CWG3065 Reachability and completeness of types

[jensmaurer]

CWG3065 proposes some cleanups around block-scope externs.

EWG should review these, and form an opinion.

[je4d]

EWG discussed this in Kona on Friday morning and took the following polls:

CWG3065: EWG Approves of CWG's proposed direction that: Reflection on a block-scope extern declaration is ill-formed (change #3), and that: Properties made available by a block-scope extern declaration are not visible outside the block (change #6).

no objection to unanimous consent.

CWG3065: Block-scope extern declarations observe the merged properties of an entity

SF	F	N	A	SA
4	7	5	0	1

consensus.

CWG3065: Block-scope extern declarations hide the effects of earlier declarations entirely

SF	F	N	A	SA
0	0	2	12	3

not consensus.

CWG3065: EWG wants a reference to ::a to ignore the properties of an immediately preceding extern int a[3]; inside the function

SF	F	N	A	SA
0	0	4	10	3

consensus against.

EWG would like to see a paper recommending the deprecation of block-scope extern declarations in C++29

SF	F	N	A	SA
8	11	0	2	1

consensus.

[erichkeane]

EWG has answered the three questions asked of CWG, so forwarding this to CWG. Additionally, we had a general guidance poll to request a paper in the future.