在Qt Creator中，我创建了一个小型库（在Python项目的“ Squaring”子文件夹中）：

squaring.h：

int squaring(int a);

squaring.c：

#include "squaring.h"
int squaring(int a){
    return a * a;
}

在eclipse中，我创建了一个尝试使用该库的Python项目（according to the instructions from the official website)：

cSquaring.pxd：

cdef extern from "Squaring/squaring.h":
    int squaring(int a)

Functions.pix：

cimport cSquaring
cpdef int count(int value):
    return cSquaring.squaring(value)

setup.py：

from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize
setup(ext_modules=cythonize([Extension("Functions",["Functions.pyx"])]))

main.py：

from Functions import count
if __name__ == '__main__':
    data = 1
    returned = count(data)
    print(returned)

使用（没有任何错误）完成C代码的编译：

python3 setup.py build_ext -i

但是当我在执行时运行main.py时，出现ImportError：

File “/home/denis/.p2/pool/plugins/org.python.pydev.core_7.3.0.201908161924/pysrc/pydevd.py”,line 2643,in <module>
main()
File “/home/denis/.p2/pool/plugins/org.python.pydev.core_7.3.0.201908161924/pysrc/pydevd.py”,line 2636,in main
globals = debugger.run(setup,None,is_module)
File “/home/denis/.p2/pool/plugins/org.python.pydev.core_7.3.0.201908161924/pysrc/pydevd.py”,line 1920,in run
return self._exec(is_module,entry_point_fn,module_name,file,globals,locals)
File “/home/denis/.p2/pool/plugins/org.python.pydev.core_7.3.0.201908161924/pysrc/pydevd.py”,line 1927,in _exec
pydev_imports.execfile(file,locals) # execute the script
File “/home/denis/.p2/pool/plugins/org.python.pydev.core_7.3.0.201908161924/pysrc/_pydev_imps/_pydev_execfile.py”,line 25,in execfile
exec(compile(contents+“\n”,‘exec’),glob,loc)
File “/home/denis/eclipse-workspace/ConnectionWithCPlusPlus/main.py”,line 1,in <module>
from Functions import count
ImportError: /home/denis/eclipse-workspace/ConnectionWithCPlusPlus/Functions.cpython-37m-x86_64-linux-gnu.so: undefined symbol: squaring

另一个使用代码Cython的项目（我没有创建C语言库，而是直接在Cython上编写了代码）工作正常。

出什么问题了？