libcxx/src/support/runtime/exception_pointer_glibcxx.ipp

// -*- 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
//
//===----------------------------------------------------------------------===//

// libsupc++ does not implement the dependent EH ABI and the functionality
// it uses to implement std::exception_ptr (which it declares as an alias of
// std::__exception_ptr::exception_ptr) is not directly exported to clients. So
// we have little choice but to hijack std::__exception_ptr::exception_ptr's
// (which fortunately has the same layout as our std::exception_ptr) copy
// constructor, assignment operator and destructor (which are part of its
// stable ABI), and its rethrow_exception(std::__exception_ptr::exception_ptr)
// function.

#include <exception>

namespace std {

namespace __exception_ptr {

struct exception_ptr {
  void* __ptr_;

  explicit exception_ptr(void*) noexcept;
  exception_ptr(const exception_ptr&) noexcept;
  exception_ptr& operator=(const exception_ptr&) noexcept;
  ~exception_ptr() noexcept;
};

} // namespace __exception_ptr

[[noreturn]] void rethrow_exception(__exception_ptr::exception_ptr);

exception_ptr::~exception_ptr() noexcept { reinterpret_cast<__exception_ptr::exception_ptr*>(this)->~exception_ptr(); }

exception_ptr::exception_ptr(const exception_ptr& other) noexcept : __ptr_(other.__ptr_) {
  new (reinterpret_cast<void*>(this))
      __exception_ptr::exception_ptr(reinterpret_cast<const __exception_ptr::exception_ptr&>(other));
}

exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept {
  *reinterpret_cast<__exception_ptr::exception_ptr*>(this) =
      reinterpret_cast<const __exception_ptr::exception_ptr&>(other);
  return *this;
}

exception_ptr exception_ptr::__from_native_exception_pointer(void* __e) noexcept {
  exception_ptr ptr{};
  new (reinterpret_cast<void*>(&ptr)) __exception_ptr::exception_ptr(__e);

  return ptr;
}

nested_exception::nested_exception() noexcept : __ptr_(current_exception()) {}

[[noreturn]] void nested_exception::rethrow_nested() const {
  if (__ptr_ == nullptr)
    terminate();
  rethrow_exception(__ptr_);
}

[[noreturn]] void rethrow_exception(exception_ptr p) {
  rethrow_exception(reinterpret_cast<__exception_ptr::exception_ptr&>(p));
}

} // namespace std