assert semantic change proposal

[David Bregman via Digitalmars-d]

On Tuesday, 5 August 2014 at 20:50:06 UTC, Jeremy Powers via 
Digitalmars-d wrote:
>>
>>
>>> Well, yes: Undefined behaviour in the sense
>>>
>> "And there will be no injection of undefined behaviour
>>                                    ^~~~~~~~~~~~~~~~~~~
>>                                    conventional sense
>>
>>
>>  - the undefined behaviour is already there if the asserted 
>> constraints
>>        ^~~~~~~~~~~~~~~~~~~
>>        altered sense
>>
>> are not valid."
>>
>
>
> I still don't quite see your point.  Perhaps I should have 
> said:  In the
> case where an asserted constraint is not met, the program is 
> invalid.
>  Being invalid it has undefined behaviour if it continues.
>
>>From another:
>
>> There is a difference between invalid and undefined: A program 
>> is invalid
>> ("buggy"), if it doesn't do what it's programmer intended, 
>> while
>> "undefined" is a matter of the language specification. The 
>> (wrong)
>> behaviour of an invalid program need not be undefined, and 
>> often isn't in
>> practice.
>>
>
> I disagree with this characterization.  Something can be buggy, 
> not doing
> what the programmer intended, while also a perfectly valid 
> program.  You
> can make wrong logic that is valid/reasonable in the context of 
> the program.
>
> Invalid in this case means the programmer has explicitly stated 
> certain
> constraints must hold, and such constraints do not hold.  So if 
> you
> continue with the program in the face of invalid constraints, 
> you have no
> guarantee what will happen - this is what I mean by 'undefined'.

You're using a nonstandard definition of undefined behavior. 
Undefined behavior has a precise meaning, that's why Timon linked 
the wiki article for you.

The regular definition of assert does not involve any undefined 
behavior, only the newly proposed one.