cast(string) for mutable array

[Nick Treleaven]

On Friday, 31 July 2026 at 13:52:12 UTC, Vindex9 wrote:
> ```d
> string fn() @trusted pure {
>     char[] arr;
>     // some manipulations...
>     return cast(string) arr;
> }
> ```
>
> Where is the line between cases where the `@trusted` tag can be 
> used and cases where the `@system` tag can be used?

`@trusted` must have a memory-safe interface. So if the elements 
of `arr` cannot be accessed as mutable after the cast, it is OK 
to use `@trusted` to cast them to immutable.

`@system` is used for a function which does not have a safe 
interface (e.g. one that accepts a `char*` parameter pointing to 
a C zero-terminated string).