Adjust to the moving target called the C++ standard. Apparently nowadays it's not allowed to define an explicit copy constructor but not an assignment operator. Consequently, defining the explicit copy constructor in terms of the implicit/automatic assignment operator for general convenience no longer works. Add assignment operators. Caution: not tested with the IBM compiler, but there's no particular reason it shouldn't work.

/* Test parameters for immediate actions */

[ ~allow macros]

letter = 'A-Z' + 'a-z'

grammar
 -> [letter:a, letter: b, !printf("immed:  %c%c\n", a, b);,
     '\n'=printf("reduce: %c%c\n", a,b);]..., -1