That is very odd, more so that it only happens on MSVC, as it doesn't look like the type of problem that would only happen on one compiler/platform.

I'll investigate it.

I haven't been able to reproduce the problem you reported. I use MSVC2015, though I sincerely doubt it would be different with MSVC2010.

I did the test like this:

r = ExecuteString(engine,
     "const int64 a1 = 4287660160; assert(formatInt(a1, '0h', 8) == 'ff908080'); \n"
     "int64 a2 = 4287660160; assert(formatInt(a2, '0h', 8) == 'ff908080'); \n"
     "const int64 a3 = 4287660160.0f; assert(formatInt(a3, '0h', 8) == 'ff908000'); \n" // due to float precision the result is different, but correct
     "int64 a4 = 4287660160.0f; assert(formatInt(a4, '0h', 8) == 'ff908000'); \n" // due to float precision the result is different, but correct
     "const int64 a5 = 4287660160.0; assert(formatInt(a5, '0h', 8) == 'ff908080'); \n"
     "int64 a6 = 4287660160.0; assert(formatInt(a6, '0h', 8) == 'ff908080'); \n"
    );
if (r != asEXECUTION_FINISHED) 
   TEST_FAILED;	

Note, 427660160.0f is not equal to 4287660160. The float type has only precision enough for 6 digits, so the 427660160.0f actually becomes 4287660032. (This of course depends on the way the float is represented in memory, but IEEE 754 standard is the most common on the CPUs).