75 Commits

Author SHA1 Message Date
Kim Gräsman
3920c1c5b1 [docs] Fix reST formatting in UsingLibcxx IWYU section
The link syntax was missing a trailing underscore, and there was an
extraneous backtick on the reference to IWYU's libcxx.imp.

Reviewed By: #libc, philnik

Spies: Mordante, libcxx-commits

Differential Revision: https://reviews.llvm.org/D157784
2023-08-15 12:16:15 -07:00
Mark de Wever
44d17cd739 [libc++][doc] Updates the release notes.
This is a preparation for the upcoming LLVM 17 release.

Reviewed By: ldionne, jloser, H-G-Hristov, #libc

Differential Revision: https://reviews.llvm.org/D154874
2023-07-17 18:41:10 +02:00
varconst
f0dfe682bc [libc++][hardening] Deprecate _LIBCPP_ENABLE_ASSERTIONS.
`_LIBCPP_ENABLE_ASSERTIONS` was used to enable the "safe" mode in
libc++. Libc++ now provides the hardened mode and the debug mode that
replace the safe mode.

For backward compatibility, enabling `_LIBCPP_ENABLE_ASSERTIONS` now
enables the hardened mode. Note that the hardened mode provides
a narrower set of checks than the previous "safe" mode (only
security-critical checks that are performant enough to be used in
production).

Differential Revision: https://reviews.llvm.org/D154997
2023-07-14 16:58:47 -07:00
Mark de Wever
a9e5773f52 [libc++][format] Implements formatting pointer.
The feature is applied as DR instead of a normal paper. MSVC STL and
libstdc++ will do the same.

Implements
- P2510R3 Formatting pointers

Depends on D153192

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D153195
2023-07-05 18:23:31 +02:00
Mark de Wever
7da669d9e5 [libc++][doc] Fixes header formatting.
This was broken in D145628; it caused the new header not to be displayed
as a header at all and show part of the markup as text.
2023-06-27 18:42:51 +02:00
Nikolas Klauser
7d3bba5e2f [libc++] Add [[nodiscard]] extensions to the functions in <bit>
Reviewed By: #libc, ldionne, Mordante

Spies: Mordante, ldionne, libcxx-commits

Differential Revision: https://reviews.llvm.org/D152653
2023-06-13 08:01:34 -07:00
Mark de Wever
9c053e6993 [libc++][format] Make public functions nodiscard.
This is an extension and only adds the functions that are a considered a
but when called and ignoring the result.

Drive-by sort all nodiscard extensions in the documentation.

Reviewed By: #libc, philnik

Differential Revision: https://reviews.llvm.org/D152097
2023-06-12 18:55:56 +02:00
Martin Storsjö
fcbbd9649a [libcxx] Fix using std::wcout/wcin on Windows with streams configured in wide mode
On Windows, the underlying file descriptors for stdout/stdin/stderr
can be reconfigured to wide mode. In the default (narrow) mode, the
charset usually isn't utf8 (as libcxx assumes), but normally a locale
specific codepage (where each codepage only can represent a small
subset of unicode characters).

By configuring the stdout file descriptor to wide mode, the user can
output wchar_t based strings without convesion to the narrow charset.
Within libcxx, don't try to use codecvt to convert this to a narrow
character encoding, but output these strings as such with fputwc.

In wide mode, such strings could be output directly with fwrite too,
but if the file descriptor hasn't been configured in wide mode, that
breaks the output (which currently works reasonably). By always
outputting one character at a time with fputwc, it works regardless
of mode of the stdout file descriptor.

For the narrow output stream, std::cout, outputting (via fwrite)
does fail when the file descriptor is set to wide mode. This matches
how it behaves with both MS STL and GNU libstdc++ too, so this is
probably acceptable.

This fixes https://github.com/llvm/llvm-project/issues/46646, and
the downstream bugs https://github.com/mstorsjo/llvm-mingw/issues/145
and https://github.com/mstorsjo/llvm-mingw/issues/222.

Differential Revision: https://reviews.llvm.org/D146398
2023-06-03 23:11:39 +03:00
Kazu Hirata
da6a1f61d9 [libc] Fix typos in documentation 2023-05-22 23:25:16 -07:00
Advenam Tacet
2fa1bec7a2 [ASan][libcxx] A way to turn off annotations for containers with a specific allocator
This revision is part of our efforts to support container annotations with (almost) every allocator.
That patch is necessary to enable support for most annotations (D136765). Without a way to turn off annotations, it's hard to use ASan with area allocators (no calls to destructors).

This is an answer to a request about it. This patch provides a solution to the aforementioned issue by introducing a new template structure `__asan_annotate_container_with_allocator`, which allows the disabling of container annotations for a specific allocator.

This patch also introduces `_LIBCPP_HAS_ASAN_CONTAINER_ANNOTATIONS_FOR_ALL_ALLOCATORS` FTM.

To turn off annotations, it is sufficient to create a template specialization with a false value using a [Unary Type Trait](https://en.cppreference.com/w/cpp/types/integral_constant).

The proposed structure is being used in the code enabling annotations for all allocators in `std::vector`, `std::basic_string`, and `std::deque`. (D136765 D146214 D146815)

Possibility to do it was added to ASan API in rGdd1b7b797a116eed588fd752fbe61d34deeb24e4 commit.

For context on not calling a destructor, look at https://eel.is/c++draft/basic.life#5 and notes there, you may also read a discussion in D136765.

Reviewed By: ldionne, philnik, #libc, hans

Spies: EricWF, mikhail.ramalho, #sanitizers, libcxx-commits, hans, vitalybuka

Differential Revision: https://reviews.llvm.org/D145628
2023-05-04 14:17:25 -07:00
Mark de Wever
68c3d66a97 [libc++][format] Improves width estimate.
As obvious from the paper's title this is an LWG issue and thus retroactively
applied to C++20. This change may the output for certain code points:
1 Considers 8477 extra codepoints as having a width 2 (as of Unicode 15)
  (mostly Tangut Ideographs)
2 Change the width of 85 unassigned code points from 2 to 1
3 Change the width of 8 codepoints (in the range U+3248 CIRCLED NUMBER
  TEN ON BLACK SQUARE ... U+324F CIRCLED NUMBER EIGHTY ON BLACK
  SQUARE) from 2 to 1, because it seems questionable to make an exception
  for those without input from Unicode

Note that libc++ already uses Unicode 15, while the Standard requires Unicode 12.
(The last time I checked MSVC STL used Unicode 14.)

So in practice the only notable change is item 3.

Implements
  P2675 LWG3780: The Paper
  format's width estimation is too approximate and not forward compatible

Benchmark before these changes
--------------------------------------------------------------------
Benchmark                          Time             CPU   Iterations
--------------------------------------------------------------------
BM_ascii_text<char>             3928 ns         3928 ns       178131
BM_unicode_text<char>          75231 ns        75230 ns         9158
BM_cyrillic_text<char>         59837 ns        59834 ns        11529
BM_japanese_text<char>         39842 ns        39832 ns        17501
BM_emoji_text<char>             3931 ns         3930 ns       177750
BM_ascii_text<wchar_t>          4024 ns         4024 ns       174190
BM_unicode_text<wchar_t>       63756 ns        63751 ns        11136
BM_cyrillic_text<wchar_t>      44639 ns        44638 ns        15597
BM_japanese_text<wchar_t>      34425 ns        34424 ns        20283
BM_emoji_text<wchar_t>          3937 ns         3937 ns       177684

Benchmark after these changes
--------------------------------------------------------------------
Benchmark                          Time             CPU   Iterations
--------------------------------------------------------------------
BM_ascii_text<char>             3914 ns         3913 ns       178814
BM_unicode_text<char>          70380 ns        70378 ns         9694
BM_cyrillic_text<char>         51889 ns        51877 ns        13488
BM_japanese_text<char>         41707 ns        41705 ns        16723
BM_emoji_text<char>             3908 ns         3907 ns       177912
BM_ascii_text<wchar_t>          3949 ns         3948 ns       177525
BM_unicode_text<wchar_t>       64591 ns        64587 ns        10649
BM_cyrillic_text<wchar_t>      44089 ns        44078 ns        15721
BM_japanese_text<wchar_t>      39369 ns        39367 ns        17779
BM_emoji_text<wchar_t>          3936 ns         3934 ns       177821

Benchmarks without "if(__code_point < (__entries[0] >> 14))"
--------------------------------------------------------------------
Benchmark                          Time             CPU   Iterations
--------------------------------------------------------------------
BM_ascii_text<char>             3922 ns         3922 ns       178587
BM_unicode_text<char>          94474 ns        94474 ns         7351
BM_cyrillic_text<char>         69202 ns        69200 ns        10157
BM_japanese_text<char>         42735 ns        42692 ns        16382
BM_emoji_text<char>             3920 ns         3919 ns       178704
BM_ascii_text<wchar_t>          3951 ns         3950 ns       177224
BM_unicode_text<wchar_t>       81003 ns        80988 ns         8668
BM_cyrillic_text<wchar_t>      57020 ns        57018 ns        12048
BM_japanese_text<wchar_t>      39695 ns        39687 ns        17582
BM_emoji_text<wchar_t>          3977 ns         3976 ns       176479

This optimization does carry its weight for the Unicode and Cyrillic
test. For the Japanese tests the gains are minor and for emoji it seems
to have no effect.

Reviewed By: ldionne, tahonermann, #libc

Differential Revision: https://reviews.llvm.org/D144499
2023-04-20 21:18:33 +02:00
Louis Dionne
17c05a44d9 [libc++] Introduce a compile-time mechanism to override __libcpp_verbose_abort
This changes the mechanism for verbose termination (again!) to make it
support compile-time customization in addition to link-time customization,
which is important for users who need fine-grained control over what code
gets generated around sites that call the verbose termination handler.

This concern had been raised to me both privately by prospecting users
and in https://llvm.org/D140944, so I think it is clearly worth fixing.

We still support _LIBCPP_AVAILABILITY_CUSTOM_VERBOSE_ABORT_PROVIDED for
a limited time since the same functionality can be achieved by overriding
the _LIBCPP_VERBOSE_ABORT macro.

Differential Revision: https://reviews.llvm.org/D141326
2023-01-24 21:39:14 -05:00
Nikolas Klauser
633927db84 [libc++] Add [[nodiscard]] extensions in <math.h>
There are quite a few functions marked `[[gnu::const]]` inside the compiler. This patch adds `[[nodiscard]]` to libc++-provided overloads of these functions to match the diagnostics produced.

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D140855
2023-01-12 18:34:49 +01:00
Christopher Di Bella
ab46648082 [libcxx] adds an include-what-you-use (IWYU) mapping file
This makes it possible for programmers to run IWYU and get more accurate
standard library inclusions. Prior to this commit, the following program
would be transformed thusly:

```cpp
// Before
 #include <algorithm>
 #include <vector>

void f() {
  auto v = std::vector{0, 1};
  std::find(std::ranges::begin(v), std::ranges::end(v), 0);
}
```

```cpp
// After
 #include <__algorithm/find.h>
 #include <__ranges/access.h>
 #include <vector>
...
```

There are two ways to fix this issue: to use [comment pragmas](https://github.com/include-what-you-use/include-what-you-use/blob/master/docs/IWYUPragmas.md)
on every private include, or to write a canonical [mapping file](https://github.com/include-what-you-use/include-what-you-use/blob/master/docs/IWYUMappings.md)
that provides the tool with a manual on how libc++ is laid out. Due to
the complexity of libc++, this commit opts for the latter, to maximise
correctness and minimise developer burden.

To mimimise developer updates to the file, it makes use of wildcards
that match everything within listed subdirectories. A script has also
been added to ensure that the mapping is always fresh in CI, and makes
the process a single step.

Finally, documentation has been added to inform users that IWYU is
supported, and what they need to do in order to leverage the mapping
file.

Closes #56937.

Differential Revision: https://reviews.llvm.org/D138189
2022-11-22 01:09:49 +00:00
Nikolas Klauser
660b243120 [libc++] Add [[nodiscard]] extensions to ranges algorithms
This mirrors what we have done in the classic algorithms

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D137186
2022-11-05 16:38:46 +01:00
Nikolas Klauser
3c355e2881 [libc++] Enable [[nodiscard]] extensions by default
Adding `[[nodiscard]]` to functions is a conforming extension and done extensively in the MSVC STL.

Reviewed By: ldionne, EricWF, #libc

Spies: #libc_vendors, cjdb, mgrang, jloser, libcxx-commits

Differential Revision: https://reviews.llvm.org/D128267
2022-09-02 21:34:20 +02:00
Nikolas Klauser
b978dfbf74 [libc++] Consolidate the different [[nodiscard]] configuration options into a single one
Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D129054
2022-08-25 22:01:34 +02:00
Louis Dionne
497705ff27 [libc++] Reorganize the documentation of extensions for integral types 2022-08-10 17:35:08 -04:00
Louis Dionne
e36f9e13bc [libc++] Allow enabling assertions when back-deploying
When back-deploying to older platforms, we can still provide assertions,
but we might not be able to provide a great implementation for the verbose
handler. Instead, we can just call ::abort().

Differential Revision: https://reviews.llvm.org/D131199
2022-08-08 08:43:34 -04:00
Mark de Wever
f712775daf [libc++][format] Exposes basic-format-string
This paper was accepted during the last plenary and is intended to be
backported to LLVM 15. When backporting the release notes in the branch
should be updated too.

Note the feature-test macro isn't updated since this will change; three
papers have updated the same macro in the same plenary.

Implements:
- P2508R1 Exposing std::basic-format-string

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D130643
2022-08-02 20:33:17 +02:00
Louis Dionne
507125af3d [libc++] Rename __libcpp_assertion_handler to __libcpp_verbose_abort
With the goal of reusing that handler to do other things besides
handling assertions (such as terminating when an exception is thrown
under -fno-exceptions), the name `__libcpp_assertion_handler` doesn't
really make sense anymore.

Furthermore, I didn't want to use the name `__libcpp_abort_handler`,
since that would give the impression that the handler is called
whenever `std::abort()` is called, which is not the case at all.

Differential Revision: https://reviews.llvm.org/D130562
2022-07-29 13:52:42 -04:00
Mark de Wever
77ccf63ef0 [libc++][doc] Extended integral type support
This addresses a request during the review of D128929.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D129310
2022-07-27 18:22:08 +02:00
Louis Dionne
7de5aca84c [libc++] Generalize the customizeable assertion handler
Instead of taking a fixed set of arguments, use variadics so that
we can pass arbitrary arguments to the handler. This is the first
step towards using the handler to handle other non-assertion-related
failures, like std::unreachable and an exception being thrown in
-fno-exceptions mode, which would improve user experience by including
additional information in crashes (right now, we call abort() without
additional information).

Differential Revision: https://reviews.llvm.org/D130507
2022-07-26 07:42:38 -04:00
Louis Dionne
deb3b5552f [libc++] Take advantage of -fexperimental-library in libc++
When -fexperimental-library is passed, libc++ will now pick up the
appropriate __has_feature flag defined by Clang to enable the
experimental library features.

As a fly-by, also update the documentation for the various TSes.

Differential Revision: https://reviews.llvm.org/D130176
2022-07-22 08:33:39 -04:00
Louis Dionne
07e984bc52 [libc++] Support int8_t and uint8_t in integer distributions as an extension
In D125283, we ensured that integer distributions would not compile when
used with arbitrary unsupported types. This effectively enforced what
the Standard mentions here: http://eel.is/c++draft/rand#req.genl-1.5.

However, this also had the effect of breaking some users that were
using integer distributions with unsupported types like int8_t. Since we
already support using __int128_t in those distributions, it is reasonable
to also support smaller types like int8_t and its unsigned variant. This
commit implements that, adds tests and documents the extension. Note that
we voluntarily don't add support for instantiating these distributions
with bool and char, since those are not integer types. However, it is
trivial to replace uses of these random distributions on char using int8_t.

It is also interesting to note that in the process of adding tests
for smaller types, I discovered that our distributions sometimes don't
provide as faithful a distribution when instantiated with smaller types,
so I had to relax a couple of tests. In particular, we do a really bad
job at implementing the negative binomial, geometric and poisson distributions
for small types. I think this all boils down to the algorithm we use in
std::poisson_distribution, however I am running out of time to investigate
that and changing the algorithm would be an ABI break (which might be
reasonable).

As part of this patch, I also added a mitigation for a very likely
integer overflow bug we were hitting in our tests in negative_binomial_distribution.
I also filed http://llvm.org/PR56656 to track fixing the problematic
distributions with int8_t and uint8_t.

Supersedes D125283.

Differential Revision: https://reviews.llvm.org/D126823
2022-07-22 08:33:01 -04:00
Louis Dionne
7300a651f5 [libc++] Re-apply "Always build c++experimental.a""
This re-applies bb939931a1ad, which had been reverted by 09cebfb978de
because it broke Chromium. The issues seen by Chromium should be
addressed by 1d0f79558ca4.

Differential Revision: https://reviews.llvm.org/D128927
2022-07-19 10:44:19 -04:00
Hans Wennborg
09cebfb978 Revert "[libc++] Always build c++experimental.a"
This caused build failures when building Clang and libc++ together on Mac:

  fatal error: 'experimental/memory_resource' file not found

See the code review for details. Reverting until the problem and how to
solve it is better understood.

(Updates to some test files were not reverted, since they seemed
unrelated and were later updated by 340b48b267b96.)

> This is the first part of a plan to ship experimental features
> by default while guarding them behind a compiler flag to avoid
> users accidentally depending on them. Subsequent patches will
> also encompass incomplete features (such as <format> and <ranges>)
> in that categorization. Basically, the idea is that we always
> build and ship the c++experimental library, however users can't
> use what's in it unless they pass the `-funstable` flag to Clang.
>
> Note that this patch intentionally does not start guarding
> existing <experimental/FOO> content behind the flag, because
> that would merely break users that might be relying on such
> content being in the headers unconditionally. Instead, we
> should start guarding new TSes behind the flag, and get rid
> of the existing TSes we have by shipping their Standard
> counterpart.
>
> Also, this patch must jump through a few hoops like defining
> _LIBCPP_ENABLE_EXPERIMENTAL because we still support compilers
> that do not implement -funstable yet.
>
> Differential Revision: https://reviews.llvm.org/D128927

This reverts commit bb939931a1adb9a47a2de13c359d6a72aeb277c8.
2022-07-18 16:57:15 +02:00
Louis Dionne
bb939931a1 [libc++] Always build c++experimental.a
This is the first part of a plan to ship experimental features
by default while guarding them behind a compiler flag to avoid
users accidentally depending on them. Subsequent patches will
also encompass incomplete features (such as <format> and <ranges>)
in that categorization. Basically, the idea is that we always
build and ship the c++experimental library, however users can't
use what's in it unless they pass the `-funstable` flag to Clang.

Note that this patch intentionally does not start guarding
existing <experimental/FOO> content behind the flag, because
that would merely break users that might be relying on such
content being in the headers unconditionally. Instead, we
should start guarding new TSes behind the flag, and get rid
of the existing TSes we have by shipping their Standard
counterpart.

Also, this patch must jump through a few hoops like defining
_LIBCPP_ENABLE_EXPERIMENTAL because we still support compilers
that do not implement -funstable yet.

Differential Revision: https://reviews.llvm.org/D128927
2022-07-08 16:58:22 -04:00
Mark de Wever
8aa596584a [libc++][doc] Removes a colon in a title. 2022-07-07 19:07:03 +02:00
Ilya Biryukov
374f938fe8 [libcxx] Fix allocator<void>::pointer in C++20 with removed members
When compiled with `-D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS`
uses of `allocator<void>::pointer` resulted in compiler errors after D104323.
If we instantiate the primary template, `allocator<void>::reference` produces
an error 'cannot form references to void'.

To workaround this, allow to bring back the `allocator<void>` specialization by defining the new `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION` macro.

To make sure the code that uses `allocator<void>` and the removed members does not break,
both `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS` and `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS` have to be defined.

Reviewed By: ldionne, #libc, philnik

Differential Revision: https://reviews.llvm.org/D126210
2022-06-15 10:55:56 +02:00
Louis Dionne
2ae52326da [libc++] Towards a simpler extern template story in libc++
The flexibility around extern template instantiation declarations in
libc++ result in a very complicated model, especially when support for
slightly different configurations (like the debug mode or assertions
in the dylib) are taken into account. That results in unexpected bugs
like http://llvm.org/PR50534 (and there have been multiple similar
bugs in the past, notably around the debug mode).

This patch gets rid of the _LIBCPP_DISABLE_EXTERN_TEMPLATE knob, which
I don't think is fundamental. Indeed, the motivation for that knob was to
avoid taking a dependency on the library, however that can be done better
by linking against the static library instead. And in fact, some parts of
the headers will always depend on things defined in the library, which
defeats the original goal of _LIBCPP_DISABLE_EXTERN_TEMPLATE.

Differential Revision: https://reviews.llvm.org/D103960
2022-06-08 22:05:07 -04:00
Louis Dionne
f3966eaf86 [libc++] Make the Debug mode a configuration-time only option
The debug mode has been broken pretty much ever since it was shipped
because it was possible to enable the debug mode in user code without
actually enabling it in the dylib, leading to ODR violations that
caused various kinds of failures.

This commit makes the debug mode a knob that is configured when
building the library and which can't be changed afterwards. This is
less flexible for users, however it will actually work as intended
and it will allow us, in the future, to add various kinds of checks
that do not assume the same ABI as the normal library. Furthermore,
this will make the debug mode more robust, which means that vendors
might be more tempted to support it properly, which hasn't been the
case with the current debug mode.

This patch shouldn't break any user code, except folks who are building
against a library that doesn't have the debug mode enabled and who try
to enable the debug mode in their code. Such users will get a compile-time
error explaining that this configuration isn't supported anymore.

In the future, we should further increase the granularity of the debug
mode checks so that we can cherry-pick which checks to enable, like we
do for unspecified behavior randomization.

Differential Revision: https://reviews.llvm.org/D122941
2022-06-07 16:33:53 -04:00
Louis Dionne
385cc25a53 [libc++] Ensure that all public C++ headers include <__assert>
This patch changes the requirement for getting the declaration of the
assertion handler from including <__assert> to including any public
C++ header of the library. Note that C compatibility headers are
excluded because we don't implement all the C headers ourselves --
some of them are taken straight from the C library, like assert.h.

It also adds a generated test to check it. Furthermore, this new
generated test is designed in a way that will make it possible to
replace almost all the existing test-generation scripts with this
system in upcoming patches.

Differential Revision: https://reviews.llvm.org/D122506
2022-03-30 15:05:31 -04:00
Louis Dionne
b0fd9497af [libc++] Add a lightweight overridable assertion handler
This patch adds a lightweight assertion handler mechanism that can be
overriden at link-time in a fashion similar to `operator new`.

This is a third take on https://llvm.org/D121123 (which allowed customizing
the assertion handler at compile-time), and https://llvm.org/D119969
(which allowed customizing the assertion handler at runtime only).

This approach is, I think, the best of all three explored approaches.
Indeed, replacing the assertion handler in user code is ergonomic,
yet we retain the ability to provide a custom assertion handler when
deploying to older platforms that don't have a default handler in
the dylib.

As-is, this patch provides a pretty good amount of backwards compatibility
with the previous debug mode:

- Code that used to set _LIBCPP_DEBUG=0 in order to get basic assertions
  in their code will still get basic assertions out of the box, but
  those assertions will be using the new assertion handler support.
- Code that was previously compiled with references to __libcpp_debug_function
  and friends will work out-of-the-box, no changes required. This is
  because we provide the same symbols in the dylib as we used to.
- Code that used to set a custom __libcpp_debug_function will stop
  compiling, because we don't provide that declaration anymore. Users
  will have to migrate to the new way of setting a custom assertion
  handler, which is extremely easy. I suspect that pool of users is
  very limited, so breaking them at compile-time is probably acceptable.

The main downside of this approach is that code being compiled with
assertions enabled but deploying to an older platform where the assertion
handler didn't exist yet will fail to compile. However users can easily
fix the problem by providing a custom assertion handler and defining
the _LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED macro to
let the library know about the custom handler. In a way, this is
actually a feature because it avoids a load-time error that one would
otherwise get when trying to run the code on the older target.

Differential Revision: https://reviews.llvm.org/D121478
2022-03-23 15:35:46 -04:00
Louis Dionne
b1fb3d75c9 [libc++] Implement C++20's P0476R2: std::bit_cast
Thanks to Arthur O'Dwyer for fixing up some of the tests.

Differential Revision: https://reviews.llvm.org/D75960
2021-09-09 11:05:54 -04:00
Louis Dionne
ff7a332e6f [libc++] Revert OpenBSD-related changes to the documentation
This commit partially reverts 0954e2b2d038 and 3fa4cff97480, which
make changes to the libc++ documentation implifying that OpenBSD is
supported. Neither of these changes have been reviewed AFAICT, so
I'm reverting as a matter of enforcing:

1. That changes get reviewed before being committed
2. That we have a discussion and a support plan for supporting
   OpenBSD officially in libc++

Please note that I would be thrilled to support OpenBSD officially in
libc++, however doing so requires more than adding a note in the docs.
In particular, please make sure you read the note in [1] about setting
up CI testing for OpenBSD.

[1]: https://libcxx.llvm.org/#platform-and-compiler-support

Differential Revision: https://reviews.llvm.org/D109373
2021-09-08 15:55:03 -04:00
Brad Smith
3fa4cff974 Mention OpenBSD in the documentation 2021-09-07 07:55:17 -04:00
Louis Dionne
2ce0df4dfb [libc++][docs] Overhaul the documentation for building and using libc++
This patch overhauls the documentation around building libc++
for vendors, and using libc++ for end-users. It also:

- Removes mention of the standalone build, which we've been trying to
  get rid of for a long time.
- Removes mention of using a local ABI installation, which we don't do
  and is documented as "not recommended".
- Removes mention of the separate libc++filesystem.a library, which isn't
  relevant anymore since filesystem support is in the main library.
- Adds mention of the GDB pretty printers and how to use them.
2021-07-06 14:09:14 -04:00
wmbat
2ff5a56e1a [libcxx][type_traits] remove std::is_literal_type and std::result_of for C++20
C++17 deprecated `std::is_literal_type` and `std::result_of`, C++20 removed them.

Implements parts of:
    * P0174R2 'Deprecating Vestigial Library Parts in C++17'.
    * P0619R4 'Reviewing Deprecated Facilities of C++17 for C++20'.

Reviewed By: ldionne, Mordante, Quuxplusone, #libc

Differential Revision: https://reviews.llvm.org/D102992
2021-07-02 17:10:19 +00:00
Louis Dionne
87784cc6fb [libc++] Undeprecate the std::allocator<void> specialization
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
2021-06-16 09:54:29 -04:00
Arthur O'Dwyer
dc066888bd [libc++] [P0619] Add _LIBCPP_ABI_NO_BINDER_BASES and remove binder typedefs in C++20.
Differential Revision: https://reviews.llvm.org/D103753
2021-06-15 15:05:44 -04:00
Arthur O'Dwyer
d42d9e10b6 [libc++] [P0619] Hide not1 and not2 under _LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS.
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
2021-05-25 16:57:16 -04:00
Louis Dionne
a3ab5120fd [libc++] Rewrite the tuple constructors to be strictly Standards conforming
This nasty patch rewrites the tuple constructors to match those defined
by the Standard. We were previously providing several extensions in those
constructors - those extensions are removed by this patch.

The issue with those extensions is that we've had numerous bugs filed
against us over the years for problems essentially caused by them. As a
result, people are unable to use tuple in ways that are blessed by the
Standard, all that for the perceived benefit of providing them extensions
that they never asked for.

Since this is an API break, I communicated it in the release notes.
I do not foresee major issues with this break because I don't think the
extensions are too widely relied upon, but we can ship it and see if we
get complaints before the next LLVM release - that will give us some
amount of information regarding how much use these extensions have.

Differential Revision: https://reviews.llvm.org/D96523
2021-04-23 12:46:37 -04:00
Jennifer Chukwu
21bef4e11e [NFC] Fixed Typos
Reviewed By: xgupta

Differential Revision: https://reviews.llvm.org/D100705
2021-04-17 22:02:23 +05:30
Arthur O'Dwyer
4b7bad9eae [libc++] Implement D2351R0 "Mark all library static cast wrappers as [[nodiscard]]"
These [[nodiscard]] annotations are added as a conforming extension;
it's unclear whether the paper will actually be adopted and make them
mandatory, but they do seem like good ideas regardless.

https://isocpp.org/files/papers/D2351R0.pdf

This patch implements the paper's effect on:
- std::to_integer, std::to_underlying
- std::forward, std::move, std::move_if_noexcept
- std::as_const
- std::identity

The paper also affects (but libc++ does not yet have an implementation of):
- std::bit_cast

Differential Revision: https://reviews.llvm.org/D99895
2021-04-12 12:29:15 -04:00
Marek Kurdej
044b892c79 [libc++] Use c++20 instead of c++2a consistently.
* The only exception is that the flag -std=c++2a is still used not to break compatibility with older compilers (clang <= 9, gcc <= 9).
* Bump _LIBCPP_STD_VER for C++20 to 20 and use 21 for the future standard (C++2b).

That's a preparation step to add c++2b support to libc++.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D93383
2021-01-07 13:11:33 +01:00
Sylvestre Ledru
72fd1033ea Doc: Links should use https 2020-03-22 22:49:33 +01:00
Louis Dionne
86dd28a547 [libc++] Use [[nodiscard]] for lock_guard, as an extension
Summary:
D64914 added support for applying [[nodiscard]] to constructors. This
commit uses that capability to flag incorrect uses of std::lock_guard
where one forgets to actually create a variable for the lock_guard.

rdar://45790820

Reviewers: mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, libcxx-commits, Quuxplusone, lebedev.ri

Tags: #libc

Differential Revision: https://reviews.llvm.org/D65900

llvm-svn: 368664
2019-08-13 11:12:28 +00:00
Louis Dionne
776acf225b [libcxx] Slightly improved policy for handling experimental features
Summary:
Following the discussion on the libcxx-dev mailing list
(http://lists.llvm.org/pipermail/libcxx-dev/2019-May/000358.html),
this implements the new policy for handling experimental features and
their deprecation. We basically add a deprecation warning for
std::experimental::filesystem, and we remove a bunch of <experimental/*>
headers that were now empty.

Reviewers: mclow.lists, EricWF

Subscribers: mgorny, christof, jkorous, dexonsmith, arphaman, libcxx-commits, jfb

Tags: #libc

Differential Revision: https://reviews.llvm.org/D62428

llvm-svn: 363072
2019-06-11 14:48:40 +00:00
J. Ryan Stinnett
d45eaf9405 [Docs] Modernize references to macOS
Summary:
This updates all places in documentation that refer to "Mac OS X", "OS X", etc.
to instead use the modern name "macOS" when no specific version number is
mentioned.

If a specific version is mentioned, this attempts to use the OS name at the time
of that version:

* Mac OS X for 10.0 - 10.7
* OS X for 10.8 - 10.11
* macOS for 10.12 - present

Reviewers: JDevlieghere

Subscribers: mgorny, christof, arphaman, cfe-commits, lldb-commits, libcxx-commits, llvm-commits

Tags: #clang, #lldb, #libc, #llvm

Differential Revision: https://reviews.llvm.org/D62654

llvm-svn: 362113
2019-05-30 16:46:22 +00:00