First Draft: Implicit Conversion of Template Instantiations

[Timon Gehr]

On 3/18/24 02:28, Timon Gehr wrote:
> On 3/16/24 16:50, Walter Bright wrote:
>> https://github.com/WalterBright/documents/blob/9dba63a4c2887bdb2b988c354ebb0d6bb44c4968/templatecast.md
>>
>> DConf: https://dconf.org/2024/online/index.html#walterb
> 
> Issue: Subtyping under indirections remains magic.
> 
> ...

Another example of a similar kind of issue:

```d
struct S(T){
     T x;
}
void main(){
     S!int[] a = [S!int(1),S!int(2),S!int(3)];
     S!(const(int))[] b = a; // error
}
```

I think this one may be just an oversight in the prototype implementation.