this directory contains the interface code between the Modula-2 front end and GCC.
In effect this is the Modula-2 compiler GCC Tree API.  It is an internal API only.
Many of these filenames match their GCC c family counterparts.  So for example
m2-decl.def and m2-decl.c are the Modula-2 front end version of c-decl.c.
