Libraries linked by full-path must have a valid library file name.
In CMake 2.4 and below it is possible to write code like
where “somelib” is supposed to be a valid library file name such as “libsomelib.a” or “somelib.lib”. For Makefile generators this produces an error at build time because the dependency on the full path cannot be found. For VS IDE and Xcode generators this used to work by accident because CMake would always split off the library directory and ask the linker to search for the library by name (-lsomelib or somelib.lib). Despite the failure with Makefiles, some projects have code like this and build only with VS and/or Xcode. This version of CMake prefers to pass the full path directly to the native build tool, which will fail in this case because it does not name a valid library file.
This policy determines what to do with full paths that do not appear to name a valid library file. The OLD behavior for this policy is to split the library name from the path and ask the linker to search for it. The NEW behavior for this policy is to trust the given path and pass it directly to the native build tool unchanged.
This policy was introduced in CMake version 2.6.1. CMake version 3.6.2 warns when the policy is not set and uses OLD behavior. Use the cmake_policy command to set it to OLD or NEW explicitly.
OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.