链接有关-fPIC的错误，即使所有源都是用-fPIC编译的

Question

我在Google上找不到一个直接的答案，而且由于我很长时间没有在Linux上做一些事情，所以我希望在这里找到帮助。在构建共享对象时，我在Ubuntu上得到了一个链接错误。链接器告诉我，即使我已经为所有源文件设置了-fPIC，也应该使用-fPIC重新编译。make输出

mkdir -p ../_Bin/Debug/HttpClientApi
g++ -fPIC -pedantic -Wall -Wextra -std=c++11 -c CentralServerClient.cpp -o ../_Bin/Debug/HttpClientApi/CentralServerClient.o
CentralServerClient.cpp:4:80: warning: unused parameter ‘pEventListener’ [-Wunused-parameter]
 void CCentralServerClient::AddEventListener(ICentralServerClientEventListener* pEventListener)
                                                                            ^
CentralServerClient.cpp:29:83: warning: unused parameter ‘pEventListener’ [-Wunused-parameter]
 void CCentralServerClient::RemoveEventListener(ICentralServerClientEventListener* pEventListener)
                                                                               ^
g++ -fPIC -pedantic -Wall -Wextra -std=c++11 -c HttpRequest.cpp -o ../_Bin/Debug/HttpClientApi/HttpRequest.o
g++ -fPIC -pedantic -Wall -Wextra -std=c++11 -c HttpResponse.cpp -o ../_Bin/Debug/HttpClientApi/HttpResponse.o
g++ -fPIC -pedantic -Wall -Wextra -std=c++11 -c IOService.cpp -o ../_Bin/Debug/HttpClientApi/IOService.o
g++ -Wl,-shared -Wl,-v -Wl,-g -o ../_Bin/Debug/HttpClientApi.so ../_Bin/Debug/HttpClientApi/CentralServerClient.o ../_Bin/Debug/HttpClientApi/HttpRequest.o ../_Bin/Debug/HttpClientApi/HttpResponse.o ../_Bin/Debug/HttpClientApi/IOService.o
collect2 version 4.9.2
/usr/bin/ld -plugin /usr/lib/gcc/x86_64-linux-gnu/4.9/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper -plugin-opt=-fresolution=/tmp/ccZ9RMHe.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --sysroot=/ --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -z relro -o ../_Bin/Debug/HttpClientApi.so /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.9/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.9 -L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../.. -shared -v -g ../_Bin/Debug/HttpClientApi/CentralServerClient.o ../_Bin/Debug/HttpClientApi/HttpRequest.o ../_Bin/Debug/HttpClientApi/HttpResponse.o ../_Bin/Debug/HttpClientApi/IOService.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.9/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crtn.o
GNU ld (GNU Binutils for Ubuntu) 2.25
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crt1.o: relocation R_X86_64_32S against `__libc_csu_fini' can not be used when making a shared object; recompile with -fPIC
/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crt1.o: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
Makefile:15: recipe for target '../_Bin/Debug/HttpClientApi.so' failed
make: *** [../_Bin/Debug/HttpClientApi.so] Error 1

gcc是gcc version 4.9.2 (Ubuntu 4.9.2-10ubuntu13)

任何帮助都是非常感谢的。

Answer 1

与其给g++ -Wl,-shared，不如给它-shared。原因是g++需要知道使用哪个crt1.o --一个适合共享库(用-fPIC编译，scrt1.o)的库，还是一个不合适的库。

当您将-shared交给g++时，它知道如何使用scrt1.o。但是当您传递‘-Wl，- shared’时，g++不知道您正在构建共享库--它“思考”，您正在构建一个普通的可执行文件(链接器确实知道正在发生什么)，并要求链接器与crt1.o链接。链接器拒绝并且你有一个错误。