DIP69 - Implement scope for escape proof references

[Dicebot via Digitalmars-d]

On Monday, 8 December 2014 at 16:57:44 UTC, Marc Schütz wrote:
>> Two issues immediately pop up:
>>
>> 1) scope is not transitive thus it doesn't work at all - you 
>> still can store slice of `scope string` as only actual 
>> ptr+length struct is protected.
>>
>> 2) even if it worked, existing definition of scope return 
>> value makes it impossible to use in typical idiomatic 
>> pipeline: `file.byLine.algo1.algo2`. Either algoX is defined 
>> to take `scope ref` and thus can't return it or it is defined 
>> to take `ref` and can't take another `scope ref` as an 
>> argument.
>
> That's why I asked the question in 
> http://forum.dlang.org/post/xdjsmwocbtxovjnathek@forum.dlang.org 
> . It seems Walter wants to allow passing `scope ref` to `ref`, 
> but then automatically treat a normal `ref` of the second 
> function as if it were `scope ref`. But I can't quite see 
> through it :-(

Yes I have seen that thread and have no idea what Walter has 
meant either. His answer only makes sense if return value scope 
is supposed to be inferred from body - what when bodies are 
guaranteed to be there everything can be inferred anyway.