Returns the pathname of the protocol buffer definition file that must be translated into Lisp source code for this PROTO-FILE component.
RESOLVE-RELATIVE-PATHNAME (PATH PARENT-PATH)
When PATH doesn't have an absolute directory component, treat it as relative to PARENT-PATH.
An ASDF operation that compiles a .proto file containing protocol buffer definitions into a Lisp source file.
Condition signalled when translating a .proto file into Lisp code fails.