Named Arguments Status Update - Overloading by name

[Dennis]

On Tuesday, 9 January 2024 at 00:08:06 UTC, Walter Bright wrote:
> ```
> string f(T)(T x) { return "x"; }
> string f(T)(T y) { return "y"; }
> ```
>
> should give an error. The order should not matter.
> (...)
> the function/template signature is not affected by the 
> parameter names, therefore two functions/templates definitions 
> with the same signature are an error.

Depending on what you consider the 'signature', that's either not 
sufficient reason to raise an ambiguity error, or not sufficient 
prevention of conflicts. Consider that the same 'signature' can 
be distinguished by constraints:

```D
string f(T)(T x) if (T.sizeof <= 2) { return "x"; }
string f(T)(T y) if (T.sizeof >= 2) { return "y"; }
```

This is allowed and works like this:
```D
pragma(msg, f(byte(0)))  // x
pragma(msg, f(int(0)))   // y
pragma(msg, f(short(0))) // error, `(short)` matches both 
templates
```

But with named arguments:

```D
pragma(msg, f(x: short(0))) // x, `(short)` matches x
pragma(msg, f(y: short(0))) // y, `(short)` matches y
```

Detecting potential overlap upfront is both a breaking change and 
mathematically impossible.