HP C A.06.05 Reference Manual

HP C/HP-UX Implementation Topics
Scope of extern Declarations
Chapter 10248
Scope of extern Declarations
Identifiers for objects and functions declared within a block and with the storage class extern
have the same linkage as any visible declaration with file scope. If there is no visible
declaration with file scope, the identifier has external linkage, and the definition remains
visible until the end of the translation unit.
However, because this is an extension to ANSI C, a warning will be issued on subsequent uses
of the identifier if the absence of this extended visibility could cause a change in behavior on a
port to another conforming implementation.