my own
compiler choked on if.b and mail.b because of this invalid
expression in nxtarg:
if(ap>ac) return(0*ap++);
The return value is still a typo, but this expression should not pose
a problem, the AST shows that the postinc has priority, uses a legit
lvalue, which result is multiplied by zero.
This was probably not intended but syntactically correct.
I could well believe it's not a typo, but a "clever" way to write
if(ap>ac) {
ap++;
return 0;
}