enforcing alias this on derived types

[John Colvin]

On Monday, 8 July 2013 at 09:52:44 UTC, John Colvin wrote:
> Most other solutions I tried failed because the compiler 
> evaluates the check (e.g. out contracts) in the interface, 
> which makes the check either semantically wrong, or statically 
> false/failed.

Woops, should be "the contract exists in the scope of the 
interface", not "the compiler evaluates the check (e.g. out 
contracts) in the interface"