// -*- 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___AVAILABILITY
#define _LIBCPP___AVAILABILITY

#include <__config>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

// Libc++ is shipped by various vendors. In particular, it is used as a system
// library on macOS, iOS and other Apple platforms. In order for users to be
// able to compile a binary that is intended to be deployed to an older version
// of a platform, Clang provides availability attributes [1]. These attributes
// can be placed on declarations and are used to describe the life cycle of a
// symbol in the library.
//
// The main goal is to ensure a compile-time error if a symbol that hasn't been
// introduced in a previously released library is used in a program that targets
// that previously released library. Normally, this would be a load-time error
// when one tries to launch the program against the older library.
//
// For example, the filesystem library was introduced in the dylib in macOS 10.15.
// If a user compiles on a macOS 10.15 host but targets macOS 10.13 with their
// program, the compiler would normally not complain (because the required
// declarations are in the headers), but the dynamic loader would fail to find
// the symbols when actually trying to launch the program on macOS 10.13. To
// turn this into a compile-time issue instead, declarations are annotated with
// when they were introduced, and the compiler can produce a diagnostic if the
// program references something that isn't available on the deployment target.
//
// This mechanism is general in nature, and any vendor can add their markup to
// the library (see below). Whenever a new feature is added that requires support
// in the shared library, two macros are added below to allow marking the feature
// as unavailable:
// 1. A macro named `_LIBCPP_AVAILABILITY_HAS_NO_<feature>` which must be defined
//    exactly when compiling for a target that doesn't support the feature.
// 2. A macro named `_LIBCPP_AVAILABILITY_<feature>`, which must always be defined
//    and must expand to the proper availability attribute for the platform.
//
// When vendors decide to ship the feature as part of their shared library, they
// can update these macros appropriately for their platform, and the library will
// use those to provide an optimal user experience.
//
// Furthermore, many features in the standard library have corresponding
// feature-test macros. The `_LIBCPP_AVAILABILITY_HAS_NO_<feature>` macros
// are checked by the corresponding feature-test macros generated by
// generate_feature_test_macro_components.py to ensure that the library
// doesn't announce a feature as being implemented if it is unavailable on
// the deployment target.
//
// Note that this mechanism is disabled by default in the "upstream" libc++.
// Availability annotations are only meaningful when shipping libc++ inside
// a platform (i.e. as a system library), and so vendors that want them should
// turn those annotations on at CMake configuration time.
//
// [1]: https://clang.llvm.org/docs/AttributeReference.html#availability

// For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY
// for a while.
#if defined(_LIBCPP_DISABLE_AVAILABILITY)
#  if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
#    define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
#  endif
#endif

// Availability markup is disabled when building the library, or when the compiler
// doesn't support the proper attributes.
#if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCXXABI_BUILDING_LIBRARY) ||                                       \
    !__has_feature(attribute_availability_with_strict) || !__has_feature(attribute_availability_in_templates) ||       \
    !__has_extension(pragma_clang_attribute_external_declaration)
#  if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
#    define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
#  endif
#endif

#if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)

// These macros control the availability of std::bad_optional_access and
// other exception types. These were put in the shared library to prevent
// code bloat from every user program defining the vtable for these exception
// types.
//
// Note that when exceptions are disabled, the methods that normally throw
// these exceptions can be used even on older deployment targets, but those
// methods will abort instead of throwing.
#  define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 1
#  define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS

#  define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS 1
#  define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS

#  define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST 1
#  define _LIBCPP_AVAILABILITY_BAD_ANY_CAST

// These macros control the availability of all parts of <filesystem> that
// depend on something in the dylib.
#  define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1
#  define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY
#  define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH
#  define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP

// This controls the availability of floating-point std::to_chars functions.
// These overloads were added later than the integer overloads.
#  define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1
#  define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT

// This controls the availability of the C++20 synchronization library,
// which requires shared library support for various operations
// (see libcxx/src/atomic.cpp). This includes <barier>, <latch>,
// <semaphore>, and notification functions on std::atomic.
#  define _LIBCPP_AVAILABILITY_HAS_SYNC 1
#  define _LIBCPP_AVAILABILITY_SYNC

// This controls whether the library claims to provide a default verbose
// termination function, and consequently whether the headers will try
// to use it when the mechanism isn't overriden at compile-time.
#  define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 1
#  define _LIBCPP_AVAILABILITY_VERBOSE_ABORT

// This controls the availability of the C++17 std::pmr library,
// which is implemented in large part in the built library.
#  define _LIBCPP_AVAILABILITY_HAS_PMR 1
#  define _LIBCPP_AVAILABILITY_PMR

// This controls the availability of the C++20 time zone database.
// The parser code is built in the library.
#  define _LIBCPP_AVAILABILITY_HAS_TZDB 1
#  define _LIBCPP_AVAILABILITY_TZDB

    // This controls the availability of C++23 <print>, which
    // has a dependency on the built library (it needs access to
    // the underlying buffer types of std::cout, std::cerr, and std::clog.
#  define _LIBCPP_AVAILABILITY_HAS_PRINT 1
#  define _LIBCPP_AVAILABILITY_PRINT

// Enable additional explicit instantiations of iostreams components. This
// reduces the number of weak definitions generated in programs that use
// iostreams by providing a single strong definition in the shared library.
//
// TODO: Enable additional explicit instantiations on GCC once it supports exclude_from_explicit_instantiation,
//       or once libc++ doesn't use the attribute anymore.
// TODO: Enable them on Windows once https://llvm.org/PR41018 has been fixed.
#  if !defined(_LIBCPP_COMPILER_GCC) && !defined(_WIN32)
#    define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1
#  else
#    define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0
#  endif

#elif defined(__APPLE__)

#  define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS                                                                 \
    (!defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) || __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 50000)

#  define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS
#  define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS

#  define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((availability(watchos, strict, introduced = 5.0)))
#  define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
#  define _LIBCPP_AVAILABILITY_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS

// <filesystem>
// clang-format off
#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) ||   \
      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \
      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) ||         \
      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000)
// clang-format on
#    define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 0
#  else
#    define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1
#  endif
#  define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY                                                                      \
    __attribute__((availability(macos, strict, introduced = 10.15)))                                                   \
    __attribute__((availability(ios, strict, introduced = 13.0)))                                                      \
    __attribute__((availability(tvos, strict, introduced = 13.0)))                                                     \
    __attribute__((availability(watchos, strict, introduced = 6.0)))
// clang-format off
#   define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH                                 \
        _Pragma("clang attribute push(__attribute__((availability(macos,strict,introduced=10.15))), apply_to=any(function,record))") \
        _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))")    \
        _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))")   \
        _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))")
#   define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP                                  \
        _Pragma("clang attribute pop")                                          \
        _Pragma("clang attribute pop")                                          \
        _Pragma("clang attribute pop")                                          \
        _Pragma("clang attribute pop")
// clang-format on

// std::to_chars(floating-point)
// clang-format off
#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 130300) ||   \
      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 160300) || \
      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 160300) ||         \
      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 90300)
// clang-format on
#    define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 0
#  else
#    define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1
#  endif
#  define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT                                                                 \
    __attribute__((availability(macos, strict, introduced = 13.3)))                                                    \
    __attribute__((availability(ios, strict, introduced = 16.3)))                                                      \
    __attribute__((availability(tvos, strict, introduced = 16.3)))                                                     \
    __attribute__((availability(watchos, strict, introduced = 9.3)))

// c++20 synchronization library
// clang-format off
#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) ||   \
       (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \
       (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) ||         \
       (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000)
// clang-format on
#    define _LIBCPP_AVAILABILITY_HAS_SYNC 0
#  else
#    define _LIBCPP_AVAILABILITY_HAS_SYNC 1
#  endif
#  define _LIBCPP_AVAILABILITY_SYNC                                                                                    \
    __attribute__((availability(macos, strict, introduced = 11.0)))                                                    \
    __attribute__((availability(ios, strict, introduced = 14.0)))                                                      \
    __attribute__((availability(tvos, strict, introduced = 14.0)))                                                     \
    __attribute__((availability(watchos, strict, introduced = 7.0)))

// __libcpp_verbose_abort
// TODO: Update once this is released
#  define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 0

#  define _LIBCPP_AVAILABILITY_VERBOSE_ABORT __attribute__((unavailable))

// std::pmr
// clang-format off
#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 140000) ||   \
      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 170000) || \
      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 170000) ||         \
      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 100000)
// clang-format on
#    define _LIBCPP_AVAILABILITY_HAS_PMR 0
#  else
#    define _LIBCPP_AVAILABILITY_HAS_PMR 1
#  endif
// TODO: Enable std::pmr markup once https://github.com/llvm/llvm-project/issues/40340 has been fixed
//       Until then, it is possible for folks to try to use `std::pmr` when back-deploying to targets that don't support
//       it and it'll be a load-time error, but we don't have a good alternative because the library won't compile if we
//       use availability annotations until that bug has been fixed.
#  if 0
#    define _LIBCPP_AVAILABILITY_PMR                                                                                   \
      __attribute__((availability(macos, strict, introduced = 14.0)))                                                  \
      __attribute__((availability(ios, strict, introduced = 17.0)))                                                    \
      __attribute__((availability(tvos, strict, introduced = 17.0)))                                                   \
      __attribute__((availability(watchos, strict, introduced = 10.0)))
#  else
#    define _LIBCPP_AVAILABILITY_PMR
#  endif

#  define _LIBCPP_AVAILABILITY_HAS_TZDB 0
#  define _LIBCPP_AVAILABILITY_TZDB __attribute__((unavailable))

// Warning: This availability macro works differently than the other macros.
// The dylib part of print is not needed on Apple platforms. Therefore when
// the macro is not available the code calling the dylib is commented out.
// The macro _LIBCPP_AVAILABILITY_PRINT is not used.
#  define _LIBCPP_AVAILABILITY_HAS_PRINT 0
#  define _LIBCPP_AVAILABILITY_PRINT __attribute__((unavailable))

// clang-format off
#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 120000)   || \
      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 150000) || \
      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 150000)         || \
      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 80000)
// clang-format on
#    define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0
#  else
#    define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1
#  endif
#else

// ...New vendors can add availability markup here...

#  error                                                                                                               \
      "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!"

#endif

// Define availability attributes that depend on _LIBCPP_HAS_NO_EXCEPTIONS.
// Those are defined in terms of the availability attributes above, and
// should not be vendor-specific.
#if defined(_LIBCPP_HAS_NO_EXCEPTIONS)
#  define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST
#  define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
#  define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
#else
#  define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST
#  define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
#  define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
#endif

#endif // _LIBCPP___AVAILABILITY