The type inference everywhere

[data pulverizer]

On Sunday, 31 October 2021 at 17:35:35 UTC, Ali Çehreli wrote:
> On 10/31/21 7:07 AM, Salih Dincer wrote:
> > ```d
> > auto foo(int value, auto s = Section(2, 60)) {
> >     int max;      /*   ^------- ?
> >     ...            */
> >     return Section (0, max)
> >   }
> > ```
> > Is possible something like above pointed. OK, I know it isn't
> because I
> > tried! Well, wouldn't it be nice if it did?
>
> Makes sense because e.g. the following works:
>
> struct S {
>   auto i = 42;
> }
>
> I bet the problem with your proposal is "auto" in that position 
> is a part of the two-word "auto ref" parameters. I don't know 
> how hard or impossible it would be to allow just "auto" there.
>
> In any case, although it would be nice for completeness, the 
> use case is so rare that I wouldn't mind repeating the type 
> twice in that usage. But I agree with you...
>
> Ali

This is a teachable moment for me, so I'll ask the question. Why 
isn't something like this the answer?

```
import std.stdio: writeln;


struct Section
{
   int x;
   int y;
}


auto foo(T)(int value, auto ref T s = Section(2, 60))
{
   //...
   return Section(0, 60);
}

void main()
{
   foo(5).writeln;
}

```