DMD 2.092 and DIP 25

[Seb]

On Saturday, 30 May 2020 at 07:00:07 UTC, Mike Parker wrote:
> The following declarations now give a deprecation warning:
>
> ```d
> struct ErrorInfo {
> private:
>     char[32] _error;
>     char[96] _message;
>
> public @nogc nothrow @property:
>     /**
>         Returns the string "Missing Symbol" to indicate a 
> symbol load failure, and
>         the name of a library to indicate a library load 
> failure.
>     */
>     const(char)* error() const { return _error.ptr; }
>
>     /**
>         Returns a symbol name for symbol load failures, and a 
> system-specific error
>         message for library load failures.
>     */
>     const(char)* message() const { return _message.ptr; }
> }
> ```
>
> I find it rather annoying, as I'm returning `const(char)*` and 
> not `char*`, but it is what it is. My question is, if I add 
> `return` to the function declarations, will this compile all 
> the way back to DMD 2.067 *without* `-preview=dip25`? It works 
> on 2.091.0. I always assumed a preview feature's syntax wasn't 
> supported without the preview switch.

Return is actually pretty old, so it will compile:

https://run.dlang.io/is/DgbYU9

Typically -preview flags are just looked at during the semantic 
phases.

Another solution could be to turn the functions into templates 
and let the compiler do its attribute inference.