This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
[Accepted as a DR at the March, 2024 meeting.]
Subclause 9.4.1 [dcl.init.general] paragraph 9 specifies:
To value-initialize an object of type T means:
- if T is a (possibly cv-qualified) class type (Clause Clause 11 [class]), then
- if T has either no default constructor (11.4.5.2 [class.default.ctor]) or a default constructor that is user-provided or deleted, then the object is default-initialized;
- otherwise, the object is zero-initialized and the semantic constraints for default-initialization are checked, and if T has a non-trivial default constructor, the object is default-initialized;
- if T is an array type, ...
The specification about checking the semantic constraints and invoking only non-trivial default constructors is overly convoluted. Omitting a call to a trivial constructor is an as-if optimization that should not be prescribed by the standard.
Proposed resolution (approved by CWG 2024-01-19):
Change in 9.4.1 [dcl.init.general] bullet 9.1.2 as follows:
- ...
- otherwise, the object is zero-initialized and
the semantic constraints for default-initialization are checked, and if T has a non-trivial default constructor, the object isthen default-initialized;