yacc - bison end of file

Question

If I forget to put an empty line at the end of any of my files my program gets a syntax error. The problem is my grammar expects a newline to end the current line. Since a newline doesn't exist bison generates a syntax error because it does not finish the rule.

How do I solve this? I tried making <<EOF>> return MY_EOF BUT when I do that lex crashes a horrible death. I guess there's code in its default EOF that I am not calling. I have no idea what functions they may be. Using EOF create the error symbol EOF is used, but is not defined as a token and has no rules

Answer 1

You could use a flex EOF rule to append a newline to the input:

<<EOF>> { static int once = 0; return once++ ? 0 : '
' }