[swift-evolution] Proposal: Initialization should not be required in precondition(false) case.
Amir Michail
a.michail at me.com
Fri Feb 12 11:26:27 CST 2016
> On Feb 12, 2016, at 12:24 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>
> On Fri, Feb 12, 2016 at 9:15 AM, Amir Michail via swift-evolution
> <swift-evolution at swift.org> wrote:
>>
>>> On Feb 12, 2016, at 12:09 PM, Radosław Pietruszewski <radexpl at gmail.com> wrote:
>>>
>>> I think what you mean is `fatalError()`.
>>>
>>> You can’t do what you suggest, because you can’t prove that the expression passed to precondition will evaluate to false. (You theoretically could if the compiler checked for you passing `false`, but that makes no sense. Just go with `fatalError` or `preconditionFailure`.)
>>>
>>
>> What’s wrong with having the compiler explicitly check for “false”?
>
> How far would you require the compiler to go? precondition(2 < 1)?
> precondition(someFunctionThatAlwaysReturnsFalse())?
> precondition(isFermatsLastTheoremTrue())?
>
Just “false”. Why would you write anything else?
> This is important to define precisely since the answer to this
> question changes the set of the programs that the compiler accepts.
>
> Dmitri
>
> --
> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/
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