Re: [jamboost] Problems

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-03-04 03:27:15

David Abrahams wrote:
> 1. All of a sudden, when I set BUILD on the jam command-line, it has no
> effect!
> Rene?
> (I happen to be using the perforce_2_4_merge version of Boost.Jam, FWIW)

I was using a fixed version of Boost.Build for some time and now tried the 
cvs head. It just gives an error on my project, so we have a regression.

> 2. When I rebuilt the 2.4 merge version on OSF and tried to use it, I still
> got a Yacc stack overflow. I know this has happened on a few other
> platforms as well. I always assumed that this would be fixed by the use of
> right recursion in the grammar. I guess one of the following must be true:
> a. Yacc is just broken on these platforms
> b. We have brought forward some left-recursion from our pre-2.4 grammar
> If it's b, we should fix it. If it's a, we should probably disable the
> running of yacc in the jamfile by default. We deliver pre-yacced source
> anyway, so most people don't need to run it.

I'm just looking at all the changes made to jamgram.yy in the Perforce 
version. I can't see any left-to-right-recursion changes at all. The only 
stack overflow related fix that I'm aware of is in compile_rules routine.

> 3. Looking at the difference between the perforce_jam_2_4 and
> perforce_2_4_merge versions of jamgram.yy, it looks as though we failed to
> catch some of the new changes. For example, the expression grammar is
> different, 

It is. I've grabbed changes that Craig McPheeters suggested on the jamming 
mailing list. I'm not sure if the merged version will be able to handle 
Boost.Build otherwise. 

> and more importantly the "func" grammar seems to be missing from
> our version:

I forgot to grab this part. And I also tested only

on target some_rule ;

syntax, but not

v = [ on target some_rule ] ;
v = [ on target return $(some_var) ] ;

variant. Indeed, test suite for jam would be very desirable. I believe that 
have fixed this problem now. I'll commit it once we decide if there are 
changes to recursion direction that I've missed.

- Volodya