[PATCH] [CMake] Update required version to 2.8.12 to improve build time with target_link_libraries(INTERFACE)

[Brad King]

On 02/23/2014 08:14 PM, NAKAMURA Takumi wrote:
> 
>   Argyrios, I'd be happy if this feature worked as optional.
> 
>   Brad, any good idea?
>   Could I twiddle cmake_minimum_required and cmake_policy explicitly there?

You can leave

 cmake_minimum_required(VERSION 2.8.8)

alone and make the new keyword arguments conditional with variables:

 if(NOT CMAKE_VERSION VERSION_LESS 2.8.12)
   set(cmake_2_8_12_INTERFACE INTERFACE)
   set(cmake_2_8_12_PRIVATE PRIVATE)
 else()
   set(cmake_2_8_12_INTERFACE)
   set(cmake_2_8_12_PRIVATE)
 endif()

Then use them like this:

 target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${ARG_LINK_LIBS})

On older versions the call will turn into

 target_link_libraries(${name} ${ARG_LINK_LIBS})

and on 2.8.12 and above it will become

 target_link_libraries(${name} INTERFACE ${ARG_LINK_LIBS})

The "cmake_2_8_12_" prefix is just to call attention to the code
to remember to simplify it when 2.8.12 or later becomes required.
Any variable names could be used, of course.

-Brad