Commit Graph

366 Commits

Author SHA1 Message Date
Louis Dionne ea5cd3b476 [libc++] Add deprecated attributes to many deprecated components
Summary:
These deprecation warnings are opt-in: they are only enabled when the
_LIBCXX_DEPRECATION_WARNINGS macro is defined, which is not the case
by default. Note that this is a first step in the right direction, but
I wasn't able to get an exhaustive list of all deprecated components
per standard, so there's certainly stuff that's missing. The list of
components this commit marks as deprecated is:

in C++11:
- auto_ptr, auto_ptr_ref
- binder1st, binder2nd, bind1st(), bind2nd()
- pointer_to_unary_function, pointer_to_binary_function, ptr_fun()
- mem_fun_t, mem_fun1_t, const_mem_fun_t, const_mem_fun1_t, mem_fun()
- mem_fun_ref_t, mem_fun1_ref_t, const_mem_fun_ref_t, const_mem_fun1_ref_t, mem_fun_ref()

in C++14:
- random_shuffle()

in C++17:
- unary_negate, binary_negate, not1(), not2()

<rdar://problem/18168350>

Reviewers: mclow.lists, EricWF

Subscribers: christof, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D48912

llvm-svn: 342843
2018-09-23 18:35:00 +00:00
Roman Lebedev c65d39a464 [libc++] Add _LIBCPP_ENABLE_NODISCARD and _LIBCPP_NODISCARD_EXT to allow pre-C++2a [[nodiscard]]
Summary:
The `[[nodiscard]]` attribute is intended to help users find bugs where
function return values are ignored when they shouldn't be. After C++17 the
C++ standard has started to declared such library functions as `[[nodiscard]]`.
However, this application is limited and applies only to dialects after C++17.
Users who want help diagnosing misuses of STL functions may desire a more
liberal application of `[[nodiscard]]`.

For this reason libc++ provides an extension that does just that! The
extension must be enabled by defining `_LIBCPP_ENABLE_NODISCARD`. The extended
applications of `[[nodiscard]]` takes two forms:

1. Backporting `[[nodiscard]]` to entities declared as such by the
   standard in newer dialects, but not in the present one.

2. Extended applications of `[[nodiscard]]`, at the libraries discretion,
   applied to entities never declared as such by the standard.

Users may also opt-out of additional applications `[[nodiscard]]` using
additional macros.

Applications of the first form, which backport `[[nodiscard]]` from a newer
dialect may be disabled using macros specific to the dialect it was added. For
example `_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17`.

Applications of the second form, which are pure extensions, may be disabled
by defining `_LIBCPP_DISABLE_NODISCARD_EXT`.

This patch was originally written by me (Roman Lebedev),
then but then reworked by Eric Fiselier.

Reviewers: mclow.lists, thakis, EricWF

Reviewed By: thakis, EricWF

Subscribers: llvm-commits, mclow.lists, lebedev.ri, EricWF, rjmccall, Quuxplusone, cfe-commits, christof

Differential Revision: https://reviews.llvm.org/D45179

llvm-svn: 342808
2018-09-22 17:54:48 +00:00
Louis Dionne 61cd687009 [libcxx] By default, do not use internal_linkage to hide symbols from the ABI
Summary:
https://reviews.llvm.org/D49240 led to symbol size problems in Chromium, and
we expect this may be the case in other projects built in debug mode too.
Instead, unless users explicitly ask for internal_linkage, we use always_inline
like we used to.

In the future, when we have a solution that allows us to drop always_inline
without falling back on internal_linkage, we can replace always_inline by
that.

Note that this commit introduces a change in contract for existing libc++
users: by default, libc++ used to guarantee that TUs built with different
versions of libc++ could be linked together. With the introduction of the
_LIBCPP_HIDE_FROM_ABI_PER_TU macro, the default behavior is that TUs built
with different libc++ versions are not guaranteed to link. This is a change
in contract but not a change in behavior, since the current implementation
still allows linking TUs built with different libc++ versions together.

Reviewers: EricWF, mclow.lists, dexonsmith, hans, rnk

Subscribers: christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D50652

llvm-svn: 339874
2018-08-16 12:44:28 +00:00
Marshall Clow 171c77b7da Selectively import timespec_get into namespace std, since some C libraries don't have it. Reviewed as https://reviews.llvm.org/D50799
llvm-svn: 339816
2018-08-15 21:19:08 +00:00
Louis Dionne 894ffdd82f [libc++] Detect C11 features on non-Clang compilers
Summary:
The macros were inside `#if defined(_LIBCPP_COMPILER_CLANG)`, which means
we would never detect C11 features on non-Clang compilers. According to
Marshall Clow, this is not the intended behavior.

Reviewers: mclow.lists, EricWF

Subscribers: krytarowski, christof, dexonsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D50748

llvm-svn: 339741
2018-08-15 00:16:41 +00:00
Louis Dionne 53ac1776f3 [libc++] Enable aligned allocation based on feature test macro, irrespective of standard
Summary:
The current code enables aligned allocation functions when compiling in C++17
and later. This is a problem because aligned allocation functions might not
be supported on the target platform, which leads to an error at link time.

Since r338934, Clang knows not to define __cpp_aligned_new when it's not
available on the target platform -- this commit takes advantage of that to
only use aligned allocation functions when they are available.

Reviewers: vsapsai, EricWF

Subscribers: christof, dexonsmith, cfe-commits, EricWF, mclow.lists

Differential Revision: https://reviews.llvm.org/D50344

llvm-svn: 339431
2018-08-10 13:24:56 +00:00
Louis Dionne ba71bd7c55 [libc++] Add the _LIBCPP_HIDE_FROM_ABI_AFTER_V1 macro
Summary:
This macro allows hiding symbols from the ABI when the library is built
with an ABI version after ABI v1, which is currently the only stable ABI.
This commit defines `_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY` to be
`_LIBCPP_HIDE_FROM_ABI_AFTER_V1`, meaning that symbols that were only
exported by the library for historical reasons are not exported anymore
in the unstable ABI.

Because of that, this commit is an ABI break for ABI v2. This ABI version
is not stable, however, so this should not be a problem.

Reviewers: EricWF, mclow.lists

Subscribers: christof, dexonsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D49914

llvm-svn: 339012
2018-08-06 14:11:50 +00:00
Hans Wennborg 25977548aa Update version to 8.0.0svn: cmake, includes files and docs
llvm-svn: 338555
2018-08-01 13:54:28 +00:00
Louis Dionne 306b73e35b [libc++] Fix GCC 7.2.0 macro redefinition warning
The warning happens when LIBCXX_ENABLE_EXCEPTIONS cmake option is not set,
and it fires every time __config is included, 33 in total.

Patch by Jason Lovett
Reviewed as https://reviews.llvm.org/D49997

llvm-svn: 338531
2018-08-01 13:13:14 +00:00
Tim Shen 38cd7de5ac Re-apply "[libcxx] implement <simd> ABI for Clang/GCC vector extension, constructors, copy_from and copy_to."
...with proper guarding #ifdefs for unsupported C++11.

llvm-svn: 338318
2018-07-30 22:27:38 +00:00
Tim Shen 6f33ea4ef6 Revert "[libcxx] implement <simd> ABI for Clang/GCC vector extension, constructors, copy_from and copy_to."
This reverts commit r338309.

llvm-svn: 338316
2018-07-30 22:21:22 +00:00
Tim Shen 47ad09b339 [libcxx] implement <simd> ABI for Clang/GCC vector extension, constructors, copy_from and copy_to.
Summary:
This patch adds a new macro _LIBCPP_HAS_NO_VECTOR_EXTENSION for detecting
whether a vector extension (\_\_attribute\_\_((vector_size(num_bytes)))) is
available.

On the top of that, this patch implements the following API:
* all constructors
* operator[]
* copy_from
* copy_to

It also defines simd_abi::native to use vector extension, if available.
In GCC and Clang, certain values with vector extension are passed by registers,
instead of memory.

Based on D41148.

Reviewers: mclow.lists, EricWF

Subscribers: cfe-commits, MaskRay, lichray, sanjoy

Differential Revision: https://reviews.llvm.org/D41376

llvm-svn: 338309
2018-07-30 21:23:13 +00:00
Louis Dionne cb3eb30636 [libc++] Introduce _LIBCPP_HIDE_FROM_ABI to replace _LIBCPP_INLINE_VISIBILITY
Summary:
This commit introduces a new macro, _LIBCPP_HIDE_FROM_ABI, whose goal is to
mark functions that shouldn't be part of libc++'s ABI. It marks the functions
as being hidden for dylib visibility purposes, and as having internal linkage
using Clang's __attribute__((internal_linkage)) when available, and
__always_inline__ otherwise.

It replaces _LIBCPP_INLINE_VISIBILITY, which was always using __always_inline__
to achieve similar goals, but suffered from debuggability and code size problems.
The full proposal, along with more background information, can be found here:

    http://lists.llvm.org/pipermail/cfe-dev/2018-July/058419.html

This commit does not rename uses of _LIBCPP_INLINE_VISIBILITY to
_LIBCPP_HIDE_FROM_ABI: this wide reaching but mechanical change can
be done later when we've confirmed we're happy with the new macro.

In the future, it would be nice if we could optionally allow dropping
any internal_linkage or __always_inline__ attribute, which could result
in code size improvements. However, this is currently impossible for
reasons explained here: http://lists.llvm.org/pipermail/cfe-dev/2018-July/058450.html

Reviewers: EricWF, dexonsmith, mclow.lists

Subscribers: christof, dexonsmith, llvm-commits, mclow.lists

Differential Revision: https://reviews.llvm.org/D49240

llvm-svn: 338122
2018-07-27 12:46:03 +00:00
Eric Fiselier 8e4a1690bf Move Filesystem namespace definition out of a clang specific ifdef block.
llvm-svn: 338103
2018-07-27 06:12:46 +00:00
Eric Fiselier 998a5c8831 Implement <filesystem>
This patch implements the <filesystem> header and uses that
to provide <experimental/filesystem>.

Unlike other standard headers, the symbols needed for <filesystem>
have not yet been placed in libc++.so. Instead they live in the
new libc++fs.a library. Users of filesystem are required to link this
library. (Also note that libc++experimental no longer contains the
definition of <experimental/filesystem>, which now requires linking libc++fs).

The reason for keeping <filesystem> out of the dylib for now is that
it's still somewhat experimental, and the possibility of requiring an
ABI breaking change is very real. In the future the symbols will likely
be moved into the dylib, or the dylib will be made to link libc++fs automagically).

Note that moving the symbols out of libc++experimental may break user builds
until they update to -lc++fs. This should be OK, because the experimental
library provides no stability guarantees. However, I plan on looking into
ways we can force libc++experimental to automagically link libc++fs.

In order to use a single implementation and set of tests for <filesystem>, it
has been placed in a special `__fs` namespace. This namespace is inline in
C++17 onward, but not before that. As such implementation is available
in C++11 onward, but no filesystem namespace is present "directly", and
as such name conflicts shouldn't occur in C++11 or C++14.

llvm-svn: 338093
2018-07-27 03:07:09 +00:00
Alexander Richardson 2a6a3fc4a3 Stop wrapping __has_include in another macro
Summary:
This is not guaranteed to work since the characters after '__has_include('
have special lexing rules that can't possibly be applied when
__has_include is generated by a macro. It also breaks the crash reproducers
generated by -frewrite-includes (see https://llvm.org/pr37990).

Reviewers: EricWF, rsmith, mclow.lists
Reviewed By: mclow.lists
Differential Revision: https://reviews.llvm.org/D49067

llvm-svn: 337824
2018-07-24 12:40:56 +00:00
Marshall Clow 75c4f5552e wrap _LIBCPP_HAS_NO_CXX14_CONSTEXPR in defined(...)
llvm-svn: 337028
2018-07-13 17:31:36 +00:00
Marshall Clow 2d1d690863 Shot in the dark to fix gcc 4.9 / c++11 build
llvm-svn: 337027
2018-07-13 17:24:59 +00:00
Marshall Clow 9cad502555 Make internal class __wrap_iter constexpr when not using libc++'s debugging mode. Introduce a new macro _LIBCPP_CONSTEXPR_IF_NODEBUG to mark this.
llvm-svn: 337019
2018-07-13 16:35:26 +00:00
Louis Dionne dc7200b486 [libc++] Take 2: Replace uses of _LIBCPP_ALWAYS_INLINE by _LIBCPP_INLINE_VISIBILITY
Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.

This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.

Note that this commit had originally been applied in r336369 and then
reverted in r336382 because of unforeseen problems. Both of these problems
have now been fixed.

Reviewers: EricWF, mclow.lists

Subscribers: christof, dexonsmith, erikvanderpoel

Differential Revision: https://reviews.llvm.org/D48892

llvm-svn: 336866
2018-07-11 23:14:33 +00:00
Louis Dionne 195a499d63 Revert "[libc++] Replace uses of _LIBCPP_ALWAYS_INLINE by _LIBCPP_INLINE_VISIBILITY"
This reverts commit r336369. The commit had two problems:
1. __pbump was marked as _LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY instead of
   _LIBCPP_INLINE_VISIBILITY, which lead to two symbols being added in the
   dylib and the check-cxx-abilist failing.

2. The LLDB tests started failing because they undefine
   `_LIBCPP_INLINE_VISIBILITY`. I need to figure out why they do that and
   fix the tests before we can go forward with this change.

llvm-svn: 336382
2018-07-05 18:41:50 +00:00
Louis Dionne 4a8f3f9948 [libc++] Replace uses of _LIBCPP_ALWAYS_INLINE by _LIBCPP_INLINE_VISIBILITY
Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.

This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.

Reviewers: EricWF

Subscribers: christof, llvm-commits, dexonsmith, erikvanderpoel, mclow.lists

Differential Revision: https://reviews.llvm.org/D48892

llvm-svn: 336369
2018-07-05 16:49:38 +00:00
JF Bastien f764dbd023 Revert "Add nonnull; use it for atomics"
That's r333325, as well as follow-up "Fix GCC handling of ATOMIC_VAR_INIT"
r333327.

Marshall asked to revert:

Let's have a discussion about how to implement this so that it is more friendly
to people with installed code bases. We've had *extremely* loud responses to
unilaterally adding warnings - especially ones that can't be easily disabled -
to the libc++ code base in the past.

llvm-svn: 333351
2018-05-26 19:44:45 +00:00
JF Bastien 1be7517aa9 Add nonnull; use it for atomics
Summary:
The atomic non-member functions accept pointers to std::atomic / std::atomic_flag as well as to the non-atomic value. These are all dereferenced unconditionally when lowered, and therefore will fault if null. It's a tiny gotcha for new users, especially when they pass in NULL as expected value (instead of passing a pointer to a NULL value). We can therefore use the nonnull attribute to denote that:

  - A warning should be generated if the argument is null
  - It is undefined behavior if the argument is null (because a dereference will segfault)

This patch adds support for this attribute for clang and GCC, and sticks to the subset of the syntax both supports. In particular, work around this GCC oddity:
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60625

The attributes are documented:

  - https://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Function-Attributes.html
  - https://clang.llvm.org/docs/AttributeReference.html#nullability-attributes

I'm authoring a companion clang patch for the __c11_* and __atomic_* builtins, which currently only warn on a subset of the pointer parameters.

In all cases the check needs to be explicit and not use the empty nonnull list, because some of the overloads are for atomic<T*> and the values themselves are allowed to be null.

<rdar://problem/18473124>

Reviewers: arphaman, EricWF

Subscribers: aheejin, christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D47225

llvm-svn: 333325
2018-05-25 23:43:53 +00:00
Reid Kleckner 6a2a5e0abb Don't do aligned allocations on MSVCRT before 19.12 (update 15.3)
Reviewers: EricWF, pcc

Subscribers: christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D45836

llvm-svn: 330372
2018-04-19 22:12:10 +00:00
Reid Kleckner 317a6ddea7 Remove impossible _MSC_VER check
Summary:
It is immediately preceded by this check:
  #if _MSC_VER < 1900
  #error "MSVC versions prior to Visual Studio 2015 are not supported"
  #endif

Reviewers: EricWF

Subscribers: christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D45829

llvm-svn: 330360
2018-04-19 19:40:12 +00:00
Petr Hosek 2b3846306d [libcxx] Set ABI version 2 as default for Fuchsia
This avoids the need for a custom generated config file which is desired
because the custom config files differs per-target which means we cannot
reuse headers across different targets.

Differential Revision: https://reviews.llvm.org/D45304

llvm-svn: 329770
2018-04-11 01:06:28 +00:00
Eric Fiselier 0913ca1978 Implement P0768r1: Library support for the Spaceship Operator.
this patch adds the <compare> header and implements all of it
except for [comp.alg].

As I understand it, the header is needed by the compiler in
when implementing the semantics of operator<=>. For that reason
I feel it's important to land this header early, despite
all compilers lacking support.

llvm-svn: 329460
2018-04-06 21:37:23 +00:00
Eric Fiselier f2918d1c24 Fix PR22634 - std::allocator doesn't respect over-aligned types.
This patch fixes std::allocator, and more specifically, all users
of __libcpp_allocate and __libcpp_deallocate, to support over-aligned
types.

__libcpp_allocate/deallocate now take an alignment parameter, and when
the specified alignment is greater than that supported by malloc/new,
the aligned version of operator new is called (assuming it's available).

When aligned new isn't available, the old behavior has been kept, and the
alignment parameter is ignored.

This patch depends on recent changes to __builtin_operator_new/delete which
allow them to be used to call any regular new/delete operator. By using
__builtin_operator_new/delete when possible, the new/delete erasure optimization
is maintained.

llvm-svn: 328180
2018-03-22 04:42:56 +00:00
Logan Chien 2b772b930e Cleanup __config indention NFC
This commit indents each level by two space characters, e.g.

#if defined(CONDITION)
#  define _LIBCPP_NAME VALUE
#else
#  define _LIBCPP_NAME VALUE
#endif

The simple #ifndef, #define, and #endif sequences are not indented, e.g.

#ifndef _LIBCPP_NAME
#define _LIBCPP_NAME ...
#endif

llvm-svn: 326027
2018-02-24 07:57:32 +00:00
Eric Fiselier 1a78ae3c89 Fix size and alignment of array<T, 0>.
An array T[1] isn't necessarily the same say when it's
a member of a struct. This patch addresses that problem and corrects
the tests to deal with it.

llvm-svn: 324545
2018-02-07 23:50:25 +00:00
Eric Fiselier 59cdf90ac8 [libc++] Fix PR35491 - std::array of zero-size doesn't work with non-default constructible types.
Summary:
This patch fixes llvm.org/PR35491 and LWG2157  (https://cplusplus.github.io/LWG/issue2157)

The fix attempts to maintain ABI compatibility by replacing the array with a instance of `aligned_storage`.

Reviewers: mclow.lists, EricWF

Reviewed By: EricWF

Subscribers: lichray, cfe-commits

Differential Revision: https://reviews.llvm.org/D41223

llvm-svn: 324526
2018-02-07 21:06:13 +00:00
Peter Collingbourne fcac3c9642 libcxx: Allow auto-linking to be disabled with a macro.
Some users may have a custom build system which gives a different
name to the libc++ archive (or does not create an archive at all,
instead passing the object files directly to the linker). Give those
users a way to disable auto-linking.

Differential Revision: https://reviews.llvm.org/D42436

llvm-svn: 323300
2018-01-24 04:30:19 +00:00
Peter Collingbourne 4801624ee3 libcxx: Provide overloads for basic_filebuf::open() et al that take wchar_t* filenames on Windows.
This is an MSVC standard library extension. It seems like a reasonable
enough extension to me because wchar_t* is the native format for
filenames on that platform.

Differential Revision: https://reviews.llvm.org/D42225

llvm-svn: 323170
2018-01-23 02:07:27 +00:00
Peter Collingbourne 4bdb80faf2 libcxx: Stop using private MSVC macros in the exception implementation.
Inline the provided "fallback" definitions (which seem to always be
taken) that expand to __cdecl into users. The fallback definitions
for the *CRTIMP* macros were wrong in the case where the CRT is being
linked statically, so define our own macro as a replacement.

Differential Revision: https://reviews.llvm.org/D42158

llvm-svn: 322617
2018-01-17 04:37:04 +00:00
Peter Collingbourne 4566d827a1 libcxx: Stop providing a definition of __GLIBC_PREREQ.
An application may determine whether the C standard library is glibc
by testing whether __GLIBC_PREREQ is defined. This breaks if libc++
provides its own definition. Instead, define our own macro in our
namespace with the desired semantics.

Differential Revision: https://reviews.llvm.org/D41892

llvm-svn: 322201
2018-01-10 18:16:58 +00:00
Saleem Abdulrasool ae20590c17 Correct mistake in pragma usage for Windows
The autolink pragma was missing the pragma name itself.  This would
result in the pragma being silently dropped.

llvm-svn: 321937
2018-01-06 18:47:03 +00:00
Hans Wennborg 6be97eca93 Update version to 7.0.0svn: cmake, include files and docs
llvm-svn: 321725
2018-01-03 15:40:29 +00:00
Marshall Clow dd74d83f84 Implement p0258r2: has_unique_object_representations
llvm-svn: 321685
2018-01-03 02:32:28 +00:00
Marshall Clow 40a01d5314 Implement most of P0607: Inline Variables for the Standard Library. This involved marking a lot of variables as inline (but only for C++17 and later).
llvm-svn: 321658
2018-01-02 17:17:01 +00:00
Sam Clegg 5029d676f8 [libcxx] Add WebAssembly support
It turns out that this is the only change required in libcxx
for it to compile with the new `wasm32-unknown-unknown-wasm`
target recently added to Clang.

Patch by Nicholas Wilson!

Differential Revision: https://reviews.llvm.org/D41073

llvm-svn: 320925
2017-12-16 18:59:50 +00:00
Saleem Abdulrasool 74f41817a5 Enable auto-linking on Windows
The MSVC driver and clang do not link against the C++ runtime
explicitly.  Instead, they rely on the auto-linking via the pragma
(through `use_ansi.h`) to link against the correct version of the C++
runtime.  Attempt to do something similar here so that linking real C++
code on Windows does not require the user to explicitly specify
`c++.lib` when using libc++ as a C++ runtime on windows.

llvm-svn: 319816
2017-12-05 19:32:49 +00:00
Petr Hosek 5c70428176 [libcxx] Support getentropy as a source of randomness for std::random_device
Use this source use on Fuchsia where this is the oficially way
to obtain randomness. This could be also used on other platforms
that already support getentropy such as *BSD or Linux.

Differential Revision: https://reviews.llvm.org/D40319

llvm-svn: 319523
2017-12-01 06:34:33 +00:00
Martin Storsjo 771edc7949 Allow to set locale on Windows.
Fix the problem PR31516 with setting locale on Windows by wrapping
_locale_t with a pointer-like class.

Reduces 74 test failures in std/localization test suite to 47 test
failures (on llvm clang, Visual Studio 2015). Number of test failures
doesn't depend on the platform (x86 or x64).

Patch by Andrey Khalyavin.

Differential Revision: https://reviews.llvm.org/D40181

llvm-svn: 318902
2017-11-23 10:38:18 +00:00
Marshall Clow 9180eb1f4a Implement p0137r1 - std::launder. Reviewed as https://reviews.llvm.org/D40144
llvm-svn: 318864
2017-11-22 19:49:03 +00:00
Eric Fiselier 0ed525382f [libc++] Shrink variant's index type when possible
Summary:
Currently `std::variant` always uses an unsigned int to store the variant index. However this isn't nessesary and causes `std::variant` to be larger than it needs to be in most cases.

This patch changes the index type to be `unsigned char` when possible, and `unsigned short` or `unsigned int` otherwise, depending on the size (Although it's questionable if it's even possible to create a variant with 65535 elements.

Unfortunately this change is an ABI break, and as such is only enabled in ABI v2.

Reviewers: mpark

Reviewed By: mpark

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D40210

llvm-svn: 318621
2017-11-19 04:19:44 +00:00
Marshall Clow 1644c12ef8 Add two new macros: _LIBCPP_NODISCARD_AFTER_CXX17 and _LIBCPP_CONSTEXPR_AFTER_CXX17, along with a way to turn off the NODISCARD one: _LIBCPP_DISABLE_NODISCARD_AFTER_CXX17. No one is using these yet, but we will be ... soon
llvm-svn: 318208
2017-11-14 22:26:50 +00:00
Dan Albert f33558b224 Revert "[libc++] Don't alias quick_exit if __ANDROID_API__ < 21"
Broke the Darwin build bots.

This reverts commit f56f1bba1ade4a408d403ff050d50e837bae47df.

llvm-svn: 317142
2017-11-01 23:43:07 +00:00
Dan Albert 5a4e27dfa6 [libc++] Don't alias quick_exit if __ANDROID_API__ < 21
Summary:
quick_exit() and at_quick_exit() were introduced in android NDK 21:
https://android.googlesource.com/platform/prebuilts/ndk/+/dev/platform/sysroot/usr/include/stdlib.h#55

This CL conditions `_LIBCPP_HAS_QUICK_EXIT` on `__ANDROID_API__ >= 21`.  The only place this macro is used is in some using declarations: `using ::quick_exit`, `using ::at_quick_exit`.

Also, add a missing include to sys/cdefs.h which is what defines `__BIONIC__`.

Reviewers: thakis, danalbert, EricWF

Reviewed By: danalbert

Subscribers: srhines, krytarowski

Differential Revision: https://reviews.llvm.org/D39479

llvm-svn: 317124
2017-11-01 21:17:56 +00:00
Eric Fiselier da0183947f Refactor _LIBCPP_<LITTLE|BIG>_ENDIAN
Previously this macro used 0/1 to indicate if it was set.
This is unlike all other libc++ configuration macros which
use ifdef/ifndef.

This patch makes this macro consistent with everything else.

llvm-svn: 315995
2017-10-17 13:16:01 +00:00