flymake-master-file-compare
flymake-master-file-compare is a compiled Lisp function in `flymake.el
'.
(flymake-master-file-compare FILE-ONE FILE-TWO)
Compare two files specified by FILE-ONE and FILE-TWO.
This function is used in sort to move most possible file names
to the beginning of the list (File.h -> File.cpp moved to top).