Python C API引入iostream导致DLL加载失败问题求助

我从网上找了个简单的Python C API示例，移除#include <iostream>可以正常导入Python，但保留这个头文件时，导入fib.pyd就报错：ImportError: DLL load failed while importing fib: 找不到指定的模块。。用的是Python 3.10，已经确认不是fib.pyd找不到或者PyInit_fib的问题。

示例代码 #

#include <Python.h>
#include <iostream>
int _fib(int n)
{
     //unimportant implementation details
     return 0;
}
static PyObject* fib(PyObject* self, PyObject* args)
{
    int n;
    return Py_BuildValue("i", _fib(n));
}
static PyMethodDef FibMethods[] = {
    {"fib", fib, METH_VARARGS, "Calculate the Fibonacci numbers (in C)."},
    {NULL, NULL, 0, NULL}  /* Sentinel */
};
static struct PyModuleDef ticlib={
    PyModuleDef_HEAD_INIT,
    "fib",
    "A fast tic tac toe implementation",
    -1,
    FibMethods,
    NULL,
    NULL,
    NULL,
    NULL

};

PyMODINIT_FUNC
PyInit_fib(void)
{
    using namespace std;
    return PyModule_Create(&ticlib);
}

依赖项对比 #

包含的异常版本（fib.dll依赖） #

$ ldd fib.dll
        ntdll.dll => /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll (0x7ffb9f9d0000)
        KERNEL32.DLL => /cygdrive/c/WINDOWS/System32/KERNEL32.DLL (0x7ffb9f1f0000)
        KERNELBASE.dll => /cygdrive/c/WINDOWS/System32/KERNELBASE.dll (0x7ffb9d1c0000)
        msvcrt.dll => /cygdrive/c/WINDOWS/System32/msvcrt.dll (0x7ffb9ed00000)
        libstdc++-6.dll => /cygdrive/c/Program Files (x86)/GtkSharp/2.12/bin/libstdc++-6.dll (0x6fc40000)
        python310.dll => /cygdrive/e/Python/Python310/python310.dll (0x7ffb2e400000)
        WS2_32.dll => /cygdrive/c/WINDOWS/System32/WS2_32.dll (0x7ffb9f0f0000)
        VERSION.dll => /cygdrive/c/WINDOWS/SYSTEM32/VERSION.dll (0x7ffb95e30000)
        RPCRT4.dll => /cygdrive/c/WINDOWS/System32/RPCRT4.dll (0x7ffb9f800000)
        libstdc++-6.dll => /cygdrive/e/msys64/mingw64/bin/libstdc++-6.dll (0x7ffb2de10000)
        ADVAPI32.dll => /cygdrive/c/WINDOWS/System32/ADVAPI32.dll (0x7ffb9db40000)
        sechost.dll => /cygdrive/c/WINDOWS/System32/sechost.dll (0x7ffb9f040000)
        ucrtbase.dll => /cygdrive/c/WINDOWS/System32/ucrtbase.dll (0x7ffb9d550000)
        VCRUNTIME140.dll => /cygdrive/c/WINDOWS/SYSTEM32/VCRUNTIME140.dll (0x7ffb84c50000)
        libgcc_s_seh-1.dll => /cygdrive/e/msys64/mingw64/bin/libgcc_s_seh-1.dll (0x7ffb98030000)
        libwinpthread-1.dll => /cygdrive/e/msys64/mingw64/bin/libwinpthread-1.dll (0x7ffb93370000)

不包含的正常版本（fib.dll依赖） #

$ ldd fib.dll
        ntdll.dll => /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll (0x7ffb9f9d0000)
        KERNEL32.DLL => /cygdrive/c/WINDOWS/System32/KERNEL32.DLL (0x7ffb9f1f0000)
        KERNELBASE.dll => /cygdrive/c/WINDOWS/System32/KERNELBASE.dll (0x7ffb9d1c0000)
        msvcrt.dll => /cygdrive/c/WINDOWS/System32/msvcrt.dll (0x7ffb9ed00000)
        python310.dll => /cygdrive/e/Python/Python310/python310.dll (0x7ffb2e400000)
        WS2_32.dll => /cygdrive/c/WINDOWS/System32/WS2_32.dll (0x7ffb9f0f0000)
        RPCRT4.dll => /cygdrive/c/WINDOWS/System32/RPCRT4.dll (0x7ffb9f800000)
        VERSION.dll => /cygdrive/c/WINDOWS/SYSTEM32/VERSION.dll (0x7ffb95e30000)
        ADVAPI32.dll => /cygdrive/c/WINDOWS/System32/ADVAPI32.dll (0x7ffb9db40000)
        sechost.dll => /cygdrive/c/WINDOWS/System32/sechost.dll (0x7ffb9f040000)
        ucrtbase.dll => /cygdrive/c/WINDOWS/System32/ucrtbase.dll (0x7ffb9d550000)
        VCRUNTIME140.dll => /cygdrive/c/WINDOWS/SYSTEM32/VCRUNTIME140.dll (0x7ffb84c50000)

问题原因与解决办法 #

从依赖对比可以看出，包含<iostream>的版本额外依赖MinGW的几个动态库：libstdc++-6.dll、libgcc_s_seh-1.dll、libwinpthread-1.dll，而且出现了两个不同路径的libstdc++-6.dll，可能存在版本冲突，导致Python找不到正确的依赖库。

解决方法：

• 添加环境变量：把MinGW的bin目录（比如示例中的E:\msys64\mingw64\bin）添加到系统PATH环境变量中，确保Python能找到这些依赖库
• 静态链接编译：编译时添加-static-libgcc -static-libstdc++ -static参数，把依赖库打包到fib.pyd中，避免动态依赖问题
• 移除不必要的头文件：代码中并未实际使用<iostream>的功能，直接删掉#include <iostream>和using namespace std;，彻底避免依赖问题

内容的提问来源于stack exchange，提问作者Julian LaGattuta