flymake-proc

Flymake is a minor Emacs mode performing on-the-fly syntax checks.

This file contains a significant part of the original flymake's
implementation, a buffer-checking mechanism that parses the output
of an external syntax check tool with regular expressions.

That work has been adapted into a flymake "backend" function,
`flymake-proc-legacy-flymake' suitable for adding to the
`flymake-diagnostic-functions' variable.