2

当我使用 expat xml 库构建程序时出现这些链接器错误。

3288 /tmp/ccFZziQa.o: In function `xml::node::load_xml(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
3289 node.cpp:(.text+0xdec): undefined reference to `XML_SetElementHandler'
3290 node.cpp:(.text+0xe08): undefined reference to `XML_SetCharacterDataHandler'
3291 node.cpp:(.text+0xe2c): undefined reference to `XML_SetUserData'
3292 node.cpp:(.text+0xe72): undefined reference to `XML_Parse'
3293 node.cpp:(.text+0xeaa): undefined reference to `XML_GetErrorCode'
3294 node.cpp:(.text+0xeb1): undefined reference to `XML_ErrorString'
3295 node.cpp:(.text+0xecb): undefined reference to `XML_GetCurrentLineNumber'

构建指令： 

g++ -v  -L /usr/lib/x86_64-linux-gnu -lexpat node.cpp

库在文件系统上：

$ 定位 libexpat.so

/lib/x86_64-linux-gnu/libexpat.so.1
/lib/x86_64-linux-gnu/libexpat.so.1.6.0
/usr/lib/x86_64-linux-gnu/libexpat.so

跑 strace 检查是否有任何明显的问题： 

2170 [pid  3361] open("/usr/include/expat.h", O_RDONLY|O_NOCTTY) = 4

3172 [pid  3364] stat("/usr/lib/x86_64-linux-gnu/libexpat.so", {st_mode=S_IFREG|0644, st_size=166032, ...}) = 0
3173 [pid  3364] open("/usr/lib/x86_64-linux-gnu/libexpat.so", O_RDONLY) = 7
3174 [pid  3364] open("/usr/lib/x86_64-linux-gnu/libexpat.so", O_RDONLY) = 8
3175 [pid  3364] stat("/tmp/ccFZziQa.o", {st_mode=S_IFREG|0600, st_size=89008, ...}) = 0
3176 [pid  3364] open("/tmp/ccFZziQa.o", O_RDONLY) = 8
3177 [pid  3364] open("/tmp/ccFZziQa.o", O_RDONLY) = 9




3172 [pid  3364] stat("/usr/lib/x86_64-linux-gnu/libexpat.so", {st_mode=S_IFREG|0644, st_size=166032, ...}) = 0
3173 [pid  3364] open("/usr/lib/x86_64-linux-gnu/libexpat.so", O_RDONLY) = 7
3174 [pid  3364] open("/usr/lib/x86_64-linux-gnu/libexpat.so", O_RDONLY) = 8
3175 [pid  3364] stat("/tmp/ccFZziQa.o", {st_mode=S_IFREG|0600, st_size=89008, ...}) = 0
3176 [pid  3364] open("/tmp/ccFZziQa.o", O_RDONLY) = 8
3177 [pid  3364] open("/tmp/ccFZziQa.o", O_RDONLY) = 9

当一切都正确加载时，为什么链接器会抛出这些错误，知道吗？

我可以在符号表中查找函数：-

$ nm -DC /usr/lib/x86_64-linux-gnu/libexpat.so |grep XML_SetElementHandler 
000000000000d4a0 T XML_SetElementHandler
4

1 回答 1

1

请参阅当前终端 (debian) 中无法识别的 gcc 新安装的库 (libexpat1-dev)。基本上，在 g++ 命令行上，将源文件移动到 expat 库之前......类似于

g++ -v node.cpp -L /usr/lib/x86_64-linux-gnu -lexpat
于 2017-05-09T16:44:54.353 回答