[libc++][NFC] Replace enable_if with __enable_if_t in a few places

Reviewed By: ldionne, #libc

Spies: jloser, libcxx-commits

Differential Revision: https://reviews.llvm.org/D128400

[libc++] Re-add transitive includes that had been removed since LLVM 14

This commit re-adds transitive includes that had been removed by
4cd04d1687f1, c36870c8e79c, a83f4b9cda57, 1458458b558d, 2e2f3

[libc++] Re-add transitive includes that had been removed since LLVM 14

This commit re-adds transitive includes that had been removed by
4cd04d1687f1, c36870c8e79c, a83f4b9cda57, 1458458b558d, 2e2f3158c604,
and 489637e66dd3. This should cover almost all the includes that had
been removed since LLVM 14 and that would contribute to breaking user
code when releasing LLVM 15.

It is possible to disable the inclusion of these headers by defining
_LIBCPP_REMOVE_TRANSITIVE_INCLUDES. The intent is that vendors will
enable that macro and start fixing downstream issues immediately. We
can then remove the macro (and the transitive includes) by default in
a future release. That way, we will break users only once by removing
transitive includes in bulk instead of doing it bit by bit a every
release, which is more disruptive for users.

Note 1: The set of headers to re-add was found by re-generating the
transitive include test on a checkout of release/14.x, which
provided the list of all transitive includes we used to provide.

Note 2: Several includes of <vector>, <optional>, <array> and <unordered_map>
have been added in this commit. These transitive inclusions were
added when we implemented boyer_moore_searcher in <functional>.

Note 3: This is a best effort patch to try and resolve downstream breakage
caused since branching LLVM 14. I wasn't able to perfectly mirror
transitive includes in LLVM 14 for a few headers, so I added a
release note explaining it. To summarize, adding boyer_moore_searcher
created a bunch of circular dependencies, so we have to break
backwards compatibility in a few cases.

Differential Revision: https://reviews.llvm.org/D128661

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[libc++] Mark standard-mandated includes as such

Reviewed By: ldionne, Mordante, #libc, saugustine

Spies: saugustine, MaskRay, arichardson, mstorsjo, jloser, libcxx-commits, arphaman

Differential

[libc++] Mark standard-mandated includes as such

Reviewed By: ldionne, Mordante, #libc, saugustine

Spies: saugustine, MaskRay, arichardson, mstorsjo, jloser, libcxx-commits, arphaman

Differential Revision: https://reviews.llvm.org/D127953

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[libc++] Removes unneeded <iterator> includes.

Reviewed By: #libc, philnik

Differential Revision: https://reviews.llvm.org/D127675

[libc++] Granularize <iterator> includes

Reviewed By: ldionne, #libc

Spies: libcxx-commits, wenlei

Differential Revision: https://reviews.llvm.org/D127445

[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 publ

[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

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[libc++] Remove <utility> includes

Reviewed By: ldionne, Quuxplusone, #libc

Spies: libcxx-commits, arphaman

Differential Revision: https://reviews.llvm.org/D121054

[libc++] Granularize <utility> includes

Reviewed By: ldionne, #libc

Spies: EricWF, libcxx-commits, arphaman

Differential Revision: https://reviews.llvm.org/D120466

[libc++] Move everything related solely to _LIBCPP_ASSERT to its own file

This is the first step towards disentangling the debug mode and assertions
in libc++. This patch doesn't make any functional

[libc++] Move everything related solely to _LIBCPP_ASSERT to its own file

This is the first step towards disentangling the debug mode and assertions
in libc++. This patch doesn't make any functional change: it simply moves
_LIBCPP_ASSERT-related stuff to its own file so as to make it clear that
libc++ assertions and the debug mode are different things. Future patches
will make it possible to enable assertions without enabling the debug
mode.

Differential Revision: https://reviews.llvm.org/D119769

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[libc++] Granularize algorithm includes

Reviewed By: Mordante, ldionne, Quuxplusone, #libc, #libc_abi

Spies: #libc_vendors, libcxx-commits, miyuki

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

[libc++] Granularize algorithm includes

Reviewed By: Mordante, ldionne, Quuxplusone, #libc, #libc_abi

Spies: #libc_vendors, libcxx-commits, miyuki

Differential Revision: https://reviews.llvm.org/D119667

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[libc++] Implement P0627R6 (Function to mark unreachable code)

Reviewed By: ldionne, Quuxplusone, #libc

Spies: arichardson, mstorsjo, libcxx-commits, mgorny

Differential Revision: https://reviews.

[libc++] Implement P0627R6 (Function to mark unreachable code)

Reviewed By: ldionne, Quuxplusone, #libc

Spies: arichardson, mstorsjo, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D119152

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[libc++] Normalize all our '#pragma GCC system_header', and regression-test.

Now we'll notice if a header forgets to include this magic phrase.

Differential Revision: https://reviews.llvm.org/D1188

[libc++] Normalize all our '#pragma GCC system_header', and regression-test.

Now we'll notice if a header forgets to include this magic phrase.

Differential Revision: https://reviews.llvm.org/D118800

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[runtimes][NFC] Remove filenames at the top of the license notice

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 st

[runtimes][NFC] Remove filenames at the top of the license notice

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.

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[libc++] Use enable_if_t instead of _EnableIf

I just ran into a compiler error involving __bind_back and some overloads
that were being disabled with _EnableIf. I noticed that the error message
was

[libc++] Use enable_if_t instead of _EnableIf

I just ran into a compiler error involving __bind_back and some overloads
that were being disabled with _EnableIf. I noticed that the error message
was quite bad and did not mention the reason for the overload being
excluded. Specifically, the error looked like this:

candidate template ignored: substitution failure [with _Args =
<ContiguousView>]: no member named '_EnableIfImpl' in 'std::_MetaBase<false>'

Instead, when using enable_if or enable_if_t, the compiler is clever and
can produce better diagnostics, like so:

candidate template ignored: requirement 'is_invocable_v<
std::__bind_back_op<1, std::integer_sequence<unsigned long, 0>>,
std::ranges::views::__transform::__fn &, std::tuple<PlusOne> &,
ContiguousView>' was not satisfied [with _Args = <ContiguousView>]

Basically, it tries to do a poor man's implementation of concepts, which
is already a lot better than simply complaining about substitution failure.

Hence, this commit uses enable_if_t instead of _EnableIf whenever
possible. That is both more straightforward than using the internal
helper, and also leads to better error messages in those cases.

I understand the motivation for _EnableIf's implementation was to improve
compile-time performance, however I believe striving to improve error
messages is even more important for our QOI, hence this patch. Furthermore,
it is unclear that _EnableIf actually improved compile-time performance
in any noticeable way (see discussion in the review for details).

Differential Revision: https://reviews.llvm.org/D108216

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[libc++] Remove workarounds for the lack of deduction guides in C++17

All supported compilers have supported deduction guides in C++17 for a
while, so this isn't necessary anymore.

Differential Rev

[libc++] Remove workarounds for the lack of deduction guides in C++17

All supported compilers have supported deduction guides in C++17 for a
while, so this isn't necessary anymore.

Differential Revision: https://reviews.llvm.org/D108213

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[libc++] Alphabetize and include-what-you-use. NFCI.

Differential Revision: https://reviews.llvm.org/D102781

[libc++] NFC: Normalize `#endif //` comment indentation

[libc++] ADL-proof vector<bool> by adding _VSTD:: qualification on calls.

This affects only vectors with weird/malicious allocators,
the same corner case covered in D91708, but for `vector<bool>` th

[libc++] ADL-proof vector<bool> by adding _VSTD:: qualification on calls.

This affects only vectors with weird/malicious allocators,
the same corner case covered in D91708, but for `vector<bool>` this time.

Also ADL-proof <__tree>, which affects only sets and maps with weird/malicious
allocators where the ADL trap is in the *fancy pointer type*.

Also drive-by _VSTD:: qualification in the guts of std::bind,
std::packaged_task, std::condition_variable.

Differential Revision: https://reviews.llvm.org/D93424

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[libc++] Consistently replace `std::` qualification with `_VSTD::` or nothing. NFCI.

I used a lot of `git grep` to find places where `std::` was being used
outside of comments and assert-messages. T

[libc++] Consistently replace `std::` qualification with `_VSTD::` or nothing. NFCI.

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

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[libc++] Remove some workarounds for C++03

We don't support any compiler that doesn't support variadics and rvalue
references in C++03 mode, so these workarounds can be dropped. There's
still *a lot

[libc++] Remove some workarounds for C++03

We don't support any compiler that doesn't support variadics and rvalue
references in C++03 mode, so these workarounds can be dropped. There's
still *a lot* of cruft related to these workarounds, but I try to tackle
a bit of it here and there.

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[libc++] Add assertions on OOB accesses in std::array when the debug mode is enabled

Like we do for empty std::array, make sure we have assertions in place
for obvious out-of-bounds issues in std::a

[libc++] Add assertions on OOB accesses in std::array when the debug mode is enabled

Like we do for empty std::array, make sure we have assertions in place
for obvious out-of-bounds issues in std::array when the debug mode is
enabled (which isn't by default).

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[libc++] NFC: Minor refactoring in std::array

[libc++] Fix issues with the triviality of std::array

The Standard is currently unimplementable. We have to pick between:

1. Not implementing constexpr support properly in std::array<T, 0>
2. Makin

[libc++] Fix issues with the triviality of std::array

The Standard is currently unimplementable. We have to pick between:

1. Not implementing constexpr support properly in std::array<T, 0>
2. Making std::array<T, 0> non-trivial even when T is trivial
3. Returning nullptr from std::array<T, 0>::begin()

Libc++ initially picked (1). In 77b9abfc8e89, we started implementing constexpr properly, but lost the guarantee of triviality. Since it seems like both (1) and (2) are really important, it seems like (3) is the only viable option for libc++, after all. This is also what other implementations are doing.

This patch moves libc++ from (1) to (3).

It also:
- Improves the test coverage for the various ways of initializing std::array
- Adds tests for the triviality of std::array
- Adds tests for the aggregate-ness of std::array

Reviewed By: #libc, miscco, EricWF, zoecarver

Differential Revision: https://reviews.llvm.org/D80821

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[libc++] Complete overhaul of constexpr support in std::array

This commit adds missing support for constexpr in std::array under all
standard modes up to and including C++20. It also transforms the

[libc++] Complete overhaul of constexpr support in std::array

This commit adds missing support for constexpr in std::array under all
standard modes up to and including C++20. It also transforms the <array>
tests to check for constexpr-friendliness under the right standard modes.

Fixes https://llvm.org/PR40124
Fixes rdar://57522096
Supersedes https://reviews.llvm.org/D60666

Differential Revision: https://reviews.llvm.org/D80452

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[libc++] NFC: Inline array<T,N>::at methods inside the class

All other methods are defined in the class, so this increases consistency.