在VSCode中使用CMake配置PyTorch C++ API的问题排查

问题描述 #

我运行PyTorch C++ API的最小示例，在macOS下用以下命令手动编译可正常运行：

mkdir build
cd build
cmake -DCMAKE_PREFIX_PATH=/absolute/path/to/libtorch ..
cmake --build . --config Release

但在VSCode中按官方文档配置时，出现CMake错误：

CMake Error at CMakeLists.txt:4 (find_package):
By not providing "FindTorch.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "Torch", but
CMake did not find one.

Could not find a package configuration file provided by "Torch" with any of
the following names:

TorchConfig.cmake
torch-config.cmake

Add the installation prefix of "Torch" to CMAKE_PREFIX_PATH or set
"Torch_DIR" to a directory containing one of the above files. If "Torch"
provides a separate development package or SDK, be sure it has been
installed.

尝试在CMakeLists.txt中添加以下命令无效：

set(CMAKE_MODULE_PATH "/Users/myusername/external_library_include/libtorch")
include_directories("/Users/myusername/external_library_include/libtorch")

解决方法 #

以下是在VSCode中配置CMAKE_PREFIX_PATH的几种有效方式：

方法1：通过CMake Tools扩展的UI配置 #

• 打开VSCode命令面板（快捷键：Cmd+Shift+P）
• 输入并选择CMake: Edit User-Local CMake Kits
• 在打开的cmake-kits.json文件中，找到对应你当前使用的编译器的kit（比如Clang），在cmakeSettings节点下添加CMAKE_PREFIX_PATH配置：

{
  "name": "Clang",
  "compilers": {
    "C": "/usr/bin/clang",
    "CXX": "/usr/bin/clang++"
  },
  "cmakeSettings": {
    "CMAKE_PREFIX_PATH": "/Users/myusername/external_library_include/libtorch"
  }
}

• 保存文件后，执行命令面板的CMake: Configure重新生成配置

方法2：修改VSCode全局settings.json #

• 打开VSCode设置（快捷键：Cmd+,）
• 搜索cmake.configureArgs，点击编辑 in settings.json
• 将-DCMAKE_PREFIX_PATH参数加入配置数组：

"cmake.configureArgs": [
  "-DCMAKE_PREFIX_PATH=/Users/myusername/external_library_include/libtorch"
]

• 保存设置后重新执行CMake配置

方法3：直接在CMakeLists.txt中指定Torch_DIR（最直接） #

不需要修改CMAKE_MODULE_PATH，直接把Torch_DIR指向libtorch中包含TorchConfig.cmake的目录（通常是libtorch/share/cmake/Torch）：

set(Torch_DIR "/Users/myusername/external_library_include/libtorch/share/cmake/Torch")
find_package(Torch REQUIRED)

这样CMake能直接定位到配置文件，无需额外设置CMAKE_PREFIX_PATH

内容的提问来源于stack exchange，提问作者MOON