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
This also removes some tests which were redundant, wrong, or never run.
Specifically,
- `libcxx/utilities/meta/stress_tests/*` were never run and are of
questionable usefulness
- `libcxx/utilities/template.bitset/includes.pass.cpp` is completely
redundant and partially incorrect
Also notably,
`libcxx/language.support/support.c.headers/support.c.headers.other/math.lerp.verify.cpp`
has been refactored to only test the standard mandate.
This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
Adds explanation why `is_constructible` evaluates to false.
This reapplies as-is e476f968bc8e438a0435d10934f148de570db8eb.
This was reverted in 16d5db71b3c38f21aa17783a8758f947dca5883f because of
a test failure in libc++.
The test failure in libc++ is interesting in that, in the absence of
nested diagnostics a bunch of diagnostics are emitted as error instead
of notes, which we cannot silence with `-verify-ignore-unexpected`.
The fix here is to prevent the diagnostics to be emitted in the first
place.
However this is clearly not ideal and we should make sure to deploy a
better solution in the clang 22 time frame, in the lines of
https://discourse.llvm.org/t/rfc-add-a-new-text-diagnostics-format-that-supports-nested-diagnostics/87641/12Fixes#150601
---------
Co-authored-by: Shamshura Egor <164661612+egorshamshura@users.noreply.github.com>
The SFINAE isn't required, since the primary `tuple` class already does
the SFINAE checks. This removes a bit of code that was only used for
these constraints.
This also moves the `tuple_element` specialization for `tuple` to
`__fwd/tuple.h` to avoid a dependency on `__tuple/sfinae_helpers.h`
(which should be moved in a follow-up).
And constrain the new `operator==` since C++26.
This patch implements parts of P2165R4, P2944R3, and a possibly improved
resolution of LWG3882. Currently, libstdc++ and MSVC STL constrain the
new overloads in the same way.
Also set feature-test macro `__cpp_lib_constrained_equality` and add
related release note, as P2944R3 will completed with this patch.
Fixes#136765Fixes#136770Fixes#105424
This reverts commit e476f968bc8e438a0435d10934f148de570db8eb.
It has introduced a failure tracked by https://github.com/llvm/llvm-project/issues/150601
One libcxx test fail if libcxx is build with no exceptions and no RTTI:
- libcxx/utilities/expected/expected.expected/value.observers.verify.cpp
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 was added to to_ulong.pass.cpp years ago by
cf1dc8d39e2c9870468ca86f7956a65c7745fece but I don't think the other
part of that commit matters here.
* Upgrade from r536225 to r563880.
* Upgrade from ab/12644632 to f8b85cc5262c6e5cbc9a92c1bab2b18b32a4c63f,
the current HEAD commit of
https://android.googlesource.com/platform/prebuilts/ndk/+/refs/heads/mirror-goog-main-ndk
The previous source of sysroots (ci.android.com), deleted its artifacts
after a short period of time, and is currently out-of-date because of
the aosp-main turndown.
Updating the Docker image also fixes two tests.
According to `[mem.poly.allocator.ctor]` the pointer contained in
`polymorphic_allocator` can never be null. The default constructor uses
`get_default_resource()`, which never returns null and the constructor
taking a pointer explicitly has a precondition that the pointer is
non-null.
This patch adds a warning and an assertion in case a user passes a null
pointer to `polymorphic_allocator` as well as marking `resource()` to
never return null.
This also fixes some tests which contained UB.
Fixes#148420
Libc++'s policy is to support only the latest released Xcode, which is
Xcode 16.x. We did update our CI jobs to Xcode 16.x, but we forgot to
update the documentation, which still mentioned Xcode 15. This patch
updates the documentation and cleans up outdated mentions of
apple-clang-15 in the test suite.
This test is currently failing in the Android CI, since the compiler
used there is too old. Once the Clang version is updated this XFAIL
should be removed again.
Added explanation why a is constructible evaluated to false. Also fixed
problem with ExtractTypeTraitFromExpression. In case std::is_xxx_v<>
with variadic pack it tries to get template argument, but fails in
expression Arg.getAsType() due to Arg.getKind() ==
TemplateArgument::ArgKind::Pack, but not
TemplateArgument::ArgKind::Type.
Reverts #144127
Fixies
https://github.com/llvm/llvm-project/pull/143309#issuecomment-2970012054
Fixes#105260
This patch applies the change as a DR to C++20. The rationale is that
the paper is more like a bug fix. It does not introduce new features, it
simply changes an existing behaviour (as a bug fix). MSVC STL DRed this
paper to C++20 as well.
This patch addresses several implementation issues in `bitset`'s
conversion functions `to_ullong` and `to_ulong`, and refactors its
converting constructor `__bitset(unsigned long long __v)` to a more
generic and elegant implementation.
Updates the implementation `std::reference_wrapper` -
[P2944R3](https://wg21.link/P2944R3) as discussed in
https://github.com/llvm/llvm-project/pull/117664#discussion_r1857826166
This PR also refactors the tests in preparation to implements the
constrained comparisons for `optional`, `variant` etc.
- Moves the test helpers (concepts and types) for testing constrained
comparisons to `test_comparisons.h`.
- Updates the `std::reference_wrapper` implementation to use the concept
`__core_convertible_to<bool>` as per comments in #135759.
Closes#138233
# References:
- [refwrap.comparisons](https://wg21.link/refwrap.comparisons)
---------
Co-authored-by: Hristo Hristov <zingam@outlook.com>
Co-authored-by: Nikolas Klauser <nikolasklauser@berlin.de>
Unconditional evaluation of `char_traits<_CharT>::length(__str)` is problematic, because it causes
UB when `__str` points to a non-null-terminated array. We should only call `length` (currently, in
`basic_string_view`'s constructor) when `__n == npos` per [bitset.cons]/8.
Drive-by change: Reduction of conditional compilation, given that
- both `basic_string_view<_CharT>::size_type` and `basic_string<_CharT>::size_type` must be
`size_t`, and thus
- both `basic_string_view<_CharT>::npos` and `basic_string<_CharT>::npos` must be `size_t(-1)`.
For the type sameness in the standard wording, see:
- [string.view.template.general]
- [basic.string.general]
- [allocator.traits.types]/6
- [default.allocator.general]/1
Fixes#143684
#109028 caused `sizeof` to be sometimes applied to function reference
types, which makes a program ill-formed. This PR handles reference types
by specializations to prevent such bogus `sizeof` expression to be
instantiated.
Fixes#142118.
Currently, libc++'s `<tuple>` is using the deprecated
`__reference_binds_to_temporary` intrinsic. This PR starts to use
`__reference_constructs_from_temporary` if possible.
It seems that `__reference_constructs_from_temporary` should be used via
an internal type traits provided in
`<__type_traits/reference_constructs_from_temporary.h>`. But given the
old intrinsic was directly used, this PR doesn't switch to the current
convention yet.
P2255R2 is related. Although the paper indicated that constructors of
`tuple` should be deleted in such a case.
---------
Co-authored-by: Nikolas Klauser <nikolasklauser@berlin.de>
Currently, built-in `char`/`wchar_t` arrays are assumed to be
null-terminated sequence with the terminator being the last element in
formatting. This doesn't conform to [format.arg]/6.9.
> otherwise, if `decay_t<TD>` is `char_type*` or `const char_type*`,
> initializes value with `static_cast<const char_type*>(v)`;
The standard wording specifies that character arrays are decayed to
pointers. When the null terminator is not the last element or there's no
null terminator (the latter case is UB), libc++ currently produces
different results.
Also fixes and hardens `formatter<CharT[N], CharT>::format` in
`<__format/formatter_string.h>`. These specializations are rarely used.
Fixes#115935. Also checks the preconditions in this case, which fixes
#116570.
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.
This patch makes instantiation of `pair` in CTAD a bit lazier to avoid
instantiating invalid `pair` specialization before the decaying explicit
deduction guide works.
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.
The existing using _ForwardLike declaration already fails with a
subsitution failure. The LWG issue was filed to clarify what should
happen for non-referencable types.
Added test to verify libc++ is already enforcing the new Mandates.
Implements:
- LWG3757 What's the effect of std::forward_like<void>(x)
Closes: #105026
The current implementation already have an __initial_descriptor which
saves the initial state. When release() is called, we will reset the
__initial_descriptor.__cur_ pointer.
This patch also updates the status of LWG3120.
Closes#104274
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
1013fe3c0cfd7582e94ef2d4bfd79da7ea1a1289 used to implement LWG2770, but
cb0d4df97490ec2d2b1cdf7574d26b1bc4063599 made LWG2770 unimplemented
again because of CWG2386.
This patch re-implements LWG2770, while keeping the libc++-specific
implementation strategy (which is controversial as noted in LWG4040).
Drive-by:
- Make the test coverage for the controversial part noted in LWG4040
libc++-only.
- Add the previously missed entry for LWG2770 to the documentation.
The `__is_referenceable` builtin has been removed from Clang, since all
its uses have been replaced by builtins themselves. This trait only
exists for GCC compatibility and to word around some issues in the other
traits. The non-builtin implementation has been refactored to use
variable templates instead, making the implementation much simpler.
* libcxx/test/support/min_allocator.h
+ Fix `tiny_size_allocator::rebind` which mistakenly said `T` instead of
`U`.
*
libcxx/test/std/algorithms/alg.modifying.operations/alg.partitions/stable_partition.pass.cpp
+ `std::stable_partition` requires bidirectional iterators.
* libcxx/test/std/containers/sequences/vector.bool/max_size.pass.cpp
+ Fix allocator type given to `std::vector<bool>`. The element types are
required to match, [N5008](https://isocpp.org/files/papers/N5008.pdf)
\[container.alloc.reqmts\]/5: "*Mandates:* `allocator_type::value_type`
is the same as `X::value_type`."
* libcxx/test/std/time/time.clock/time.clock.utc/types.compile.pass.cpp
+ Mark `is_steady` as `[[maybe_unused]]`, as it appears within
`LIBCPP_STATIC_ASSERT` only.
*
libcxx/test/std/algorithms/alg.modifying.operations/alg.rotate/rotate.pass.cpp
*
libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/swap_ranges.pass.cpp
* libcxx/test/std/utilities/utility/utility.swap/swap_array.pass.cpp
+ Fix MSVC warning C4127 "conditional expression is constant".
`TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED` was introduced for this
purpose, so it should be used consistently.
* libcxx/test/std/numerics/numeric.ops/numeric.ops.gcd/gcd.pass.cpp
+ Fix `gcd()` precondition violation for `signed char`. This test case
was causing `-128` to be passed as a `signed char` to `gcd()`, which is
forbidden.
* libcxx/test/std/containers/sequences/array/assert.iterators.pass.cpp
*
libcxx/test/std/containers/sequences/vector/vector.modifiers/assert.push_back.invalidation.pass.cpp
*
libcxx/test/std/input.output/iostream.format/print.fun/no_file_description.pass.cpp
+ Split some REQUIRES and XFAIL lines. This is a "nice to have" for
MSVC's internal test harness, which is extremely simple and looks for
exact comment matches to skip tests. We can recognize the specific lines
"REQUIRES: has-unix-headers" and "XFAIL: msvc", but it's a headache to
maintain if they're chained with other conditions.
* libcxx/test/support/sized_allocator.h
+ Fix x86 truncation warnings. `std::allocator` takes `std::size_t`, so
we need to `static_cast`.
*
libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/offset_range.pass.cpp
+ Fix x86 truncation warning. `std::min()` is returning
`std::streamoff`, which was being unnecessarily narrowed to
`std::size_t`.
*
libcxx/test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp
+ Fix MSVC warning C4127 "conditional expression is constant" for an
always-true branch. This was very recently introduced by #129008 making
`N` constexpr. As it's a local constant just nine lines above, we don't
need to test whether 100 is greater than 0.
Recent Clang-21 builds improved the deprecated diagnotics. This
uncovered missing guards in libc++ internally.
Note: This patch should be a separate commit and not merged.
For testing purposes they are combined.
Reviewed as part of #130497.
