How to break const

[Timon Gehr]

On 06/20/2012 09:16 AM, deadalnix wrote:
> Le 19/06/2012 17:49, Timon Gehr a écrit :
>>
>> The question is, what the meaning of 'const' references should be:
>>
>> 1. data cannot be changed transitively through the reference
>>
>> 2. the reference can reference both 'const' and 'immutable' data and
>> 'immutable' data can transitively not be changed through the
>> reference.
>>
>>
>> 1. requires transitive const for delegate context pointers, 2. does not.
>>
>
> No, 2. require 1., even if the initialization is broken.
>
> class Foo {
>      void delegate() dg;
>
>      this(immutable void delegate() dg) immutable {
>          thid.dg = dg;
>      }
> }
>
> Now, as delegate doesn't carry the constness of its context, an
> immutable instance of Foo can refers to something that isn't immutable.

Clarification: 'const' means 'const'. No other qualifiers.

There is no 'const' in that example code. 'immutable' obviously needs to 
be transitive regardless of the particular interpretation of 'const'.