Re: [Boost-users] [Spirit] [bind] Compiler warning dependent on number of rules?

Subject: Re: [Boost-users] [Spirit] [bind] Compiler warning dependent on number of rules?
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-11-04 23:10:50

On Wed, Nov 4, 2009 at 1:24 AM, Norbert Wenzel <n_wenzel_at_[hidden]> wrote:
> Hello,
>
> I'm currently parsing some data using Spirit together with boost::bind
> to set the callbacks for Spirit. In release build I get a compiler (gcc
> 4.4.1) warning from bind:
> warning: dereferencing pointer ‘val’ does break strict-aliasing rules
>
> I was able to find the lines causing this problem by commenting them
> out, rebuilding and the error got away. The strange thing is, that when
> I copy some other parsing rules, that previously compiled without any
> warning, I get the same warning again.
>
> When trying to create a simple example to post here, it seemed that the
> actual parsing code (that is the only code that uses boost::bind) was
> exchangeable. It was the number of options in the parsing rule that
> caused the warning to appear (which I really do not understand).
>
> The parsing rule looks like this:
>
> parse(someString.c_str(),
> (
> *(
> str_p('+') >> str_p('(') >> real_p[boost::bind(&Object::func_param,
> boost::ref(m_curObmect), _1)] >> str_p(')') |
> str_p('+')[boost::bind(&Object::func, boost::ref(m_curObject), _1)] /*|
>
> str_p('+') >> str_p('(') >> real_p[boost::bind(&Object::func_param,
> boost::ref(m_curObmect), _1)] >> str_p(')') |
> str_p('+')[boost::bind(&Object::func, boost::ref(m_curObject), _1)]
> [... to be repeated ...] */
>
> )
> )
> ,
> space_p).full;
>
> The goal is to find either "+" or "+(double)", which works as expected.
> causesThe signatures of the Object functions are
> Object::func_param(double param); and
> Object::func(char);
>
> The rule can be copied 7 times, leading to 14 options, without any
> warning. If I add one 8th copy of these lines, or if I just add a 15th
> option (independent of the actual line I copy) I get the warning again.
>
> My system is an Ubuntu Karmic 64bit machine, using gcc 4.4.1, boost 1.39
> headers and simply including "boost/spirit.hpp", which means I get the
> deprecation warning for that file at the moment.
>
> I'd be thankful for any suggestions, since for now, I do not even know
> where to look further. I do not have any idea what might cause this warning.

Not sure what is causing the problem, do you have a reduced test-case
we can see?

Also, two things.
1)  You *really* should be posting this to the Spirit mailing list
instead, will get faster responses and from knowledgeable people.
2)  You *really* should be using Spirit.Qi, not Spirit.Classic.  Your
grammar's will be much shorter, much faster, and much easier.