Uniqueness of structured binding names
_N4868_.6.4.1 [basic.scope.declarative]
Richard Smith

Created on 2016-07-20.00:00:00 last changed 7 months ago


Date: 2019-02-15.00:00:00

Proposed resolution (February, 2019):

Change _N4868_.6.4.1 [basic.scope.declarative] paragraph 4 as follows:

Given a set of declarations in a single declarative region, each of which specifies the same unqualified name,

  • they shall all refer to the same entity, or all refer to functions and function templates; or

  • exactly one declaration shall declare a class name or enumeration name that is not a typedef name and the other declarations shall all refer to the same variable, non-static data member, or enumerator, or all refer to functions and function templates; in this case the class name or enumeration name is hidden (_N4868_.6.4.10 [basic.scope.hiding]). [Note: A structured binding (9.6 [dcl.struct.bind]), namespace name (9.8 [basic.namespace]), or a class template name (Clause Clause 13 [temp]) must be unique in its declarative region (9.8.3 [namespace.alias], Clause Clause 13 [temp]). —end note]

Date: 2017-04-15.00:00:00

Notes from the April, 2017 teleconference:

Structured bindings have no C compatibility implications, so the tag/nontag treatment need not apply.

Date: 2019-02-15.00:00:00

[Accepted as a DR at the February, 2019 meeting.]

The current wording is not clear regarding examples like the following:

  struct A { int x; } a; 
  struct B {} b; template<int> int &get(const B&); 
  struct C {}; int c[1]; 
  auto [A] = a; // ok? 
  auto [B] = b; // ok? 
  auto [C] = c; // ok? 
Date User Action Args
2020-12-15 00:00:00adminsetmessages: + msg6354
2020-12-15 00:00:00adminsetstatus: drafting -> cd5
2018-02-27 00:00:00adminsetmessages: + msg5893
2016-07-20 00:00:00admincreate