Re: Best Practice: lexer error to silent parser abort

[Akim Demaille]

Hi Simon,

> Le 1 janv. 2019 à 23:19, Simon Richter <address@hidden> a écrit :
> 
> Hi,
> 
> I'm wondering what would be the best way to communicate from the lexer
> to the parser that the lexer detected something it could not tokenize
> (in my case, characters outside the allowed character set).
> 
> In this case, it is fairly obvious that we want to abort, without a call
> to yyerror, but properly destructing and deallocating any values still
> on the stack.
> 
> The best way I can think of at the moment would be to define an
> additional token type that isn't used in any rule, return that from the
> lexer, and create a shortcut between lexer and parser that silences yyerror.

Bison 3.6 will offer a means to do this: returning YYerror from the scanner.
Please, have a look at this commit:

https://lists.gnu.org/r/bison-patches/2020-04/msg00180.html

and give a try to this beta:

https://lists.gnu.org/r/bison-patches/2020-04/msg00181.html

Cheers!