;; using the same *compilation* buffer. this necessitates re-parsing markers.
;; FILE-STRUCTURE is a list of
-;; ((FILENAME . DIRECTORY) FORMATS (LINE LOC ...) ...)
+;; ((FILENAME DIRECTORY) FORMATS (LINE LOC ...) ...)
;; FILENAME is a string parsed from an error message. DIRECTORY is a string
;; obtained by following directory change messages. DIRECTORY will be nil for