CMP0049 ------- Do not expand variables in target source entries. CMake 2.8.12 and lower performed an extra layer of variable expansion when evaluating source file names:: set(a_source foo.c) add_executable(foo \${a_source}) .. note: no cmake highlighting since this syntax is deprecated This was undocumented behavior. The ``OLD`` behavior for this policy is to expand such variables when processing the target sources. The ``NEW`` behavior for this policy is to issue an error if such variables need to be expanded. This policy was introduced in CMake version 3.0. CMake version |release| warns when the policy is not set and uses ``OLD`` behavior. Use the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly. .. include:: DEPRECATED.txt