Add CMake comments

they explain why we need the no-warn flag

Author: DuncanMcBain

src/game_of_life/CMakeLists.txt

@@ -5,5 +5,7 @@ target_link_libraries(GameOfLife PRIVATE
                                  Magnum::Magnum Magnum::GL Magnum::Application
                                  Magnum::Shaders Magnum::Primitives)
 
+# `using enum` is apparently a C++ 20 extension, but is widely supported,
+# so we can use it without a feature test (and this skips the warning).
 target_compile_options(GameOfLife PUBLIC ${SYCL_FLAGS} -Wno-c++20-extensions)
 target_link_options(GameOfLife PUBLIC ${SYCL_FLAGS})

src/mandelbrot/CMakeLists.txt

@@ -6,5 +6,7 @@ target_link_libraries(Mandelbrot PRIVATE
                                  Magnum::Magnum Magnum::GL Magnum::Application
                                  Magnum::Shaders Magnum::Primitives)
 
+# `using enum` is apparently a C++ 20 extension, but is widely supported,
+# so we can use it without a feature test (and this skips the warning).
 target_compile_options(Mandelbrot PUBLIC ${SYCL_FLAGS} -Wno-c++20-extensions)
 target_link_options(Mandelbrot PUBLIC ${SYCL_FLAGS})