left shift count >= width of type

[MarÃy Ãkos <akos at maroy dot hu>]

Hi,

When using gcc3 for mingw, I always get a "left shift count >= width of 
type" error when including a specific boost header, 
boost-1_39/boost/date_time/filetime_functions.hpp, at line 101, which 
looks like:

        const uint64_t c1 = 27111902UL;
        const uint64_t c2 = 3577643008UL; // issues warning without 'UL'
        const uint64_t shift = (c1 << 32) + c2;


where uint64_t is an unsigned long long.


interestingly, if I add the above code in a simple function, no warning 
occurs. but, if I add the above code into a function template (as it is 
in the boost include file), I do get the warning. so something like:


    template< typename T >
    void foo() {
        /* shift is difference between 1970-Jan-01 & 1601-Jan-01
        * in 100-nanosecond intervals */
        const uint64_t c1 = 27111902UL;
        const uint64_t c2 = 3577643008UL; // issues warning without 'UL'
        const uint64_t shift = (c1 << 32) + c2;
    }


will result in a warning, without the template, it does not.

what is the reason for this warning, and how can it be averted?


Akos