assert semantic change proposal

[deadalnix via Digitalmars-d]

On Sunday, 3 August 2014 at 21:57:08 UTC, John Carter wrote:
> On Sunday, 3 August 2014 at 19:47:27 UTC, David Bregman wrote:
>
>> Walter has proposed a change to D's assert function as follows 
>> [1]:
>> "The compiler can make use of assert expressions to improve 
>> optimization, even in -release mode."
>
> Hmm. I really really do like that idea.
>
> I suspect it is one of those ideas of Walter's that has 
> consequences that reach further than anyone foresees..... but 
> that's OK, because it is fundamentally the correct course of 
> action, it's implications foreseen and unforeseen will be 
> correct.
>
> One "near term" implication is to permit deeper static checking 
> of the code.
>

I allow myself to chime in. I don't have much time to follow the 
whole thing, but I have this in my mind for quite a while.

First thing first, the proposed behavior is what I had in mind 
for SDC since pretty much day 1. It already uses hint for the 
optimizer to tell it the branch won't be taken, but I 
definitively want to go further.

By definition, when an assert has been removed in release that 
would have failed in debug, you are in undefined behavior land 
already. So there is no reason not to optimize.