/usr/include/boost/asio/ssl/impl/context.ipp:571:33: error: invalid use of incomplete type ‘SSL_CTX {aka struct ssl_ctx_st}’ ::sk_X509_pop_free(handle_->extra_certs, X509_free); ^ In file included from /usr/include/openssl/crypto.h:31:0, from /usr/include/openssl/bio.h:20, ...