Direction for @safe/-dip1000

[Florian Weimer]

I've tried to figure out where this is heading. Is the eventual 
goal (irrespective of mechanism) that sticking `@safe` onto the 
`main` function will ensure memory safety for the whole program?

What about data races in updates of multi-word variables? For 
example, the Go language makes avoiding them the responsibility 
of the programmer, but Java ensures that data races cannot 
subvert the type system (although with the demise of the security 
manager, some people argue that this should be changed).