Set compiler warnings on a per-target basis

cmake/CompilerWarnings.cmake

@@ -2,8 +2,8 @@
 #
 # https://github.com/lefticus/cppbestpractices/blob/master/02-Use_the_Tools_Available.md
 
-# Helper function to enable compiler warnings for a specific set of files
-function(set_file_warnings)
+# Helper function to enable compiler warnings for a specific target
+function(set_target_warnings target)
     option(WARNINGS_AS_ERRORS "Treat compiler warnings as errors" FALSE)
 
     set(MSVC_WARNINGS
@@ -97,7 +97,5 @@ function(set_file_warnings)
         message(AUTHOR_WARNING "No compiler warnings set for '${CMAKE_CXX_COMPILER_ID}' compiler.")
     endif()
 
-    foreach(WARNING ${FILE_WARNINGS})
-        set_property(SOURCE ${ARGV} APPEND_STRING PROPERTY COMPILE_FLAGS " ${WARNING}")
-    endforeach()
+    target_compile_options(${target} PRIVATE ${FILE_WARNINGS})
 endfunction()

cmake/Macros.cmake

@@ -17,7 +17,7 @@ macro(csfml_add_library target)
     target_include_directories(${target} PUBLIC ${PROJECT_SOURCE_DIR}/include)
 
     # add warnings
-    set_file_warnings(${THIS_SOURCES})
+    set_target_warnings(${target})
 
     # require C11 and C++17
     target_compile_features(${target} PUBLIC c_std_11 cxx_std_17)