This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 119a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2026-01-10
Subclause 6.8.2 [intro.object] bullet 9.3 specifies that any objects resulting from define_static_array are potentially overlapping (i.e. may have a non-unique address), include std::array<T, 0>.
Subclause 13.2 [temp.param] paragraph 13 (after issue 3111) specifies that template parameter objects are distinct.
Subclause 21.4.3 [meta.define.static] specifies that reflect_static_array results in a template parameter object.
These requirements appear to be contradictory. However, it was observed that "distinct object" is referring to the abstract machine notion of an object; objects can be distinct (resulting in different std::meta::info values when reflected upon) even if they have the same address.
It was further observed that only reflection facilities produce array values as template parameter objects; template arguments do not. It is design-intended that such array values can share storage with string literals and backing arrays of initializer lists.
Proposed resolution (approved by CWG 2026-01-09):
Change in 6.8.2 [intro.object] bullet 9.3 as follows:
An object is a potentially non-unique object if it is
- a string literal object (5.13.5 [lex.string]),
- the backing array of an initializer list (9.5.4 [dcl.init.ref]), or
the object introduced by a call to std::meta::reflect_constant_array or std::meta::reflect_constant_stringa template parameter object of array type (21.4.3 [meta.define.static]), or- a subobject thereof.
Change in 13.2 [temp.param] paragraph 13 as follows:
[ Note: There can be template parameter objects of array type (21.4.3 [meta.define.static]), but such an object is never denoted by an id-expression that names a constant template parameter. Such an object can have an address that is not unique among all other in-lifetime objects (6.8.2 [intro.object]). -- end note ]