llvm-project/libcxx/include/__algorithm/pstl_rotate_copy.h
Louis Dionne 7b4622514d
[libc++] Fix missing and incorrect push/pop macros (#79204)
We recently noticed that the unwrap_iter.h file was pushing macros, but
it was pushing them again instead of popping them at the end of the
file. This led to libc++ basically swallowing any custom definition of
these macros in user code:

    #define min HELLO
    #include <algorithm>
    // min is not HELLO anymore, it's not defined

While investigating this issue, I noticed that our push/pop pragmas were
actually entirely wrong too. Indeed, instead of pushing macros like
`move`, we'd push `move(int, int)` in the pragma, which is not a valid
macro name. As a result, we would not actually push macros like `move`
-- instead we'd simply undefine them. This led to the following code not
working:

    #define move HELLO
    #include <algorithm>
    // move is not HELLO anymore

Fixing the pragma push/pop incantations led to a cascade of issues
because we use identifiers like `move` in a large number of places, and
all of these headers would now need to do the push/pop dance.

This patch fixes all these issues. First, it adds a check that we don't
swallow important names like min, max, move or refresh as explained
above. This is done by augmenting the existing
system_reserved_names.gen.py test to also check that the macros are what
we expect after including each header.

Second, it fixes the push/pop pragmas to work properly and adds missing
pragmas to all the files I could detect a failure in via the newly added
test.

rdar://121365472
2024-01-25 15:48:46 -05:00

86 lines
3.0 KiB
C++

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_PSTL_ROTATE_COPY_H
#define _LIBCPP___ALGORITHM_PSTL_ROTATE_COPY_H
#include <__algorithm/pstl_backend.h>
#include <__algorithm/pstl_copy.h>
#include <__algorithm/pstl_frontend_dispatch.h>
#include <__type_traits/is_execution_policy.h>
#include <optional>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
_LIBCPP_BEGIN_NAMESPACE_STD
template <class>
void __pstl_rotate_copy();
template <class _ExecutionPolicy,
class _ForwardIterator,
class _ForwardOutIterator,
class _RawPolicy = __remove_cvref_t<_ExecutionPolicy>,
enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
__rotate_copy(_ExecutionPolicy&& __policy,
_ForwardIterator&& __first,
_ForwardIterator&& __middle,
_ForwardIterator&& __last,
_ForwardOutIterator&& __result) noexcept {
return std::__pstl_frontend_dispatch(
_LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_rotate_copy, _RawPolicy),
[&__policy](_ForwardIterator __g_first,
_ForwardIterator __g_middle,
_ForwardIterator __g_last,
_ForwardOutIterator __g_result) -> optional<_ForwardOutIterator> {
auto __result_mid =
std::__copy(__policy, _ForwardIterator(__g_middle), std::move(__g_last), std::move(__g_result));
if (!__result_mid)
return nullopt;
return std::__copy(__policy, std::move(__g_first), std::move(__g_middle), *std::move(__result_mid));
},
std::move(__first),
std::move(__middle),
std::move(__last),
std::move(__result));
}
template <class _ExecutionPolicy,
class _ForwardIterator,
class _ForwardOutIterator,
class _RawPolicy = __remove_cvref_t<_ExecutionPolicy>,
enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _ForwardOutIterator rotate_copy(
_ExecutionPolicy&& __policy,
_ForwardIterator __first,
_ForwardIterator __middle,
_ForwardIterator __last,
_ForwardOutIterator __result) {
auto __res =
std::__rotate_copy(__policy, std::move(__first), std::move(__middle), std::move(__last), std::move(__result));
if (!__res)
std::__throw_bad_alloc();
return *__res;
}
_LIBCPP_END_NAMESPACE_STD
#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ALGORITHM_PSTL_ROTATE_COPY_H