change-log-goto-source-1 is a compiled Lisp function in `add-log.el'.

(change-log-goto-source-1 TAG REGEXP FILE BUFFER &optional WINDOW FIRST LAST)

Search for tag TAG in buffer BUFFER visiting file FILE.
REGEXP is a regular expression for TAG. The remaining arguments
are optional: WINDOW denotes the window to display the results of
the search. FIRST is a position in BUFFER denoting the first
match from previous searches for TAG. LAST is the position in
BUFFER denoting the last match for TAG in the last search.