> install.log was no help, the message I quoted was everything
> relevant.
> I took a stab at running gdb through yacc, but the compiler
> optimized the code to the point finding the problem was
> nearly impossible.....best I can say is its somewhere in the
> dofmt() function (lib9/fmt/dofmt.c) or something it calls.

i trust you ran yacc under gdb not gdb through yacc. :-)
the problem is unlikely to be with the print. it likely
occurred in argument parsing.

one thing that should be fixed in p9p is the ARGF() calls
should be replaced with EARGF(usage()) in setup(). the
definition of usage should be

fprint(2, "usage: yacc [-Dn] [-vdS] [-o outputfile] [-s stem] grammar\n");

once that is fixed, it would be interesting to see if yacc
prints a usage statement instead of printing the garbage.

assuming that things are still broken, i would suggest
adding fprint(2, "...") statements in setup to understand
where things are going wrong.

- erik