#175913 removed that `__builtin_assume_dereferenceable(ptr, 0)` implies
`ptr != nullptr`, which should allow us to use the builtin with LLVM 23.
This reverts commit 776c09c212e945fdceeae240b42c38df3dd34727.
`__builtin_assume_dereferenceable` currently implies that the pointer
given to it is non-null, even if the size is zero. This causes
miscompilations, since we consider [nullptr, nullptr) to be a valid
range.
Reverts llvm/llvm-project#167697
[P1789R3](https://isocpp.org/files/papers/P1789R3.pdf) was accepted for
C++26 through LWG motion 14 at the 2025 Kona meeting. This patch
implements it, along with tests and documentation changes.
Closes#167268
---------
Co-authored-by: Tsche <che@pydong.org>
`[[nodiscard]]` should be applied to functions where discarding the
return value is most likely a correctness issue.
- https://libcxx.llvm.org/CodingGuidelines.html
1. `hash<shared_ptr>`, `hash<unique_ptr>`, `std::integer_sequence<>`
etc.
2. Also implements fixes to
https://github.com/llvm/llvm-project/issues/169634 on the go (issues
discovered during current implementation)
---------
Co-authored-by: A. Jiang <de34@live.cn>
Co-authored-by: Hristo Hristov <zingam@outlook.com>
This is done in two ways:
1) `index_sequence_for` is back-ported as `__index_sequence_for`
2) Extra functions just to expand the parameter pack are replaced with
lambdas
https://wg21.link/#support
`[[nodiscard]]` should be applied to functions where discarding the
return value is most likely a correctness issue.
- https://libcxx.llvm.org/CodingGuidelines.html#apply-nodiscard-where-relevant
The following was implemented in this patch:
- [x] `<compare>`
- [x] `<corotine>`
- [x] `<initializer_list>`
- [x] Integer comparisons
---------
Co-authored-by: Hristo Hristov <zingam@outlook.com>
Co-authored-by: A. Jiang <de34@live.cn>
The Trivial Relocation feature has been removed from the C++26 working
draft. Based on discussions in Kona, it is unlikely that the
"replaceable" type concept will come back in the C++29 time frame.
Since we don't have a use for the type trait in the library at the
moment, remove the code associated to it. If we end up needing something
like it in the future, we can always add it back.
There is a tradition to use U.S. English spellings for APIs. For
example, it's uninitialized_fill and not uninitialised_fill,
specialization not specialisation, etcetera.
This specializes `__lazy_synth_three_way_comparator` to forward to
`__default_three_way_comparator` if the comparator desugars to
`__greater_tag`. This is the same as the desugaring to `__less_tag`
except that the sign has to be inverted.
This uses the new `__builtin_lt_synthesises_from_spaceship` builtin from
clang to use three way comparison for arbitrary user-defined types that
only provide a spaceship operator.
The original PR has been reverted because of an LLDB test failure. This
patch now works around the test failure by simply allowing the new
symbols to show up in a stack trace.
This reverts commit 72c04bb882ad70230bce309c3013d9cc2c99e9a7.
Original commit message:
This patch replaces `__can_extract_key` with an overload set to try to
extract the key. This simplifies the code, since we don't need to have
separate overload sets for the unordered and associative containers. It
also allows extending the set of extraction cases more easily, since we
have a single place to define how the key is extracted.
This patch replaces `__can_extract_key` with an overload set to try to
extract the key. This simplifies the code, since we don't need to have
separate overload sets for the unordered and associative containers. It
also allows extending the set of extraction cases more easily, since we
have a single place to define how the key is extracted.
This has two benefits:
- It is less likely that the macro will be copy-pasted around when
unnecessary
- We can drop `_LIBCPP_HIDE_FROM_ABI` from any member functions once we
are able to make `_LIBCPP_HIDE_FROM_ABI` the default within libc++
The internal API is a lot more complicated than it actually needs to be.
This refactors the internal API to match the features and names of the
public one.
This patch does a few things:
- `__libcpp_is_signed_integer` and `__libcpp_is_unsigned_integer` are
refactored to be variable templates instead of class templates.
- the two traits are merged into a single header
`<__type_traits/integer_traits.h>`.
- `__libcpp_signed_integer`, `__libcpp_unsigned_integer` and
`__libcpp_integer` are moved into the same header.
- The above mentioned concepts are renamed to `__signed_integer`,
`__unsigned_integer` and `__signed_or_unsigned_integer` respectively.
This makes it clearer what the functions actually do. As a nice
side-effect it also avoids a function call. If the C++03 header split is
successful we could drop `__get_pair` entirely.
That type trait represents whether move-assigning an object is
equivalent to destroying it and then move-constructing a new one from
the same argument. This will be useful in a few places where we may want
to destroy + construct instead of doing an assignment, in particular
when implementing some container operations in terms of relocation.
This is effectively adding a library emulation of P2786R12's
is_replaceable trait, similarly to what we do for trivial relocation.
Eventually, we can replace this library emulation by the real
compiler-backed trait.
This is building towards #129328.
This patch makes instantiation of `pair` in CTAD a bit lazier to avoid
instantiating invalid `pair` specialization before the decaying explicit
deduction guide works.
This avoids instantiating multiple classes, reducing compile times. This
patch also introduces `__underyling_type_t` for internal use, similar to
other type traits.
Currently, places where we call __libcpp_allocate must drop type
information on the ground even when they actually have such information
available. That is unfortunate since some toolchains and system
allocators are able to provide improved security when they know what
type is being allocated.
This is the purpose of http://wg21.link/p2719, where we introduce a new
variant of `operator new` which takes a type in its interface. A
different but related issue is that `std::allocator` does not honor any
in-class `T::operator new` since it is specified to call the global
`::operator new` instead.
This patch closes the gap to make it trivial for implementations that
provide typed memory allocators to actually benefit from that
information in more contexts, and also makes libc++ forward-compatible
with future proposals that would fix the existing defects in
`std::allocator`. It also makes the internal allocation API higher level
by operating on objects instead of operating on bytes of memory.
Since this is a widely-used function and making this a template could
have an impact on debug info sizes, I tried minimizing the number of
templated layers by removing `__do_deallocate_handle_size`, which was
easy to replace with a macro (and IMO this leads to cleaner code).
This allows forwarding an object as a specific type. This is usually
useful when using `deducing this` to avoid calling any functions in a
deriving class.
This disentangles the code which previously had a mix of many #ifdefs, a
non-versioned namespace and a versioned namespace. It also makes it
clearer which parts of <new> are implemented on Windows by including <new.h>.
This introduces a new `__scope_guard` without any fancy features. The
scope guard is used in `<string>` to simplify some of the ASan
annotations (especially by making it harder to forget them where
exceptions are thrown).
Rewriting `__alloc()` and `__dealloc()` template functions to avoid errors when `small_buffer.h` is
included in the modules LIT tests. For example:
```
test-suite-install/include/c++/v1/__utility/small_buffer.h:69:81: error: use of undeclared identifier 'align_val_t'
# | 69 | byte* __allocation = static_cast<byte*>(::operator new[](sizeof(_Stored), align_val_t{alignof(_Stored)}));
# | | ^
```
Around half of the tests are based on the tests Arthur O'Dwyer's
original implementation of std::flat_map, with modifications and
removals.
partially implement #105190
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>`.
`__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.
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.
