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

326. Wording for definition of trivial constructor

[Voted into WP at October 2003 meeting.]

In 11.4.5 [class.ctor] paragraph 5, the standard says "A constructor is trivial if [...]", and goes on to define a trivial default constructor. Taken literally, this would mean that a copy constructor can't be trivial (contrary to 11.4.5.3 [class.copy.ctor] paragraph 6). I suggest changing this to "A default constructor is trivial if [...]". (I think the change is purely editorial.)

Proposed Resolution (revised October 2002):

Change 11.4.5 [class.ctor] paragraph 5-6 as follows:

A default constructor for a class X is a constructor of class X that can be called without an argument. If there is no user-declared user-declared constructor for class X, a default constructor is implicitly declared. An implicitly-declared implicitly-declared default constructor is an inline public member of its class. A default constructor is trivial if it is an implicitly-declared default constructor and if:

• its class has no virtual functions (11.7.3 [class.virtual]) and no virtual base classes (11.7.2 [class.mi]), and
• all the direct base classes of its class have trivial default constructors, and
• for all the nonstatic data members of its class that are of class type (or array thereof), each such class has a trivial default constructor.

Otherwise, the default constructor is non-trivial.

Change 11.4.7 [class.dtor] paragraphs 3-4 as follows (the main changes are removing italics):

If a class has no user-declared user-declared destructor, a destructor is declared implicitly. An implicitly-declared implicitly-declared destructor is an inline public member of its class. A destructor is trivial if it is an implicitly-declared destructor and if:

• all of the direct base classes of its class have trivial destructors and
• for all of the non-static data members of its class that are of class type (or array thereof), each such class has a trivial destructor.

Otherwise, the destructor is non-trivial non-trivial.

In 11.5 [class.union] paragraph 1, change "trivial constructor" to "trivial default constructor".

In 6.7.7 [class.temporary] paragraph 3, add to the reference to 11.4.5 [class.ctor] a second reference, to 11.4.5.3 [class.copy.ctor].