Why doesn't the compiler at least warn on this == null

Question

Why does the C# compiler not even complain with a warning on this code? :

if (this == null)
{
   // ...
}

Obviously the condition will

Answer 1

This also falls in line with other warnings C# does (or not does for that matter) like:

if(true)
or 
if(1 == 1)

These will also always have the same result no matter what.