x::yaml::newaliasnode is a x::yaml::newnode that writes a reference to an anchor, of the same name. A node that's already written to the YAML document, a mapping node, a sequence node, or even a scalar node must have a matching anchor.

At this time, LibCXX does not verify that the alias reference is valid. It is up to the application to make sure that the alias reference is valid, otherwise parsing the YAML document will result in a thrown exception.