DIP69 - Implement scope for escape proof references

[Sebastiaan Koppe via Digitalmars-d]

On Saturday, 6 December 2014 at 12:38:24 UTC, Ola Fosheim Grøstad 
wrote:
> On Saturday, 6 December 2014 at 04:31:48 UTC, Sebastiaan Koppe 
> wrote:
>> What about also adding the inverse of scope? Then scope can be 
>> inferred. As in:
>>
>> ```
>> void foo(int* p);
>> void free(P)(consume P* p);
>
>
> Yes, this is much better. When I suggested it, it was rejected 
> because D is too concerned about breaking existing code. Which 
> is a not-very-good argument since this breaking change is 
> concervative (you only have to add "consume" or something 
> similar when the compiler complains).
Hmm, I see.

Whenever I suggest to break something at my job - which, 
admittedly is much easier there than in a language - I get faced 
with some serious reluctance. My argument is always the same: It 
is going to make you happy, eventually.

How would it break anything though? Wouldn't functions eligible 
for `consume` already have the programmer ensuring the arguments 
haven't escaped before/after the function call? In case they did 
a bad job - sure it would break - but it would have been a bug.
>
> The obvious solution is to do as you suggest and in addition do 
> all @safe analysis on a high level IR layer using dataflow 
> through and through.
I am a big proponent of dataflow analyses, but I got the feeling 
people think is it pretty hard. Couldn't find much detailed 
papers on it, so I don't know.