compilation-filter-hook is a variable defined in `compile.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Hook run after `compilation-filter' has inserted a string into the buffer.
It is called with the variable `compilation-filter-start' bound
to the position of the start of the inserted text, and point at
its end.

If Emacs lacks asynchronous process support, this hook is run
after `call-process' inserts the grep output into the buffer.