CMakeLists.txt: Set CMake policy CMP0054 to NEW.

This prevents the following warnings upon a second cmake run:

  CMake Warning (dev) at /usr/share/cmake-3.10/Modules/CMakePushCheckState.cmake:65 (if):
    Policy CMP0054 is not set: Only interpret if() arguments as variables or
    keywords when unquoted.  Run "cmake --help-policy CMP0054" for policy
    details.  Use the cmake_policy command to set the policy and suppress this
    warning.
    Quoted variables like "HAVE_CXX_ATOMICS_WITHOUT_LIB" will no longer be
    dereferenced when the policy is set to NEW.  Since the policy is not set
    the OLD behavior will be used.
  Call Stack (most recent call first):
    CMakeLists.txt:123 (cmake_push_check_state)
    CMakeLists.txt:139 (check_working_cxx_atomics)
  This warning is for project developers.  Use -Wno-dev to suppress it.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3482980958f6ffbf557f95526d7b9f1a9fca0361..1e81a60ce37ee24dfc7d985ca8e7728a48f96fa7 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,6 +29,11 @@ if(POLICY CMP0071)
        cmake_policy(SET CMP0071 NEW)
 endif()
 
+# Only interpret if() arguments as variables or keywords when unquoted.
+if(POLICY CMP0054)
+       cmake_policy(SET CMP0054 NEW)
+endif()
+
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/CMake")
 
 #===============================================================================