Cmake warning (#230)

* Update CMake FetchContent and bump externals

For modern CMake use the new CMP0135 policy, i.e.,
use timestamps from extraction of tarballs

Bump internal submodules to latest releases:
nlohmman-json: 3.11.2
spdlog: 1.11.0

* Bump CMake version

Now to 3.24, which is where the option to handle
extract time timestamps was introduced

* Use optional policy specifier

Address the timestamp issue differently, using a query for the
policy, which indicates a newer cmake, and only setting the policy
if that test passes

This allows us to be still compaible with much older cmake versions

CMakeLists.txt

@@ -6,6 +6,11 @@ cmake_minimum_required(VERSION 3.3)
 # From CMake 3, we can set the project version easily in one go
 project(prmon VERSION 3.0.2)
 
+# For newer CMakes we ensure correct handling of extracting GTest from tarball
+if (POLICY CMP0135)
+  cmake_policy(SET CMP0135 NEW)
+endif (POLICY CMP0135)
+
 #--- Define basic build settings -----------------------------------------------
 # - Use GNU-style hierarchy for installing build products
 include(GNUInstallDirs)

README.md

@@ -249,4 +249,4 @@ to CMake using `Gperftools_ROOT_DIR`.
 
 # Copyright
 
-Copyright (c) 2018-2022 CERN.
+Copyright (c) 2018-2023 CERN.

package/tests/CMakeLists.txt

@@ -14,7 +14,7 @@ if(${CMAKE_CXX_COMPILER_ID} STREQUAL "Clang")
   set_target_properties(mem-burner PROPERTIES COMPILE_FLAGS "-fno-builtin")
 endif()
 
-if (${CMAKE_VERSION} VERSION_GREATER "3.14.0" AND BUILD_GTESTS)
+if (BUILD_GTESTS)
 
     include(FetchContent)
     FetchContent_Declare(