Inherent code performance advantages of D over C?

[Walter Bright]

On 12/15/2013 3:52 AM, Timon Gehr wrote:
> On 12/15/2013 02:20 AM, Walter Bright wrote:
>> On 12/14/2013 4:36 PM, Timon Gehr wrote:
>>> I cannot cast data from my own storage allocator to immutable because the
>>> behaviour will be undefined.
>>>
>>> http://dlang.org/const3.html
>>>
>>> Is this a documentation bug? What should be the actual rules?
>>
>> It means it's up to you to ensure it is correct.
>
> Undefined behaviour is a term with a precise meaning. That site says that
> casting a reference to immutable while there are still live mutable references
> to memory reachable by that reference leads to undefined behaviour. It is not
> possible to 'ensure it is correct'.

You, as the guy who wrote the code, will (or should) know that there are no 
other live references, hence you are telling the compiler "trust me, I know 
there aren't any".