c++/142: Re: Anonyous unions prevent proper linking.

["Martin v. Loewis" <martin at loewis dot home dot cs dot tu-berlin dot de>]

>Number:         142
>Category:       c++
>Synopsis:       Anonyous unions prevent proper linking.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          analyzed
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 26 12:06:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Karl Nelson <kenelson@ece.ucdavis.edu>
>Release:        2.95.2
>Organization:
>Environment:
>Description:
 Original-Message-Id: <199910200840.BAA17883@teal.ece.ucdavis.edu>
 Date: Wed, 20 Oct 1999 01:40:16 -0700


 Problem description:
   If a class is defined within an anonymous union the functions
 within contain the index number of the anonymous union within them.
 This number in not unique as it it increments for each class.  Thus
 if a different number of anonymous unions appear functions will not
 link.

 Affected platforms and versions:
   platforms all, version 2.95 

 Switchs needed to cause error:
   None. Default behavior demonstrate error. 

 Sample:  (This must be in 3 seperate files to demonstrate improper
 linking,)
 --------------------------test.h--------------------------------
 struct A
   {
     union {
       void *v;
       struct B {
	 static void foo();
	} b;
     };
   };
 --------------------------test1.cc------------------------------
 struct C
   {
    union {  
     void *i;
     int j;
    };
   };

 #include "test.h"

 main()
   {
     A::B::foo();
   }
 --------------------------test2.cc------------------------------
 #include "test.h"

 void A::B::foo() {};
 ----------------------------------------------------------------

 compile with:  c++ test1.cc test2.cc

 Sample Output:
 > c++ test1.cc test2.cc
 /tmp/ccftbB1R.o: In function `main':
 /tmp/ccftbB1R.o(.text+0x7): undefined reference to `A::._1::B::foo(void)'
 collect2: ld returned 1 exit status

 A::B::foo is properly defined.  This should have linked.

 --Karl


>How-To-Repeat:
>Fix:
>Release-Note:
>Audit-Trail:
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