use more warnings from trezor-mcu

Makefile

@@ -1,8 +1,35 @@
-CC     = gcc
+CC        = gcc
-CFLAGS = -Os -Wall -Wextra -Wno-sequence-point -Wundef
+
+OPTFLAGS  = -Os -g
+
+CFLAGS   += $(OPTFLAGS) \
+            -W \
+            -Wall \
+            -Wextra \
+            -Wimplicit-function-declaration \
+            -Wredundant-decls \
+            -Wstrict-prototypes \
+            -Wundef \
+            -Wshadow \
+            -Wpointer-arith \
+            -Wformat \
+            -Wreturn-type \
+            -Wsign-compare \
+            -Wmultichar \
+            -Wformat-nonliteral \
+            -Winit-self \
+            -Wuninitialized \
+            -Wformat-security \
+            -Werror
+
+# disable sequence point warning because of AES code
+CFLAGS += -Wno-sequence-point
+
+# disable certain optimizations and features when small footprint is required
 ifdef SMALL
 CFLAGS += -DUSE_PRECOMPUTED_IV=0 -DUSE_PRECOMPUTED_CP=0 -DUSE_PUBKEY_VALIDATE=0
 endif
+
 OBJS   = bignum.o ecdsa.o secp256k1.o rand.o hmac.o bip32.o bip39.o pbkdf2.o base58.o
 OBJS  += ripemd160.o
 OBJS  += sha2.o

test-openssl.c

@@ -30,7 +30,7 @@
 #include "ecdsa.h"
 #include "rand.h"
 
-int main()
+int main(void)
 {
 	uint8_t sig[64], pub_key33[33], pub_key65[65], priv_key[32], msg[256], buffer[1000], hash[32], *p;
 	uint32_t i, j, msg_len;

tests.c

@@ -1090,7 +1090,7 @@ Suite *test_suite(void)
 }
 
 // run suite
-int main()
+int main(void)
 {
 	int number_failed;
 	Suite *s = test_suite();