> On 14 Oct 2018, at 16:54, Akim Demaille <[email protected]> wrote: > > Le 14 oct. 2018 à 16:43, Akim Demaille <[email protected]> a écrit : > >> Yes, I read that too, and found it extremely ambiguous. > > And Steve Johnson’s paper is just the same. > > https://www.epaperpress.com/lexandyacc/download/yacc.pdf > > By default, the value of a rule is the value of the first element in it ($1). > Thus, grammar rules of the form > A:B; > frequently need not have an explicit action.
POSIX probably got it from there through copy-and-paste, then. So rules with empty RHS do not have any default value. What happen with Bison's default value in such a case, that is, what does it get when there is no $1?
