ADL

[Tobias M via Digitalmars-d]

On Saturday, 3 September 2016 at 10:33:22 UTC, Walter Bright 
wrote:
> I don't think it is a template issue. It's a name lookup issue. 
> There's LINQ in C#, for example.

I think it is.

The problem is lookup of dependent symbols (see C++ two phase 
lookup). Without real templates, all lookup can be done at 
definition time.
I'm not very familiar with LINQ, but generally C# uses uses 
interfaces as constraints on generics, similar to traits/type 
classes. Lookup is then done once, considering only the 
interfaces, not for each the concrete type.