Pure Factory Functions 💔 `inout`

[ag0aep6g]

On Friday, 10 February 2023 at 15:23:04 UTC, Kagamin wrote:
> This doesn't work:
>
> ```d
> struct A
> {
> 	const int[] a;
> }
> pure A a(const int[] b)
> {
> 	return A(b);
> }
> void e()
> {
> 	int[] b;
> 	immutable A c=a(b);
> }
> ```

The spec currently says that the result of a pure factory 
function "has mutable indirections". It should probably say that 
the result "has *only* mutable indirections".

Then it would be clear that `a` is not a pure factory function.