cmake: Toolchain abstraction: Introduce toolchain_cc_warning_base

This is placeholder for base warning flags, common to most toolchains.

The intent here is to abstract Zephyr's dependence on toolchains,
thus allowing for easier porting to other, perhaps commercial,
toolchains and/or usecases.

No functional change expected.

Signed-off-by: Danny Oerndrup <daor@demant.com>

CMakeLists.txt

@@ -197,13 +197,8 @@ toolchain_cc_nostdinc()
 
 zephyr_compile_options(
   -g # TODO: build configuration enough?
-  -Wall
-  -Wformat
-  -Wformat-security
-  -Wno-format-zero-length
   -imacros ${AUTOCONF_H}
   -ffreestanding
-  -Wno-main
   -fno-common
   ${TOOLCHAIN_C_FLAGS}
 )
@@ -232,6 +227,9 @@ if(CONFIG_LIB_CPLUSPLUS)
   toolchain_ld_cpp()
 endif()
 
+# @Intent Add the basic toolchain warning flags
+toolchain_cc_warning_base()
+
 # ==========================================================================
 #
 # cmake -DW=... settings
@@ -262,7 +260,6 @@ zephyr_cc_option(-fno-asynchronous-unwind-tables)
 zephyr_cc_option(-fno-pie)
 zephyr_cc_option(-fno-pic)
 zephyr_cc_option(-fno-strict-overflow)
-zephyr_cc_option(-Wno-pointer-sign)
 
 if(CONFIG_OVERRIDE_FRAME_POINTER_DEFAULT)
   if(CONFIG_OMIT_FRAME_POINTER)
@@ -311,9 +308,6 @@ zephyr_cc_option_ifdef(CONFIG_STACK_USAGE            -fstack-usage)
 # Force an error when things like SYS_INIT(foo, ...) occur with a missing header.
 zephyr_cc_option(-Werror=implicit-int)
 
-# Prohibit void pointer arithmetic. Illegal in C99
-zephyr_cc_option(-Wpointer-arith)
-
 # If the compiler supports it, strip the ${ZEPHYR_BASE} prefix from the
 # __FILE__ macro used in __ASSERT*, in the
 # .noinit."/home/joe/zephyr/fu/bar.c" section names and in any

cmake/compiler/gcc/target_warnings.cmake

@@ -2,6 +2,23 @@
 
 # See root CMakeLists.txt for description and expectations of these macros
 
+macro(toolchain_cc_warning_base)
+
+  zephyr_compile_options(
+    -Wall
+    -Wformat
+    -Wformat-security
+    -Wno-format-zero-length
+    -Wno-main
+  )
+
+  zephyr_cc_option(-Wno-pointer-sign)
+
+  # Prohibit void pointer arithmetic. Illegal in C99
+  zephyr_cc_option(-Wpointer-arith)
+
+endmacro()
+
 macro(toolchain_cc_warning_dw_1)
 
   zephyr_compile_options(