[libc++] Use __enable_if_t and is_integral in cstddef

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D126469

[libc++] Granularize parts of <type_traits>

`<type_traits>` is quite a large header, so I'll granularize it in a few steps.

Reviewed By: ldionne, #libc

Spies: libcxx-commits, mgorny

Differential

[libc++] Granularize parts of <type_traits>

`<type_traits>` is quite a large header, so I'll granularize it in a few steps.

Reviewed By: ldionne, #libc

Spies: libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124755

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[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 the ability to use the std::nullptr_t emulation in C++03 mode

Back in https://reviews.llvm.org/D109459, we stopped using the C++03
emulation for std::nullptr_t by default, which was

[libc++] Remove the ability to use the std::nullptr_t emulation in C++03 mode

Back in https://reviews.llvm.org/D109459, we stopped using the C++03
emulation for std::nullptr_t by default, which was an ABI break. We
still left a knob for users to turn it back on if they were broken by
the change, with a note that we would remove that knob after one release.

The time has now come to remove the knob and clean up the std::nullptr_t
emulation.

Differential Revision: https://reviews.llvm.org/D114786

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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++][NFC] Add namespace comments in ranges

With this patch there should be no more namespaces without closing comment

Reviewed By: ldionne, Quuxplusone, #libc

Spies: libcxx-commits

Differenti

[libc++][NFC] Add namespace comments in ranges

With this patch there should be no more namespaces without closing comment

Reviewed By: ldionne, Quuxplusone, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D118668

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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++] Add an option to disable wide character support in libc++

Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It

[libc++] Add an option to disable wide character support in libc++

Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.

Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.

Differential Revision: https://reviews.llvm.org/D111265

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[libc++][NFC] Remove #endif comments for really small conditionals on _LIBCPP_HAS_NO_UNICODE_CHARS

We generally don't put a comment on the #endif when the #if block is so small
that it's unambiguous

[libc++][NFC] Remove #endif comments for really small conditionals on _LIBCPP_HAS_NO_UNICODE_CHARS

We generally don't put a comment on the #endif when the #if block is so small
that it's unambiguous what the #endif refers to.

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[libc++] Use the using_if_exists attribute when provided

As discussed on cfe-dev [1], use the using_if_exists Clang attribute when
the compiler supports it. This makes it easier to port libc++ on to

[libc++] Use the using_if_exists attribute when provided

As discussed on cfe-dev [1], use the using_if_exists Clang attribute when
the compiler supports it. This makes it easier to port libc++ on top of
new platforms that don't fully support the C Standard library.

Previously, libc++ would fail to build when trying to import a missing
declaration in a <cXXXX> header. With the attribute, the declaration will
simply not be imported into namespace std, and hence it won't be available
for libc++ to use. In many cases, the declarations were *not* actually
required for libc++ to work (they were only surfaced for users to use
them as std::XXXX), so not importing them into namespace std is acceptable.

The same thing could be achieved by conscious usage of `#ifdef` along
with platform detection, however that quickly creates a maintenance
problem as libc++ is ported to new platforms. Furthermore, this problem
is exacerbated when mixed with vendor internal-only platforms, which can
lead to difficulties maintaining a downstream fork of the library.

For the time being, we only use the using_if_exists attribute when it
is supported. At some point in the future, we will start removing #ifdef
paths that are unnecessary when the attribute is supported, and folks
who need those #ifdef paths will be required to use a compiler that
supports the attribute.

[1]: http://lists.llvm.org/pipermail/cfe-dev/2020-June/066038.html

Differential Revision: https://reviews.llvm.org/D90257

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[libc++] s/_LIBCPP_NO_HAS_CHAR8_T/_LIBCPP_HAS_NO_CHAR8_T/g

This was raised in D94511.

Differential Revision: https://reviews.llvm.org/D100736

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

[libc++] Implement D2351R0 "Mark all library static cast wrappers as [[nodiscard]]"

These [[nodiscard]] annotations are added as a conforming extension;
it's unclear whether the paper will actually

[libc++] Implement D2351R0 "Mark all library static cast wrappers as [[nodiscard]]"

These [[nodiscard]] annotations are added as a conforming extension;
it's unclear whether the paper will actually be adopted and make them
mandatory, but they do seem like good ideas regardless.

https://isocpp.org/files/papers/D2351R0.pdf

This patch implements the paper's effect on:
- std::to_integer, std::to_underlying
- std::forward, std::move, std::move_if_noexcept
- std::as_const
- std::identity

The paper also affects (but libc++ does not yet have an implementation of):
- std::bit_cast

Differential Revision: https://reviews.llvm.org/D99895

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Avoid using std::max_align_t in pre-C++11 mode

Always depend on the compiler to have a correct implementation of
max_align_t in stddef.h and don't provide a fallback. For pre-C++11,
require __STDCPP

Avoid using std::max_align_t in pre-C++11 mode

Always depend on the compiler to have a correct implementation of
max_align_t in stddef.h and don't provide a fallback. For pre-C++11,
require __STDCPP_NEW_ALIGNMENT__ in <new> as provided by clang in all
standard modes. Adjust test cases to avoid testing or using max_align_t
in pre-C++11 mode and also to better deal with alignof(max_align_t)>16.
Document requirements of the alignment tests around natural alignment of
power-of-two-sized types.

Differential revision: https://reviews.llvm.org/D73245

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[libc++] Revert 03dd205c151 "Adjust max_align_t handling"

That commit was made without approval from a libc++ reviewer, and it
also broke the build in C++03 mode.

Adjust max_align_t handling

Depend on the compiler to provide a correct implementation of
max_align_t. If __STDCPP_NEW_ALIGNMENT__ is missing and C++03 mode has
been explicitly enabled, provide a mi

Adjust max_align_t handling

Depend on the compiler to provide a correct implementation of
max_align_t. If __STDCPP_NEW_ALIGNMENT__ is missing and C++03 mode has
been explicitly enabled, provide a minimal fallback in <new> as
alignment of the largest primitive types.

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[libc++] Remove cycle between <type_traits> and <cstddef>

This was caused by byte depending on traits. This patch moves
the minimal amount of meta-programming into <cstddef> to break the cycle.

Update more file headers across all of the LLVM projects in the monorepo
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.

We understand that

Update more file headers across all of the LLVM projects in the monorepo
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351648

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Implement the infrastructure for feature-test macros. Very few actual feature test macros, though. Reviewed as: https://reviews.llvm.org/D51955

llvm-svn: 342073

Teach libc++ to use native NetBSD's max_align_t

Summary:
The NetBSD headers ship with max_align_t, that is not
compatible with the fallback version in libc++.

There is no defined a compiler specifi

Teach libc++ to use native NetBSD's max_align_t

Summary:
The NetBSD headers ship with max_align_t, that is not
compatible with the fallback version in libc++.

There is no defined a compiler specific symbol in the headers like:
- __CLANG_MAX_ALIGN_T_DEFINED
- _GCC_MAX_ALIGN_T
- __DEFINED_max_align_t

Sponsored by <The NetBSD Foundation>

Reviewers: chandlerc, dlj, EricWF, joerg

Reviewed By: joerg

Subscribers: bsdjhb, llvm-commits, cfe-commits

Differential Revision: https://reviews.llvm.org/D47814

llvm-svn: 340224

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[NFC][libc++] Consistently use spaces to indent

rdar://problem/19988944

llvm-svn: 338933

Implement LWG2950: std::byte operations are misspecified

llvm-svn: 318125

Implement P0298R3: 'std::byte'. Reviewed as https://reviews.llvm.org/D31022

llvm-svn: 298689

Check for musl-libc's max_align_t in addition to other variants.

Summary:
Libcxx will define its own max_align_t when it is not available. However, the
availability checks today only check for Clang

Check for musl-libc's max_align_t in addition to other variants.

Summary:
Libcxx will define its own max_align_t when it is not available. However, the
availability checks today only check for Clang's definition and GCC's
definition. In particular, it does not check for musl's definition, which is the
same as GCC's but guarded with a different macro.

Reviewers: mclow.lists, EricWF

Reviewed By: EricWF

Subscribers: chandlerc, cfe-commits

Differential Revision: https://reviews.llvm.org/D28478

llvm-svn: 294683

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PR25118: move system_header pragma before uses of include_next to avoid extension warnings for people finding libc++ headers via -I paths.

llvm-svn: 249788