Weird DIP1000 issue

[ag0aep6g]

On 08.02.23 00:42, 0xEAB wrote:
> ```d
> void main() @safe {
>      auto mb = MBuf();
>      auto vr = VRes!X();
>      foreach(c; vr.errors)
>          mb.write(c);
> }
> 
> struct X { }
> 
> struct MBuf {
>      const(ubyte)[] _bufferList;
>      void write(Buffers...)(Buffers buffers) {
>          foreach (buffer; buffers) { }
>      }
> }
> 
> struct VErr { string m; }
> 
> struct VRes(Data) {
>      VErr[Data.tupleof.length] _errors;
>      auto errors() {
>          import std.algorithm;
>          return _errors[].filter!(e => e.m);
>      }
> }
> ```
[...]
> While I’m by no means sure that this is a bug, I would really hope for 
> it to be one.

Here's a further reduction of one aspect of your snippet that looks like 
a bug to me:

----
alias VErr = char*;

ref front_r(ref VErr r) { return r; }
ref front_p(VErr* p) { return *p; }
ref front_s(VErr[] s) { return s[0]; }

VErr g;

void main() @safe
{
     VErr[1] _errors;
     g = _errors[0]; /* copy from static array: ok */
     g = front_r(_errors[0]); /* copy from `ref` via `ref`: ok */
     g = front_p(&_errors[0]); /* copy from `ref` via pointer:
                                  fails, should work */
     g = front_s(_errors[]); /* copy from `ref` via slice:
                                fails, should work */
}
----