inout delegate

[Steven Schveighoffer via Digitalmars-d]

On 10/2/16 2:55 AM, Manu via Digitalmars-d wrote:
> Can someone explain this to me?
>
> class Test
> {
>   inout(int) f() inout { return 10; }
>
>   void t()
>   {
>     f(); // calls fine with mutable 'this'
>     auto d = &this.f; // error : inout method Test.f is not callable
> using a mutable this
>     d();
>   }
> }
>
> That error message seems very unhelpful, and it's not true. Of course
> an inout method is callable with a mutable 'this'...
>
> I suspect that the problem is the type for the delegate; "inout(int)
> delegate()" doesn't leave anything for the type system to resolve the
> inout with.
> I guess the expectation is that this delegate has it's inout-ness
> resolved when you capture the delegate:
>   is(typeof(&this.f) == int delegate())
> Or if 'this' were const:
>   is(typeof(&this.f) == const(int) delegate())

I think this is a bug, and I 100% agree with you. The type of the 
delegate should be based on the mutability of 'this'.

The error message probably stems from logic that was meant to prevent 
invalid const/immutable delegate capture, but inout wasn't thought of.

-Steve