Re: RFC: generate the default semantic action

[Hans Åberg]

> On 14 Oct 2018, at 16:54, Akim Demaille <address@hidden> wrote:
> 
> Le 14 oct. 2018 à 16:43, Akim Demaille <address@hidden> 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?