We currently have a custom utility `__reverse_range`, which does
basically the same thing as `views::reverse` and the only place where we
use it is in `ranges::reverse_copy`. Instead of this special utility, we
can simply use `views::reverse`.
This has originally been introduced due to compile time concerns.
However, there doesn't seem to actually be a significant compile time
regression overall.
Create a new `__capacity_aware_iterator` iterator type which wraps an
existing iterator, takes its container as a template parameter, and
encodes the maximum amount of elements the container can hold. The main
objective is to prevent iterator mixups between different containers
(e.g. `vector`).
Resolves#148131
- Unlock `std::optional<T&>` implementation
- Allow instantiations of `optional<T(&)(...)>` and `optional<T(&)[]>`
but disables `value_or()` and `optional::iterator` + all `iterator`
related functions
- Update documentation
- Update tests
This patch does two things.
(1) It replaces SFINAE with `if constexpr`, avoiding some overload
resolution and unnecessary boilerplate.
(2) It removes an overload from `__for_each_n` to forward to
`__for_each`, since `__for_each` doesn't provide any further
optimizations.
We've built up quite a few links directly to github within the code
base. We should instead use `llvm.org/PR<issue-number>` to link to bugs,
since that is resilient to the bug tracker changing in the future. This
is especially relevant for tests linking to bugs, since they will
probably be there for decades to come. A nice side effect is that these
links are significantly shorter than the GH links, making them much less
of an eyesore.
This patch also replaces a few links that linked to the old bugzilla
instance on llvm.org.
Currently `_LIBCPP_NO_ITERATOR_BASES` controls both whether specific
classes derive from `iterator` and whether `reverse_iterator` has a
second member variable. These two changes are orthogonal though, and one
can be applied in all langauge modes while the other change is only
conforming for C++17 and later.
Resolves#105430
- Implement all required pieces of P3168R2
- Leverage existing `wrap_iter` and `bounded_iter` classes to implement
the `optional` regular and hardened iterator type, respectively
- Update documentation to match
Fixes#108624
This allows `flat_map::insert(Iter, Iter)` to directly forward to
underlying containers' `insert(Iter, Iter)`, instead of inserting one
element at a time, when input models "product iterator". atm,
`flat_map::iterator` and `zip_view::iterator` are "product iterator"s.
This gives about almost 10x speed up in my benchmark with -03 (for both
before and after)
```cpp
Benchmark Time CPU Time Old Time New CPU Old CPU New
-----------------------------------------------------------------------------------------------------------------------------------------------
flat_map::insert_product_iterator_flat_map/32 -0.5028 -0.5320 149 74 149 70
flat_map::insert_product_iterator_flat_map/1024 -0.8617 -0.8618 3113 430 3112 430
flat_map::insert_product_iterator_flat_map/8192 -0.8877 -0.8877 26682 2995 26679 2995
flat_map::insert_product_iterator_flat_map/65536 -0.8769 -0.8769 226235 27844 226221 27841
flat_map::insert_product_iterator_zip/32 -0.5844 -0.5844 162 67 162 67
flat_map::insert_product_iterator_zip/1024 -0.8754 -0.8754 3427 427 3427 427
flat_map::insert_product_iterator_zip/8192 -0.8934 -0.8934 28134 3000 28132 3000
flat_map::insert_product_iterator_zip/65536 -0.8783 -0.8783 229783 27960 229767 27958
OVERALL_GEOMEAN -0.8319 -0.8332 0 0 0 0
```
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
`__has_iterator_typedefs` is only used in the up-to-C++17 implementation
of `type_traits`. To make that clearer the struct is moved into that
code block.
`_ITER_TRAITS` and `_ITER_CONCEPT` are really implenentation details of
`<__iterator/concetps.h>`, so it makes more sense to put them there than
into `<__iterator/iterator_traits.h>`.
Fixes#135351
This PR update CATD guides to associative containers (`std::map`,
`std::multimap`, `std::unordered_map`, `std::unordered_multimap`,
`std::flat_map`, `std::flat_multimap`).
- Updated template alias for deduction guides for the relevant
associative containers.
- Added a new test to verify the deduction guides with `std::map`,
`std::multimap`, `std::unordered_map`, `std::unordered_multimap`,
`std::flat_map`, `std::flat_multimap`.
This patch enhances the performance of `std::for_each_n` when used with
segmented iterators, leading to significant performance improvements,
summarized in the tables below. This addresses a subtask of
https://github.com/llvm/llvm-project/issues/102817.
The std::advance function has a clear precondition that it can only be
called with a negative distance when a bidirectional iterator is used.
However, prev() and next() don't have such preconditions explicitly,
they inherit it from calling advance().
This patch removes assertions in prev() and next() that were duplicates
of similar ones in advance(), and removes a copy-pasted comment that was
trying to justify the use of _LIBCPP_ASSERT_PEDANTIC but IMO is creating
confusion with little benefit.
Requirements on character-like types are updated unconditionally,
because `basic_string` does requires the default-constructibility. It
might be possible to make `basic_string_view` support classes with
non-public trivial default constructor, but this doesn't seem sensible.
libcxxabi's `ItaniumDemangle.h` is also updated to avoid deprecated
features.
This set usage of operator& instead of std::addressof seems not be easy
to "abuse". Some seem easy to misuse, like basic_ostream::operator<<,
trying to do that results in compilation errors since the `widen`
function is not specialized for the hijacking character type. Hence
there are no tests.
This PR restricts construction to cases where reference types of
source/destination iterators are (`T&`, `T&`) or (`T&`, `const T&`) (
where `T` can be const).
Fixes#50058.
We can't `static_assert` `__libcpp_is_contiguous_iterator` for
`__wrap_iter` currently because `__wrap_iter` is also used for wrapping
user-defined fancy pointers.
Fixes#115002.
This patch introduces a new kind of bounded iterator that knows the size
of its valid range at compile-time, as in std::array. This allows computing
the end of the range from the start of the range and the size, which requires
storing only the start of the range in the iterator instead of both the start
and the size (or start and end). The iterator wrapper is otherwise identical
in design to the existing __bounded_iter.
Since this requires changing the type of the iterators returned by
std::array, this new bounded iterator is controlled by an ABI flag.
As a drive-by, centralize the tests for std::array::operator[] and add
missing tests for OOB operator[] on non-empty arrays.
Fixes#70864
The std::prev function appeared to work on non Cpp17BidirectionalIterators, however it
behaved strangely by being the identity function. That was extremely misleading and
potentially dangerous, since several recent iterators that are C++20 bidirectional_iterators
don't satisfy the Cpp17BidirectionalIterator named requirement. For example:
auto zv = std::views::zip(vec1, vec2);
auto it = zv.begin() + 5;
auto it2 = std::prev(it); // "it2" will be the same as "it", instead of the previous one
Here, zip_view::iterator is a c++20 random_access_iterator, but it only satisfies the
Cpp17InputIterator named requirement because its reference type is a proxy type. Hence
`std::prev` would silently accept that iterator but it would do a no-op instead of going
to the previous position.
This patch changes `std::prev(it)` to produce an error at compile-time when instantiated
with a type that is not a Cpp17BidirectionalIterator.
Fixes#109456
`reverse_iterator` supports either c++20 `bidirectional_iterator` or
`Cpp17BidirectionalIterator `
http://eel.is/c++draft/reverse.iter.requirements
The current `reverse_iterator` uses `std::prev` in its `operator->`,
which only supports the `Cpp17BidirectionalIterator` properly.
If the underlying iterator is c++20 `bidirectional_iterator` but does
not satisfy the named requirement `Cpp17BidirectionalIterator`,
(examples are `zip_view::iterator`, `flat_map::iterator`), the current
`std::prev` silently compiles but does a no-op and returns the same
iterator back. So `reverse_iterator::operator->` will silently give a
wrong answer.
Even if we fix the behaviour of `std::prev`, at best, we could fail to
compile the code. But this is not ok, because we need to support this
kind of iterators in `reverse_iterator`.
The solution is simply to not use `std::prev`.
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
Currently, the library-internal feature test macros are only defined if
the feature is not available, and always have the prefix
`_LIBCPP_HAS_NO_`. This patch changes that, so that they are always
defined and have the prefix `_LIBCPP_HAS_` instead. This changes the
canonical use of these macros to `#if _LIBCPP_HAS_FEATURE`, which means
that using an undefined macro (e.g. due to a missing include) is
diagnosed now. While this is rather unlikely currently, a similar change
in `<__configuration/availability.h>` caught a few bugs. This also
improves readability, since it removes the double-negation of `#ifndef
_LIBCPP_HAS_NO_FEATURE`.
The current patch only touches the macros defined in `<__config>`. If
people are happy with this approach, I'll make a follow-up PR to also
change the macros defined in `<__config_site>`.
Add `[[nodiscard]]` attribute to `std::prev` and `std::next`. Those are
potential pitfalls for users who might think they mutate the iterator.
Fixes#109452
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.
Many headers include `<cstddef>` just for size_t, and pulling in
additional content (e.g. the traits used for std::byte) is unnecessary.
To solve this problem, this patch splits up `<cstddef>` into
subcomponents so that headers can include only the parts that they
actually require.
This has the added benefit of making the modules build a lot stricter
with respect to IWYU, and also providing a canonical location where we
define `std::size_t` and friends (which were previously defined in
multiple headers like `<cstddef>` and `<ctime>`).
After this patch, there's still many places in the codebase where we
include `<cstddef>` when `<__cstddef/size_t.h>` would be sufficient.
This patch focuses on removing `<cstddef>` includes from __type_traits
to make these headers non-circular with `<cstddef>`. Additional
refactorings can be tackled separately.
This patch implements https://wg21.link/p2609r3.
The test code was originally authored by JMazurkiewicz.
Notes:
- P2609R3 is not officially a Defect Report, but MSVC STL
implements it in C++20 mode.
Moreover, P2609R3 and P2997R1 touch exactly the same set of
concepts, and MSVC STL and libc++ have already treated P2997R1
as a DR.
- This patch also adjusted feature-test macros.
+ In C++20 mode, the value of __cpp_lib_ranges should be `202110L` because
- `202202L` covers `range_adaptor_closure` (P2387R3), and
- `202207L` covers move-only types in range adaptors (P2494R2).
And all of these changes are only available since C++23 mode.
+ In C++23 mode, the value should be `202406L` because
- `202211L` covers removing poison overloads (P2602R2),
- `202302L` covers relaxing projected value types (P2609R3), and
- `202406L` covers removing requirements on `iter_common_reference_t` (P2997R1).
And all of these changes are already or being implemented.
Fixes#105253.
Co-authored-by: Jakub Mazurkiewicz <mazkuba3@gmail.com>
We originally put implementation-detail function objects into individual
namespaces for `std::ranges` without a good reason for doing so. This
practice was continued, presumably because there was prior art. Since
there's no reason to keep these namespaces, this commit removes them,
which will slightly impact binary size.
This commit does not apply to CPOs, some of which need additional work.
This is a followup of https://github.com/llvm/llvm-project/pull/99343.
Since that patch was quite late in the LLVM-19 release cycle some of the
unneeded relational operator were not removed in C++20.
This removes them and gives the change a bit more "baking" time, just in
case there are issues with this change in user code. This change is
intended to be an NFC.
This implements the requirements for the container iterator requirements
for array, deque, vector, and `vector<bool>`.
Implements:
- LWG3352 strong_equality isn't a thing
Implements parts of:
- P1614R2 The Mothership has Landed
Fixes: https://github.com/llvm/llvm-project/issues/62486
~~NB: This PR depends on #78876. Ignore the first commit when reviewing,
and don't merge it until #78876 is resolved. When/if #78876 lands, I'll
clean this up.~~
This partially restores parity with the old, since removed debug build.
We now can re-enable a bunch of the disabled tests. Some things of note:
- `bounded_iter`'s converting constructor has never worked. It needs a
friend declaration to access the other `bound_iter` instantiation's
private fields.
- The old debug iterators also checked that callers did not try to
compare iterators from different objects. `bounded_iter` does not
currently do this, so I've left those disabled. However, I think we
probably should add those. See
https://github.com/llvm/llvm-project/issues/78771#issuecomment-1902999181
- The `std::vector` iterators are bounded up to capacity, not size. This
makes for a weaker safety check. This is because the STL promises not to
invalidate iterators when appending up to the capacity. Since we cannot
retroactively update all the iterators on `push_back()`, I've instead
sized it to the capacity. This is not as good, but at least will stop
the iterator from going off the end of the buffer.
There was also no test for this, so I've added one in the `std`
directory.
- `std::string` has two ambiguities to deal with. First, I opted not to
size it against the capacity. https://eel.is/c++draft/string.require#4
says iterators are invalidated on an non-const operation. Second,
whether the iterator can reach the NUL terminator. The previous debug
tests and the special-case in https://eel.is/c++draft/string.access#2
suggest no. If either of these causes widespread problems, I figure we
can revisit.
- `resize_and_overwrite.pass.cpp` assumed `std::string`'s iterator
supported `s.begin().base()`, but I see no promise of this in the
standard. GCC also doesn't support this. I fixed the test to use
`std::to_address`.
- `alignof.compile.pass.cpp`'s pointer isn't enough of a real pointer.
(It needs to satisfy `NullablePointer`, `LegacyRandomAccessIterator`,
and `LegacyContiguousIterator`.) `__bounded_iter` seems to instantiate
enough to notice. I've added a few more bits to satisfy it.
Fixes#78805
As time went by, a few files have become mis-formatted w.r.t.
clang-format. This was made worse by the fact that formatting was not
being enforced in extensionless headers. This commit simply brings all
of libcxx/include in-line with clang-format again.
We might have to do this from time to time as we update our clang-format
version, but frankly this is really low effort now that we've formatted
everything once.
## Abstract
This pull request implements LWG3672: `common_iterator::operator->()`
should return by value. The current implementation specifies that this
function should return the underlying pointer by reference (`T*
const&`), but it would be more intuitive to return it by value (`T*`).
## Reference
- [Draft C++ Standard:
[common.iter.access]](https://eel.is/c++draft/common.iter.access)
- [LWG3672](https://cplusplus.github.io/LWG/issue3672)
