分段故障琐碎的精神语法分析器

问题描述

我正在与我的灵奇解析器频繁的段错误。

I'm running into frequent segfaults with my Spirit Qi parser.

消磨时间来调试问题之后（我发现不可能神交踪迹），我决定把修剪下来到最小的例子。谁能告诉我我做错了，如果有什么？

After spending days to debug the issue (I found the stacktraces impossible to grok) I decided to trim it down to a minimal example. Can anyone tell what I'm doing wrong, if anything?

保存code作为bug.cpp，用 G ++ -Wall -o错误bug.cpp编译，你应该是好去。

Save code as bug.cpp, compile with g++ -Wall -o bug bug.cpp and you should be good to go.

//#define BOOST_SPIRIT_DEBUG_PRINT_SOME 80
//#define BOOST_SPIRIT_DEBUG
#include <boost/spirit/version.hpp>
#include <boost/spirit/include/qi.hpp>
#include <iostream>
#include <fstream>
#include <iterator>
#include <string>

namespace /*anon*/
{
    using namespace boost::spirit::qi;

    template <typename Iterator, typename
        Skipper> struct bug_demo :
            public grammar<Iterator, Skipper>
    {
        bug_demo() :
            grammar<Iterator, Skipper>(story, "bug"),
            story(the),
            the("the")
        {
//          BOOST_SPIRIT_DEBUG_NODE(story);
//          BOOST_SPIRIT_DEBUG_NODE(the);
        }

        rule<Iterator, Skipper> story, the;
    };

    template <typename It>
        bool do_parse(It begin, It end)
    {
        bug_demo<It, space_type> grammar;
        return phrase_parse(begin, end, grammar, space);
    }
}

int main()
{
    std::cout << "Spirit version: " << std::hex << SPIRIT_VERSION << std::endl;

    try
    {
        std::string contents = "the lazy cow";
        if (do_parse(contents.begin(), contents.end()))
            return 0;
    } catch (std::exception e)
    {
        std::cerr << "exception: " << e.what() << std::endl;
    }
    return 255;
}

我已经测试了这个

I've tested this with

• 先按g ++ 4.4，4.5，4.6和


• 增压版本1.42（Ubuntu的猫鼬）和1.46.1.1（整洁的）

的输出是

sehe@meerkat:/tmp$ ./bug
Spirit version: 2020
Segmentation fault

或者，用升压1.46.1将报告精神版本：2042

Or, with boost 1.46.1 it will report Spirit version: 2042

推荐答案

更改初始化顺序，你在你的答案建议只是隐藏的问题。实际的问题是，规则＆LT;＆GT; 的有适当的C ++复制语义。您可以通过重写你的gramar初始化为解决这个问题：

Changing the initialization order as you suggested in your answer just hides the problem. The actual problem is, that rule<>'s have proper C++ copy semantics. You can fix this by rewriting your gramar initialization as:

bug_demo() :
    grammar<Iterator, Skipper>(story, "bug"),
    story(the.alias()),
    the("the")
{}

有关的理由和更详细的说明，请参阅 href=\"http://boost-spirit.com/home/articles/doc-addendum/faq/#aliases\">。

For a rationale and a more detailed explanation, see here.

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