gecko-dev/build/unix/stdc++compat/stdc++compat.cpp

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <ostream>
#include <istream>
#include <string>
#include <stdarg.h>
#include <stdio.h>
#include <mozilla/Assertions.h>

/* GLIBCXX_3.4.8  is from gcc 4.1.1 (111691)
   GLIBCXX_3.4.9  is from gcc 4.2.0 (111690)
   GLIBCXX_3.4.10 is from gcc 4.3.0 (126287)
   GLIBCXX_3.4.11 is from gcc 4.4.0 (133006)
   GLIBCXX_3.4.12 is from gcc 4.4.1 (147138)
   GLIBCXX_3.4.13 is from gcc 4.4.2 (151127)
   GLIBCXX_3.4.14 is from gcc 4.5.0 (151126)
   GLIBCXX_3.4.15 is from gcc 4.6.0 (160071)
   GLIBCXX_3.4.16 is from gcc 4.6.1 (172240)
   GLIBCXX_3.4.17 is from gcc 4.7.0 (174383)
   GLIBCXX_3.4.18 is from gcc 4.8.0 (190787)
   GLIBCXX_3.4.19 is from gcc 4.8.1 (199309)
   GLIBCXX_3.4.20 is from gcc 4.9.0 (199307)
   GLIBCXX_3.4.21 is from gcc 5.0 (210290)
   GLIBCXX_3.4.22 is from gcc 6.0 (222482)

This file adds the necessary compatibility tricks to avoid symbols with
version GLIBCXX_3.4.16 and bigger, keeping binary compatibility with
libstdc++ 4.6.1.

WARNING: all symbols from this file must be defined weak when they
overlap with libstdc++.
*/

#define GLIBCXX_VERSION(a, b, c) (((a) << 16) | ((b) << 8) | (c))

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 18)
// Implementation of utility functions for the prime rehash policy used in
// unordered_map and unordered_set.
#include <unordered_map>
#include <tr1/unordered_map>
namespace std
{
  size_t __attribute__((weak))
  __detail::_Prime_rehash_policy::_M_next_bkt(size_t __n) const
  {
    tr1::__detail::_Prime_rehash_policy policy(_M_max_load_factor);
    size_t ret = policy._M_next_bkt(__n);
    _M_next_resize = policy._M_next_resize;
    return ret;
  }

  pair<bool, size_t> __attribute__((weak))
  __detail::_Prime_rehash_policy::_M_need_rehash(size_t __n_bkt,
                                                 size_t __n_elt,
                                                 size_t __n_ins) const
  {
    tr1::__detail::_Prime_rehash_policy policy(_M_max_load_factor);
    policy._M_next_resize = _M_next_resize;
    pair<bool, size_t> ret = policy._M_need_rehash(__n_bkt, __n_elt, __n_ins);
    _M_next_resize = policy._M_next_resize;
    return ret;
  }
}
#endif

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 20)
namespace std {

    /* We shouldn't be throwing exceptions at all, but it sadly turns out
       we call STL (inline) functions that do. */
    void __attribute__((weak)) __throw_out_of_range_fmt(char const* fmt, ...)
    {
        va_list ap;
        char buf[1024]; // That should be big enough.

        va_start(ap, fmt);
        vsnprintf(buf, sizeof(buf), fmt, ap);
        buf[sizeof(buf) - 1] = 0;
        va_end(ap);

        __throw_range_error(buf);
    }

}
#endif

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 20)
/* Technically, this symbol is not in GLIBCXX_3.4.20, but in CXXABI_1.3.8,
   but that's equivalent, version-wise. Those calls are added by the compiler
   itself on `new Class[n]` calls. */
extern "C" void __attribute__((weak))
__cxa_throw_bad_array_new_length()
{
    MOZ_CRASH();
}
#endif

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 21)
/* While we generally don't build with exceptions, we have some host tools
 * that do use them. libstdc++ from GCC 5.0 added exception constructors with
 * char const* argument. Older versions only have a constructor with
 * std::string. */
namespace std {
    __attribute__((weak)) runtime_error::runtime_error(char const* s)
    : runtime_error(std::string(s))
    {
    }
}
#endif

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 21)
/* Expose the definitions for the old ABI, allowing us to call its functions */
#define _GLIBCXX_THREAD_ABI_COMPAT 1
#include <thread>

namespace std {
  /* The old ABI has a thread::_M_start_thread(shared_ptr<_Impl_base>),
   * while the new has thread::_M_start_thread(unique_ptr<_State>, void(*)()).
   * There is an intermediate ABI at version 3.4.21, with
   * thread::_M_start_thread(shared_ptr<_Impl_base>, void(*)()).
   * The void(*)() parameter is only there to keep a reference to pthread_create
   * on the caller side, and is unused in the implementation
   * We're creating an entry point for the new and intermediate ABIs, and make
   * them call the old ABI. */

  __attribute__((weak))
  void thread::_M_start_thread(shared_ptr<_Impl_base> impl, void (*)())
  {
    _M_start_thread(std::move(impl));
  }

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 22)
  /* We need a _Impl_base-derived class wrapping a _State to call the old ABI
   * from what we got by diverting the new API */
  struct StateWrapper: public thread::_Impl_base {
    unique_ptr<thread::_State> mState;

    StateWrapper(unique_ptr<thread::_State> aState)
    : mState(std::move(aState))
    { }

    void _M_run() override
    {
      mState->_M_run();
    }
  };

  __attribute__((weak))
  void thread::_M_start_thread(unique_ptr<_State> aState, void (*)())
  {
    auto impl = std::make_shared<StateWrapper>(std::move(aState));
    _M_start_thread(std::move(impl));
  }

  /* For some reason this is a symbol exported by new versions of libstdc++,
   * even though the destructor is default there too */
  __attribute__((weak)) thread::_State::~_State() = default;
#endif
}
#endif

#if MOZ_LIBSTDCXX_VERSION >= GLIBCXX_VERSION(3, 4, 21)
namespace std
{
  /* Instantiate this template to avoid GLIBCXX_3.4.21 symbol versions
   * depending on optimization level */
  template basic_ios<char, char_traits<char> >::operator bool() const;
}
#endif