[libc++][modules] Fix missing and incorrect includes (#108850)

This patch adds a large number of missing includes in the libc++ headers
and the test suite. Those were found as part of the effort to

[libc++][modules] Fix missing and incorrect includes (#108850)

This patch adds a large number of missing includes in the libc++ headers
and the test suite. Those were found as part of the effort to move
towards a mostly monolithic top-level std module.

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[libc++][NFC] Use [[__nodiscard__]] unconditionally (#80454)

`__has_cpp_attribute(__nodiscard__)` is always true now, so we might as
well replace `_LIBCPP_NODISCARD`. It's one less macro that can r

[libc++][NFC] Use [[__nodiscard__]] unconditionally (#80454)

`__has_cpp_attribute(__nodiscard__)` is always true now, so we might as
well replace `_LIBCPP_NODISCARD`. It's one less macro that can result in
bad diagnostics.

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[libc++] Speed up set_intersection() by fast-forwarding over ranges of non-matching elements with one-sided binary search. (#75230)

One-sided binary search, aka meta binary search, has been in the p

[libc++] Speed up set_intersection() by fast-forwarding over ranges of non-matching elements with one-sided binary search. (#75230)

One-sided binary search, aka meta binary search, has been in the public
domain for decades, and has the general advantage of being constant time
in the best case, with the downside of executing at most 2*log(N)
comparisons vs classic binary search's exact log(N). There are two
scenarios in which it really shines: the first one is when operating
over non-random-access iterators, because the classic algorithm requires
knowing the container's size upfront, which adds N iterator increments
to the complexity. The second one is when traversing the container in
order, trying to fast-forward to the next value: in that case the
classic algorithm requires at least O(N*log(N)) comparisons and, for
non-random-access iterators, O(N^2) iterator increments, whereas the
one-sided version will yield O(N) operations on both counts, with a
best-case of O(log(N)) comparisons which is very common in practice.

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[libc++] Fix missing and incorrect push/pop macros (#79204)

We recently noticed that the unwrap_iter.h file was pushing macros, but
it was pushing them again instead of popping them at the end of t

[libc++] Fix missing and incorrect push/pop macros (#79204)

We recently noticed that the unwrap_iter.h file was pushing macros, but
it was pushing them again instead of popping them at the end of the
file. This led to libc++ basically swallowing any custom definition of
these macros in user code:

#define min HELLO
#include <algorithm>
// min is not HELLO anymore, it's not defined

While investigating this issue, I noticed that our push/pop pragmas were
actually entirely wrong too. Indeed, instead of pushing macros like
`move`, we'd push `move(int, int)` in the pragma, which is not a valid
macro name. As a result, we would not actually push macros like `move`
-- instead we'd simply undefine them. This led to the following code not
working:

#define move HELLO
#include <algorithm>
// move is not HELLO anymore

Fixing the pragma push/pop incantations led to a cascade of issues
because we use identifiers like `move` in a large number of places, and
all of these headers would now need to do the push/pop dance.

This patch fixes all these issues. First, it adds a check that we don't
swallow important names like min, max, move or refresh as explained
above. This is done by augmenting the existing
system_reserved_names.gen.py test to also check that the macros are what
we expect after including each header.

Second, it fixes the push/pop pragmas to work properly and adds missing
pragmas to all the files I could detect a failure in via the newly added
test.

rdar://121365472

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[libc++] Refactor __less

This simplifies the usage of `__less` by making the class not depend on the types compared, but instead the `operator()`. We can't remove the template completely because we

[libc++] Refactor __less

This simplifies the usage of `__less` by making the class not depend on the types compared, but instead the `operator()`. We can't remove the template completely because we explicitly instantiate `std::__sort` with `__less<T>`.

Reviewed By: ldionne, #libc

Spies: arichardson, EricWF, libcxx-commits, mgrang

Differential Revision: https://reviews.llvm.org/D145285

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[libc++][NFC] Prefer type aliases over structs

Reviewed By: ldionne, #libc

Spies: sstefan1, libcxx-commits, jeroen.dobbelaere

Differential Revision: https://reviews.llvm.org/D134901

[libc++][NFC] Rename the constexpr macros

This was discussed on Discord with the consensus that we should rename the macros.

Reviewed By: ldionne, Mordante, var-const, avogelsgesang, jloser, #libc

[libc++][NFC] Rename the constexpr macros

This was discussed on Discord with the consensus that we should rename the macros.

Reviewed By: ldionne, Mordante, var-const, avogelsgesang, jloser, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D131498

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[libc++][ranges] implement `std::ranges::set_symmetric_difference`

[libc++][ranges] implement `std::ranges::set_symmetric_difference`

Differential Revision: https://reviews.llvm.org/D129520

[libc++] Implement ranges::find_end, ranges::search{, _n}

Reviewed By: var-const, #libc, huixie90

Spies: thakis, h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews

[libc++] Implement ranges::find_end, ranges::search{, _n}

Reviewed By: var-const, #libc, huixie90

Spies: thakis, h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124079

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Revert "[libc++] Implement ranges::find_end, ranges::search{, _n}"

This reverts commit 76a76518507ccc59ccdad5b83f44dc8c3d9593c7.

[libc++] Implement ranges::find_end, ranges::search{, _n}

Reviewed By: var-const, #libc, huixie90

Spies: h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.or

[libc++] Implement ranges::find_end, ranges::search{, _n}

Reviewed By: var-const, #libc, huixie90

Spies: h-vetinari, huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D124079

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[lib++][ranges][NFC] Refactor `iterator_operations.h` to use tags.

Change the mechanism in `iterator_operations.h` to pass around a generic
policy tag indicating whether an internal function is bein

[lib++][ranges][NFC] Refactor `iterator_operations.h` to use tags.

Change the mechanism in `iterator_operations.h` to pass around a generic
policy tag indicating whether an internal function is being invoked from
a "classic" STL algorithm or a ranges algorithm. `IterOps` is now
a template class specialized on the policy tag.

The advantage is that this mechanism is more generic and allows defining
arbitrary conditions in a clean manner.

Also add a few more iterator functions to `IterOps`.

Differential Revision: https://reviews.llvm.org/D129390

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[libc++] Rename variables to use the snake case instead of camel case

For some reason the pre-commit CI of https://reviews.llvm.org/D129233 was all green so I didn't spot this
https://reviews.llvm.o

[libc++] Rename variables to use the snake case instead of camel case

For some reason the pre-commit CI of https://reviews.llvm.org/D129233 was all green so I didn't spot this
https://reviews.llvm.org/B174525

Reviewed By: #libc, philnik, Mordante

Differential Revision: https://reviews.llvm.org/D129503

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[libc++][ranges] implement `std::ranges::set_intersection`

implement `std::ranges::set_intersection` by reusing the classic `std::set_intersenction`
added unit tests

Differential Revision: https://

[libc++][ranges] implement `std::ranges::set_intersection`

implement `std::ranges::set_intersection` by reusing the classic `std::set_intersenction`
added unit tests

Differential Revision: https://reviews.llvm.org/D129233

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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++] Alphabetize header #includes. NFCI.

The NFC part of D116809. We still want to enforce this in CI,
but the mechanism for that is still to-be-determined.

Differential Revision: https://revie

[libc++] Alphabetize header #includes. NFCI.

The NFC part of D116809. We still want to enforce this in CI,
but the mechanism for that is still to-be-determined.

Differential Revision: https://reviews.llvm.org/D116809

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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] Move all algorithms into their own headers

This is a fairly mechanical change, it just moves each algorithm into
its own header. This is intended to be a NFC.

This commit re-applies 7ed7d4

[libcxx] Move all algorithms into their own headers

This is a fairly mechanical change, it just moves each algorithm into
its own header. This is intended to be a NFC.

This commit re-applies 7ed7d4ccb899, which was reverted in 692d7166f771
because the Modules build got broken. The modules build has now been
fixed, so we're re-committing this.

Differential Revision: https://reviews.llvm.org/D103583

Attribution note
----------------
I'm only committing this. This commit is a mix of D103583, D103330 and
D104171 authored by:

Co-authored-by: Christopher Di Bella <cjdb@google.com>
Co-authored-by: zoecarver <z.zoelec2@gmail.com>

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[libcxx][gardening] Move all algorithms into their own headers.

This is a fairly mechanical change, it just moves each algorithm into its own header. This is a NFC.

Note: during this change, I burn

[libcxx][gardening] Move all algorithms into their own headers.

This is a fairly mechanical change, it just moves each algorithm into its own header. This is a NFC.

Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."

Differential Revision: https://reviews.llvm.org/D103583

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