Remove obsolete policy settings

[steveire]

Summary

The line

cmake_minimum_required(VERSION 3.4.3)

already has the effect of setting to NEW all policies present in that
release:

https://cmake.org/cmake/help/v3.4/manual/cmake-policies.7.html

[steveire]

ping? This should be a striaghtforward lgtm from anyone.

[dblaikie]

looks good, thanks! (do you have commit rights - or would you like me to commit this for you?)

[steveire]

I have commit rights, thanks!

[smeenai]

llvm/trunk/CMakeLists.txt

16 ↗

(On Diff #159990)

This removal was incorrect. https://cmake.org/cmake/help/v3.4/policy/CMP0056.html says "Unlike most policies, CMake version 3.4.3 does not warn by default when this policy is not set and simply uses OLD behavior (and even the latest version's documentaion says the same).

In general, @beanz, @phosek, @mgorny and I make good reviewers for CMake changes.

[smeenai]

llvm/trunk/CMakeLists.txt

16 ↗

(On Diff #159990)

Ah, nevermind, the document you linked seems more authoritative than the individual policy page's one. That's confusing documentation though.

CMakeLists.txt

 # See docs/CMake.html for instructions about how to build LLVM with CMake.
 
 cmake_minimum_required(VERSION 3.4.3)
 
-cmake_policy(SET CMP0022 NEW)
-
-cmake_policy(SET CMP0048 NEW)
-
 # CMake 3.1 and higher include generator expressions of the form
 # $<TARGETLIB:obj> in the SOURCES property.  These need to be
 # stripped everywhere that access the SOURCES property, so we just
 # defer to the OLD behavior of not including generator expressions
 # in the output for now.
 cmake_policy(SET CMP0051 OLD)
 
-cmake_policy(SET CMP0056 NEW)
-
-cmake_policy(SET CMP0057 NEW)
-
 if(POLICY CMP0068)
   cmake_policy(SET CMP0068 NEW)
   set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
 endif()
 
 if(NOT DEFINED LLVM_VERSION_MAJOR)
   set(LLVM_VERSION_MAJOR 8)
 endif()