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


2590. Underlying type should determine size and alignment requirements of an enum

Section: 9.7.1  [dcl.enum]     Status: DR     Submitter: Brian Bi     Date: 2022-05-15

[Accepted as a DR at the November, 2022 meeting.]

Subclause 9.7.1 [dcl.enum] specifies how the underlying type of an enumeration is determined, and, for enumerations whose underlying type is fixed, specifies that the enumeration has the same set of values as the underlying type. However, the specification does not relate the size and alignment requirements of the enumeration to those of the underlying type. Those ought to be the same.

Suggested resolution [SUPERSEDED]:

Add a new paragraph after 9.7.1 [dcl.enum] paragraph 8:

For an enumeration whose underlying type is fixed, ...

An enumeration has the same size, value representation, and alignment requirements (6.7.6 [basic.align]) as its underlying type. Furthermore, each value of an enumeration has the same representation as the same value of the underlying type.

Two enumeration types are layout-compatible enumerations if ...

Proposed resolution (approved by CWG 2022-08-26):

Add a new paragraph after 9.7.1 [dcl.enum] paragraph 8:

For an enumeration whose underlying type is fixed, ...

An enumeration has the same size, value representation, and alignment requirements (6.7.6 [basic.align]) as its underlying type. Furthermore, each value of an enumeration has the same representation as the corresponding value of the underlying type.

Two enumeration types are layout-compatible enumerations if ...