Could not find a package configuration file provided by “Torch“ with any of the following names:问题解决

问题描述

CMakeLists.txt文件如下：

cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
project(custom_ops)

find_package(Torch REQUIRED)

add_executable(example-app example-app.cpp)
target_link_libraries(example-app "${TORCH_LIBRARIES}")
set_property(TARGET example-app PROPERTY CXX_STANDARD 14)

执行命令报错：

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.

问题原因

可以看出，就是在第四行，寻找包的时候出错了，没有找到对应的包

只有在cmake中依赖了其他的包，我们才能才在代码中使用#include 而不会出现编译错误

那么需要知道find_package的用法，即寻找依赖包，我的理解是，cmake会默认在系统的安装目录去寻找，如果是通过包管理命令直接安装的包，例如opencv，可能会在/usr/local下，不需要自己添加额外的处理。但是如果是自己下载解压的动态库，或者自己编译源码得到的动态库，就需要进行额外的处理了，具体包括：

• 如果是下载解压的动态库，那么只需要找到需要的库的.cmake文件即可，这一步需要需要手动指定此文件的目录，让cmake找到它：

export Torch_DIR=/local/xxx/env/lib/python3.8/site-packages/torch/share/cmake

如何得到这个路径呢？
可以执行：

python -c 'import torch;print(torch.utils.cmake_prefix_path)'

• 如果是自己编译源码得到的动态库，可能要自己写cmake文件？【具体实现方式见参考资料】

问题解决

export Torch_DIR=/local/xxx/env/lib/python3.8/site-packages/torch/share/cmake

参考资料

“轻松搞定CMake”系列之find_package用法详解
Cmake之深入理解find_package()的用法