LibreSSL と Boost.ASIO.SSL を組み合わせて使う事になった場合に ::SSL_CTX_get_default_passwd_cb_userdata 等複数箇所で翻訳時エラーが生じてしまう場合の応急対処法 ref: http://qiita.com/usagi/items/acee410849ca8f4f9c11

file0.txt

...include/boost/asio/ssl/impl/context.ipp: In destructor 'boost::asio::ssl::context::~context()':
.../include/boost/asio/ssl/impl/context.ipp:232:25: error: '::SSL_CTX_get_default_passwd_cb_userdata' has not been declared
     void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
                         ^~

file1.cpp

#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
    void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
#else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
    void* cb_userdata = handle_->default_passwd_callback_userdata;
#endif // (OPENSSL_VERSION_NUMBER >= 0x10100000L)

file2.cpp

#if (OPENSSL_VERSION_NUMBER >= 0x10002000L) \
    && (OPENSSL_VERSION_NUMBER < 0x10100000L)
    ::SSL_COMP_free_compression_methods();
#endif // (OPENSSL_VERSION_NUMBER >= 0x10002000L)

file3.cpp

# define OPENSSL_VERSION_NUMBER  0x10100040L
# ifdef OPENSSL_FIPS
#  define OPENSSL_VERSION_TEXT    "OpenSSL 1.1.0d-fips-dev  xx XXX xxxx"
# else
#  define OPENSSL_VERSION_TEXT    "OpenSSL 1.1.0d-dev  xx XXX xxxx"
# endif

file4.cpp

/* These will never change */
#define OPENSSL_VERSION_NUMBER  0x20000000L
#define OPENSSL_VERSION_TEXT    LIBRESSL_VERSION_TEXT
#define OPENSSL_VERSION_PTEXT   " part of " OPENSSL_VERSION_TEXT

file5.cpp

#define LIBRESSL_VERSION_NUMBER       0x2030200fL
#define LIBRESSL_VERSION_TEXT "LibreSSL 2.3.2"

file6.cpp

/// @brief LibreSSL と Boost.ASIO.SSL の OpenSSL-1.1 API 対応判定の偽装処理
/// @ref http://qiita.com/usagi/items/acee410849ca8f4f9c11
/// @{
#if LIBRESSL_VERSION_NUMBER <= 0x2050100fL
  #include <openssl/opensslv.h>
  #undef OPENSSL_VERSION_NUMBER
  #define OPENSSL_VERSION_NUMBER 0x10001fffL
#endif
/// @}

#include <boost/asio/ssl.hpp>