This is exactly what was clarified by DR 2643:
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2643

On Mon, Feb 17, 2025 at 4:17 PM Andrey Semashev via Std-Discussion <
std-discussion_at_[hidden]> wrote:

> On 2/18/25 00:16, Andrey Semashev wrote:
> > On 2/17/25 23:09, Vladimir Grigoriev via Std-Discussion wrote:
> >> In p. 5 of the section 6.2 Declarations and definitions of the C++23
> >> Standard there is written
> >>
> >> 5 In the definition of an object, the type of that object shall not be
> >> an incomplete type (6.8), an abstract class type (11.7.4), or a
> >> (possibly multi-dimensional) array thereof
> >>
> >> Also in p.5 of the sub-section 6.8.1 General of the section 6.8 Types
> >> there is written
> >>
> >> ...The type of a pointer to array of unknown bound, or of a type defined
> >> by a typedef declaration to be an array of unknown bound, cannot be
> >> completed.
> >>
> >> And further there is followed an example (Example 3)
> >>
> >> class X; // X is an incomplete type
> >> extern X* xp; // xp is a pointer to an incomplete type
> >> extern int arr[]; // the type of arr is incomplete
> >> typedef int UNKA[]; // UNKA is an incomplete type
> >> UNKA* arrp; // arrp is a pointer to an incomplete type
> >> UNKA** arrpp;
> >>
> >> But according to the first provided quote this object definition
> >>
> >> UNKA* arrp; // arrp is a pointer to an incomplete type
> >>
> >> is invalid because such a pointer has an incomplete type.
> >>
> >> So it looks like the example does not make sense or do I have missed
> >> something?
> >
> > I'm not sure which version of the standard you're reading, but the
> > current wording is different. I'm guessing you're referring to Note 2 in
> > paragraph 6:
>
> I meant Note 3, sorry for the typo.
>
> > http://eel.is/c++draft/basic.types.general#6
> >
> > <quote>
> > The type of a pointer or reference to array of unknown bound permanently
> > points to or refers to an incomplete type.
> > An array of unknown bound named by a typedef declaration permanently
> > refers to an incomplete type.
> > In either case, the array type cannot be completed.
> > </quote>
> >
> > Note the text refers to the *array* type, not the *pointer* type. The
> > pointer type itself is always complete, even if the pointee type is
> > incomplete.
> >
>
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