-# flag checks are grouped together to speed the checks up a bit..
-CFLAGS += $(call cc-option,-Wall -Wshadow,)
-CFLAGS += $(call cc-option,-Wundef -Wold-style-definition -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations,)
-CFLAGS += $(call cc-option,-Os -fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
-CFLAGS += $(call cc-option,-static-libgcc -funsigned-char,)
-CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-loops=1,)
+CFLAGS += $(call cc-option,-Wall,)
+CFLAGS += $(call cc-option,-Wshadow,)
+CFLAGS += $(call cc-option,-Wwrite-strings,)
+CFLAGS += $(call cc-option,-Wundef,)
+CFLAGS += $(call cc-option,-Wstrict-prototypes,)
+CFLAGS += $(call cc-option,-Wunused -Wunused-parameter,)
+CFLAGS += $(call cc-option,-Wunused-function -Wunused-value,)
+CFLAGS += $(call cc-option,-Wmissing-prototypes -Wmissing-declarations,)
+# warn about C99 declaration after statement
+CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
+# If you want to add more -Wsomething above, make sure that it is
+# still possible to build bbox without warnings.
+
+ifeq ($(CONFIG_WERROR),y)
+CFLAGS += $(call cc-option,-Werror,)
+## TODO:
+## gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC) is a PITA:
+## const char *ptr; ... off_t v = *(off_t*)ptr; -> BOOM
+## and no easy way to convince it to shut the hell up.
+## We have a lot of such things all over the place.
+## Classic *(off_t*)(void*)ptr does not work,
+## and I am unwilling to do crazy gcc specific ({ void *ppp = ...; })
+## stuff in macros. This would obfuscate the code too much.
+## Maybe try __attribute__((__may_alias__))?
+#CFLAGS += $(call cc-ifversion, -eq, 0404, -fno-strict-aliasing)
+endif
+# gcc 3.x emits bogus "old style proto" warning on find.c:alloc_action()
+CFLAGS += $(call cc-ifversion, -ge, 0400, -Wold-style-definition)
+
+CFLAGS += $(call cc-option,-fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
+# -fno-guess-branch-probability: prohibit pseudo-random guessing
+# of branch probabilities (hopefully makes bloatcheck more stable):
+CFLAGS += $(call cc-option,-fno-guess-branch-probability,)
+CFLAGS += $(call cc-option,-funsigned-char -static-libgcc,)
+CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-labels=1 -falign-loops=1,)