How to find ports name from package that is a flavor?

[cracauer@]

Given (1) a ports tree and (2) the name of a package that is a non-default flavor of a differently named port, how do I find which port it is coming from?

E.g. qemu-guest-agent

 

[MG]

Maybe make -n of the port that has flavors and grep out the dependency builds that it triggers with this flavor enabled, and hope you recognize the special case port?

 

[Charlie_]

$ pkg search -o qemu-guest-agent
emulators/qemu                 QEMU CPU Emulator (guest agent)