Re: [Boost-users] Boost::spirit program crashes

Subject: Re: [Boost-users] Boost::spirit program crashes
From: Joel de Guzman (joel_at_[hidden])
Date: 2010-03-26 05:01:57

On 3/26/2010 3:35 PM, Lars Rohwedder wrote:
> Here my stripped version still crashes with segfault:
>
> ----<snio>----
> #include<boost/spirit.hpp>
> #include<iostream>
>
> using namespace boost::spirit;
>
> struct Configurable
> {
>      const char*   name;   // name of the configurable module
>      const rule<>&  parser; // parser for config items, normally
>                            // a couple of OR-connected terms.
> };
>
> rule<>  __ = ch_p(' '); // separator char. was a bit more complex
>                         // in the original code
>
> std::string conn, port, ident_name, ident_pw;
>
[...]
>
> // a simplicistic parser that still crashes:
> const Configurable cfg = { "Hardtest", +( __ ) };
>
>
> int main(int argc, char** argv)
> {
>    // original config string:
>    // "connect foo.bar:123 identity root fF2.oby!sy" or the like.
>    parse("hard ", cfg.parser);  //<--- CRASHES!
>
>    // this works:
>    // parse("hard ", +(__) );
> };
> ----<snap>----
>
[...]
> Perhaps somebody knows an answer except "use spirit 2!" :-)

You have a dangling reference to a rule here:

    const rule<>&  parser;

when you do this:

    const Configurable cfg = { "Hardtest", +( __ ) };

+( __ ) creates a temporary rule and you assign the address of that
to cfg.parser. Remove the reference:

    const rule<> parser;

Keep in mind though that "classic" spirit rules are not copyable.
So don't go and copy your cfg around.

Regards,
-- 
Joel de Guzman
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