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随着解析器的增长，我将一些规则分成不同的翻译单元（TU），链接器问题也随之增加。经过数周的尝试和错误都没有成功，我将我的约 50 条规则减少到（希望）这里展示的最小示例。我在使用 boost spirit x3 的单独解析器时阅读了相关的链接错误并进行了检查，我在上下文 typedef 中使用iso8859_1::space_type并稍后调用iso8859_1::space。另外我不让编译器推断 iterator_type。

通过替换一些东西，我更喜欢链接器错误：

In function `bool x3::rule<parser::string_literal_class, ast::string_literal, false>::parse<std::string::const_iterator, x3::context<x3::error_handler_tag, std::reference_wrapper<x3::error_handler<std::string::const_iterator > > const, x3::context<x3::skipper_tag, x3::char_class<char_encoding::iso8859_1, x3::space_tag> const, x3::unused_type> >, x3::variant<ast::string_literal> >(std::string::const_iterator&, std::string::const_iterator const&, x3::context<x3::error_handler_tag, std::reference_wrapper<x3::error_handler<std::string::const_iterator > > const, x3::context<x3::skipper_tag, x3::char_class<char_encoding::iso8859_1, x3::space_tag> const, x3::unused_type> > const&, x3::unused_type, x3::variant<ast::string_literal>&) const':

main.cpp: .text._ZNK5boost6spirit2x34ruleIN6parser20string_literal_classEN3ast14string_literalELb0EE5parseIN9__gnu_cxx17__normal_iteratorIPKcNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEENS1_7contextINS1_17error_handler_tagEKSt17reference_wrapperINS1_13error_handlerISJ_EEENSK_INS1_11skipper_tagEKNS1_10char_classINS0_13char_encoding9iso8859_1ENS1_9space_tagEEENS1_11unused_typeEEEEENS1_7variantIJS6_EEEEEbRT_RKS13_RKT0_SY_RT1_[_ZNK5boost6spirit2x34ruleIN6parser20string_literal_classEN3ast14string_literalELb0EE5parseIN9__gnu_cxx17__normal_iteratorIPKcNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEENS1_7contextINS1_17error_handler_tagEKSt17reference_wrapperINS1_13error_handlerISJ_EEENSK_INS1_11skipper_tagEKNS1_10char_classINS0_13char_encoding9iso8859_1ENS1_9space_tagEEENS1_11unused_typeEEEEENS1_7variantIJS6_EEEEEbRT_RKS13_RKT0_SY_RT1_]+0x37): undefined reference to `bool parser::parse_rule<std::string::const_iterator, x3::context<x3::error_handler_tag, std::reference_wrapper<x3::error_handler<std::string::const_iterator > > const, x3::context<x3::skipper_tag, x3::char_class<char_encoding::iso8859_1, x3::space_tag> const, x3::unused_type> >, x3::variant<ast::string_literal> >(x3::rule<parser::string_literal_class, ast::string_literal, false>, std::string::const_iterator&, std::string::const_iterator const&, x3::context<x3::error_handler_tag, std::reference_wrapper<x3::error_handler<std::string::const_iterator > > const, x3::context<x3::skipper_tag, x3::char_class<char_encoding::iso8859_1, x3::space_tag> const, x3::unused_type> > const&, x3::variant<ast::string_literal>&)'

我对__gnu_cxx17迭代器很恼火（来自 libstdc++??）。我确实尝试了 g++7.1.0，结果相同。

附加文件以使用 CMake 文件重现链接器错误（使用选项 LINKER_ERROR 获取或什至不获取（没有 TU 的单体构建））。

ast.hpp

#ifndef AST_HPP_
#define AST_HPP_

#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <string>

#include <boost/fusion/include/adapt_struct.hpp>

namespace ast {
    namespace x3 = boost::spirit::x3;

    struct string_literal {
        std::string literal;
    };

    using primary = x3::variant<string_literal>;
    using factor = x3::variant<primary>;
}

BOOST_FUSION_ADAPT_STRUCT(ast::string_literal,
    literal
)

#endif // AST_HPP_

语法定义.hpp

#include "ast.hpp"
#include <boost/spirit/home/x3.hpp>
#if defined(LINKER_ERROR)
#include "literal.hpp"
#endif

namespace parser {

   namespace x3 = boost::spirit::x3;

    struct factor_class;
    struct primary_class;
#if !defined(LINKER_ERROR)
    struct string_literal_class;
#endif

    typedef x3::rule<factor_class, ast::factor> factor_type;
    typedef x3::rule<primary_class, ast::primary> primary_type;
#if !defined(LINKER_ERROR)
    typedef x3::rule<string_literal_class, ast::string_literal> string_literal_type;
#endif

    factor_type const factor{ "factor" };
    primary_type const primary{ "primary" };
#if !defined(LINKER_ERROR)
    string_literal_type const string_literal{ "string_literal" };
#endif

#if defined(LINKER_ERROR)
    namespace {
        auto const& string_literal = parser_api::string_literal();
    }
#endif

    auto const factor_def = primary;

    auto const primary_def = string_literal;

#if !defined(LINKER_ERROR)
    auto const string_literal_def =
        x3::lexeme ['"' >> *x3::char_ >> '"' ]
        ;
#endif

    BOOST_SPIRIT_DEFINE(factor, primary)
#if !defined(LINKER_ERROR)
    BOOST_SPIRIT_DEFINE(
            string_literal
    )
#endif
}

文字定义.hpp

#ifndef PARSER_LITERAL_DEF_HPP_
#define PARSER_LITERAL_DEF_HPP_

#include "literal.hpp"

namespace parser {

    namespace x3 = boost::spirit::x3;

    string_literal_type const string_literal { "string_literal" };

    auto const string_literal_def =
        x3::lexeme ['"' >> *x3::char_ >> '"' ];

    BOOST_SPIRIT_DEFINE(
        string_literal
    )
}

namespace parser_api {
    parser::string_literal_type const& string_literal()
    {
        return parser::string_literal;
    }
}

#endif /* PARSER_LITERAL_DEF_HPP_ */

文字.cpp

#include "literal_def.hpp"
#include "parser_config.hpp"

namespace parser {
    namespace x3 = boost::spirit::x3;

    BOOST_SPIRIT_INSTANTIATE(
        string_literal_type,
        iterator_type,
        context_type
    );
}

字面量.hpp

#ifndef PARSER_LITERAL_HPP_
#define PARSER_LITERAL_HPP_

#include "ast.hpp"
#include <boost/spirit/home/x3.hpp>

namespace parser {

    namespace x3 = boost::spirit::x3;

    struct string_literal_class;
    typedef x3::rule<string_literal_class, ast::string_literal> string_literal_type;

    BOOST_SPIRIT_DECLARE(string_literal_type);
}

namespace parser_api {
    parser::string_literal_type const& string_literal();
}

#endif /* PARSER_LITERAL_HPP_ */

主文件

#include "grammar_def.hpp"
#include "parser_config.hpp"
#include <iostream>

int main()
{
    namespace x3 = boost::spirit::x3;

    ast::factor  attr;

    std::string input{ "a * b" };
    parser::iterator_type iter = input.begin();
    parser::iterator_type const end = input.end();

    parser::error_handler_type error_handler(iter, end, std::cerr);

    auto const parser =
        x3::with<x3::error_handler_tag>(std::ref(error_handler))
        [
              parser::factor
        ];

    bool success = x3::phrase_parse(iter, end, parser, x3::iso8859_1::space, attr);

    return 0;
}

parser_config.hpp

#ifndef PARSER_CONFIG_HPP_
#define PARSER_CONFIG_HPP_

#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/utility/error_reporting.hpp>

namespace parser {
    namespace x3 = boost::spirit::x3;

    template <typename Iterator>
    using error_handler = x3::error_handler<Iterator>;
    using error_handler_tag = x3::error_handler_tag;

    typedef std::string::const_iterator                 iterator_type;
    typedef error_handler<iterator_type>                error_handler_type;
    typedef x3::phrase_parse_context<
            x3::iso8859_1::space_type>::type            phrase_context_type;
    typedef x3::with_context<
        error_handler_tag
        , std::reference_wrapper<error_handler_type> const
        , phrase_context_type
    >::type                                             context_type;
}

#endif /* CONFIG_HPP_ */

最后是CMakeLists.txt

cmake_minimum_required(VERSION 3.6)

project(x3_linker_error LANGUAGES CXX)
find_package(Boost REQUIRED COMPONENTS system)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
# lib
add_library(${PROJECT_NAME}_x3 STATIC
    literal.cpp
)
# exe
add_executable(${PROJECT_NAME}
    main.cpp
)
target_link_libraries(${PROJECT_NAME}
    PRIVATE
    ${PROJECT_NAME}_x3
    ${Boost_SYSTEM_LIBRARY}
)

set(CMAKE_VERBOSE_MAKEFILE ON)
option(LINKER_ERROR "Enforce the linker error" ON)
if(LINKER_ERROR)
message("## Build to show linker errors")
target_compile_definitions(${PROJECT_NAME}_x3 PRIVATE LINKER_ERROR)
target_compile_definitions(${PROJECT_NAME} PRIVATE LINKER_ERROR)
endif()

该代码也在wandbox。

将 parser_api::string_literal() 设置到实例文件 literal.cpp 也不会改变结果（如预期的那样）。希望这不是我的愚蠢错误，但几周后我终于...

附录

我还测试了 Joel de Guzman 的提示以插入int x = context_type{};到 literal.cpp 和 main.cpp 以获取使用的上下文 - 它都相同：

x3_linker_error/literal.cpp
'boost::spirit::x3::context<boost::spirit::x3::error_handler_tag, const std::reference_wrapper<boost::spirit::x3::error_handler<__gnu_cxx::__normal_iterator<const char*, std::__cxx11::basic_string<char> > > >, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, const boost::spirit::x3::char_class<boost::spirit::char_encoding::iso8859_1, boost::spirit::x3::space_tag>, boost::spirit::x3::unused_type> >::context(<brace-enclosed initializer list>)'

x3_linker_error/main.cpp
'boost::spirit::x3::context<boost::spirit::x3::error_handler_tag, const std::reference_wrapper<boost::spirit::x3::error_handler<__gnu_cxx::__normal_iterator<const char*, std::__cxx11::basic_string<char> > > >, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, const boost::spirit::x3::char_class<boost::spirit::char_encoding::iso8859_1, boost::spirit::x3::space_tag>, boost::spirit::x3::unused_type> >::context(<brace-enclosed initializer list>)'
4

1 回答 1

0

在拉里·埃文斯的帮助下，问题得以解决。详情请关注spirit-general邮件列表。

这样的代码片段是正确的。似乎问题确实出现在另一个上下文中，因为之前将 > 更改为 >> 时出现链接错误，并由 Seth 讨论过。

解决方案是使用/克隆拉里的精神.x3 的get_rhs分支

git clone --branch get_rhs https://github.com/cppljevans/spirit.git destination

并使用定义BOOST_ERROR_CODE_HEADER_ONLY的 . 从 Boost 1.64 开始的 Spirit.X3 无法编译。我已经调整了 CMake 文件以反映更改（并克隆到 cppljevans）并添加了 Larry 编译日志中看到的进一步定义：

cmake_minimum_required(VERSION 3.6)

project(x3_linker_error LANGUAGES CXX)
find_package(Boost REQUIRED COMPONENTS system)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

# lib
add_library(${PROJECT_NAME}_x3 STATIC
    literal.cpp
)
target_include_directories(${PROJECT_NAME}_x3
    PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/cppljevans/include
)
target_compile_definitions(${PROJECT_NAME}_x3 PRIVATE 
    BOOST_SPIRIT_GET_RHS_CRTP=1 BOOST_SPIRIT_ATTR_XFORM_IN_RULE=1
)

# exe
add_executable(${PROJECT_NAME}
    main.cpp
)
target_include_directories(${PROJECT_NAME}
    PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/cppljevans/include
)
target_compile_definitions(${PROJECT_NAME} PRIVATE 
    BOOST_SPIRIT_GET_RHS_CRTP=1 BOOST_SPIRIT_ATTR_XFORM_IN_RULE=1
    BOOST_ERROR_CODE_HEADER_ONLY 
)
target_link_libraries(${PROJECT_NAME}
    PRIVATE
    ${PROJECT_NAME}_x3
    ${Boost_SYSTEM_LIBRARY}
)

set(CMAKE_VERBOSE_MAKEFILE ON)

option(LINKER_ERROR "Enforce the linker error" ON)

if(LINKER_ERROR)
message("## Build to show linker errors")
target_compile_definitions(${PROJECT_NAME}_x3 PRIVATE LINKER_ERROR)
target_compile_definitions(${PROJECT_NAME} PRIVATE LINKER_ERROR)
endif()
于 2017-06-04T05:07:45.873 回答