CMake: Condition core_name tests on CMake version (#224)

As those tests require C++20 only compile them with CMake 3.12+ to be able to use `cxx_std_20`

Author: Flamefire

test/CMakeLists.txt

@@ -16,13 +16,17 @@ foreach (testsourcefile ${CORE_RUN_FILES})
     add_dependencies(tests pfr_core_${testname})
 endforeach()
 
-file(GLOB CORE_NAME_RUN_FILES "core_name/run/*.cpp")
-foreach (testsourcefile ${CORE_NAME_RUN_FILES})
-    get_filename_component(testname ${testsourcefile} NAME_WE)
-    add_executable(pfr_corename_${testname} ${testsourcefile})
-    target_compile_features(pfr_corename_${testname} PUBLIC cxx_std_20)
-    target_link_libraries(pfr_corename_${testname} Boost::pfr Boost::core Boost::container_hash)
-    target_include_directories(pfr_corename_${testname} PRIVATE ../../../)
-    add_test(NAME pfr_corename_${testname} COMMAND pfr_corename_${testname})
-    add_dependencies(tests pfr_corename_${testname})
-endforeach()
+if(CMAKE_VERSION VERSION_LESS 3.12)
+    message(AUTHOR_WARNING "Disabling core_name tests as CMake version 3.12+ is required but using ${CMAKE_VERSION}")
+else()
+    file(GLOB CORE_NAME_RUN_FILES "core_name/run/*.cpp")
+    foreach (testsourcefile ${CORE_NAME_RUN_FILES})
+        get_filename_component(testname ${testsourcefile} NAME_WE)
+        add_executable(pfr_corename_${testname} ${testsourcefile})
+        target_compile_features(pfr_corename_${testname} PUBLIC cxx_std_20)
+        target_link_libraries(pfr_corename_${testname} Boost::pfr Boost::core Boost::container_hash)
+        target_include_directories(pfr_corename_${testname} PRIVATE ../../../)
+        add_test(NAME pfr_corename_${testname} COMMAND pfr_corename_${testname})
+        add_dependencies(tests pfr_corename_${testname})
+    endforeach()
+endif()