Issue 0011.02: Does extern link to a static declaration that is not visible?

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

Authors: Rich Peterson, WG14
Date: 1992-12-10
Reference document: X3J11/90-008
Submitted against: C90
Status: Fixed
Fixed in: C90 TC1
Converted from: dr.htm, dr_011.html

Interpretation of extern

Consider the code:

/* File scope */
 static int i;           /* declaration 1 */

 main()
 {
 extern int i;           /* declaration 2 */
 {
     extern int i;       /* declaration 3 */
 }
 }

A literal reading of subclause 6.1.2.2 says that declarations 1 and 2 have internal linkage, but that declaration 3 has external linkage (since declaration 1 is not visible, being hidden by declaration 2). (This combination of internal and external linkage is undefined by subclause 6.1.2.2, page 21, lines 27-28.)

Is this what is intended?

Comment from WG14 on 1997-09-23:

Correction

In subclause 6.1.2.2, page 21, change:

If the declaration of an identifier for an object or a function contains the storage-class specifier extern, the identifier has the same linkage as any visible declaration of the identifier with file scope. If there is no visible declaration with file scope, the identifier has external linkage.

to:

For an identifier declared with the storage-class specifier extern in a scope in which a prior declaration of that identifier is visible*****, if the prior declaration specifies internal or external linkage, the linkage of the identifier at the latter declaration becomes the linkage specified at the prior declaration. If no prior declaration is visible, or if the prior declaration specifies no linkage, then the identifier has external linkage. [Footnote *: As specified in 6.1.2.1, the latter declaration might hide the prior declaration.]