The error message is telling you that you have referenced two functions, yyerror()
and computSymbolIndex()
, which you have not defined.
For the first one, you will need to provide a definition for that function. It is not provided by yacc, but it won't be hard to write. (All it needs to do here is probably just print the error and exit(1)
.)
For the second one, you will need to fix your typo.