"Kenji Hara" <k.hara.pg@gmail.com> wrote in message
news:mailman.336.1384083327.9546.digitalmars-d@puremagic.com...

>
> This is valid. Because not only strongly pure function will return unique
> object.
>

> For example:
>  immutable(int)[] foo(int[] iarr) pure { ... }
>  int[] marr = foo([1,2,3]);
>  // foo will never return the arr argument (without unsafe cast).
>

This one is incorrect, the value returned from foo could be an immutable
global.  The unique conversion is only capable of changing non-mutable to
immutable, not the other way around.

Maybe you meant something like this?

int[] foo(const(int)[] iarr) pure { ... }