I am trying to build a C++ static library in Linux (Ubuntu 18.04 in my case) using GCC using a Makefile. I noticed the issue is not with the makefile itself but the way I'm trying to compile and build with GCC. Before I explain a bit more on the GCC side, here is how my current project hierarchy looks like.
The project uses Pybind11 header only library which resides in the External_Libraries directory.
My class definition and implementation, naming Core.h and Core.cpp reside in Internal_libraries along with py_utilities.h and any.hpp which contain some utility functions. (These two files are not used though). and finally test_lib.cpp which uses Core.h resides in the root.
This is how it looks :
📦MainDirectory ┣📂External_Libraries ┃┗📂Pybind11 ┃┗📂Pybind11 ┃┗📂Include ┃┣📂Internal_Libraries ┃┣📜Core.h ┃┣📜Core.cpp ┃┣📜py_utilities.h ┃┣📜any.hpp ┃┗📜test_lib.cpp Now, the project as you can see, depends on Pybind11 include directories and also <Python.h> plus pythons lib directories.
I face the same undefined errors both when I try to build the static library or the normal executable.
I include the needed search paths (include and library) to the GCC like this :
- Building
Core.o:
g++ -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages -c ./Internal_Libraries/Core.cpp -o Core.o- Building
test_lib.o:
g++ -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages -c test_lib.cpp -o test_lib.oand finally :
- Building test_lib executable:
g++ -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages test_lib.o Core.o -o test_libThis is where it fails and I get lots of undefined errors which I guess is related to the linker, however I provided the needed paths, so I'm at a loss whats gone wrong here!
These are the errors I get by the way :
g++ -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages test_lib.o Core.o -o test_libtest_lib.o: In function `pybind11::cast_error::set_error() const':test_lib.cpp:(.text._ZNK8pybind1110cast_error9set_errorEv[_ZNK8pybind1110cast_error9set_errorEv]+0x29): undefined reference to `PyExc_RuntimeError'test_lib.cpp:(.text._ZNK8pybind1110cast_error9set_errorEv[_ZNK8pybind1110cast_error9set_errorEv]+0x34): undefined reference to `PyErr_SetString'test_lib.o: In function `pybind11::error_scope::error_scope()':test_lib.cpp:(.text._ZN8pybind1111error_scopeC2Ev[_ZN8pybind1111error_scopeC5Ev]+0x27): undefined reference to `PyErr_Fetch'test_lib.o: In function `pybind11::error_scope::~error_scope()':...Core.o: In function `std::enable_if<((!std::is_floating_point<int>::value)&&std::is_signed<int>::value)&&((sizeof (int))<=(sizeof (long))), pybind11::handle>::type pybind11::detail::type_caster<int, void>::cast<int>(int, pybind11::return_value_policy, pybind11::handle)':Core.cpp:(.text._ZN8pybind116detail11type_casterIivE4castIiEENSt9enable_ifIXaaaantsrSt17is_floating_pointIT_E5valuesrSt9is_signedIS6_E5valuelestS6_stlENS_6handleEE4typeES6_NS_19return_value_policyESA_[_ZN8pybind116detail11type_casterIivE4castIiEENSt9enable_ifIXaaaantsrSt17is_floating_pointIT_E5valuesrSt9is_signedIS6_E5valuelestS6_stlENS_6handleEE4typeES6_NS_19return_value_policyESA_]+0x2c): undefined reference to `PyLong_FromSsize_t'Core.o: In function `pybind11::array_t<unsigned char, 16>::ensure(pybind11::handle)':Core.cpp:(.text._ZN8pybind117array_tIhLi16EE6ensureENS_6handleE[_ZN8pybind117array_tIhLi16EE6ensureENS_6handleE]+0x70): undefined reference to `PyErr_Clear'Core.o: In function `pybind11::array_t<unsigned char, 16>::raw_array_t(_object*)':Core.cpp:(.text._ZN8pybind117array_tIhLi16EE11raw_array_tEP7_object[_ZN8pybind117array_tIhLi16EE11raw_array_tEP7_object]+0x26): undefined reference to `PyExc_ValueError'Core.cpp:(.text._ZN8pybind117array_tIhLi16EE11raw_array_tEP7_object[_ZN8pybind117array_tIhLi16EE11raw_array_tEP7_object]+0x35): undefined reference to `PyErr_SetString'collect2: error: ld returned 1 exit statushere is the link to the full error log : error log
In case the contents of Core.h is important here it is :
#ifndef CORE_H#define CORE_H/* If we are we on Windows, we want a single define for it.*/#if !defined(_WIN32) && (defined(__WIN32__) || defined(WIN32) || defined(__MINGW32__)) #define _WIN32#endif /* _WIN32 */#if defined(_WIN32) && defined(_CORE_BUILD_DLL)/* We are building CORE as a Win32 DLL */ #define CORE_API __declspec(dllexport)#elif defined(_WIN32) && defined(CORE_DLL)/* We are calling CORE as a Win32 DLL */ #define CORE_API __declspec(dllimport)#elif defined(__GNUC__) && defined(_CORE_BUILD_DLL)/* We are building CORE as a shared / dynamic library */#define CORE_API __attribute__((visibility("default")))#else/* We are building or calling CORE as a static library */ #define CORE_API#endif#include <iostream>#include <string>#include <vector>#include <functional>#include <memory>#include <pybind11/pybind11.h>#include <pybind11/embed.h>#include <pybind11/numpy.h>#include <pybind11/stl.h>#include <pybind11/functional.h>namespace py = pybind11;using namespace py::literals;typedef void(*CallbackFn)(bool, std::string, py::array_t<uint8_t>&);typedef std::function<void(std::string)> LogFunction;typedef void * HANDLE;class CORE_API Core{private: py::scoped_interpreter guard{}; py::object serviceUtilsModule; py::object cls; py::object obj; py::object startFunc;...public: Core(); Core(bool showFeed); Core(LogFunction logInfo); Core(LogFunction logInfo, LogFunction logWarning); Core(LogFunction logInfo, LogFunction logWarning, LogFunction logDebug); Core(LogFunction logInfo, LogFunction logWarning, LogFunction logDebug, std::vector<CallbackFn> callbackList);... ~Core(); void Start(bool async= false); py::list GetCallbacks(void);... static void DefaultLoger(std::string str);};extern "C"{ //COREAPI wchar_t** GetResults(wchar_t* word, int* length, int threshold = 9); CORE_API void Start(bool); CORE_API void Stop(void); CORE_API void SetCpuAffinity(int mask); CORE_API void AddCallback(CallbackFn callback); CORE_API void RemoveCallback(CallbackFn callback); CORE_API void* GetCallbacks(void); CORE_API void DefaultLoger(char* str); CORE_API void* CreateHandle(); CORE_API void* GetCurrentHandle(); CORE_API void DisposeCurrentHandle(); CORE_API void SetCurrentHandle(void* handle); CORE_API void* GetHandle(); CORE_API void DisposeHandle(void*);}#endif // !CORE_HThe project works fine under windows and visual c++ v14 (VS2015) and now I'm trying to do the same thing in Linux using GCC. It seems I'm doing something wrong obviously but I cant seem to know where I have gone wrong! what am I missing here?
Update:
After following tis link on manually compile pybind11, I ended up doing :
g++ -O3 -Wall -std=c++11 -fPIC -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages -c ./Internal_Libraries/Core.cpp -o Core.og++ -O3 -Wall -std=c++11 -fPIC -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages -c test_lib.cpp -o test_lib.og++ -O3 -Wall -std=c++11 -fPIC -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages test_lib.o Core.o -o test_libPlease note that, I removed the shared keyword from the commands above so it doesnt create the shared library!
Having said that the last command still gives linker errors :
g++ -O3 -Wall -std=c++11 -fPIC -I./External_Libraries/pybind11/pybind11/include -I/home/rika/anaconda3/include/python3.7m -L/home/rika/anaconda3/lib -L/home/rika/anaconda3/lib/python3.7/site-packages test_lib.o -o test_libtest_lib.o: In function `pybind11_static_get':test_lib.cpp:(.text.pybind11_static_get[pybind11_static_get]+0x3): undefined reference to `PyProperty_Type'test_lib.o: In function `pybind11_static_set':test_lib.cpp:(.text.pybind11_static_set[pybind11_static_set]+0x12): undefined reference to `PyProperty_Type'test_lib.o: In function `pybind11::cast_error::set_error() const':test_lib.cpp:(.text._ZNK8pybind1110cast_error9set_errorEv[_ZNK8pybind1110cast_error9set_errorEv]+0x10): undefined reference to `PyExc_RuntimeError'test_lib.cpp:(.text._ZNK8pybind1110cast_error9set_errorEv[_ZNK8pybind1110cast_error9set_errorEv]+0x1c): undefined reference to `PyErr_SetString'test_lib.o: In function `pybind11::detail::translate_exception(std::__exception_ptr::exception_ptr)':...test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0x9a): undefined reference to `PyTuple_Size'test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0xaa): undefined reference to `PyTuple_GetItem'test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0xd3): undefined reference to `PyObject_Str'test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0x1cc): undefined reference to `PyDict_Contains'test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0x3c1): undefined reference to `PyDict_Contains'test_lib.cpp:(.text._ZN8pybind116detail5printENS_5tupleENS_4dictE[_ZN8pybind116detail5printENS_5tupleENS_4dictE]+0x518): undefined reference to `PyImport_ImportModule'test_lib.o: In function `void pybind11::print<(pybind11::return_value_policy)1, pybind11::list>(pybind11::list&&)':test_lib.cpp:(.text._ZN8pybind115printILNS_19return_value_policyE1EJNS_4listEEEEvDpOT0_[_ZN8pybind115printILNS_19return_value_policyE1EJNS_4listEEEEvDpOT0_]+0x21): undefined reference to `PyDict_New'test_lib.o: In function `main':test_lib.cpp:(.text.startup+0x34): undefined reference to `Core::Core(bool)'test_lib.cpp:(.text.startup+0x41): undefined reference to `Core::SetCpuAffinity(int)'test_lib.cpp:(.text.startup+0x4b): undefined reference to `Core::Start(bool)'test_lib.cpp:(.text.startup+0x5b): undefined reference to `Core::GetCallbacks()'test_lib.cpp:(.text.startup+0x85): undefined reference to `Core::GetCallbacks()'test_lib.cpp:(.text.startup+0x107): undefined reference to `PyObject_Str'collect2: error: ld returned 1 exit status