On Sunday, 26 March 2023 at 02:16:15 UTC, Steven Schveighoffer
wrote:
On 3/25/23 9:45 AM, Olivier Prat wrote:
[...]
It's because a Range keeps a copy of the array (Array is a
reference counted type). Since that is labeled `const`, then
editing the Range is forbidden.
Inside SortedRange, it has this, which is causing the issue:
```d
static if (isForwardRange!Range)
@property auto save()
{
// Avoid the constructor
typeof(this) result = this;
result._input = _input.save;
return result;
}
```
Overwriting the input isn't possible here, because it contains
a const member.
Now, this possibly could be fixed with something like:
`return typeof(this)(_input.save);`
But it might just push the error to another place.
The whole thing is kind of ugly.
There is a note inside the Array Range which says it's trying
to work around some old bug that is now marked as "works for
me", so maybe that can be reexamined.
https://github.com/dlang/phobos/blob/17b1a11afd74f9f8a69af93d77d4548a557e1b89/std/container/array.d#L137
-Steve
Thanks to both of you for the answers. It confirms my
investigation and my workaround is to cast the const ranges into
their non const versions, when I encounter these issues. Not very
pretty.
