Move Constructor Syntax

[RazvanN]

On Wednesday, 9 October 2024 at 08:38:52 UTC, Jonathan M Davis 
wrote:
> On Wednesday, October 9, 2024 12:54:21 AM MDT Manu via

This PR: https://github.com/dlang/dmd/pull/16429 implements the 
generation of multiple copy constructors as described by 
Jonathan. It's green and if merged it would alleviate the issues 
for fields with copy constructors. However, for the 
metaprogramming part there really isn't any way to identify 
whether a templated function is a copy constructor without 
instantiating the copy constructor, therefore the compiler cannot 
know whether such a struct has a copy constructor or not.

Marking the copy constructor with some particular syntax will 
solve the problem, however, you still need to perform some checks 
upon instantiation to make sure the that instantiated function 
respects the copy constructor signature.

Also, I agree with Jonathan and Paul that any discussion 
regarding the syntax of the move constructor should also include 
the copy constructor since we want to have consistent syntax 
across special functions. We don't want to have:

```d
struct S
{
     this(ref S s);   // copy constructor
     =this(S s);      // move constructor
       ... or ...
      this.move;
}
```

Regards,
RazvanN