Fixing implicit copies of InputRanges [was: Re: Mir Random [WIP]]

[Andrei Alexandrescu via Digitalmars-d]

On 11/26/2016 01:55 AM, Martin Nowak wrote:
> On Saturday, 26 November 2016 at 06:46:19 UTC, Martin Nowak wrote:
>> Maybe non-copyability needs to become a requirement for InputRanges.
>
> Could have an optional .clone if copying is supported.
> What would be an InputRange where copying is correct?

Input ranges with disabled this(this) would be a major breaking change 
that we probably cannot bear (and shouldn't because the gain is small). 
I think an input range would be at best "pure reference" in the sense 
that popFront advances all copies to the same position. -- Andrei