scope(exit) without exception handling?

[Timon Gehr]

On 05/16/2012 11:17 PM, Jonathan M Davis wrote:
> On Wednesday, May 16, 2012 23:05:07 Timon Gehr wrote:
>> On 05/16/2012 08:59 AM, Walter Bright wrote:
>>> On 5/15/2012 8:54 PM, Mehrdad wrote:
>>>> Is there any way for me to use scope(exit) (or perhaps a destructor,
>>>> like RAII)
>>>> to mean, "Execute this block of code for me when the block is exited,
>>>> will ya?",
>>>> *without* introducing dependencies on exception handling?
>>>
>>> Make sure the guarded code is 'nothrow', and it should work.
>>
>> Doesn't that imply that 'in'-contract checking might leave the program
>> in an invalid state?
>
> Well, according to Walter, there is no guarantee that _any_ cleanup will be
> done when an Error is thrown (including AssertError), so yes, there's the
> possibility that an in contract could leave the program in an invalid state if
> it fails.

The issue is not relevant for failing contracts. 'in' contracts might 
pass even if some assertion errors were thrown during their evaluation.

> However, with the current implementation, as I understand it, it
> _is_ guaranteed that cleanup will be done for Errors. But if the try and
> finally blocks are indeed removed, then that would seem to indicate that
> there's a case where there _won't_ be any cleaup for Errors in spite of the
> fact that Don (and and Dan?) tried to make sure that it _was_ guaranteed. But
> if the cleanup doesn't happen, it would still be within what Walter considers
> to be guarantee for Errors as far as the spec goes.
>
> - Jonathan M Davis

Exactly, this is somewhat bothersome.