包含CMakeLists.txt是运行时的当前目录。相反，每当需要相对于CMakeLists.txt的路径时，使用 $ {CMAKE_CURRENT_SOURCE_DIR} 。例如：

Don't assume that the directory containing CMakeLists.txt is the current directory at runtime. Instead, use ${CMAKE_CURRENT_SOURCE_DIR} whenever you want a path relative to the CMakeLists.txt. For example:

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/hdr)