assume, assert, enforce, @safe

[Jonathan M Davis via Digitalmars-d]

On Thursday, 31 July 2014 at 20:49:18 UTC, Timon Gehr wrote:
> On 07/31/2014 09:37 PM, Jonathan M Davis wrote:
>> disable contracts, turn assert(0) into a halt
>> instruction, and disable bounds checking in @system and 
>> @trusted code.
>> So, if you want to keep the assertions and contracts and 
>> whatnot in,
>
> Unfortunately, if used pervasively, assertions and contracts 
> and whatnot may actually hog the speed of a program in a way 
> that breaks the deal.
>
> Disabling assertions (and whatnot), assuming assertions to be 
> true (and disabling whatnot) and leaving all assertions and 
> whatnot in are different trade-offs, of which assuming all 
> assertions to be true is the most dangerous one. Why hide this 
> behaviour in '-release'?

I'm afraid that I don't see the problem. If you want assertions 
left in in your release/production builds, then don't use 
-release. If you want them removed, then use -release. Are you 
objecting to the fact that the compiler can do further 
optimizations based on the fact that the assertions are presumed 
to be true if they're removed? I really don't see any problem 
with that. You're screwed regardless if the assertions would have 
failed. By their very nature, if an assertion would have failed, 
your program is an invalid state, so if you don't want to risk 
having code run that would have failed an assertion, then just 
don't compile with -release. And if you are willing to assume 
that the assertions won't fail and have them disabled in your 
release build, then you might as well gain any extra 
optimizations that can be made from assuming that the assertion 
is true. You're already making that assumption anyway and 
potentially letting your program enter an invalid state.

>> just don't use -release and use -boundscheck=safe to get the 
>> bounds
>> checking changes that -release does.
>>
>> - Jonathan M Davis
>
> This leaves assertions and contracts in though.

Which is precisely what Ary was looking to do. He wanted to use 
-release but not have assertions removed, and using 
-boundscheck=safe instead of -release does that (though further 
posts by him seem to indicate that he doesn't want the @system 
bounds checking removed either, which means that he should just 
skip -release and all related flags entirely).

- Jonathan M Davis