[make] add a way for a module to opt into additional warnings

Move -Wmissing-declarations and -Wmissing-prototypes into this bucket.
Opt in most of the core top level modules in the system. More to follow.

app/rules.mk

@@ -5,4 +5,6 @@ MODULE := $(LOCAL_DIR)
 MODULE_SRCS += \
 	$(LOCAL_DIR)/app.c
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk

arch/rules.mk

@@ -4,5 +4,7 @@ MODULE := $(LOCAL_DIR)
 
 MODULE_SRCS := $(LOCAL_DIR)/arch.c
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk
 

dev/rules.mk

@@ -12,4 +12,6 @@ MODULE_SRCS += \
 	$(LOCAL_DIR)/class/fb_api.c \
 	$(LOCAL_DIR)/class/netif_api.c \
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk

engine.mk

@@ -71,8 +71,17 @@ GLOBAL_CPPFLAGS := --std=c++14 -fno-exceptions -fno-rtti -fno-threadsafe-statics
 GLOBAL_ASMFLAGS := -DASSEMBLY
 GLOBAL_LDFLAGS :=
 
-# flags that are sometimes nice to enable to catch problems but too strict to have on all the time
-#GLOBAL_COMPILEFLAGS += -Wmissing-declarations
+# flags that are sometimes nice to enable to catch problems but too strict to have on all the time.
+# add to global flags from time to time to find things, otherwise only available with a module
+# option (see make/module.mk re: MODULE_OPTIONS).
+EXTRA_MODULE_COMPILEFLAGS := -Wmissing-declarations
+EXTRA_MODULE_CFLAGS := -Wmissing-prototypes
+EXTRA_MODULE_CPPFLAGS :=
+EXTRA_MODULE_ASMFLAGS :=
+
+#GLOBAL_COMPILEFLAGS += -Wpacked
+#GLOBAL_COMPILEFLAGS += -Wpadded
+#GLOBAL_COMPILEFLAGS += -Winline
 
 # if WERROR is set, add to the compile args
 ifeq (true,$(call TOBOOL,$(WERROR)))

kernel/novm/rules.mk

@@ -5,4 +5,6 @@ MODULE := $(LOCAL_DIR)
 MODULE_SRCS += \
 	$(LOCAL_DIR)/novm.c
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk

kernel/rules.mk

@@ -24,4 +24,6 @@ else
 MODULE_DEPS += kernel/novm
 endif
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk

kernel/vm/rules.mk

@@ -8,4 +8,6 @@ MODULE_SRCS += \
 	$(LOCAL_DIR)/vm.c \
 	$(LOCAL_DIR)/vmm.c \
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk

lib/libc/rules.mk

@@ -26,6 +26,8 @@ MODULE_FLOAT_SRCS += \
 
 MODULE_COMPILEFLAGS += -fno-builtin
 
+MODULE_OPTIONS := extra_warnings
+
 include $(LOCAL_DIR)/string/rules.mk
 
 include make/module.mk

make/module.mk

@@ -20,6 +20,7 @@
 
 # MODULE_OPTIONS : space delimited list of options
 # currently defined options:
+#   extra_warnings - add additional warnings to the front of the module deps
 #   float - module uses floating point instructions/code
 
 # the minimum module rules.mk file is as follows:
@@ -55,13 +56,30 @@ GLOBAL_INCLUDES += $(MODULE_SRCDIR)/include
 MODULES += $(MODULE_DEPS)
 
 # parse options
-ifeq ($(filter float,$(MODULE_OPTIONS)),float)
+MODULE_OPTIONS_COPY := $(sort $(MODULE_OPTIONS))
+ifneq (,$(findstring float,$(MODULE_OPTIONS)))
 # floating point option just forces all files in the module to be
 # compiled with floating point compiler flags.
-$(info MODULE $(MODULE) has float option)
+#$(info MODULE $(MODULE) has float option)
 MODULE_FLOAT_SRCS := $(sort $(MODULE_FLOAT_SRCS) $(MODULE_SRCS))
 MODULE_SRCS :=
+MODULE_OPTIONS_COPY := $(filter-out float,$(MODULE_OPTIONS_COPY))
 endif
+ifneq (,$(findstring extra_warnings,$(MODULE_OPTIONS)))
+# add some extra warnings to the various module compiler switches.
+# add these extra switches first so it's possible for the rules.mk file
+# that invoked us to override with a -Wno-...
+MODULE_COMPILEFLAGS := $(EXTRA_MODULE_COMPILEFLAGS) $(MODULE_COMPILEFLAGS)
+MODULE_CFLAGS := $(EXTRA_MODULE_CFLAGS) $(MODULE_CFLAGS)
+MODULE_CPPFLAGS := $(EXTRA_MODULE_CPPFLAGS) $(MODULE_CPPFLAGS)
+MODULE_ASMFLAGS := $(EXTRA_MODULE_ASMFLAGS) $(MODULE_ASMFLAGS)
+MODULE_OPTIONS_COPY := $(filter-out extra_warnings,$(MODULE_OPTIONS_COPY))
+endif
+
+ifneq ($(MODULE_OPTIONS_COPY),)
+$(error MODULE $(MODULE) has unrecognized option(s) $(MODULE_OPTIONS_COPY))
+endif
+
 
 #$(info module $(MODULE))
 #$(info MODULE_COMPILEFLAGS = $(MODULE_COMPILEFLAGS))

platform/rules.mk

@@ -8,6 +8,8 @@ MODULE_SRCS += \
 	$(LOCAL_DIR)/init.c \
 	$(LOCAL_DIR)/power.c
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk
 
 

target/rules.mk

@@ -5,5 +5,7 @@ MODULE := $(LOCAL_DIR)
 MODULE_SRCS += \
 	$(LOCAL_DIR)/init.c
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk
 

top/rules.mk

@@ -14,4 +14,6 @@ MODULE_SRCS := \
 	$(LOCAL_DIR)/init.c \
 	$(LOCAL_DIR)/main.c \
 
+MODULE_OPTIONS := extra_warnings
+
 include make/module.mk