Re: [PATCH nft] parser_bison: on syntax errors, output expected tokens

[Florian Westphal <fw@strlen.de>]

Jan Kończak <jan.konczak@cs.put.poznan.pl> wrote:
> Now, on syntax erros, e.g., 'nft create fable filter', the user sees:
>    Error: syntax error, unexpected string
>    create fable filter
>           ^^^^^
> The patch builds an error message that lists what the parser expects
> to see, in that case it would print:
>    Error: syntax error, unexpected string
>    expected any of: synproxy, table, chain, set, element, map,
>    flowtable, ct, counter, limit, quota, secmark
>    create fable filter
>           ^^^^^

Thanks, this looks great.
Just a note that there might be slight delay with this getting applied
because we'd like to make a new release soon.

> Heed that the list of possible items on the parser's side is not
> always consistent with expectations.
> For instance, lexer/parser recognizes 'l4proto' in this command:
>    nft add rule ip F I meta l4proto tcp
> as a generic '%token <string> STRING', while 'iifname' in 
>    nft add rule ip F I meta iifname eth0
> is recognized as a '%token IIFNAME'
> In such case the parser is only able to say that right after 'meta'
> it expects 'iifname' or 'string', rather than 'iifname' and 'l4proto'.

Yes, thats fine.

We should move this to flex keywords, this STRING hack dates back to
the pre-flex-start-conditions era where adding new meta keywords might
have broken existing rulesets.