foo.cc: In function 'int main()':
foo.cc:19:13: error: name lookup of 'i' changed for ISO 'for' scoping [-fpermissive]
     cout << i;
             ^
foo.cc:19:13: note: if you use '-fpermissive' G++ will accept your code
foo.cc:7:9: warning: unused variable 'a' [-Wunused-variable]
     int a[m+1];
         ^