Syntax check is considered possible if there's an entry in
flymake-allowed-file-name-masks matching buffer's filename and
init-function returns non-
Two syntax check modes are distinguished:
These modes are handled inside init/cleanup/getfname functions, see Adding support for a new syntax check tool.
Flymake contains implementations of all functionality required to support different syntax check modes described above (making temporary copies, finding master files, etc.), as well as some tool-specific (routines for Make, Ant, etc.) code.