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Ensure coroutine case labels are deterministic when __COUNTER__ is used.

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Coroutine implementations can be included from multiple translation
units in a different order. When __COUNTER__ is used (for MSVC), this
means that the values yielded by __COUNTER__ for a particular coroutine
can differ between TUs.
This commit is contained in:
Christopher Kohlhoff
2025-12-01 22:49:47 +11:00
parent fc1b01e27c
commit f9157802a7
1 changed files with 30 additions and 8 deletions
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38
include/boost/asio/coroutine.hpp
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@@ -276,12 +276,34 @@ private:
bool modified_;
};
class coroutine_base_value
{
public:
constexpr coroutine_base_value(int value) : value_(value) {}
constexpr operator bool() const { return false; }
constexpr int get() const { return value_; }
private:
int value_;
};
} // namespace detail
} // namespace asio
} // namespace boost
#if !defined(BOOST_ASIO_CORO_VALUE_INIT)
# if defined(_MSC_VER)
# define BOOST_ASIO_CORO_VALUE_INIT __COUNTER__
# else // defined(_MSC_VER)
# define BOOST_ASIO_CORO_VALUE_INIT __LINE__
# endif // defined(_MSC_VER)
#endif // !defined(BOOST_ASIO_CORO_VALUE_INIT)
#define BOOST_ASIO_CORO_REENTER(c) \
switch (::boost::asio::detail::coroutine_ref _coro_value = c) \
if (constexpr ::boost::asio::detail::coroutine_base_value \
_coro_base_value = BOOST_ASIO_CORO_VALUE_INIT) \
{ \
} \
else switch (::boost::asio::detail::coroutine_ref _coro_value = c) \
case -1: if (_coro_value) \
{ \
goto terminate_coroutine; \
@@ -319,12 +341,12 @@ private:
} \
else
#if defined(_MSC_VER)
# define BOOST_ASIO_CORO_YIELD BOOST_ASIO_CORO_YIELD_IMPL(__COUNTER__ + 1)
# define BOOST_ASIO_CORO_FORK BOOST_ASIO_CORO_FORK_IMPL(__COUNTER__ + 1)
#else // defined(_MSC_VER)
# define BOOST_ASIO_CORO_YIELD BOOST_ASIO_CORO_YIELD_IMPL(__LINE__)
# define BOOST_ASIO_CORO_FORK BOOST_ASIO_CORO_FORK_IMPL(__LINE__)
#endif // defined(_MSC_VER)
# define BOOST_ASIO_CORO_YIELD \
BOOST_ASIO_CORO_YIELD_IMPL( \
BOOST_ASIO_CORO_VALUE_INIT + 1 - _coro_base_value.get())
# define BOOST_ASIO_CORO_FORK \
BOOST_ASIO_CORO_FORK_IMPL( \
BOOST_ASIO_CORO_VALUE_INIT + 1 - _coro_base_value.get())
#endif // BOOST_ASIO_COROUTINE_HPP