He shows us Flex/Yacc and shift/reduce errors then moves on. I'd greatly appreciate tools tips to either - help better diagnose where/why shift/reduce arises i

He shows us Flex/Yacc and shift/reduce errors then moves on. I'd greatly appreciate tools tips to either - help better diagnose where/why shift/reduce arises in the context of a given grammar - argument if Prat or another approach entirely avoids shif/reduce errors.