For example, when doing:

      int64 int64_value = 1;
      int64_value.to_string();

This is what gcc outputs on AMD64 (with -Wall) :

warning: format ‘%lli’ expects type ‘long long int’, but argument 2 has type ‘gint64’


It would be good if vala could be changed to use the correct format strings for the target architecture instead of hardcoding the 32-bit x86 ones. This also breaks stuff like:
   
    print("%li", int64_value);

which results in Vala giving:
    error: Argument 2: Cannot convert from `int64' to `long'
        print("%li", int64_value);     
                     ^^^^^^^^^^^
although "%li" is the correct format for int64 on amd64 architecture.