Shortcut evaluation for hierarchy of in contracts

[Daniel Murphy]

I don't disagree that tightening contracts for derived functions is a bad 
idea.
I didn't mean the contract should fail, I meant that the program should fail 
with an error that the contract is invalid.

"Timon Gehr" <timon.gehr at gmx.ch> wrote in message 
news:iuklvm$pks$1 at digitalmars.com...
> Now, sure, if the parents contract is
>
> in{assert(a<=10);}
>
> and the child's contract is
>
> in{assert(a<=5);}
>
> then that is almost certainly an error because the child's contract fails 
> to
> loosen any restrictions.
> But to catch this in the general case, the compiler would have to 
> incorporate a
> theorem prover.
> (And validity of D code would start to depend on the quality of the 
> theorem prover
> of the respective D compiler ;))

This can be caught at runtime without a theorem prover. (And I think it 
should be)