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[libc++] Temporarily not use compiler intrinsics for some type traits in Objective-C++ mode.
Currently, there are bugs in Clang's intrinsics for type traits when handling Objective-C++ `id` (e.g. in `add_pointer`). As a temporary workaround, don't use these intrinsics in the Objective-C++ mode. Differential Revision: https://reviews.llvm.org/D145186 (cherry picked from commit 87cf39a)
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‎libcxx/include/__config

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@@ -1259,6 +1259,12 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
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# define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName) static_assert(true, "")
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#endif
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// TODO(varconst): currently, there are bugs in Clang's intrinsics when handling Objective-C++ `id`, so don't use
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// compiler intrinsics in the Objective-C++ mode.
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# ifdef __OBJC__
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# define _LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS
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# endif
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#endif // __cplusplus
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#endif // _LIBCPP___CONFIG

‎libcxx/include/__type_traits/add_pointer.h

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@@ -22,7 +22,7 @@
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if __has_builtin(__add_pointer)
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#if !defined(_LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS) && __has_builtin(__add_pointer)
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template <class _Tp>
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using __add_pointer_t = __add_pointer(_Tp);
@@ -39,7 +39,7 @@ template <class _Tp> struct __add_pointer_impl<_Tp, false>
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template <class _Tp>
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using __add_pointer_t = typename __add_pointer_impl<_Tp>::type;
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#endif // __has_builtin(__add_pointer)
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#endif // !defined(_LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS) && __has_builtin(__add_pointer)
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template <class _Tp>
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struct add_pointer {

‎libcxx/include/__type_traits/remove_pointer.h

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@@ -17,7 +17,7 @@
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if __has_builtin(__remove_pointer)
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#if !defined(_LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS) && __has_builtin(__remove_pointer)
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template <class _Tp>
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struct remove_pointer {
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using type _LIBCPP_NODEBUG = __remove_pointer(_Tp);
@@ -34,7 +34,7 @@ template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const volat
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template <class _Tp>
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using __remove_pointer_t = typename remove_pointer<_Tp>::type;
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#endif // __has_builtin(__remove_pointer)
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#endif // !defined(_LIBCPP_WORKAROUND_OBJCXX_COMPILER_INTRINSICS) && __has_builtin(__remove_pointer)
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#if _LIBCPP_STD_VER > 11
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template <class _Tp> using remove_pointer_t = __remove_pointer_t<_Tp>;

‎libcxx/test/std/utilities/meta/meta.trans/objc_support.pass.mm

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@@ -0,0 +1,106 @@
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// REQUIRES: objective-c++
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// Simple test to check that type traits support Objective-C types.
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#include <type_traits>
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#include "test_macros.h"
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@interface I;
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@end
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// add_pointer
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static_assert(std::is_same<std::add_pointer<id>::type, id*>::value, "");
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static_assert(std::is_same<std::add_pointer<I>::type, I*>::value, "");
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// add_lvalue_reference
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static_assert(std::is_same<std::add_lvalue_reference<id>::type, id&>::value, "");
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static_assert(std::is_same<std::add_lvalue_reference<I>::type, I&>::value, "");
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// add_rvalue_reference
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static_assert(std::is_same<std::add_rvalue_reference<id>::type, id&&>::value, "");
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static_assert(std::is_same<std::add_rvalue_reference<I>::type, I&&>::value, "");
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// decay
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static_assert(std::is_same<std::decay<id>::type, id>::value, "");
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static_assert(std::is_same<std::decay<I>::type, I>::value, "");
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static_assert(std::is_same<std::decay<id(&)[5]>::type, id*>::value, "");
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// __libcpp_is_referenceable
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<id>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<id*>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<id&>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<id&&>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<I>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<I*>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<I&>::value, "");
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LIBCPP_STATIC_ASSERT(std::__libcpp_is_referenceable<I&&>::value, "");
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// remove_all_extents
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static_assert(std::is_same<std::remove_all_extents<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_all_extents<id[5]>::type, id>::value, "");
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static_assert(std::is_same<std::remove_all_extents<id[5][10]>::type, id>::value, "");
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static_assert(std::is_same<std::remove_all_extents<I>::type, I>::value, "");
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// remove_const
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static_assert(std::is_same<std::remove_const<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_const<const id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_const<I>::type, I>::value, "");
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static_assert(std::is_same<std::remove_const<const I>::type, I>::value, "");
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// remove_cv
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static_assert(std::is_same<std::remove_cv<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_cv<const volatile id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_cv<I>::type, I>::value, "");
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static_assert(std::is_same<std::remove_cv<const volatile I>::type, I>::value, "");
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#if TEST_STD_VER >= 20
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// remove_cvref
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static_assert(std::is_same<std::remove_cvref<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_cvref<const volatile id&>::type, id>::value, "");
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static_assert(std::is_same<std::remove_cvref<const volatile id&&>::type, id>::value, "");
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static_assert(std::is_same<std::remove_cvref<I>::type, I>::value, "");
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static_assert(std::is_same<std::remove_cvref<const volatile I&>::type, I>::value, "");
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static_assert(std::is_same<std::remove_cvref<const volatile I&&>::type, I>::value, "");
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#endif
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// remove_extent
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static_assert(std::is_same<std::remove_all_extents<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_all_extents<id[5]>::type, id>::value, "");
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static_assert(std::is_same<std::remove_all_extents<I>::type, I>::value, "");
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// remove_pointer
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static_assert(!std::is_same<std::remove_pointer<id>::type, id>::value, "");
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// The result of removing and re-adding pointer to `id` should be still `id`.
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static_assert(std::is_same<std::remove_pointer<id>::type*, id>::value, "");
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static_assert(std::is_same<std::add_pointer<std::remove_pointer<id>::type>::type, id>::value, "");
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static_assert(std::is_same<std::remove_pointer<std::add_pointer<id>::type>::type, id>::value, "");
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// remove_reference
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static_assert(std::is_same<std::remove_reference<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_reference<id&>::type, id>::value, "");
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static_assert(std::is_same<std::remove_reference<const id&>::type, const id>::value, "");
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static_assert(std::is_same<std::remove_reference<id&&>::type, id>::value, "");
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static_assert(std::is_same<std::remove_reference<const id&&>::type, const id>::value, "");
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static_assert(std::is_same<std::remove_reference<I>::type, I>::value, "");
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static_assert(std::is_same<std::remove_reference<I&>::type, I>::value, "");
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static_assert(std::is_same<std::remove_reference<const I&>::type, const I>::value, "");
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static_assert(std::is_same<std::remove_reference<I&&>::type, I>::value, "");
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static_assert(std::is_same<std::remove_reference<const I&&>::type, const I>::value, "");
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// remove_volatile
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static_assert(std::is_same<std::remove_volatile<id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_volatile<volatile id>::type, id>::value, "");
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static_assert(std::is_same<std::remove_volatile<I>::type, I>::value, "");
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static_assert(std::is_same<std::remove_volatile<volatile I>::type, I>::value, "");
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int main(int, char**) {
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return 0;
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}

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