python - 在 C++ 中使用 MinGW 嵌入 python3.6 链接失败

Question

尝试在Win10 64位系统上用C++嵌入python3.6。Python 由 python-3.6.1-amd64.exe 安装。CMakeList.txt 如下所示

cmake_minimum_required(VERSION 3.8)
project(EmbedPython)

set(CMAKE_CXX_STANDARD 11)

set(SOURCE_FILES main.cpp)
find_package(PythonLibs REQUIRED)
include_directories(${PYTHON_INCLUDE_DIRS})
add_executable(EmbedPython ${SOURCE_FILES} ${PYTHON_INCLUDE_DIRS})
target_link_libraries(EmbedPython ${PYTHON_LIBRARIES})

然后 CMake 找到了 Python 包。

PYTHON_INCLUDE_DIR C:/Program Files (x86)/Python36/include
PYTHON_LIBRARY C:/Program Files (x86)/Python36/libs/python36.lib

Find a comment on github它在谈论 API 问题。

# used to embed python script
find_package(PythonLibs 2.7 REQUIRED) # this has to be 2.7 because the 3.0 API requires argv to be wchar_t** rather than the default char**
include_directories(${PYTHON_INCLUDE_DIRS})
target_link_libraries( assignment ${PYTHON_LIBRARIES})

下面的错误是我所面临的。

[ 50%] Building CXX object CMakeFiles/EmbedPython.dir/main.cpp.obj
[100%] Linking CXX executable EmbedPython.exe
CMakeFiles\EmbedPython.dir/objects.a(main.cpp.obj): In function `main':
D:/Projects/EmbedPython/main.cpp:16: undefined reference to `_imp__Py_Initialize'
D:/Projects/EmbedPython/main.cpp:17: undefined reference to `_imp__PyUnicode_DecodeFSDefault'
D:/Projects/EmbedPython/main.cpp:20: undefined reference to `_imp__PyImport_Import'
D:/Projects/EmbedPython/main.cpp:24: undefined reference to `_imp__PyObject_GetAttrString'
D:/Projects/EmbedPython/main.cpp:27: undefined reference to `_imp__PyCallable_Check'
D:/Projects/EmbedPython/main.cpp:28: undefined reference to `_imp__PyTuple_New'
D:/Projects/EmbedPython/main.cpp:30: undefined reference to `_imp__PyLong_FromLong'
D:/Projects/EmbedPython/main.cpp:38: undefined reference to `_imp__PyTuple_SetItem'
D:/Projects/EmbedPython/main.cpp:40: undefined reference to `_imp__PyObject_CallObject'
D:/Projects/EmbedPython/main.cpp:43: undefined reference to `_imp__PyLong_AsLong'
D:/Projects/EmbedPython/main.cpp:49: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:55: undefined reference to `_imp__PyErr_Occurred'
D:/Projects/EmbedPython/main.cpp:56: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:63: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:67: undefined reference to `_imp__Py_FinalizeEx'
collect2.exe: error: ld returned 1 exit status
mingw32-make.exe[3]: *** [EmbedPython.exe] Error 1
mingw32-make.exe[2]: *** [CMakeFiles/EmbedPython.dir/all] Error 2
mingw32-make.exe[1]: *** [CMakeFiles/EmbedPython.dir/rule] Error 2
mingw32-make.exe: *** [EmbedPython] Error 2
CMakeFiles\EmbedPython.dir\build.make:96: recipe for target 'EmbedPython.exe' failed
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/EmbedPython.dir/all' failed
CMakeFiles\Makefile2:78: recipe for target 'CMakeFiles/EmbedPython.dir/rule' failed
Makefile:117: recipe for target 'EmbedPython' failed

不确定如何使项目运行。任何帮助将不胜感激。

编辑:make VERBOSE=1

的结果

D:\Projects\EmbedPython\cmake-build-debug>make VERBOSE=1
"C:\Program Files\JetBrains\CLion 172.2273.4\bin\cmake\bin\cmake.exe" -HD:\Projects\EmbedPython -BD:\Projects\EmbedPython\cmake-build-debug --check-build-system CMakeFiles\Makefile.cmake 0
"C:\Program Files\JetBrains\CLion 172.2273.4\bin\cmake\bin\cmake.exe" -E cmake_progress_start D:\Projects\EmbedPython\cmake-build-debug\CMakeFiles D:\Projects\EmbedPython\cmake-build-debug\CMakeFiles\progress.marks
make -f CMakeFiles\Makefile2 all
make[1]: Entering directory 'D:/Projects/EmbedPython/cmake-build-debug'
make -f CMakeFiles\EmbedPython.dir\build.make CMakeFiles/EmbedPython.dir/depend
make[2]: Entering directory 'D:/Projects/EmbedPython/cmake-build-debug'
"C:\Program Files\JetBrains\CLion 172.2273.4\bin\cmake\bin\cmake.exe" -E cmake_depends "MinGW Makefiles" D:\Projects\EmbedPython D:\Projects\EmbedPython D:\Projects\EmbedPython\cmake-build-debug D:\Projects\EmbedPython\cmake-build-debug D:\Projects\EmbedPython\cmake-build-debug\CMakeFiles\EmbedPython.dir\DependInfo.cmake --color=
make[2]: Leaving directory 'D:/Projects/EmbedPython/cmake-build-debug'
make -f CMakeFiles\EmbedPython.dir\build.make CMakeFiles/EmbedPython.dir/build
make[2]: Entering directory 'D:/Projects/EmbedPython/cmake-build-debug'
[ 50%] Linking CXX executable EmbedPython.exe
"C:\Program Files\JetBrains\CLion 172.2273.4\bin\cmake\bin\cmake.exe" -E cmake_link_script CMakeFiles\EmbedPython.dir\link.txt --verbose=1
"C:\Program Files\JetBrains\CLion 172.2273.4\bin\cmake\bin\cmake.exe" -E remove -f CMakeFiles\EmbedPython.dir/objects.a
C:\PROGRA~2\MINGW-~1\I686-6~1.0-P\mingw32\bin\ar.exe cr CMakeFiles\EmbedPython.dir/objects.a @CMakeFiles\EmbedPython.dir\objects1.rsp
C:\PROGRA~2\MINGW-~1\I686-6~1.0-P\mingw32\bin\G__~1.EXE -g   -Wl,--whole-archive CMakeFiles\EmbedPython.dir/objects.a -Wl,--no-whole-archive  -o EmbedPython.exe -Wl,--out-implib,libEmbedPython.dll.a -Wl,--major-image-version,0,--minor-image-version,0 @CMakeFiles\EmbedPython.dir\linklibs.rsp
CMakeFiles\EmbedPython.dir/objects.a(main.cpp.obj): In function `main':
D:/Projects/EmbedPython/main.cpp:16: undefined reference to `_imp__Py_Initialize'
D:/Projects/EmbedPython/main.cpp:17: undefined reference to `_imp__PyUnicode_DecodeFSDefault'
D:/Projects/EmbedPython/main.cpp:20: undefined reference to `_imp__PyImport_Import'
D:/Projects/EmbedPython/main.cpp:24: undefined reference to `_imp__PyObject_GetAttrString'
D:/Projects/EmbedPython/main.cpp:27: undefined reference to `_imp__PyCallable_Check'
D:/Projects/EmbedPython/main.cpp:28: undefined reference to `_imp__PyTuple_New'
D:/Projects/EmbedPython/main.cpp:30: undefined reference to `_imp__PyLong_FromLong'
D:/Projects/EmbedPython/main.cpp:38: undefined reference to `_imp__PyTuple_SetItem'
D:/Projects/EmbedPython/main.cpp:40: undefined reference to `_imp__PyObject_CallObject'
D:/Projects/EmbedPython/main.cpp:43: undefined reference to `_imp__PyLong_AsLong'
D:/Projects/EmbedPython/main.cpp:49: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:55: undefined reference to `_imp__PyErr_Occurred'
D:/Projects/EmbedPython/main.cpp:56: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:63: undefined reference to `_imp__PyErr_Print'
D:/Projects/EmbedPython/main.cpp:67: undefined reference to `_imp__Py_FinalizeEx'
collect2.exe: error: ld returned 1 exit status
CMakeFiles\EmbedPython.dir\build.make:97: recipe for target 'EmbedPython.exe' failed
make[2]: *** [EmbedPython.exe] Error 1
make[2]: Leaving directory 'D:/Projects/EmbedPython/cmake-build-debug'
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/EmbedPython.dir/all' failed
make[1]: *** [CMakeFiles/EmbedPython.dir/all] Error 2
make[1]: Leaving directory 'D:/Projects/EmbedPython/cmake-build-debug'
Makefile:82: recipe for target 'all' failed
make: *** [all] Error 2

Answer 1

我遇到了完全相同的问题，只是在尝试构建 example 时使用 Python 3.7来自 Python 手册。

我的系统是64位的Windows，安装的Python是64位的3.7(来自Anaconda3)，编译器是32位的MinGW 5.3.0(来自Qt 5.11)。

对我有用的最简单的解决方案如下:

• 下载Windows x86 embeddable zip file来自 this页面。
• 将该存档的内容放入您正在构建的项目中的文件夹中。
• 不要安装该存档中的任何内容，也不要将其放在系统路径中。
• 将上述文件夹添加到 gcc 库搜索路径，使用:-L"path/to/folder/"
• 将 python 库添加到链接器，使用 -l"python37" (将 37 替换为您下载的任何版本)
• 如前所述here (这很难找到!)，添加一个定义，使用 -DPy_BUILD_CORE_BUILTIN=1 (也可以在 #define DPy_BUILD_CORE_BUILTIN 1 之前编写 #include - Python header ，但我不推荐这样做)
• 使用 -I"path/to/include" 提供 Python header 的路径.我使用了 Anaconda 中的那个，例如-I"c:/Users/user/Anaconda3/include/" .任何安装的 header 都可以，只要确保它来自相同版本(也可以使用来自旧版本的 header ，但这可能会导致时空连续体破裂)
• 确保#include <Python.h>如手册中所述，在任何其他包含之前。

作为旁注，MinGW 链接器 (ld) 多年来一直是完美的内容，如果您只给它“dll”文件。如果您没有并且只执行动态链接，则不需要“lib”或“a”。这就是为什么我只是告诉链接器使用 python37 .

它实际上smart enough查找类似 python37.lib 的文件, python37.dll & libpython37.a .

另请注意，“可嵌入的 zip”只是嵌入 Python 所需的最低限度。

作为最后的评论，与声明相反 here ，从 GCC 链接到使用 MSVS 编译的库(反之亦然)没有任何问题，只要该库使用普通的 C 接口(interface)，因为该接口(interface)几乎是唯一的东西兼容任何给定平台的不同编译器。

这几乎就是 Python 使用 C 接口(interface)(没有别的，甚至不是 C++)进行扩展和嵌入的确切原因 - 允许编写代码任何语言，使用任何工具集，与 Python 交互。