enhanced version that tests all the optimizations.

(the .c generated prior to optimization contains
a zero-sized union though, which is wrong)

test/cdata.in

+n = a | b | c | d | e;
+o = a( int aa );
+p = a | b;
+q = a | b | c(int cc) | d | e;
+r = a | b | c(int cc) | d( string dd) | e;
+s = a(int aa) | b | c | d | e;
+
 intlist = null "null" | cons( int first, intlist next ) 1 " , " 2;
 illist  = null "null" | cons( intlist first, illist next ) "[ " 1 " ] , " 2;
 idtree  = leaf( string id ) "leaf '" 1 "'"