Compiler Warning (level 4) C4214

nonstandard extension used : bit field types other than int

Microsoft C/C++ allows bitfield structure members to be of any integral type.

The following is an example of this error:

struct bitfields
{
   unsigned short j:4;  // warning
};

This extension can prevent your code from being portable to other compilers and will generate an error under the /Za command-line option.