小编Wen*_*kob的帖子

通常需要确保CMake构建项目在编译后最终位于某个位置，并且该add_custom_command(..POST_BUILD...)命令是实现该目标的通用设计模式：

add_custom_command(
  TARGET mytarget
  POST_BUILD
  COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:mytarget> ${CMAKE_BINARY_DIR}/final_destination
)

令人遗憾的是，当所讨论的目标位于相对于包含add_custom_command调用的文件的子目录中时，该文件是通过add_subdirectory()命令递归编译的。尝试这样做会导致以下错误消息：

CMake Warning (dev) at CMakeLists.txt:4 (add_custom_command):
  Policy CMP0040 is not set: The target in the TARGET signature of
  add_custom_command() must exist.  Run "cmake --help-policy CMP0040" for
  policy details.  Use the cmake_policy command to set the policy and
  suppress this warning.

  TARGET 'mytarget' was not created in this directory.
This warning is for project developers.  Use -Wno-dev to suppress it.

在许多情况下，有一个简单的解决方法：只需确保该add_custom_command() …