Order of evaluation for named arguments

[Salih Dincer]

On Sunday, 30 March 2025 at 07:00:19 UTC, Walter Bright wrote:
>
> I suggest changing the spec.
>
> P.S. the reason D has a defined behavior for this is because 
> C/C++ leave it implementation-defined.

C++ does not support named arguments natively, so there’s no 
direct comparison. However, function arguments in C++ have 
unspecified evaluation order—it is implementation-defined.

In C#, named arguments are evaluated in the order they appear in 
the function call, not in the order of parameters.

```C
using System;

class Program {
     static void Foo(int a, int b) {
         Console.WriteLine($"a: {a}, b: {b}");
     }

     static void Main() {
         int x = 0;
         Foo(b: ++x, a: ++x);
     }
}
```
> Expected and Actual Output in C#:
> 
> a: 2, b: 1

If D wants consistency with other languages like C# and Python, 
it should enforce left-to-right evaluation at the call site. 
However, modifying the spec would be the "easier" solution, but 
that would make D behave unpredictably compared to other 
languages.

Given that Walter Bright tends to avoid complex changes, he will 
likely suggest updating the spec rather than enforcing 
left-to-right evaluation. But if D wants to be intuitive and 
predictable, aligning with C#'s approach makes the most sense.

SDB at 79