Implement the exposition-only concepts specified in
`[special.mem.concepts]`. These are all thin wrappers over other
concepts.
Reviewed By: #libc, Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D114761
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
Also fix a few places in the `shared_ptr` implementation where
`element_type` was passed to the `__is_compatible` helper. This could
result in `remove_extent` being applied twice to the pointer's template
type (first by the definition of `element_type` and then by the helper),
potentially leading to somewhat less readable error messages for some
incorrect code.
Differential Revision: https://reviews.llvm.org/D112092
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
Make sure we provide the correct It::difference_type member and update
the tests and synopses to be accurate.
Supersedes D102657 and D103101 (thanks to the original authors).
Differential Revision: https://reviews.llvm.org/D103273
C++17 deprecated std::iterator and removed it as a base class for all
iterator adaptors. We implement that change, but we still provide a way
to inherit from std::iterator in the few cases where doing otherwise
would be an ABI break.
Supersedes D101729 and the std::iterator base parts of D103101 and D102657.
Differential Revision: https://reviews.llvm.org/D103171
This patch gets rid of technical debt around std::pointer_safety which,
I claim, is entirely unnecessary. I don't think anybody has used
std::pointer_safety in actual code because we do not implement the
underlying garbage collection support. In fact, P2186 even proposes
removing these facilities entirely from a future C++ version. As such,
I think it's entirely fine to get rid of complex workarounds whose goals
were to avoid breaking the ABI back in 2017.
I'm putting this up both to get reviews and to discuss this proposal for
a breaking change. I think we should be comfortable with making these
tiny breaks if we are confident they won't hurt anyone, which I'm fairly
confident is the case here.
Differential Revision: https://reviews.llvm.org/D100410
This makes it clear that headers like <memory> which include auto_ptr
only do that when compiling under an older Standard, or when the removed
feature is explicitly requested.
As mandated by the Standard's various synopses, e.g. [iterator.synopsis].
Searching the TeX source for '#include' is a good way to find all of these
mandates.
The new tests are all autogenerated by utils/generate_header_inclusion_tests.py.
I was SHOCKED by how many mandates there are, and how many of them
libc++ wasn't conforming with.
Differential Revision: https://reviews.llvm.org/D99309
This patch implements 2802. Requires _Deleter to have call operator and be move constructible. Based on D62233.
Refs PR37637.
Differential Revision: https://reviews.llvm.org/D62274
- Implement C++20's changes to `reverse_iterator`, so that it won't be
accidentally counted as a contiguous iterator in C++20 mode.
- Implement C++20's changes to `move_iterator` as well.
- `move_iterator` should not be contiguous. This fixes a bug where
we optimized `std::copy`-of-move-iterators in an observable way.
Add a regression test for that bugfix.
- Add libcxx tests for `__is_cpp17_contiguous_iterator` of all relevant
standard iterator types. Particularly check that vector::iterator
is still considered contiguous in all C++ modes, even C++03.
After this patch, there continues to be no supported way to write your
own iterator type in C++17-and-earlier such that libc++ will consider it
"contiguous"; however, we now fully support the C++20 approach (in C++20
mode only). If you want user-defined contiguous iterators in C++17-and-earlier,
libc++'s position is "please upgrade to C++20."
Differential Revision: https://reviews.llvm.org/D94807
The implementation had a lot of boilerplate and was more complicated than
necessary. This NFC refactoring introduces a few macros to reduce code
duplication, and uses a consistent style and formatting for the whole file.
Differential Revision: https://reviews.llvm.org/D94544
This patch updates `allocate_shared` to call `allocator_traits::construct`
when creating the object held inside the shared_pointer, and
`allocator_traits::destroy` when destroying it. This resolves
the part of P0674R1 that was originally filed as LWG2070.
This change is landed separately from the rest of P0674R1 because it is
incredibly tricky from an ABI perspective.
This is the reason why this change is so tricky is that we previously
used EBO in a compressed pair to store both the allocator and the object
type stored in the `shared_ptr`. However, starting in C++20, P0674
requires us to use Allocator construction for initializing the object type.
That requirement rules out the use of the EBO for the object type, since
using the EBO implies that the base will be initialized when the control
block is initialized (and hence we can't do it through Allocator construction).
Hence, supporting P0674 requires changing how we store the object type
inside the control block, which we do while being ABI compatible by using
some trickery with a properly aligned char buffer.
Fixes https://llvm.org/PR41900
Supersedes https://llvm.org/D62760
Differential Revision: https://reviews.llvm.org/D91201
Checking that `T` is constructible from `Args...` is technically not
required by the Standard, although any implementation will obviously
error out if that's not satisfied. However, this check is incompatible
with using Allocator construction in the control block (upcoming change
as part of implementing P0674), so I'm removing it now to reduce the
upcoming diff as much as possible.
Differential Revision: https://reviews.llvm.org/D93246
This commit is a step towards making it easier to add support for arrays
in allocate_shared. Adding support for arrays will require writing multiple
functions, and the current complexity of writing allocate_shared is
prohibitive for understanding.
Differential Revision: https://reviews.llvm.org/D93130
In addition to making the code a lot easier to grasp by localizing many
helper functions to the only file where they are actually needed, this
will allow creating helper functions that depend on allocator_traits
outside of <memory>.
This is done as part of implementing array support in allocate_shared,
which requires non-trivial array initialization algorithms that would be
better to keep out of <memory> for sanity. It's also a first step towards
splitting up our monolithic headers into finer grained ones, which will
make it easier to reuse functionality across the library. For example,
it's just weird that we had to define `addressof` inside <type_traits>
to avoid circular dependencies -- instead it's better to implement those
in true helper headers.
Differential Revision: https://reviews.llvm.org/D93074
Everywhere, normalize the whitespace to `::new (EXPR) T`.
Everywhere, normalize the spelling of the cast to `(void*)EXPR`.
Without the cast to `(void*)`, the expression triggers ADL on GCC.
(I think this is a GCC bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98249)
Even if it doesn't trigger ADL, it still seems incorrect to use any argument
that's not exactly `(void*)` because that opens the possibility of overload
resolution picking a user-defined overload of `operator new`, which would be
wrong.
Differential Revision: https://reviews.llvm.org/D93153
This simplifies the implementation, and it appears to be equivalent since
make_shared was allocating memory with std::allocator anyway.
Differential Revision: https://reviews.llvm.org/D93071
This is the first of a series of patches leading up to the implementation
of P0674r1, i.e. array support in allocate_shared. I am splitting this
up into multiple patches because the overall change is very tricky and
I want to isolate potential breakage.
The static_assert in "libcxx/include/memory" was the main offender here,
but then I figured I might as well `git grep -i instantat` and fix all
the instances I found. One was in user-facing HTML documentation;
the rest were in comments or tests.
I used a lot of `git grep` to find places where `std::` was being used
outside of comments and assert-messages. There were three outcomes:
- Qualified function calls, e.g. `std::move` becomes `_VSTD::move`.
This is the most common case.
- Typenames that don't need qualification, e.g. `std::allocator` becomes `allocator`.
Leaving these as `_VSTD::allocator` would also be fine, but I decided
that removing the qualification is more consistent with existing practice.
- Names that specifically need un-versioned `std::` qualification,
or that I wasn't sure about. For example, I didn't touch any code in
<atomic>, <math.h>, <new>, or any ext/ or experimental/ headers;
and I didn't touch any instances of `std::type_info`.
In some deduction guides, we were accidentally using `class Alloc = typename std::allocator<T>`,
despite `std::allocator<T>`'s type-ness not being template-dependent.
Because `std::allocator` is a qualified name, this did parse as we intended;
but what we meant was simply `class Alloc = allocator<T>`.
Differential Revision: https://reviews.llvm.org/D92250
This reverts commit 620adacf87.
Fix: unsupport C++03 for the new test, define helpers before __swap_allocator
(1) Add _VSTD:: qualification to __swap_allocator.
(2) Add _VSTD:: qualification consistently to __to_address.
(3) Add some more missing _VSTD:: to <vector>, with a regression test.
This part is cleanup after d9a4f936d0.
Note that a vector whose allocator actually runs afoul of any of these ADL calls will
likely also run afoul of simple things like `v1 == v2` (which is also an ADL call).
But, still, libc++ should be consistent in qualifying function calls wherever possible.
Relevant blog post: https://quuxplusone.github.io/blog/2019/09/26/uglification-doesnt-stop-adl/
Differential Revision: https://reviews.llvm.org/D91708
Konstantin Varlamov