Compiler Warning (levels 2 and 4) C4200

nonstandard extension used : zero-sized array in struct/union

A structure or union contained an array with zero size.

This is a level-4 warning when Microsoft extensions are enabled (/Ze) and a level-2 warning when Microsoft extensions are disabled (/Za).

The following is an example of this error:

struct S { int a[0]; };  // warning