DIP1000: The return of 'Extend Return Scope Semantics'

[ag0aep6g]

On 13.06.21 04:58, Walter Bright wrote:
> You're right. @system then.

Even an @system function must obey the spec (as long as it's called 
correctly). An @system `move` still wouldn't be allowed to do `target = 
source;` when `source` is `scope`.

A way forward could be leaving `scope` off:

----
void move(ref int* source, ref int* target) @safe
{
     target = source; /* ok now */
}
----

Then one has to use @trusted when calling `move` one `scope` things:

----
void main() @safe
{
     int* source1;
     int* target1;
     move(source1, target1); /* non-scope things just work */

     int local;
     int* source2 = &local;
     () @trusted { /* scope things need @trusted */
         scope int* target2;
         move(source2, target2);
     } ();
}
----

As always, applying @trusted correctly is hard and prone to errors.

If you don't want to change the language, it seems to me that replacing 
`move` with a function that has the parameters swapped is the way to go.