DIP 1017--Add Bottom Type--Final Review

[Johannes Loher]

Am 17.01.19 um 18:17 schrieb Tim:
> An advantage of the bottom type over an attribute is, that it is part of
> the function type. A library allowing to set a custom error handler
> could specify that the error handler must not return:
> alias ErrorHandler = TBottom function(string msg);

You could also do this with an attribute. Consider the following:

```
void bar() @system
{

}

void main()
{
    alias SafeFun = void function() @safe;
    SafeFun safeFun = &bar; // Error: cannot implicitly convert
expression & bar of type void function() @system to void function() @safe
}
```

You could do the same thing for an `@noreturn` attribute:

```
alias ErrorHandler = void function(string msg) @noreturn;
```

What I am trying to say: `@noreturn` could also be part of the type of
the function.