bison: m4 subprocess failed

[fswarbrick]

Trying to port gpm (General Purpose Mouse package), https://github.com/telmich/gpm, and I'm getting the following during the make step:

config.status: executing libtool commands
touch src/.depend # to prevent unecessary warnings
make -C src dep
make[1]: Entering directory '/u/dvfjs/repos/gpm/src'
bison -y  /u/dvfjs/repos/gpm/src/prog/gpm-root.y && mv y.tab.c prog/gpm-root.c
bison: m4 subprocess failed
make[1]: *** [Makefile:149: prog/gpm-root.c] Error 1
make[1]: Leaving directory '/u/dvfjs/repos/gpm/src'
make: *** [Makefile:33: dep] Error 2

Any thoughts?

[IgorTodorovskiIBM]

I believe bison accepts --debug as an option for more information.
I vaguely recall seeing this issue, which I believe was fixed via this PR zopencommunity/bisonport#13 and using the z/OS Open Tools m4. Are you using /bin/m4 or zot's m4?

[fswarbrick]

I'm using z/OS Tools version. There is not, in fact, a version of bison or m4 provided with z/OS (there is yacc). Anyway, the --debug option only traces the grammar, and it's not even getting that far.
Both bison and m4 look to be the most recent z/OS Tools version.