Issue 0017.11: Is struct t; struct t; valid?

This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.

Authors: Derek M. Jones, WG14
Date: 1992-12-10
Reference document: X3J11/90-056
Submitted against: C90
Status: Closed
Converted from: dr.htm, dr_017.html

Clarification of incomplete struct declaration

Referring to subclause 6.5.2.3, page 62:

struct t;
 struct t; /* Is this undefined? */

People seem to think that the above is undefined.

The problem arises because no rules exist for compatibility of incomplete structures or unions.

Comment from WG14 on 1997-09-23:

Response

The proposed example is valid. Nothing in the standard prohibits it.

The relevant citation is subclause 6.5.2.3 Semantics, paragraph 2:

A declaration of the form

    struct-or-union  identifier ;

specifies a structure or union type and declares a tag, both visible only within the scope in which the declaration occurs. It specifies a new type distinct from any type with the same tag in an enclosing scope (if any).