g++不能静态链接libmongcxx(r3.0.2)，但是动态链接工作

Question

我在这里使用mongodb站点的示例代码来说明问题。OS: ArchLiux，c++是到g++的链接

dean@dell_xps_13 ~$ c++ --版本c++ (GCC) 6.2.1 20160830版权(C) 2016FreeSoftwareFoundation，Inc.这是免费软件，请参阅复制条件的来源。没有任何保证，即使是适销性或适合某一特定用途。

代码在test.cc文件中

#include <iostream>

#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/json.hpp>

#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>

int main(int, char**) {
  mongocxx::instance inst{};
  mongocxx::client conn{mongocxx::uri{}};

  bsoncxx::builder::stream::document document{};

  auto collection = conn["testdb"]["testcollection"];
  document << "hello" << "world";

  collection.insert_one(document.view());
  auto cursor = collection.find({});

  for (auto&& doc : cursor) {
    std::cout << bsoncxx::to_json(doc) << std::endl;
  }
}

首先将其编译为对象文件：

c++ -g -std=c++11 -i./include -I/usr/include/bsoncxx/v_noabi -I/usr/include/mongocxx/v_noabi -Wall -o test.o -c ./test.cc

在没有-static的情况下链接它可以：

c++ test.o -o测试-静态-libgcc-静态-libstdc++ -L/usr/lib -lpthread -lmongocxx -lbsoncxx -lboost_log -lboost_log_setup -lboost_system -lboost_thread -lboost_filesystem

它可以运行并打印出一些消息：

[dean@dell_xps_13 mongo-cxx-driver-r3.0.2]$ ./test
{
    "_id" : {
        "$oid" : "58218e821b489308ae4411d1"
    }, 
    "hello" : "world"
}

现在使用-static选项获取错误

c++ test.o -o测试-静态-libgcc-静态-libstdc++ -static -L/usr/lib -lpthread -lmongocxx -lbsoncxx -lboost_log -lboost_log_setup -lboost_system -lboost_thread -lboost_filesystem

许多错误消息显示如下：

/usr/lib/libmongocx.a(client.cpp.o)：在函数mongocxx::v_noabi::client::client(mongocxx::v_noabi::uri const&, mongocxx::v_noabi::options::client const&)': /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x28): undefined reference tomongoc_client_new_from_uri的未定义引用mongoc_client_destroy' /usr/lib/libmongocxx.a(client.cpp.o): In function mongocxx::v_noabi::client::operator=(mongocxx::v_noabi::client&&)'：/home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp中:(.text+0x190)：对mongoc_client_destroy' /usr/lib/libmongocxx.a(client.cpp.o): In function mongocxx：：v_noabi：：client：：~client()‘的未定义引用:对mongoc_client_destroy' /usr/lib/libmongocxx.a(client.cpp.o): In function mongocxx::v_noabi::client::read_concern(mongocxx::v_noabi::read_concern)'：/home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.的未定义引用cpp:(.text+0x214)：对mongoc_client_set_read_concern' /usr/lib/libmongocxx.a(client.cpp.o): In function mongocxx::v_noabi::client::read_concern() const‘的未定义引用:对mongoc_client_get_read_concern' /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x24b): undefined reference tomongoc_read_concern_copy’/home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x27c)：未定义引用mongoc_read_concern_destroy' /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x2a3): undefined reference tomongoc_read_concern_的未定义引用销毁‘/usr/lib/libmongocx.a(client.cpp.o)：函数mongocxx::v_noabi::client::read_preference(mongocxx::v_noabi::read_preference)': /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x3a4): undefined reference tomongoc_client_set_read_prefs’/usr/lib/libmongocx.a(client.cpp.o)：函数mongocxx::v_noabi::client::read_preference() const': /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x3c3): undefined reference tomongoc_client_get_read_prefs中未定义的对mongoc_read_prefs_copy' /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x3fc): undefined reference tomongoc_read_prefs_destroy‘/home/mongocxx::v_noabi::client::read_preference() const': /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x3c3): undefined reference to/work的引用/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x423)：未定义对mongoc_read_prefs_destroy' /usr/lib/libmongocxx.a(client.cpp.o): In function mongocxx::v_noabi::client::uri() const‘的引用: /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x463)：未定义对mongoc_client_get_uri' /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x46b): undefined reference tomongoc_uri_copy’/home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x49c)：的引用未定义的对mongoc_uri_destroy' /home/dean/work/github/mongo-cxx-driver/src/mongocxx/client.cpp:(.text+0x4c3): undefined reference tomongoc_uri_destroy‘/usr/lib/libmongocx.a(client.cpp.o)的引用:在函数`mongocxx::v_noabi::client::write_concern() const’中：

……

/usr/lib/libbsoncx.a(oid.cpp.o)：函数bsoncxx::v_noabi::oid::to_string[abi:cxx11]() const': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x139): undefined reference tobson_oid_to_string‘/usr/lib/libbsoncx.a(oid.cpp.o)：函数bsoncxx::v_noabi::oid::get_time_t() const': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x1ea): undefined reference tobson_oid_get_time_t/usr/lib/libbsoncx.a(oid.cpp.o)：函数bsoncxx::v_noabi::oid_compare(bsoncxx::v_noabi::oid const&, bsoncxx::v_noabi::oid const&)': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x24f): undefined reference tobson_oid_compare’/usr/lib/libbsoncx.a(oid.cpp.o)：在函数bsoncxx::v_noabi::operator<(bsoncxx::v_noabi::oid const&, bsoncxx::v_noabi::oid const&)': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x2af): undefined reference tobson_oid_compare‘/usr/lib/libbsoncx.a(oid.cpp.o)：函数bsoncxx::v_noabi::operator>(bsoncxx::v_noabi::oid const&, bsoncxx::v_noabi::oid const&)': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x30f): undefined reference tobson_oid_compare‘/usr/lib/libbsoncx.a(oid.cpp.o)：函数bsoncxx::v_noabi::operator<=(bsoncxx::v_noabi::oid const&, bsoncxx::v_noabi::oid const&)': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x36f): undefined reference tobson_oid_compare/usr/lib/libbsoncx.a(oid.cpp.o)：在函数bsoncxx::v_noabi::operator>=(bsoncxx::v_noabi::oid const&, bsoncxx::v_noabi::oid const&)': /home/dean/work/github/mongo-cxx-driver/src/bsoncxx/oid.cpp:(.text+0x3cf): undefined reference tobson_oid_compare’‘中src/bsoncxx/oid.cpp:(.text+0x42f)：对`bson_oid_compare‘的更多未定义引用遵循collect2:错误: ld返回1个退出状态

Answer 1

-static标志强制链接器只接受静态库，而不接受任何共享库。换句话说，它不需要在运行时依赖动态库才能运行。很可能mongocxx有一些依赖关系。要实现静态链接，需要您的库的存档(.a)版本存在于系统中。

另一个可能的问题是，链接器命令行中的静态库的顺序确实很重要，因此，如果依赖于不同的静态库，这也可能是一个问题。链接器将按照命令行的顺序处理库，并且从每个静态库中只提取所需的符号(与链接器当时拥有的信息一样多)。

使用nm。会给你一个符号名。