Ignore -O, -W and -g and other flags

main.c

@@ -133,6 +133,21 @@ static void parse_args(int argc, char **argv) {
       continue;
     }
 
+    // These options are ignored for now.
+    if (!strncmp(argv[i], "-O", 2) ||
+        !strncmp(argv[i], "-W", 2) ||
+        !strncmp(argv[i], "-g", 2) ||
+        !strncmp(argv[i], "-std=", 5) ||
+        !strcmp(argv[i], "-ffreestanding") ||
+        !strcmp(argv[i], "-fno-builtin") ||
+        !strcmp(argv[i], "-fno-omit-frame-pointer") ||
+        !strcmp(argv[i], "-fno-stack-protector") ||
+        !strcmp(argv[i], "-fno-strict-aliasing") ||
+        !strcmp(argv[i], "-m64") ||
+        !strcmp(argv[i], "-mno-red-zone") ||
+        !strcmp(argv[i], "-w"))
+      continue;
+
     if (argv[i][0] == '-' && argv[i][1] != '\0')
       error("unknown argument: %s", argv[i]);
 

test/driver.sh

@@ -103,4 +103,10 @@ check -D
 echo foo | $chibicc -Dfoo=bar -Ufoo -E - | grep -q foo
 check -U
 
+# ignored options
+$chibicc -c -O -Wall -g -std=c11 -ffreestanding -fno-builtin \
+         -fno-omit-frame-pointer -fno-stack-protector -fno-strict-aliasing \
+         -m64 -mno-red-zone -w -o /dev/null $tmp/empty.c
+check 'ignored options'
+
 echo OK