build - CMake warnings disappear when using other CMAKE_BUILD_TYPE -

i'm using cmake version 3.5.1. if cmake executed on project -dcmake_build_type=release argument warnings cmake warning (dev) policy cmp0043 cmakelists.txt shown.

but when use -dcmake_build_type=debug (and nothing else changed) curiously warnings not longer shown, when adding -wdev -wdeprecated.

why warnings disappearing when using other build type , how them back?