对`Py_DecodeLocale'的未定义引用

Question

我正在将 Python 嵌入到 C++ 项目中，示例代码来自 https://docs.python.org/3/extending/embedding.html#very-high-level-embedding:

CMakeLists.txt

：

cmake_minimum_required(VERSION 3.20)
project(python_in_cpp)

set(CMAKE_CXX_STANDARD 11)

# sudo apt install libpython3.11-dev

find_package(PythonLibs 3.11 REQUIRED)

find_package(Python COMPONENTS Interpreter Development)

message("Python_FOUND:${Python_FOUND}")
message("Python_VERSION:${Python_VERSION}")
message("Python_Development_FOUND:${Python_Development_FOUND}")
message("Python_LIBRARIES:${Python_LIBRARIES}")

include_directories(${Python_INCLUDE_DIRS})

link_directories(
        ${Python3_LIBRARY_DIRS}
        ${Python3_RUNTIME_LIBRARY_DIRS}
)

link_libraries(${Python3_LIBRARIES})

add_executable(python_in_cpp main.cpp)

main.cpp

：

#define PY_SSIZE_T_CLEAN
#include <Python.h>

int
main(int argc, char *argv[])
{
    wchar_t *program = Py_DecodeLocale(argv[0], NULL);
    if (program == NULL) {
        fprintf(stderr, "Fatal error: cannot decode argv[0]\n");
        exit(1);
    }
    Py_SetProgramName(program);  /* optional but recommended */
    Py_Initialize();
    PyRun_SimpleString("from time import time,ctime\n"
                       "print('Today is', ctime(time()))\n");
    if (Py_FinalizeEx() < 0) {
        exit(120);
    }
    PyMem_RawFree(program);
    return 0;
}

CMake 日志显示

Python

和

PythonLibs

都找到了，但是在编译时，我收到了关于几个未定义引用的错误：

main.cpp:(.text+0x1f): undefined reference to `Py_DecodeLocale'
/usr/bin/ld: main.cpp:(.text+0x63): undefined reference to `Py_SetProgramName'
/usr/bin/ld: main.cpp:(.text+0x68): undefined reference to `Py_Initialize'
/usr/bin/ld: main.cpp:(.text+0x7c): undefined reference to `PyRun_SimpleStringFlags'
/usr/bin/ld: main.cpp:(.text+0x81): undefined reference to `Py_FinalizeEx'
/usr/bin/ld: main.cpp:(.text+0x9e): undefined reference to `PyMem_RawFree'

我该如何修复它来构建这个项目？

---

我安装了几个python：

$ apt list --installed | grep "lib*python"

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libpython3-dev/stable,now 3.11.2-1+b1 amd64 [installed]
libpython3-stdlib/stable,now 3.11.2-1+b1 amd64 [installed,automatic]
libpython3.11-dev/stable-security,now 3.11.2-6+deb12u3 amd64 [installed]
libpython3.11-minimal/stable-security,now 3.11.2-6+deb12u3 amd64 [installed,automatic]
libpython3.11-stdlib/stable-security,now 3.11.2-6+deb12u3 amd64 [installed,automatic]
libpython3.11/stable-security,now 3.11.2-6+deb12u3 amd64 [installed,automatic]

Answer 1

这是一个愚蠢的错字。您打印了

Python_LIBRARIES

，但在

Python3_LIBRARIES

语句中使用了

link_libraries

。

为了避免将来出现此类问题，您应该更喜欢使用模块提供的导入目标。

您可以用这一行替换您的三个语句（

include_directories

、

link_directories

和

link_libraries

）：

target_link_libraries(python_in_cpp Python::Python)

确保将其放在 after

add_executable

声明中。