Commit Graph

2463 Commits

Author SHA1 Message Date
Eric Fiselier
a831287399 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.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@328180 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-22 04:42:56 +00:00
Marshall Clow
256f187bc6 Implement LWG3034: P0767R1 breaks previously-standard-layout types
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@328064 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-21 00:36:05 +00:00
Marshall Clow
dfeb9b2af7 Implement LWG3035: std::allocator's constructors should be constexpr.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@328059 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-20 23:02:53 +00:00
Marshall Clow
483bc7c64a Implement LWG 3039 and 3041 - 'Treating Unnecessary decay'.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@328054 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-20 22:37:37 +00:00
Petr Hosek
698b695147 [CMake] Copy the generated __config header into build directory
When the generated __config file is being used, it is currently only
copied during installation process. However, that means that the file
that gets copied into LLVM build directory is the vanilla __config file,
and any parts of the build that depend on the just built toolchain like
sanitizers will get that instead of the generated version. To avoid this
issue, we need to copy the generated header into the LLVM build
directory as well.

Differential Revision: https://reviews.llvm.org/D43797

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@327194 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-10 01:20:11 +00:00
Vedant Kumar
2b588cbf15 Low-hanging fruit optimization in string::__move_assign().
shrink_to_fit() ends up doing a lot work to get information that we
already know since we just called clear(). This change seems concise
enough to be worth the couple extra lines and my benchmarks show that it
is indeed a pretty decent win. It looks like the same thing is going on
twice in __copy_assign_alloc(), but I didn't want to go overboard since
this is my first contribution to llvm/libc++.

Patch by Timothy VanSlyke!

Differential Revision: https://reviews.llvm.org/D41976

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@327064 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-08 21:15:26 +00:00
Marshall Clow
46b8a51b49 Implement LWG#2518 - Non-member swap for propagate_const should call member swap
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@327005 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-08 15:01:50 +00:00
Logan Chien
7102892bf3 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


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@326027 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-24 07:57:32 +00:00
Mikhail Maltsev
df7a35ce32 [libcxx] Do not include the C math.h header before __config
Summary:
Certain C libraries require configuration macros defined in __config
to provide the correct functionality for libc++. This patch ensures
that the C header math.h is always included after the __config
header. It also adds a Windows-specific #if guard for the case when
the C math.h file is included the second time, as suggested by
Marshall in https://reviews.llvm.org/rL323490.

Fixes PR36382.

Reviewers: mclow.lists, EricWF

Reviewed By: mclow.lists

Subscribers: cfe-commits, pcc, christof, rogfer01

Differential Revision: https://reviews.llvm.org/D43579

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@325760 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-22 09:34:08 +00:00
Peter Collingbourne
61494b519c libcxx: Unbreak external thread library configuration.
Differential Revision: https://reviews.llvm.org/D42503

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@325723 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-21 21:36:18 +00:00
Mikhail Maltsev
c4658abe60 [libcxx] Improve accuracy of complex asinh and acosh
Summary:
Currently std::asinh and std::acosh use std::pow to compute x^2. This
results in a significant error when computing e.g. asinh(i) or
acosh(-1).

This patch expresses x^2 directly via x.real() and x.imag(), like it
is done in libstdc++/glibc, and adds tests that checks the accuracy.

Reviewers: EricWF, mclow.lists

Reviewed By: mclow.lists

Subscribers: christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D41629

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@325510 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-19 15:41:36 +00:00
Bruce Mitchener
26a02748eb Fix incorrect indentation.
Reviewers: mclow.lists

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D43167

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@325087 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-14 00:29:38 +00:00
Dimitry Andric
52474820e4 Put type attributes after class keyword
Summary:
Compiling `<functional>` in C++17 or higher mode results in:

```
functional:2500:1: warning: attribute '__visibility__' is ignored, place it after "class" to apply attribute to type declaration [-Wignored-attributes]
_LIBCPP_TYPE_VIS
^
__config:701:46: note: expanded from macro '_LIBCPP_TYPE_VIS'
#    define _LIBCPP_TYPE_VIS __attribute__ ((__visibility__("default")))
                                             ^
1 warning generated.
```

Fix it by putting the attribute after the `class` keyword.

Reviewers: EricWF, mclow.lists

Reviewed By: EricWF

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D43209

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@325027 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-13 17:40:59 +00:00
Marshall Clow
806a6ec645 Implement LWG 2835 - fix <tgmath.h>
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324923 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-12 19:13:24 +00:00
Marshall Clow
f72f21907c Implement LWG#2908 - The less-than operator for shared pointers could do more, and mark 2878 as complete as well (we already do that)
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324911 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-12 17:26:40 +00:00
Marshall Clow
b8cb776511 While implementing P0777 - preventing unnecessary decay, I found some non-public uses of decay that could be replaced by __uncvref. NFC intented
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324895 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-12 15:41:25 +00:00
Eric Fiselier
22a291c94e Fix libcxx MSVC C++17 redefinition of 'align_val_t'
Patch from 	charlieio@outlook.com

Reviewed as https://reviews.llvm.org/D42354

When the following command is used:

> clang-cl -std:c++17 -Iinclude\c++\v1 hello.cc c++.lib

An error occurred:

In file included from hello.cc:1:
In file included from include\c++\v1\iostream:38:
In file included from include\c++\v1\ios:216:
In file included from include\c++\v1\__locale:15:
In file included from include\c++\v1\string:477:
In file included from include\c++\v1\string_view:176:
In file included from include\c++\v1\__string:56:
In file included from include\c++\v1\algorithm:643:
In file included from include\c++\v1\memory:656:
include\c++\v1\new(165,29):  error: redefinition of 'align_val_t'
enum class _LIBCPP_ENUM_VIS align_val_t : size_t { };
                            ^
C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.12.25827\include\vcruntime_new.h(43,16):  note:
      previous definition is here
    enum class align_val_t : size_t {};
               ^
1 error generated.
vcruntime_new.h has defined align_val_t, libcxx need hide align_val_t.

This patch fixes that error.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324853 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-11 22:00:19 +00:00
Marshall Clow
a8de063568 Fix a typo in the synopsis comment. NFC. Thanks to K-ballo for the catch
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324851 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-11 21:51:49 +00:00
Eric Fiselier
9e6ac074ee Use multi-key tree search for {map, set}::{count, equal_range}
Patch from ngolovliov@gmail.com
Reviewed as: https://reviews.llvm.org/D42344

As described in llvm.org/PR30959, the current
implementation of std::{map, key}::{count, equal_range} in libcxx is
non-conforming. Quoting the C++14 standard [associative.reqmts]p3

> The phrase “equivalence of keys” means the equivalence relation imposed by
> the comparison and not the operator== on keys. That is, two keys k1 and k2 are
> considered to be equivalent if for the comparison object comp,
> comp(k1, k2) == false && comp(k2, k1) == false.

In the same section, the requirements table states the following:

> a.equal_range(k) equivalent to make_pair(a.lower_bound(k), a.upper_bound(k))
> a.count(k) returns the number of elements with key equivalent to k

The behaviour of libstdc++ seems to conform to the standard here.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324799 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-10 02:53:47 +00:00
Chih-Hung Hsieh
02ad8ad921 Revert "Revert "Revert "Turn off extern templates for most uses."""
This reverts commit 75746a3228.

Bug: 72411393
Test: normal build, and build with clang 7.0 in system/core/demangle
Change-Id: I6c67b5210e131600ad9706afd2e1cbd7f7f40237
2018-02-09 13:37:40 -08:00
Mikhail Maltsev
171ed2198d [libcxx] Avoid spurious construction of valarray elements
Summary:
Currently libc++ implements some operations on valarray by using the
resize method. This method has a parameter with a default value.
Because of this, valarray may spuriously construct and destruct
objects of valarray's element type.
    
This patch fixes this issue and adds corresponding test cases.


Reviewers: EricWF, mclow.lists

Reviewed By: mclow.lists

Subscribers: rogfer01, cfe-commits

Differential Revision: https://reviews.llvm.org/D41992

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324596 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-08 11:33:48 +00:00
Marshall Clow
5b1e87e52d Implement deduction guide for basic_string as described in P0433
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324569 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-08 06:34:03 +00:00
Eric Fiselier
c0acd34e9a 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.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324545 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-07 23:50:25 +00:00
Dan Albert
f835096310 Merge to upstream r324534.
Test: make checkbuild
Test: ./run_tests.py --bitness 32
Test: ./run_tests.py --bitness 64
Bug: None
Change-Id: I0913bfcee6cebafae3f1f663bb442d1ad4682006
2018-02-07 14:10:41 -08:00
Dan Albert
73660f725a Stop using __strtonum_fallback on Android.
Fallback implementations are now provided by bionic when necessary,
which these may conflict with.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324534 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-07 21:58:48 +00:00
Marshall Clow
088e6015b2 Fix PR#31454 - 'basic_string<T>::push_back() crashes if sizeof(T)>sizeof(long long)'. We were mishandling the small-string optimization calculations for very large 'characters'. This may be an ABI change (change the size of) strings of very large 'characters', but since they never worked, I'm not too concerned.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324531 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-07 21:30:17 +00:00
Eric Fiselier
6cb35ede81 [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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324526 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-07 21:06:13 +00:00
Marshall Clow
31810d9c0b Remove more of the std::experimental bits that are now in std::. All the _v type aliases, conjunction/disjunction, apply, etc. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324423 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-06 23:13:48 +00:00
Marshall Clow
52f9ca28a3 Implement P0777: Treating unnecessay decay
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324398 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-06 20:56:55 +00:00
Marshall Clow
f477af5fda Fix misleading indentation; replace a couple of NULLs with nullptr. Resolves https://reviews.llvm.org/D42945 ; thanks to Bruce Mitchener for the patch.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324378 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-06 18:58:05 +00:00
Nirav Dave
610fc67809 Revert "[libc++] Fix PR35491 - std::array of zero-size doesn't work with non-default constructible types."
Revert "Fix initialization of array<const T, 0> with GCC."
Revert "Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed."

This reverts commit r324182, r324185, and r324194 which were causing issues with zero-length std::arrays.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324309 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-06 03:03:37 +00:00
Marshall Clow
b50d2443d5 Remove <experimental/string_view>; use <string_view> instead. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324290 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-05 23:43:34 +00:00
Eric Fiselier
13177172d0 Fix initialization of array<const T, 0> with GCC.
Previously, when handling zero-sized array of const objects we
used a const version of aligned_storage_t, which is not an array type.
However, GCC complains about initialization of the form: array<const T, 0> arr = {};

This patch fixes that bug by making the dummy object used to represent
the zero-sized array an array itself. This avoids GCC's complaints
about the uninitialized const member.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324194 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-04 08:02:35 +00:00
Eric Fiselier
4d0f42850b Implement LWG 3014 - Fix more noexcept issues in filesystem.
This patch removes the noexcept declaration from filesystem
operations which require creating temporary paths or
creating a directory iterator. Either of these operations
can throw.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324192 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-04 07:35:36 +00:00
Eric Fiselier
0b47a655ac Implement LWG2989: path's streaming operators allow everything under the sun.
Because path can be constructed from a ton of different types, including string
and wide strings, this caused it's streaming operators to suck up all sorts
of silly types via silly conversions. For example:

using namespace std::experimental::filesystem::v1;
std::wstring w(L"wide");
std::cout << w; // converts to path.

This patch tentatively adopts the resolution to LWG2989 and fixes the issue
by making the streaming operators friends of path.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324189 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-04 03:10:53 +00:00
Eric Fiselier
122c064a76 Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed.
The standard isn't exactly clear how std::array should handle zero-sized arrays
with const element types. In particular W.R.T. copy assignment, swap, and fill.

This patch takes the position that those operations should be ill-formed,
and makes changes to libc++ to make it so.

This follows up on commit r324182.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324185 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-04 02:17:02 +00:00
Eric Fiselier
f3224ac007 [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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324182 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-04 01:03:08 +00:00
Richard Smith
dfb1351077 Make std::get_temporary_buffer respect overaligned types when possible
Patch by Chris Kennelly!

Differential Revision: https://reviews.llvm.org/D41746


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324020 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 22:24:45 +00:00
Marshall Clow
b21316f66c Remove std::experimental::sample; use std::sample instead. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323979 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 16:36:08 +00:00
Marshall Clow
14698bce22 Remove <experimental/numeric>; use <numeric> instead. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323975 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 15:49:27 +00:00
Marshall Clow
f8d223fe63 Remove <experimental/any>; use <any> instead. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323972 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 15:21:14 +00:00
Marshall Clow
95db3d2871 Remove <experimental/optional>; use <optional> instead. See https://libcxx.llvm.org/TS_deprecation.html
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323971 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 14:54:25 +00:00
Marshall Clow
75075c6be0 Add static_asserts to basic_ios and basic_stream_buf to ensure that that the traits match the character type. This is a requirement on the user - now we get consistent failures at compile time instead of incomprehensible error messages or runtime failures. This is also LWG#2994 - not yet adopted.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323945 91177308-0d34-0410-b5e6-96231b3b80d8
2018-02-01 03:55:27 +00:00
Marshall Clow
37e4c9b159 Implement LWG2870: Default value of parameter theta of polar should be dependent
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323918 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-31 21:42:39 +00:00
Peter Collingbourne
27c341db41 Fix the BinaryPredicate form of std::is_permutation to not rely on operator==
According to [1], forms 2 and 4 of std::is_permutation should use the passed in
binary predicate to compare elements. operator== should only be used for forms
1 and 3 which do not take a binary predicate.

This CL fixes forms 2 and 4 which relied on operator== for some comparisons.

[1] http://en.cppreference.com/w/cpp/algorithm/is_permutation

Patch by Thomas Anderson!

Differential Revision: https://reviews.llvm.org/D42518

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323563 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-26 21:23:27 +00:00
Peter Collingbourne
2b64fcb946 libcxx: Use vcruntime declarations for typeinfo on Windows.
We need to use the vcruntime declarations on Windows to avoid an
ODR violation involving rtti.obj, which provides the definition of
the runtime function implementing dynamic_cast and depends on the
vcruntime implementations of bad_cast and bad_typeid.

Differential Revision: https://reviews.llvm.org/D42220

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323491 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-26 01:22:17 +00:00
Peter Collingbourne
6b5c08ab34 libcxx: Move #include_next <math.h> out of header guard in wrapper header.
Code on Windows expects to be able to do:

 #define _USE_MATH_DEFINES
 #include <math.h>

and receive the definitions of mathematical constants, even if <math.h>
has previously been included. To support this scenario, re-include
<math.h> every time the wrapper header is included.

Differential Revision: https://reviews.llvm.org/D42403

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323490 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-26 01:19:23 +00:00
Eric Fiselier
8864da5e78 Fix PR35564 - std::list splice/erase incorrectly throw in debug mode.
There was a bug in the implementation of splice where the container
sizes were updated before decrementing one of the iterators. Afterwards,
the result of decrementing the iterator was flagged as UB by the debug
implementation because the container was reported to be empty.

This patch fixes that bug by delaying the updating of the container
sizes until after the iterators have been correctly constructed.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323390 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-25 00:02:48 +00:00
Eric Fiselier
8592d0abce Fix missing return in __tuple_leaf::__can_bind_reference when __reference_binds_to_temporary added in r323380.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323389 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-24 23:10:02 +00:00
Marshall Clow
cc7048888e Implement LWG2783: stack::emplace() and queue::emplace() should return decltype(auto)
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323385 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-24 22:42:25 +00:00