Is there a way to indicate that a method will never return?

Assuming we have the following (very basic code)

public int Foo()
{
    while (true)
    {

    }
    // No "return 0" etc. needed here.
}

the compiler can understand that this method will never return, and therefore displays a warning and also it does not require the method to have a return statement.

If we have the case

public void WontExit()
{
    while (true)
    {

    }
}

public int Foo()
{
    this.WontExit();
    return default(int); // This is needed here.
}

a return statement is needed, because the compiler can seemingly not foresee that it will never be reached.

• Why does the compiler allow for omitting the return statement in the first case? Why doesn't it also require a return statement? (What are the internals here?)
• Is there any way to indicate the compiler (or reachability analysis) that in the second case, the return code path will also never be reached?