diff -u | a2ps -Eudiff --prologue=diff
"very nice output" he says.
So I got to the bottom of my problem with the Renesas H8 compiler. The internal file it couldn't open? The object file for the source it was compiling. Because the directory (./obj/Debug/) it wanted to put the object code into didn't exist. I'd deleted it to effect a 'make clean' (the makefile tree doesn't have that recipe) assuming the compiler was smart enough to recreate it. I was wrong.
*grumble* It was a major loss of time, but not a total loss. I got assigned to move some drivers for our Sparc targets over from Solaris 2.8 to 2.10, mostly as an exercise to get me familiar with that platform. So far, it's been recompiling under 2.10. (Of course, it was two days to get 2.10 up and running with compilers...)