be cross-toolchain-friendly. The primary use case for this are Windows-hosted cross-toolchains. Windows doesn't really have a concept of symlinks. So, when the monorepo is cloned, those symlinks turn to ordinary text files. Previously, if we cross-compiled libc++ for some symlink-friendly system (e. g. Linux) and ran tests on the target system, some tests would fail. This patch makes them pass.
Reviewers: ldionne, #libc
Reviewed By: ldionne, #libc
Subscribers: EricWF, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D78200
Instead of storing static_test_env (with all the symlinks) in the repo,
we create it on the fly to be cross-toolchain-friendly. The primary
use case for this are Windows-hosted cross-toolchains. Windows doesn't
really have a concept of symlinks. So, when the monorepo is cloned,
those symlinks turn to ordinary text files. Previously, if we
cross-compiled libc++ for some symlink-friendly system (e. g. Linux) and
ran tests on the target system, some tests would fail. This patch makes
them pass.
Differential Revision: https://reviews.llvm.org/D78200
The tests were disabled under ASAN/MSAN because old Clangs were very
slow to build the test cases. However, I checked with the Clang used
on our build bots and the tests are not slow to build anymore, so the
tests can be re-enabled.
Summary:
pr42199
When using regex_constants::match_prev_avail, it is defined that
--first is valid, and match_not_bol and match_not_bow should be
ignored. At the moment these flags are not ignored. This fixis that.
Reviewers: ldionne, miyuki, EricWF, mclow.lists, #libc
Reviewed By: ldionne, miyuki, #libc
Subscribers: broadwaylamb, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D75622
The libcxx.util utilities don't work properly, and we should remove them
when we get rid of compiler.py. In particular, libcxx.util.to_string
appears to be completely broken.
On Windows, quoting with single-quotes is both unnecessary and incorrect.
If the arguments are properly handled by Lit (which they are), quoting
should not be necessary.
Tests that require support for Clang-verify are already marked as such
explicitly by their extension, which is .verify.cpp. Requiring the use
of an explicit Lit feature is, after thought, not really helpful.
This is a change in design: we have been bitten in the past by tests not
being enabled when we thought they were. However, the issue was mostly
with file extensions being ignored. The fix for that is not to blindly
require explicit features all the time, but instead to report all files
that are in the suite but that don't match any known test format. This
can be implemented in a follow-up patch.
This reverts commit 51a60ed14c, since the test still doesn't pass on
Windows. Marking the test as UNSUPORTED on Windows again until I've
figured out the problem.
Instead of completely disabling the tests on Apple, which makes them
disabled on all platforms we test (and hence useless), this commit
disables only the assertions that actually fail. I also created a
bug report to track re-enabling them (https://llvm.org/PR45739).
These two locale tests are disabled because they were said to "pass in
an uncontrolled manner on Apple platforms". This commit re-enables them
to see what that means, and whether that is still relevant on the
platforms we test.
Before this commit, the tests were either XFAILed or UNSUPPORTED on
Apple and Linux, which is pretty much all the systems we support. If
the tests truly don't work anywhere, they should be removed instead.
This allows defining Lit features that can be enabled or disabled based
on compiler support, and parameters that are passed on the command line.
The main benefits are:
- Feature detection is entirely based on the substitutions provided in
the TestingConfig object, which is simpler and decouples it from the
complicated compiler emulation infrastructure.
- The syntax is declarative, which makes it easy to see what features
and parameters are accepted by the test suite. This is significantly
less entangled than the current config.py logic.
- Since feature detection is based on substitutions, it works really
well on top of the new format, and custom Lit configurations can be
created easily without being based on `config.py`.
This commit is a reapplication of 6d58030c8c, which was reverted in
8f24c4b72f because it broke Python 3 support. This re-application
supports Python 3.
Differential Revision: https://reviews.llvm.org/D78381
Defining the nested types `reference` and `iterator_concept` of `reverse_iterator<I>` necessarily requires `I` to be complete in C++20. These tests that verify that `std::map<int, X>::reverse_iterator` can be instantiated when `X` is incomplete are going to have a bad time.
Differential Revision: https://reviews.llvm.org/D78944
This allows defining Lit features that can be enabled or disabled based
on compiler support, and parameters that are passed on the command line.
The main benefits are:
- Feature detection is entirely based on the substitutions provided in
the TestingConfig object, which is simpler and decouples it from the
complicated compiler emulation infrastructure.
- The syntax is declarative, which makes it easy to see what features
and parameters are accepted by the test suite. This is significantly
less entangled than the current config.py logic.
- Since feature detection is based on substitutions, it works really
well on top of the new format, and custom Lit configurations can be
created easily without being based on `config.py`.
Differential Revision: https://reviews.llvm.org/D78381
The runtime for Blocks may not be available even though the Blocks
language extension _is_ available. Instead of potentially failing,
this commit is much more conservative and assumes the runtime for
Blocks is only provided on Apple platforms.
Differential Revision: https://reviews.llvm.org/D78757
Instead of having different names for the same Lit feature accross code
bases, use the same name everywhere. This NFC commit is in preparation
for a refactor where all three projects will be using the same Lit
feature detection logic, and hence it won't be convenient to use
different names for the feature.
Differential Revision: https://reviews.llvm.org/D78370
When the new libc++ test format was enabled, warnings were accidentally
dropped cause they were not part of the %{compile_flags} substitution.
This commit adds them back, however `-Werror` is only used for non-verify
tests (cause it doesn't make sense for verify tests).
This commit is a re-application of 20fd624380, which was reverted in
5ec6fdb058 because it broke the C++03 bot. This failure should have
been fixed in b4fb705e77.
When the new libc++ test format was enabled, warnings were accidentally
dropped cause they were not part of the %{compile_flags} substitution.
This commit adds them back, however `-Werror` is only used for non-verify
tests (cause it doesn't make sense for verify tests).
This was originally committed as f8452ddfcc and reverted in 7cb1aa9d93.
The issue was that shell builtins were being escaped too, and apparently
Bash won't execute a builtin when it is quoted e.g. '!'. Instead, it
thinks it's a command and it can't find it.
Re-committing the change with that issue fixed.
These substitutions are strongly tied to the operation of the test
format, so it makes sense to have them defined by the test format
instead of the Lit configuration. They should be defined regardless
of which configuration is in use.
Marked unsupported for C++03 and C++11 since this test uses alias
declarations, and at least one C++03 bot was failing with
-Wc++11-extensions.
Change-Id: I8c3a579edd7eb83e0bc74e85d116b68f22400161
When running the tests through `lit` directly instead of through `check-cxx`,
it is required to manually build the `cxx` (and often `cxx_experimental`)
targets. Instead of having to do that manually, this commit adds a new
target `check-cxx-deps` that does that for you.
When building these tests without modules in the whole test suite,
the __config_site macro definitions are not included anymore in the
%{compile_flags}. This causes the _LIBCPP_HAS_NO_THREADS define not
to be picked up, and the test to XPASS on single-threaded systems.
This is a stop-gap measure to fix the build bots, however the proper
solution would be to always pass the __config_site defines as compiler
macros, whether we build with modules or not.
Avoid using <sys/types.h> in those tests so that we can run them on
non-AIX systems (otherwise this test is basically dead-code on all
the build bots I'm aware of). Also, split up the test to allow using
.compile.pass.cpp tests instead of .sh.cpp tests, since that is the
last test referencing the %{compile} substitution explicitly.
Instead of being ShTests that use clang-verify (and without the proper
REQUIRES annotation), create .verify.cpp tests instead with the right
REQUIRES annotation.
By renaming .fail.cpp tests that don't need clang-verify to .compile.fail.cpp,
the new test format will not try to compile these tests with clang-verify,
and the old test format will work just the same. However, this allows
removing a workaround that requires parsing each test looking for
clang-verify markup.
After this change, a .fail.cpp test should always have clang-verify markup.
When clang-verify is not supported by the compiler, we will just check that
these tests fail to compile. When clang-verify is supported, these tests
will be compiled with clang-verify whether they have markup or not (so
they should have markup, or they will fail).
This simplifies the test suite and also ensures that all of our .fail.cpp
tests provide clang-verify markup. If it's impossible for a test to have
clang-verify markup, it can be moved to a .compile.fail.cpp test, which
are unconditionally just checked for compilation failure.
With this patch, .verify.cpp tests explicitly require clang-verify, but
no other test types require clang-verify out of the box. This will allow
making several .fail.cpp tests that don't have any clang-verify markup
to be just .compile.fail.cpp tests, which in turn should allow removing
a long standing workaround that requires parsing tests to detect whether
they have any clang-verify markup in them.
There are no such tests in the libc++ test suite, and I want to move
away from `.fail.cpp` tests (in favour of something else) too, which
require a workaround.
Instead of spamming a bunch of available features that are not actually
used anywhere, only set those that are actually used in the test suite.
In the future, this should probably be based on the target triple only,
with the ability to have wildcards in the triple.
The libc++ test suite currently defines several features that are not
used anywhere in the tests, or that are redundant with other features.
For the purpose of simplifying config.py and to ease the bring up of a
new configuration, this commit removes some of these features:
- rename dylib-has-no-filesystem to c++filesystem-disabled, which exists
- rename apple-darwin to just darwin, which is already set
- remove useless setting of libstdc++, which is already set correctly
- remove libcpp-abi-unstable, which is not used anywhere
- remove the glibc-XXX features, which are not used anywhere
The libc++ test suite has a lot of old Lit features used to XFAIL tests
and mark them as UNSUPPORTED. Many of them are to workaround problems on
old compilers or old platforms. As time goes by, it is good to go and
clean those up to simplify the configuration of the test suite, and also
to reflect the testing reality. It's not useful to have markup that gives
the impression that e.g. clang-3.3 is supported, when we don't really
test on it anymore (and hence several new tests probably don't have the
necessary markup on them).
Patch from Christopher Di Bella (cjdb@google.com)
Reviewed as https://reviews.llvm.org/D74291
Adds `std::same_as` to libc++. Since there aren't clang-format rules for
//requires-expressions//, I'll need to disable the formatter in certain areas.
std::optional requires C++17. Instead of only running the test above
C++14, this commit removes uses of std::optional from the test (it's
already tested in block.objc.pass.mm).
Broke builders that emit different diagnostics. e.g.:
error: 'warning' diagnostics seen but not expected:
Line 13: alias declarations are a C++11 extension
Line 20: alias declarations are a C++11 extension
This reverts commit ff87813715.
It has never been used, and it actually doesn't really work because it
assumes that the target supports Python. Instead, it's better to just
use `!` since we're running ShTests in system shells anyway.
This allows both the old and the new testing formats to handle these
tests with modules enabled.
We also include the modules flags in the %{flags} substitution, which
means that .sh.cpp tests in the old format and all tests in the new
format will use modules flags when enabled.
Otherwise, files don't link when using a GNU linker, which is more
sensitive on the order of the source file relative to the various
linked libraries. See http://c-faq.com/lib/libsearch.html for an
explanation of the problem.
Both test formats are equivalent, so this *should* not be a problem.
We've fixed a couple of failures uncovered by the first time we tried
making the switch, so this new attempt should go even farther.
If failures are noticed, it should be fine to revert this commit, but
please give a heads up afterwards so we know to address the issues!
Also note that it is still possible to use the old format by passing
`--param=use_old_format=True` when running Lit for the time being.
The LitConfig is shared across the whole test suite. However, since
enabling recursive expansion can be a breaking change for some test
suites, it's important to confine the setting to test suites that
enable it explicitly.
Note that other issues were raised with the way recursiveExpansionLimit
operates. However, this commit simply moves the setting to the right
place -- the mechanism by which it works can be improved independently.
Differential Revision: https://reviews.llvm.org/D77415
We had a workaround because GCC 5 does not evaluate static assertions
that are dependent on template parameters. This commit removes the
workaround and marks the corresponding tests as unsupported with GCC 5.
This has the benefit of bringing the new and the old test formats closer
without having to carry a workaround for an old compiler in the new
test format.
Otherwise, we're missing some flags like the flags that are used by
sanitizer builds and the 32-bit builds. In the long term, I think it
would be better to have only %{compile_flags} and %{link_flags}, but
for the benefit of adopting the new format by default, I think it's OK
to add %{flags} to it.
This reverts commit 1580c76c4a.
This causes libcxx/selftest/newformat/sh.cpp/substitutions.sh.cpp to
fail with a linker error on Fedora 31 (x86-64) release (no assert)
builds.
Both test formats are equivalent, so this *should* not be a problem.
However, I'm taking advantage of the week-end to test this and see if
there are any failures. If so, it should be fine to revert this until
the failures have been addressed.
For the time being, it is still possible to use the old format by passing
`--param=use_old_format=True` when running Lit.
Always depend on the compiler to have a correct implementation of
max_align_t in stddef.h and don't provide a fallback. For pre-C++11,
require __STDCPP_NEW_ALIGNMENT__ in <new> as provided by clang in all
standard modes. Adjust test cases to avoid testing or using max_align_t
in pre-C++11 mode and also to better deal with alignof(max_align_t)>16.
Document requirements of the alignment tests around natural alignment of
power-of-two-sized types.
Differential revision: https://reviews.llvm.org/D73245
Louis Dionne