warning C26101: Failing to use interlocked operation properly for variable <var>.

Windows APIs offer a variety of interlocked operations. Annotation _Interlocked_ specifies that a variable should only be accessed through an interlocked operation. Warning C26101 is issued when an access is not consistent with the _Interlocked_ annotation.

The following example generates warning C26101 because there is a violation of the _Interlocked_ contract.

CRITICAL_SECTION cs;
typedef struct _DATA
{
    _Interlocked_ LONG data;
} DATA;

void Safe(DATA* p)
{
    InterlockedIncrement(&p->data); // OK
}

void Unsafe(DATA* p)
{
    p->data += 1; // Warning C26101
    EnterCriticalSection(&cs);
    LeaveCriticalSection(&cs);
}