Code cleanup / warnings:

Makefile

@@ -1,15 +1,71 @@
-CFLAGS?=-O2 -g -Wall -W $(shell pkg-config --cflags librtlsdr)
-LDLIBS+=$(shell pkg-config --libs librtlsdr) -lpthread -lm
-CC?=gcc
+# warn about (roughly):
+#  * deviations from standard
+#  * global functions that are not exported
+#  * empty argument list in declarations
+COM_WARNS=      -Wall \
+		-Wextra \
+		-Wpedantic \
+		-Wmissing-declarations \
+		-Wdouble-promotion \
+		-Wnull-dereference \
+		-Wmissing-include-dirs \
+		-Wswitch-default \
+		-Wunused-parameter \
+		-Wuninitialized \
+		-Wshadow \
+		-Wbad-function-cast \
+		-Wcast-qual \
+		-Wcast-align \
+		-Wwrite-strings \
+		-Wstrict-prototypes \
+		-Wredundant-decls \
+		-Wnested-externs \
+		-Wincompatible-pointer-types
+# TODO: These require some work.
+#	-Wconversion \
+#	-Wfloat-equal
+GCC_WARNS=      -Wchkp \
+		-Walloc-zero \
+		-Wduplicated-branches \
+		-Wduplicated-cond \
+		-Wc99-c11-compat \
+		-Wjump-misses-init \
+		-Wlogical-op \
+		-Wrestrict
+CLANG_WARNS=
+
+
+COM_OFLGS=      -fstrict-aliasing \
+		-fstack-protector
+GCC_OFLGS=      -fdelete-null-pointer-checks \
+		-ftree-vrp \
+		-funsafe-loop-optimizations \
+		-flto-odr-type-merging
+CLANG_OFLGS=
+
+
+CC ?= gcc
+CID=$(shell $(CC) -v 2>&1 | grep "version" | cut -d' ' -f1)
+
+CFLAGS ?= -std=gnu99 -O2 -g
+CFLAGS += $(COM_WARNS) $(COM_OFLGS)
+ifeq "$(CID)" "gcc"
+	CFLAGS += $(GCC_WARNS) $(GCC_OFLGS)
+else
+	CFLAGS += $(CLANG_WARNS) $(CLANG_OFLGS)
+endif
+
+CFLAGS += $(shell pkg-config --cflags librtlsdr)
+LDLIBS += $(shell pkg-config --libs librtlsdr) -lpthread -lm
 PROGNAME=dump1090
 
-all: dump1090
+all: $(PROGNAME)
 
 %.o: %.c
 	$(CC) $(CFLAGS) -c $<
 
-dump1090: dump1090.o anet.o
-	$(CC) -g -o dump1090 dump1090.o anet.o $(LDFLAGS) $(LDLIBS)
+$(PROGNAME): dump1090.o anet.o
+	$(CC) -o $@ $^ $(LDFLAGS) $(LDLIBS)
 
 clean:
-	rm -f *.o dump1090
+	@$(RM) -v *.o $(PROGNAME)

anet.c

@@ -188,7 +188,7 @@ int anetTcpNonBlockConnect(char *err, char *addr, int port)
     return anetTcpGenericConnect(err,addr,port,ANET_CONNECT_NONBLOCK);
 }
 
-int anetUnixGenericConnect(char *err, char *path, int flags)
+static int anetUnixGenericConnect(char *err, char *path, int flags)
 {
     int s;
     struct sockaddr_un sa;
@@ -366,7 +366,7 @@ int anetPeerToString(int fd, char *ip, int *port) {
     return 0;
 }
 
-int anetSockName(int fd, char *ip, int *port) {
+static int __attribute__((__unused__)) anetSockName(int fd, char *ip, int *port) {
     struct sockaddr_in sa;
     socklen_t salen = sizeof(sa);