This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

989. Misplaced list-initialization example

[Voted into WP at March, 2010 meeting.]

The final set of declarations in the example following 9.4.5 [dcl.init.list] bullet 3.3 is:

    struct S2 {
      int m1;
      double m2,m3;
    };
    S2 s21 = { 1, 2, 3.0 };    // OK
    S2 s22 { 1.0, 2, 3 };      // error: narrowing
    S2 s23 {};                 // OK: default to 0,0,0

However, S2 is an aggregate. Aggregates are handled in bullet 1, while bullet 3 deals with classes with constructors. This part of the example should be moved to the first bullet.

Proposed resolution (October, 2009):

Move the S2 example from bullet 3 to bullet 1 in 9.4.5 [dcl.init.list] paragraph 3:

• If T is an aggregate, aggregate initialization is performed (9.4.2 [dcl.init.aggr]).

  [Example:

    double ad[] = { 1, 2.0 };   // OK
    int ai[] = { 1, 2.0 };      // error: narrowing
  
    struct S2 {
      int m1;
      double m2,m3;
    };
    S2 s21 = { 1, 2, 3.0 };     // OK
    S2 s22 { 1.0, 2, 3 };       // error: narrowing
    S2 s23 {};                  // OK: default to 0,0,0
  

  —end example]

• Otherwise, if T is a specialization...

• Otherwise, if T is a class type...

  [Example:

    ...
    S s3 { };                   // OK: invoke #2
  
    struct S2 {
      int m1;
      double m2,m3;
    };
    S2 s21 = { 1, 2, 3.0 };     // OK
    S2 s22 { 1.0, 2, 3 };       // error: narrowing
    S2 s23 {};                  // OK: default to 0,0,0
  

  —end example]

• ...