Re: YYEOF shouldn't be defined with bison -y

[Akim Demaille]

Hi!

I’m coming long after the discussion, sorry.

> Le 5 déc. 2017 à 02:32, Dimitrios Apostolou <address@hidden> a écrit :
> 
> On Mon, 04 Dec 2017 21:24:40 +0100,
> Kaz Kylheku wrote:
>> 
>> On 03.12.2017 18:34, Dimitrios Apostolou wrote:
>>> Hello list,
>>> 
>>> I am configuring the build using AC_PROG_YACC, which invokes bison with "-y"
>>> option.  But bison-generated parser compiled successfully, and YYEOF
>>> extension
>>> in the parser remained undetected.
>>> 
>>> Generating the parser with "byacc" on the other hand creates a file that
>>> does
>>> not compile because of undefined symbol YYEOF.
>> 
>> What is your error report?
>> 
>> Are you saying that you cannot boostrap a build of Bison using Byacc?
> 
> My error report has nothing to do with bootstrapping Bison, sorry for not
> being clear.
> 
> I am generating a parser as part of a different project, and that project is
> configured with AC_PROG_YACC. As such, it invokes Bison with "-y" option, and
> I would expect that Bison tries hard to fail when the parser uses non-portable
> features, such as YYEOF.
> 
> This is not the case however, and the project was released, and this was
> discovered after longtime that somebody built it with byacc instead of
> Bison. With that version of byacc, the generated parser C code failed to build
> with "undefined symbol YYEOF".
> 
> I would expect that "bison -y" undefines YYEOF, so that the software that uses
> YYEOF fails to build.

There’s something which is not fully clear here: unless _you_ used YYEOF
somewhere in your code, there’s no reason for the parser not to be
compilable with byacc.

So I expect that you did use YYEOF.  In which case, the question is rather:
where was it used, to what purpose, and how would you have expected to
write it independently of YYEOF?