Is this a bug in std.typecons.Tuple.slice?

[tsbockman via Digitalmars-d-learn]

On Sunday, 7 February 2016 at 02:11:15 UTC, Marco Leise wrote:
> I understand that. We just have a different perspective on the 
> problem. Your priorities:
>
> - don't break what's not broken
> - .slice! lends on opSlice and should return by ref
>
> My priorities:
>
> - type of .slice! should be as if constructing with same
>   values from scratch
> - keep code additions in Phobos to a minimum
>
> Why do I insist on the return type? Because surprisingly simple 
> code breaks if it doesn't match. Not everything can be covered 
> by runtime conversions in D.

I think the key question is, do users care about being able to 
modify the original `Tuple` instance indirectly through `slice`?

If yes, then the only workable solutions I can see are:

1) My current proposal (insert a hidden padding member at the 
beginning of the slice `Tuple`)

2) Don't return a `Tuple` at all - return a dedicated 
`TupleSlice` type that is implicitly convertible to `Tuple`. This 
approach would work with the example you came up with, but 
implementing `TupleSlice` well could be very complex, I think.

If not, then I have no fundamental objection to Saurabh Das' 
approach, although I think the PR needs work.

We should start a new thread in "General" to ask whether people 
care about the `ref`-ness of `Tuple` slices is really the 
deciding factor.