This patch implements the forwarding to frozen C++03 headers as
discussed in
https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc. In the
RFC, we initially proposed selecting the right headers from the Clang
driver, however consensus seemed to steer towards handling this in the
library itself. This patch implements that direction.
At a high level, the changes basically amount to making each public
header look like this:
```
// inside <vector>
#ifdef _LIBCPP_CXX03_LANG
# include <__cxx03/vector>
#else
// normal <vector> content
#endif
```
In most cases, public headers are simple umbrella headers so there isn't
much code in the #else branch. In other cases, the #else branch contains
the actual implementation of the header.
This is in relation to mr #93350. It was merged to main, but reverted
because of failing sanitizer builds on PowerPC.
The fix includes replacing the hard-coded threshold constants (e.g.
`__overflow_threshold`) for different floating-point sizes by a general
computation using `std::ldexp`. Thus, it should now work for all architectures.
This has the drawback of not being `constexpr` anymore as `std::ldexp`
is not implemented as `constexpr` (even though the standard mandates it
for C++23).
Closes#92782
The 3-dimentionsional `std::hypot(x,y,z)` was sub-optimally implemented.
This lead to possible over-/underflows in (intermediate) results which
can be circumvented by this proposed change.
The idea is to to scale the arguments (see linked issue for full
discussion).
Tests have been added for problematic over- and underflows.
Closes#92782
Implementing the Hermite polynomials which are part of C++17's
mathematical special functions. The goal is to get early feedback which
will make implementing the other functions easier. Integration of
functions in chunks (e.g. `std::hermite` at first, then `std::laguerre`,
etc.) might make sense as well (also see note on boost.math below).
I started out from this abandoned merge request:
https://reviews.llvm.org/D58876 .
The C++23 standard defines them in-terms of `/* floating-point type */`
arguments. I have not looked into that.
Note, there is still an ongoing discussion on discourse whether
importing boost.math is an option.
This significantly simplifies the implementation and improves the
codegen. The only downside is that the accuracy can be marginally worse,
but that is up to the compiler to decide with this change, which means
it can be controlled by compiler flags.
Differential Revision: https://reviews.llvm.org/D155312
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.
These were required a long time ago due to `static_assert` not actually
being available in C++03. Now `static_assert` is simply mapped to
`_Static_assert` in C++03, making the additional parens unnecessary.
Originally, we used __libcpp_verbose_abort to handle assertion failures.
That function was declared from all public headers. Since we don't use
that mechanism anymore, we don't need to declare __libcpp_verbose_abort
from all public headers, and we can clean up a lot of unnecessary
includes.
This patch also moves the definition of the various assertion categories
to the <__assert> header, since we now rely on regular IWYU for these
assertion macros.
rdar://105510916
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
Even though constexpr implicitly makes functions inline, we try not to
rely on this implicit effect in the code base. We are mostly consistent
about using `inline` on non-template free-functions to make it clear
that we don't have an ODR violation.
This patch simply fixes a few places where we didn't explicitly use
inline on non-template free functions, presumably because they were
constexpr.
Fixes#75227
In preparation for running clang-format on the whole code base, we are
also removing mentions of the legacy _LIBCPP_INLINE_VISIBILITY macro in
favor of the newer _LIBCPP_HIDE_FROM_ABI.
We're still leaving the definition of _LIBCPP_INLINE_VISIBILITY to avoid
creating needless breakage in case some older patches are checked-in
with mentions of the old macro. After we branch for LLVM 18, we can do
another pass to clean up remaining uses of the macro that might have
gotten introduced by mistake (if any) and remove the macro itself at the
same time. This is just a minor convenience to smooth out the transition
as much as possible.
See
https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
for the clang-format proposal.
This brings most of the enable_ifs in libc++ to the same style. It also has the nice side-effect of reducing the size of names of these symbols, since the depedent return type is shorter.
Reviewed By: #libc, ldionne
Spies: ldionne, libcxx-commits
Differential Revision: https://reviews.llvm.org/D157787
This brings most of the enable_ifs in libc++ to the same style. It also has the nice side-effect of reducing the size of names of these symbols, since the depedent return type is shorter.
Reviewed By: #libc, ldionne
Spies: ldionne, libcxx-commits
Differential Revision: https://reviews.llvm.org/D157736
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
We normally use the `__libcpp_` prefix to backport functions, but that doesn't really make sense here. The functions are always available. Using `__constexpr_` makes the intended use of the functions clear.
Reviewed By: Mordante, #libc
Spies: libcxx-commits
Differential Revision: https://reviews.llvm.org/D139521
An issue I often see in codebases compiled for unusual platforms is
that header search paths are specified manually and are subtly wrong.
For example, people will manually add `-isystem <some-toolchain>/usr/include`,
which ends up messing up the layering of header search paths required by
libc++ (because the C Standard Library now appears *before* libc++ in
the search paths). Without this patch, this will end up causing
compilation errors that are pretty inscrutable. This patch aims to
improve the user experience by diagnosing this issue explicitly.
In all cases I can think of, I would expect that a compilation error
occur if these header search paths are not layered properly. This
should only provide an explicit diagnostic instead of failing due
to seemingly unrelated compilation errors.
Differential Revision: https://reviews.llvm.org/D131441
This patch changes the requirement for getting the declaration of the
assertion handler from including <__assert> to including any public
C++ header of the library. Note that C compatibility headers are
excluded because we don't implement all the C headers ourselves --
some of them are taken straight from the C library, like assert.h.
It also adds a generated test to check it. Furthermore, this new
generated test is designed in a way that will make it possible to
replace almost all the existing test-generation scripts with this
system in upcoming patches.
Differential Revision: https://reviews.llvm.org/D122506
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
In addition to being more consistent with our approach for helpers, this
solves an actual issue where <cmath> was using numeric_limits but never
including the <limits> header directly. In a normal setup, this is not
an issue because the <math.h> header included by <cmath> does include
<limits>. However, I did stumble upon some code where that didn't work,
most likely because they were placing their own <math.h> header in front
of ours. I didn't bother investigating further.
Differential Revision: https://reviews.llvm.org/D115282
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
I just ran into a compiler error involving __bind_back and some overloads
that were being disabled with _EnableIf. I noticed that the error message
was quite bad and did not mention the reason for the overload being
excluded. Specifically, the error looked like this:
candidate template ignored: substitution failure [with _Args =
<ContiguousView>]: no member named '_EnableIfImpl' in 'std::_MetaBase<false>'
Instead, when using enable_if or enable_if_t, the compiler is clever and
can produce better diagnostics, like so:
candidate template ignored: requirement 'is_invocable_v<
std::__bind_back_op<1, std::integer_sequence<unsigned long, 0>>,
std::ranges::views::__transform::__fn &, std::tuple<PlusOne> &,
ContiguousView>' was not satisfied [with _Args = <ContiguousView>]
Basically, it tries to do a poor man's implementation of concepts, which
is already a lot better than simply complaining about substitution failure.
Hence, this commit uses enable_if_t instead of _EnableIf whenever
possible. That is both more straightforward than using the internal
helper, and also leads to better error messages in those cases.
I understand the motivation for _EnableIf's implementation was to improve
compile-time performance, however I believe striving to improve error
messages is even more important for our QOI, hence this patch. Furthermore,
it is unclear that _EnableIf actually improved compile-time performance
in any noticeable way (see discussion in the review for details).
Differential Revision: https://reviews.llvm.org/D108216
As discussed on cfe-dev [1], use the using_if_exists Clang attribute when
the compiler supports it. This makes it easier to port libc++ on top of
new platforms that don't fully support the C Standard library.
Previously, libc++ would fail to build when trying to import a missing
declaration in a <cXXXX> header. With the attribute, the declaration will
simply not be imported into namespace std, and hence it won't be available
for libc++ to use. In many cases, the declarations were *not* actually
required for libc++ to work (they were only surfaced for users to use
them as std::XXXX), so not importing them into namespace std is acceptable.
The same thing could be achieved by conscious usage of `#ifdef` along
with platform detection, however that quickly creates a maintenance
problem as libc++ is ported to new platforms. Furthermore, this problem
is exacerbated when mixed with vendor internal-only platforms, which can
lead to difficulties maintaining a downstream fork of the library.
For the time being, we only use the using_if_exists attribute when it
is supported. At some point in the future, we will start removing #ifdef
paths that are unnecessary when the attribute is supported, and folks
who need those #ifdef paths will be required to use a compiler that
supports the attribute.
[1]: http://lists.llvm.org/pipermail/cfe-dev/2020-June/066038.html
Differential Revision: https://reviews.llvm.org/D90257
Summary:
AIX system's stdlib.h provide different overload of abs and div
depending on compiler versions.
For example, std::div(long, long) and std::abs(long) are not available
from OS's stdlib.h when building with clang, but they are available
when building with xlclang compiler.
Therefore, we need to provide those extra overloads in libc++'s stdlib.h
when OS's stdlib.h does not.
Differential Revision: https://reviews.llvm.org/D99767
I used a lot of `git grep` to find places where `std::` was being used
outside of comments and assert-messages. There were three outcomes:
- Qualified function calls, e.g. `std::move` becomes `_VSTD::move`.
This is the most common case.
- Typenames that don't need qualification, e.g. `std::allocator` becomes `allocator`.
Leaving these as `_VSTD::allocator` would also be fine, but I decided
that removing the qualification is more consistent with existing practice.
- Names that specifically need un-versioned `std::` qualification,
or that I wasn't sure about. For example, I didn't touch any code in
<atomic>, <math.h>, <new>, or any ext/ or experimental/ headers;
and I didn't touch any instances of `std::type_info`.
In some deduction guides, we were accidentally using `class Alloc = typename std::allocator<T>`,
despite `std::allocator<T>`'s type-ness not being template-dependent.
Because `std::allocator` is a qualified name, this did parse as we intended;
but what we meant was simply `class Alloc = allocator<T>`.
Differential Revision: https://reviews.llvm.org/D92250
Summary: Update status page and test synopsis. Add synopsis in <cmath>.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D80456
The new meta-programming primitives are lower cost than the old versions. This patch removes those old versions and switches libc++ to use the new ones.
llvm-svn: 364160
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.
This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.
Note that this commit had originally been applied in r336369 and then
reverted in r336382 because of unforeseen problems. Both of these problems
have now been fixed.
Reviewers: EricWF, mclow.lists
Subscribers: christof, dexonsmith, erikvanderpoel
Differential Revision: https://reviews.llvm.org/D48892
llvm-svn: 336866
