Template type inference problem

[Salih Dincer]

On Wednesday, 9 October 2024 at 07:02:32 UTC, Manu wrote:
>
> I did nothing. I just did work-around and moved on... but I 
> think this is
> definitely a bug.
> Just another random edge case in a sea of annoying edge cases! 
> :P

If it's not too special, in what application will you use this? 
Please consider me as an amateur who is new to D. Because I am a 
programmer who almost never uses const. I have a hard time 
understanding what the benefits of what you are doing are. Okay, 
this code (single template parameter) looks very appealing to me 
too:

```d
template S(T)
{
   auto S(const(T)[] data, const(T) *sum)
     => Result(data, sum);

   struct Result {
     const(T)[] data;

     const(T) *total;
     auto sum() const
       => *total;

     string id;
     auto toString() const
       => format("%s: %s, %s%s", id, sum,
                       T.stringof, data);
   }
}

import std;
void main()
{
   auto arr = [1, 2, 3, 4, 5];
   auto sum = arr.sum;
   auto s = arr.S(&sum);
        s.id = "Sum of the Elements";
   s.writeln;// Sum of the Elements: 15, int[1, 2, 3, 4, 5]
   ++sum;
   assert(s.sum == 16);
}
```

But even if sum cannot be changed in the returned Result, since 
the data array is already copied, doesn't the fact that it is 
const change anything?

SDB at 79