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 // -*- 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___CONFIGURATION_ABI_H
 #define _LIBCPP___CONFIGURATION_ABI_H
 
 #include <__config_site>
 #include <__configuration/compiler.h>
 #include <__configuration/platform.h>
 
 #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
 #  pragma GCC system_header
 #endif
 
 // FIXME: ABI detection should be done via compiler builtin macros. This
 // is just a placeholder until Clang implements such macros. For now assume
 // that Windows compilers pretending to be MSVC++ target the Microsoft ABI,
 // and allow the user to explicitly specify the ABI to handle cases where this
 // heuristic falls short.
 #if _LIBCPP_ABI_FORCE_ITANIUM && _LIBCPP_ABI_FORCE_MICROSOFT
 #  error "Only one of _LIBCPP_ABI_FORCE_ITANIUM and _LIBCPP_ABI_FORCE_MICROSOFT can be true"
 #elif _LIBCPP_ABI_FORCE_ITANIUM
 #  define _LIBCPP_ABI_ITANIUM
 #elif _LIBCPP_ABI_FORCE_MICROSOFT
 #  define _LIBCPP_ABI_MICROSOFT
 #else
 #  if defined(_WIN32) && defined(_MSC_VER)
 #    define _LIBCPP_ABI_MICROSOFT
 #  else
 #    define _LIBCPP_ABI_ITANIUM
 #  endif
 #endif
 
 #if _LIBCPP_ABI_VERSION >= 2
 // Change short string representation so that string data starts at offset 0,
 // improving its alignment in some cases.
 #  define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 // Fix deque iterator type in order to support incomplete types.
 #  define _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
 // Fix undefined behavior in how std::list stores its linked nodes.
 #  define _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB
 // Fix undefined behavior in  how __tree stores its end and parent nodes.
 #  define _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
 // Fix undefined behavior in how __hash_table stores its pointer types.
 #  define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
 #  define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
 #  define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE
 // Override the default return value of exception::what() for bad_function_call::what()
 // with a string that is specific to bad_function_call (see http://wg21.link/LWG2233).
 // This is an ABI break on platforms that sign and authenticate vtable function pointers
 // because it changes the mangling of the virtual function located in the vtable, which
 // changes how it gets signed.
 #  define _LIBCPP_ABI_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE
 // Enable optimized version of __do_get_(un)signed which avoids redundant copies.
 #  define _LIBCPP_ABI_OPTIMIZED_LOCALE_NUM_GET
 // Give reverse_iterator<T> one data member of type T, not two.
 // Also, in C++17 and later, don't derive iterator types from std::iterator.
 #  define _LIBCPP_ABI_NO_ITERATOR_BASES
 // Use the smallest possible integer type to represent the index of the variant.
 // Previously libc++ used "unsigned int" exclusively.
 #  define _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
 // Unstable attempt to provide a more optimized std::function
 #  define _LIBCPP_ABI_OPTIMIZED_FUNCTION
 // All the regex constants must be distinct and nonzero.
 #  define _LIBCPP_ABI_REGEX_CONSTANTS_NONZERO
 // Re-worked external template instantiations for std::string with a focus on
 // performance and fast-path inlining.
 #  define _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
 // Enable clang::trivial_abi on std::unique_ptr.
 #  define _LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI
 // Enable clang::trivial_abi on std::shared_ptr and std::weak_ptr
 #  define _LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI
 // std::random_device holds some state when it uses an implementation that gets
 // entropy from a file (see _LIBCPP_USING_DEV_RANDOM). When switching from this
 // implementation to another one on a platform that has already shipped
 // std::random_device, one needs to retain the same object layout to remain ABI
 // compatible. This switch removes these workarounds for platforms that don't care
 // about ABI compatibility.
 #  define _LIBCPP_ABI_NO_RANDOM_DEVICE_COMPATIBILITY_LAYOUT
 // Don't export the legacy __basic_string_common class and its methods from the built library.
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
 // Don't export the legacy __vector_base_common class and its methods from the built library.
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON
 // According to the Standard, `bitset::operator[] const` returns bool
 #  define _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL
 // Fix the implementation of CityHash used for std::hash<fundamental-type>.
 // This is an ABI break because `std::hash` will return a different result,
 // which means that hashing the same object in translation units built against
 // different versions of libc++ can return inconsistent results. This is especially
 // tricky since std::hash is used in the implementation of unordered containers.
 //
 // The incorrect implementation of CityHash has the problem that it drops some
 // bits on the floor.
 #  define _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION
 // Remove the base 10 implementation of std::to_chars from the dylib.
 // The implementation moved to the header, but we still export the symbols from
 // the dylib for backwards compatibility.
 #  define _LIBCPP_ABI_DO_NOT_EXPORT_TO_CHARS_BASE_10
 // Define std::array/std::string_view iterators to be __wrap_iters instead of raw
 // pointers, which prevents people from relying on a non-portable implementation
 // detail. This is especially useful because enabling bounded iterators hardening
 // requires code not to make these assumptions.
 #  define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_ARRAY
 #  define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW
 // Dont' add an inline namespace for `std::filesystem`
 #  define _LIBCPP_ABI_NO_FILESYSTEM_INLINE_NAMESPACE
 // std::basic_ios uses WEOF to indicate that the fill value is
 // uninitialized. However, on platforms where the size of char_type is
 // equal to or greater than the size of int_type and char_type is unsigned,
 // std::char_traits<char_type>::eq_int_type() cannot distinguish between WEOF
 // and WCHAR_MAX. This ABI setting determines whether we should instead track whether the fill
 // value has been initialized using a separate boolean, which changes the ABI.
 #  define _LIBCPP_ABI_IOS_ALLOW_ARBITRARY_FILL_VALUE
 // Historically, libc++ used a type called `__compressed_pair` to reduce storage needs in cases of empty types (e.g. an
 // empty allocator in std::vector). We switched to using `[[no_unique_address]]`. However, for ABI compatibility reasons
 // we had to add artificial padding in a few places.
 //
 // This setting disables the addition of such artificial padding, leading to a more optimal
 // representation for several types.
 #  define _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
 #elif _LIBCPP_ABI_VERSION == 1
 #  if !(defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF))
 // Enable compiling copies of now inline methods into the dylib to support
 // applications compiled against older libraries. This is unnecessary with
 // COFF dllexport semantics, since dllexport forces a non-inline definition
 // of inline functions to be emitted anyway. Our own non-inline copy would
 // conflict with the dllexport-emitted copy, so we disable it. For XCOFF,
 // the linker will take issue with the symbols in the shared object if the
 // weak inline methods get visibility (such as from -fvisibility-inlines-hidden),
 // so disable it.
 #    define _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
 #  endif
 // Feature macros for disabling pre ABI v1 features. All of these options
 // are deprecated.
 #  if defined(__FreeBSD__) && __FreeBSD__ < 14
 #    define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #  endif
 #endif
 
 // We had some bugs where we use [[no_unique_address]] together with construct_at,
 // which causes UB as the call on construct_at could write to overlapping subobjects
 //
 // https://github.com/llvm/llvm-project/issues/70506
 // https://github.com/llvm/llvm-project/issues/70494
 //
 // To fix the bug we had to change the ABI of some classes to remove [[no_unique_address]] under certain conditions.
 // The macro below is used for all classes whose ABI have changed as part of fixing these bugs.
 #define _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS __attribute__((__abi_tag__("llvm18_nua")))
 
 // Changes the iterator type of select containers (see below) to a bounded iterator that keeps track of whether it's
 // within the bounds of the original container and asserts it on every dereference.
 //
 // ABI impact: changes the iterator type of the relevant containers.
 //
 // Supported containers:
 // - `span`;
 // - `string_view`.
 // #define _LIBCPP_ABI_BOUNDED_ITERATORS
 
 // Changes the iterator type of `basic_string` to a bounded iterator that keeps track of whether it's within the bounds
 // of the original container and asserts it on every dereference and when performing iterator arithmetics.
 //
 // ABI impact: changes the iterator type of `basic_string` and its specializations, such as `string` and `wstring`.
 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_STRING
 
 // Changes the iterator type of `vector` to a bounded iterator that keeps track of whether it's within the bounds of the
 // original container and asserts it on every dereference and when performing iterator arithmetics. Note: this doesn't
 // yet affect `vector<bool>`.
 //
 // ABI impact: changes the iterator type of `vector` (except `vector<bool>`).
 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_VECTOR
 
 // Changes the iterator type of `array` to a bounded iterator that keeps track of whether it's within the bounds of the
 // container and asserts it on every dereference and when performing iterator arithmetic.
 //
 // ABI impact: changes the iterator type of `array`, its size and its layout.
 // #define _LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY
 
 // [[msvc::no_unique_address]] seems to mostly affect empty classes, so the padding scheme for Itanium doesn't work.
 #if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING)
 #  define _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
 #endif
 
 // Tracks the bounds of the array owned by std::unique_ptr<T[]>, allowing it to trap when accessed out-of-bounds.
 // Note that limited bounds checking is also available outside of this ABI configuration, but only some categories
 // of types can be checked.
 //
 // ABI impact: This causes the layout of std::unique_ptr<T[]> to change and its size to increase.
 //             This also affects the representation of a few library types that use std::unique_ptr
 //             internally, such as the unordered containers.
 // #define _LIBCPP_ABI_BOUNDED_UNIQUE_PTR
 
 #if defined(_LIBCPP_COMPILER_CLANG_BASED)
 #  if defined(__APPLE__)
 #    if defined(__i386__) || defined(__x86_64__)
 // use old string layout on x86_64 and i386
 #    elif defined(__arm__)
 // use old string layout on arm (which does not include aarch64/arm64), except on watch ABIs
 #      if defined(__ARM_ARCH_7K__) && __ARM_ARCH_7K__ >= 2
 #        define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 #      endif
 #    else
 #      define _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 #    endif
 #  endif
 #endif
 
 #endif // _LIBCPP___CONFIGURATION_ABI_H

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