ArchLinux has just received packages for OpenSSL 1.1.1, which provides support for TLS 1.3.
ssl_manager_openssl.cpp attempts to increment TLS version counts for TLS 1.3, if it is compiled against a version of OpenSSL which exposes a relevant preprocessor macro. However, TLSVersionCounts is missing the member variable which needs to be incremented.
This causes compilation to fail.
We likely additionally need an "unknown" field. MongoDB binaries compiled against old versions of OpenSSL, but dynamically linked against newer versions may be able to negotiate TLS 1.3 while not having access to compile time constants which identify the protocol.
In order to test this functionality, we will need to add support for TLS 1.3 to be used in tlsDisableProtocols, on platforms that support the protocol