This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

2552. Constant evaluation of non-defining variable declarations

[Accepted as a DR at the June, 2023 meeting.]

Paper P2242 (Non-literal variables (and labels and gotos) in constexpr functions) added 7.7 [expr.const] bullet 5.2:

• a control flow that passes through a declaration of a variable with static (6.7.6.2 [basic.stc.static]) or thread (6.7.6.3 [basic.stc.thread]) storage duration;

It seems that block-scope extern (i.e. non-defining) declarations are covered by the above bullet, but only definitions should be in view here.

Proposed resolution (approved by CWG 2023-06-15):

1. Change in 7.7 [expr.const] bullet 5.2 as follows:

   • a control flow that passes through a declaration of a block variable (6.4.3 [basic.scope.block]) with static (6.7.6.2 [basic.stc.static]) or thread (6.7.6.3 [basic.stc.thread]) storage duration;