Implicit conversions of head-const to tail-const ranges

[Paul Backus]

On Wednesday, 24 March 2021 at 10:25:41 UTC, Per Nordlöw wrote:
> On Tuesday, 23 March 2021 at 20:44:03 UTC, Paul Backus wrote:
>> You can't do a naive `const(Range!T)` -> `Range!(const(T))` 
>> conversion, because there may be `static if` statements (or 
>> other reflection) inside the `Range` template that cause 
>> incompatible structs to be generated for `T` and `const(T)`.
>
> I don't quite follow what this refers to. Can you give a code 
> reference or sample?

struct Example(T)
{
     static if (isMutable!T)
         T t;
     else
         T* ptr;
}

It would be incorrect to allow `const(Example!int)` to implicitly 
convert to `Example!(const(int))`.