为什么我得到pthread_mutexattr_settype的未定义引用？

Question

我正在尝试编译和链接Novell LDAP C SDK中的示例文件,但由于pthread库中有3个未解析的符号,链接失败.我在Ubuntu 13.10(Saucy)上使用gcc 4.8.1.我已将pthread库正确地包含在命令行中的最后一个库中,但这些特定符号仍未解析.

$ gcc -Wl,-trace-symbol=pthread_mutexattr_settype -Wl,-trace-symbol=pthread_mutexattr_init   -Wl,-trace-symbol=pthread_mutex_trylock  -o search search.o -L../lib -lldapsdk -lpthread

../lib/libldapsdk.so: reference to pthread_mutexattr_settype<br>
../lib/libldapsdk.so: reference to pthread_mutexattr_init<br>
../lib/libldapsdk.so: reference to pthread_mutex_trylock<br>
/lib/i386-linux-gnu/libpthread.so.0: definition of pthread_mutexattr_settype<br>
/lib/i386-linux-gnu/libpthread.so.0: definition of pthread_mutexattr_init<br>
/lib/i386-linux-gnu/libpthread.so.0: definition of pthread_mutex_trylock<br>
../lib/libldapsdk.so: undefined reference to pthread_mutexattr_settype<br>
../lib/libldapsdk.so: undefined reference to pthread_mutex_trylock<br>
../lib/libldapsdk.so: undefined reference to pthread_mutexattr_init<br>
collect2: error: ld returned 1 exit status

$ readelf --all  /lib/i386-linux-gnu/libpthread.so.0|grep pthread_mutexattr_settype<br>
   114: 00009d90    36 FUNC    GLOBAL DEFAULT   13 pthread_mutexattr_settype@@GLIBC_2.1<br>
   493: 00009d90    36 FUNC    GLOBAL DEFAULT   13 pthread_mutexattr_settype

Answer 1

_{只需将评论作为答案撰写,因为根据其他用户的反馈证明它是有用的.}

请传递-pthread给编译器(不带-l).另请参阅gcc - 编译时-pthread标志的重要性.

Answer 2

在cmake中你可以添加set( CMAKE_CXX_FLAGS " -pthread " )

不要编辑间距!