Re: Different conflicts between byacc and bison

[Kaz Kylheku]

On 2021-11-04 01:57, Domingo Alvarez Duarte wrote:
> Also tested with the latest byacc from 
> https://invisible-island.net/byacc/:
>
> ====
>
> ./yacc -V
> ./yacc - 2.0 20210808
>
> byacc-20210808/yacc gram.y
> byacc-20210808/yacc: 21 shift/reduce conflicts, 3 reduce/reduce 
> conflicts.

Now, I've not looked at that grammar at all, or where those conflicts 
are coming
from, and which ones are different between Bison and Bycc. Zero analysis 
here.

Therefore, I don't intend to offer the the following remarks as being 
relevant
to what you are seeing. But, you never know.

I also use both Bison and Byacc, and have come across some differences.

In my particular case, it was a situation where I had to do some extra 
things
in the grammar to make Byacc happy that Bison didn't need:

https://www.kylheku.com/cgit/txr/commit/?id=899655aa3b256dab10e764889c8323a53a585a04

My comment in this 2015 commit records what I think I was able to learn
from the investigation:

| Bison doesn't need this because it has $default actions which reduce
| regardless of the lookahead token. BYacc insists on reducing only
| if it can match $end (end of input), and not other tokens, which
| constitute syntax errors.

Perhaps useful, perhaps not.

Cheers ...