*This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21
Core Issues List revision 110b.
See http://www.open-std.org/jtc1/sc22/wg21/ for the official
list.*

2023-01-15

#### 2120.
Array as first non-static data member in standard-layout class

**Section: **Clause 11 [class]
**Status: **CD4
**Submitter: **Hubert Tong
**Date: **2015-05-06

[Moved to DR at the October, 2015 meeting.]

The specification for determining whether a derived class
is a standard-layout class, considering the types of its bases
and those associated with its initial member, overlooked the
case of a class whose first member is an array.

**Proposed resolution (May, 2015):**

Change Clause 11 [class] paragraph 7 as follows:

...*M*(`X`) is defined as follows:

If `X` is a non-union class type, the
set *M*(`X`) is empty if
`X` has no (possibly inherited (
11.7 [class.derived])) non-static data members;
otherwise, it consists of the type of the first non-static
data member of `X` (where said member may be an anonymous
union), `X`_{0}, and the elements of
*M*(`X`_{0}).

If `X` is a union type, the set *M*(`X`) is
the union of all *M*(`U`_{i}) and the set
containing all `U`_{i}, where each
`U`_{i} is the type of the *i*th
non-static data member of `X`.

If `X` is an array type with element type
`X`_{e}, the set *M*(`X`) consists of
`X`_{e} and the elements of
*M*(`X`_{e}).

If `X` is a non-class, non-array type, the
set *M*(`X`) is empty.

[*Note:* *M*(`X`) is the set of the types of all
non-base-class subobjects that are guaranteed in a
standard-layout class to be at a zero offset in
`X`. —*end note*]