PL/I for GCC is an implementation of PL/I as a frontend for GCC. Very interesting, as it is not a precompiler with C output and, unlike earlier projects, does not aim to be only a subset implementation (although, of course, at the moment only a subset is implemented - but it is constantly growing). I admit, I still like the baroque syntax of PL/I, even though it has been many years since I programmed with it.