Struct copy constructor with inout

[Steven Schveighoffer]

On Tuesday, 14 November 2023 at 13:58:17 UTC, Paul Backus wrote:

> It's easier to see if you compare the actual and expected 
> argument lists side-by-side
>
>     Expected: (ref const(S1) s) const
>     Actual:   (    const(S1)  )
>                                 ^^^^^
>                      Mismatched 'this' argument

This would be a much better output. Is this something you made up 
or did you get it from one of the compilers? LDC2, which is what 
I tested with, reported in the format that I mentioned.

It might be something to add to the compiler that mismatches in 
`this` qualifiers should be reported separately, especially since 
the mutable form has no explicit qualifier. But I guess this is 
only an issue for constructors, because normal const functions 
can be called with mutable objects.

That being said, I still consider this a bug, if the inout 
version works, the const version should work as well. I don't see 
the difference.

So an interesting thing, if I change the `int i` to `int *i` in 
`S2`, instead of compiling I get the error:

```
Error: `inout` constructor `testinoutctor.S2.this` creates const 
object, not mutable
```

Which gives a much nicer error message!

-Steve