Is @safe still a work-in-progress?

[Walter Bright]

On 8/21/2018 2:17 PM, Atila Neves wrote:
> Well, no. The syntax isn't the same for member functions. The examples from the 
> actual DIP don't compile. There it says:
> 
> -------
> scope can be applied to function return values (even though it is not a type 
> qualifier). It must be applied to the left of the declaration, in the same way 
> ref is:
> 
> scope int* foo();     // applies to return value
> --------
> 
> Except:
> 
> -------
> struct MyStruct { scope int* foo() scope; }
> 
> foo.d(1): Error: redundant attribute scope
> -------
> Meaning the first `scope` actually applies to `this`. Writing this out as a 
> non-member function won't help me declare member functions!
> 
> I still don't know how to return a ref/pointer that's scoped. And I thought I'd 
> written code that did that. Maybe I did. I'm very confused.

Here's how you make it work:

---
@safe:

struct MyStruct {
     ref int foo() return;
     int* bar() return;
}

ref int sun() {
     MyStruct s;
     return s.foo(); // returning s.foo() escapes a reference to local variable s
}

int* moon() {
     MyStruct s;
     return s.bar(); // returning s.bar() escapes a reference to local variable s
}
---
In effect, the 'return' on 'foo()' says:

     The return value of foo() contains the address of 'this', and if the return 
escapes the scope of what 'this' is a ref to, then it's an error.