## Abstract
This pull request implements LWG3715: `view_interface::empty` is
overconstrained. Here is an example similar to those described in the
report, which compiles with `-stdlib=libstdc++` but failed to compile
with `-stdlib=libc++`:
```cpp
// https://godbolt.org/z/EWEoTzah3
std::istringstream input("1 2 3 4 5");
auto i = std::views::istream<int>(input);
auto r = std::views::counted(i.begin(), 4) | std::views::take(2);
assert(!r.empty());
```
## Reference
- [Draft C++ Standard:
[view.interface.general]](https://eel.is/c++draft/view.interface.general)
- [LWG3715](https://wg21.link/LWG3715)
This patch runs clang-format on all of libcxx/include and libcxx/src, in
accordance with the RFC discussed at [1]. Follow-up patches will format
the benchmarks, the test suite and remaining parts of the code. I'm
splitting this one into its own patch so the diff is a bit easier to
review.
This patch was generated with:
find libcxx/include libcxx/src -type f \
| grep -v 'module.modulemap.in' \
| grep -v 'CMakeLists.txt' \
| grep -v 'README.txt' \
| grep -v 'libcxx.imp' \
| grep -v '__config_site.in' \
| xargs clang-format -i
A Git merge driver is available in libcxx/utils/clang-format-merge-driver.sh
to help resolve merge and rebase issues across these formatting changes.
[1]: https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
Replace most uses of `_LIBCPP_ASSERT` with
`_LIBCPP_ASSERT_UNCATEGORIZED`.
This is done as a prerequisite to introducing hardened mode to libc++.
The idea is to make enabling assertions an opt-in with (somewhat)
fine-grained controls over which categories of assertions are enabled.
The vast majority of assertions are currently uncategorized; the new
macro will allow turning on `_LIBCPP_ASSERT` (the underlying mechanism
for all kinds of assertions) without enabling all the uncategorized
assertions (in the future; this patch preserves the current behavior).
Differential Revision: https://reviews.llvm.org/D153816
This change is almost fully mechanical. The only interesting change is in `generate_feature_test_macro_components.py` to generate `_LIBCPP_STD_VER >=` instead. To avoid churn in the git-blame this commit should be added to the `.git-blame-ignore-revs` once committed.
Reviewed By: ldionne, var-const, #libc
Spies: jloser, libcxx-commits, arichardson, arphaman, wenlei
Differential Revision: https://reviews.llvm.org/D143962
When we ship LLVM 16, <ranges> won't be considered experimental anymore.
We might as well do this sooner rather than later.
Differential Revision: https://reviews.llvm.org/D132151
All supported compilers that support C++20 now support concepts. So, remove
`_LIB_LIBCPP_HAS_NO_CONCEPTS` in favor of `_LIBCPP_STD_VER > 17`. Similarly in
the tests, remove `// UNSUPPORTED: libcpp-no-concepts`.
Differential Revision: https://reviews.llvm.org/D121528
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
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
This is the first step towards disentangling the debug mode and assertions
in libc++. This patch doesn't make any functional change: it simply moves
_LIBCPP_ASSERT-related stuff to its own file so as to make it clear that
libc++ assertions and the debug mode are different things. Future patches
will make it possible to enable assertions without enabling the debug
mode.
Differential Revision: https://reviews.llvm.org/D119769
As suggested in D117966.
These conditional noexcepts are *permitted* by the Standard (as long
as there were no mistakes in them, I guess); but not *mandated*.
The Standard doesn't put any noexcept-specifications on these member functions.
The same logic would apply to `transform_view::iterator::operator*`
and `transform_view::iterator::operator[]`, but the Standard mandates
conditional noexcept on `iter_move(transform_view::iterator)`, and
I think it doesn't make much sense to say "moving from this iterator
is conditionally noexcept but not-moving from it is noexcept(false),"
so I'm leaving transform_view alone for now.
Differential Revision: https://reviews.llvm.org/D119374
The logic here is that we are disabling *only* things in `std::ranges::`.
Everything in `std::` is permitted, including `default_sentinel`, `contiguous_iterator`,
`common_iterator`, `projected`, `swappable`, and so on. Then, we include
anything from `std::ranges::` that is required in order to make those things
work: `ranges::swap`, `ranges::swap_ranges`, `input_range`, `ranges::begin`,
`ranges::iter_move`, and so on. But then that's all. Everything else (including
notably all of the "views" and the `std::views` namespace itself) is still
locked up behind `_LIBCPP_HAS_NO_INCOMPLETE_RANGES`.
Differential Revision: https://reviews.llvm.org/D118736
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
The macro that opts out of `std::ranges::` functionality is called
`_LIBCPP_HAS_NO_INCOMPLETE_RANGES`, and is unrelated to this macro
which is specifically about _compiler_ support for the _syntax_.
The only non-mechanical diff here is in `<__config>`.
Differential Revision: https://reviews.llvm.org/D118507
Implement LWG3549 by making `view_interface` not inherit from `view_base`. Types
are still views if they have a public and unambiguous derivation from
`view_interface`, so adjust the `enable_view` machinery as such to account for
that.
Differential Revision: https://reviews.llvm.org/D117714
Some types that inherit from `view_interface` do not meet the
preconditions. This came up during discussion
in https://reviews.llvm.org/D112631. Currently, the behavior is IFNDR,
but the preconditions can be easily checked, so let's do so.
In particular, we know each public member function calls the
`__derived()` private function, so we can do the check there. We
intentionally do it as a `static_assert` instead of a `requires` clause
to avoid hard erroring in some cases, such as with incomplete types. An
example hard error is:
```
llvm-project/build/include/c++/v1/__ranges/view_interface.h:48:14: note: because 'sizeof(_Tp)' would be invalid: invalid application of 'sizeof' to an incomplete type 'MoveOnlyForwardRange'
requires { sizeof(_Tp); } &&
^
llvm-project/build/include/c++/v1/__ranges/view_interface.h:73:26: error: no matching member function for call to '__derived'
return ranges::begin(__derived()) == ranges::end(__derived());
^~~~~~~~~
llvm-project/libcxx/test/std/ranges/range.utility/view.interface/view.interface.pass.cpp:187:31: note: in instantiation of function template specialization 'std::ranges::view_interface<MoveOnlyForwardRange>::empty<Mov
eOnlyForwardRange>' requested here
assert(!std::move(moveOnly).empty());
```
Reviewed By: Quuxplusone, Mordante, #libc
Differential Revision: https://reviews.llvm.org/D112665
We've been forgetting to add those to most of the <ranges> review.
To avoid forgetting in the future, I added an item in the pre-commit
checklist.
Differential Revision: https://reviews.llvm.org/D106287
This has been broken out of D104170 since it should be merged whether or
not we go ahead with the module map changes.
Differential Revision: https://reviews.llvm.org/D104175
