CMP0007

list command no longer ignores empty elements.

This policy determines whether the list command will ignore empty elements in the list. CMake 2.4 and below list commands ignored all empty elements in the list. For example, a;b;;c would have length 3 and not 4. The OLD behavior for this policy is to ignore empty list elements. The NEW behavior for this policy is to correctly count empty elements in a list.

This policy was introduced in CMake version 2.6.0. CMake version 3.19.0-rc3 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.