[libc++] Implement P0174R2 (Deprecating Vestigial Library Parts in C++17)

Reviewed By: ldionne, Mordante, #libc

Spies: jwakely, libcxx-commits

Differential Revision: https://reviews.llvm.org/D1273

[libc++] Implement P0174R2 (Deprecating Vestigial Library Parts in C++17)

Reviewed By: ldionne, Mordante, #libc

Spies: jwakely, libcxx-commits

Differential Revision: https://reviews.llvm.org/D127387

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[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 erro

[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

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[libc++] Implement P0401R6 (allocate_at_least)

Reviewed By: ldionne, var-const, #libc

Spies: mgorny, libcxx-commits, arichardson

Differential Revision: https://reviews.llvm.org/D122877

Revert "[libc++] Remove extension to support allocator<const T>"

This reverts commit 276ca873. That commit has quite a history at this
point. It was first landed in dbc647643577, which broke std::sh

Revert "[libc++] Remove extension to support allocator<const T>"

This reverts commit 276ca873. That commit has quite a history at this
point. It was first landed in dbc647643577, which broke std::shared_ptr<T const>
and was reverted in 9138666f5. It was then re-applied in 276ca873, with
the std::shared_ptr issue fixed, but it caused widespread breakage at
Google (which suggests it would cause similar breakage in the wild too),
so now I'm reverting again.

Instead, I will add a escape hatch that vendors can turn on to enable
the extension and perform a phased transition over one or two releases
like we sometimes do when things become non-trivial.

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[libc++] Remove extension to support allocator<const T>

This extension is a portability trap for users, since no other standard
library supports it. Furthermore, the Standard explicitly allows
imple

[libc++] Remove extension to support allocator<const T>

This extension is a portability trap for users, since no other standard
library supports it. Furthermore, the Standard explicitly allows
implementations to reject std::allocator<cv T>, so allowing it is
really going against the current.

This was discovered in D120684: this extension required `const_cast`ing
in `__construct_range_forward`, a fishy bit of code that can be removed
if we don't support the extension anymore.

This is a re-application of dbc647643577, which was reverted in 9138666f5
because it broke std::shared_ptr<T const>. Tests have now been added and
we've made sure that std::shared_ptr<T const> wouldn't be broken in this
version.

Differential Revision: https://reviews.llvm.org/D120996

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Revert "[libc++] Remove extension to support allocator<const T>"

This reverts commit bed3240bf7d196a17cc31f1c5b59b4721017e638.

I will need to add more tests for std::shared_ptr<T const> before
re-l

Revert "[libc++] Remove extension to support allocator<const T>"

This reverts commit bed3240bf7d196a17cc31f1c5b59b4721017e638.

I will need to add more tests for std::shared_ptr<T const> before
re-landing this.

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[libc++] Remove extension to support allocator<const T>

This extension is a portability trap for users, since no other standard
library supports it. Furthermore, the Standard explicitly allows
imple

[libc++] Remove extension to support allocator<const T>

This extension is a portability trap for users, since no other standard
library supports it. Furthermore, the Standard explicitly allows
implementations to reject std::allocator<cv T>, so allowing it is
really going against the current.

This was discovered in D120684: this extension required `const_cast`ing
in `__construct_range_forward`, a fishy bit of code that can be removed
if we don't support the extension anymore.

Differential Revision: https://reviews.llvm.org/D120996

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[libc++] Revert "Protect users from relying on detail headers" & related changes

This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9,
which were related to the original commit).

[libc++] Revert "Protect users from relying on detail headers" & related changes

This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9,
which were related to the original commit). As landed, 5aaefa51 had
unintended consequences on some downstream bots and didn't have proper
coverage upstream due to a few subtle things. Implementing this is
something we should do in libc++, however we'll first need to address
a few issues listed in https://reviews.llvm.org/D106124#3349710.

Differential Revision: https://reviews.llvm.org/D120683

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[libcxx][modules] protects users from relying on detail headers

libc++ has started splicing standard library headers into much more
fine-grained content for maintainability. It's very likely that ou

[libcxx][modules] protects users from relying on detail headers

libc++ has started splicing standard library headers into much more
fine-grained content for maintainability. It's very likely that outdated
and naive tooling (some of which is outside of LLVM's scope) will
suggest users include things such as <__ranges/access.h> instead of
<ranges>, and Hyrum's law suggests that users will eventually begin to
rely on this without the help of tooling. As such, this commit
intends to protect users from themselves, by making it a hard error for
anyone outside of the standard library to include libc++ detail headers.

Differential Revision: https://reviews.llvm.org/D106124

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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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[libc++] Remove _LIBCPP_DEFAULT

clang has `= default` as an extension in c++03, so just use it.

Reviewed By: ldionne, Quuxplusone, #libc

Spies: libcxx-commits

Differential Revision: https://revie

[libc++] Remove _LIBCPP_DEFAULT

clang has `= default` as an extension in c++03, so just use it.

Reviewed By: ldionne, Quuxplusone, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D115275

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[libcxx] Make allocator<T>:allocate throw bad_array_new_length

Currently the member functions std::allocator<T>::allocate,
std::experimental::pmr::polymorphic_allocator::allocate and
std::resource_a

[libcxx] Make allocator<T>:allocate throw bad_array_new_length

Currently the member functions std::allocator<T>::allocate,
std::experimental::pmr::polymorphic_allocator::allocate and
std::resource_adaptor<T>::do_allocate throw an exception of type
std::length_error when the requested size exceeds the maximum size.

According to the C++ standard ([allocator.members]/4,
[mem.poly.allocator.mem]/1), std::allocator<T>::allocate and
std::pmr::polymorphic_allocator::allocate must throw a
std::bad_array_new_length exception in this case.

The patch fixes the issue with std::allocator<T>::allocate and changes
the type the exception thrown by
std::experimental::pmr::resource_adaptor<T>::do_allocate to
std::bad_array_new_length as well for consistency.

The patch resolves LWG 3237, LWG 3038 and LWG 3190.

Reviewed By: ldionne, #libc, Quuxplusone

Differential Revision: https://reviews.llvm.org/D110846

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[libc++] Disallow volatile types in std::allocator

LWG 2447 is marked as `Complete`, but there is no `static_assert` to
reject volatile types in `std::allocator`. See the discussion at
https://revie

[libc++] Disallow volatile types in std::allocator

LWG 2447 is marked as `Complete`, but there is no `static_assert` to
reject volatile types in `std::allocator`. See the discussion at
https://reviews.llvm.org/D108856.

Add `static_assert` in `std::allocator` to disallow volatile types. Since this
is an implementation choice, mark the binding test as `libc++` only.

Remove tests that use containers backed by `std::allocator` that test
the container when used with a volatile type.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D109056

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[libc++][NFC] Remove useless _LIBCPP_PUSH_MACROS

Only files that actually use min/max are required to do this dance.

Differential Revision: https://reviews.llvm.org/D108778

[libcxx][modularisation] moves <utility> content out of <type_traits>

Moves:

* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
`__utility/${FUNCTION_NAME}`.
* `std::swap_ranges`

[libcxx][modularisation] moves <utility> content out of <type_traits>

Moves:

* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
`__utility/${FUNCTION_NAME}`.
* `std::swap_ranges` and `std::iter_swap` into
`__algorithm/${FUNCTION_NAME}`

Differential Revision: https://reviews.llvm.org/D103734

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[libc++] Make sure std::allocator<void> is always trivial

When we removed the allocator<void> specialization, the triviality of
std::allocator<void> changed because the primary template had a
non-tr

[libc++] Make sure std::allocator<void> is always trivial

When we removed the allocator<void> specialization, the triviality of
std::allocator<void> changed because the primary template had a
non-trivial default constructor and the specialization didn't
(so std::allocator<void> went from trivial to non-trivial).

This commit fixes that oversight by giving a trivial constructor to
the primary template when instantiated on cv-void.

This was reported in https://llvm.org/PR50299.

Differential Revision: https://reviews.llvm.org/D104398

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[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
w

[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

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Revert "[libcxx][module-map] creates submodules for private headers"

This reverts commit f1417eb9b1f51b689c78dd8cb0114c1749dd2845 as it
uncovered a Clang bug PR50592.

[libcxx][module-map] creates submodules for private headers

Most of our private headers need to be treated as submodules so that
Clang modules can export things correctly. Previous commits that spli

[libcxx][module-map] creates submodules for private headers

Most of our private headers need to be treated as submodules so that
Clang modules can export things correctly. Previous commits that split
monolithic headers into smaller chunks were unaware of this requirement,
and so this is being addressed in one fell swoop. Moving forward, most
new headers will need to have their own submodule (anything that's
conditionally included is exempt from this rule, which means `__support`
headers aren't made into submodules).

This hasn't been marked NFC, since I'm not 100% sure that's the case.

Differential Revision: https://reviews.llvm.org/D103551

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

[libc++] Split std::allocator out of <memory>

Differential Revision: https://reviews.llvm.org/D100216