cmake: add cflags utility macros

CMakeLists.txt

@@ -19,6 +19,7 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
 endif()
 
 include(cmake/git.cmake)
+include(cmake/util.cmake)
 
 include(cmake/config.cmake)
 configure_file(
@@ -28,10 +29,17 @@ configure_file(
 
 include("arch/${ARCH}/config/toolchain.cmake")
 
-# Used by the KASSERT macro for printing the filename relative to the source root
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__FILENAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")
+gay_append_cmake_c_flags(
+    -ggdb
+    -pipe
+    -nostdinc
+    -ffreestanding
+    -fno-stack-protector
+    -Wused-but-marked-unused
+    # Used by the KASSERT macro for printing the filename relative to the source root
+    "-D__FILENAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'"
+)
 
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pipe -nostdinc -ffreestanding -fno-stack-protector")
 set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -pipe -D_ASM_SOURCE")
 if(DEBUG)
     # -Og on gcc optimizes for the best debugging experience, but apparently this
@@ -39,12 +47,12 @@ if(DEBUG)
     # you're supposed to use -O0 in order to get the most submissive and debuggable
     # code instead:
     # <https://clang.llvm.org/docs/CommandGuide/clang.html#code-generation-options>
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -ggdb")
+    gay_append_cmake_c_flags(-O0)
     # i don't think -O0 does anything for assembly code, but it can't hurt to
     # have it in there just in case (somebody check on this at some point plz)
-    set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -O0 -ggdb")
+    gay_append_cmake_asm_flags(-O0)
 else()
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2 -ggdb")
+    gay_append_cmake_c_flags(-O2)
 endif()
 
 # --whole-archive ensures no (seemingly) unused symbols

cmake/util.cmake

@@ -0,0 +1,13 @@
+# Copyright (C) 2021 fef <owo@fef.moe>.  All rights reserved.
+
+macro(gay_append_cmake_c_flags)
+    foreach(flag IN ITEMS ${ARGN})
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${flag}")
+    endforeach()
+endmacro()
+
+macro(gay_append_cmake_asm_flags)
+    foreach(flag IN ITEMS ${ARGN})
+        set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} ${flag}")
+    endforeach()
+endmacro()