John Regehr on "Use of Assertions"

[Meta]

On Wednesday, 5 September 2018 at 10:30:46 UTC, Ola Fosheim 
Grøstad wrote:
> On Monday, 3 September 2018 at 16:53:35 UTC, Meta wrote:
>> This battle has been fought over and over, with no movement on 
>> either side, so I'll just comment that nobody what John Nails 
>> or anyone else says, my personal opinion is that you're 100% 
>> wrong on that point :-)
>
> Well, John Regehr seems to argue that you shouldn't use asserts 
> for optimization even if they are turned on as the runtime 
> might override a failed assert.
>
> «As developers, we might want to count on a certain kind of 
> behavior when an assertion fails. For example, Linux’s BUG_ON() 
> is defined to trigger a kernel panic. If we weaken Linux’s 
> behavior, for example by logging an error message and 
> continuing to execute, we could easily end up adding 
> exploitable vulnerabilities.»
>
> So…

I don't disagree. I think the only sane way to use asserts as an 
optimization guide is when the program will abort if the 
condition does not hold. That, to me, makes perfect sense, since 
you're basically telling the compiler "This condition must be 
true past this assertion point, because otherwise program 
execution will not continue past this point". You're ensuring 
that the condition specified in the assert is true by definition. 
Not having that hard guarantee but still using asserts as an 
optimization guide is absolutely insane, IMO.