Before looking at alias resulting type, (and accessibility) we look at names and indeed, NetworkPacket might be MultiCmdQueueCallback::NetworkPacket or PlcMsgFactoryImplCallback::NetworkPacket The fact they both point to Networking::NetworkPacket is irrelevant. We do first name resolution, which results in ambiguity.
They are equivalent, from the standard (emphasis mine) (7.1.3.2): A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. It has the same semantics as if it were introduced by the typedef specifier. In particular, it … Read more
They are equivalent, from the standard (emphasis mine) (7.1.3.2): A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. It has the same semantics as if it were introduced by the typedef specifier. In particular, it … Read more