c++/4871: value argument destructor called twice when a virtual method is called in virtual inherited class

[jamie@turbolabs.com]

>Number:         4871
>Category:       c++
>Synopsis:       value argument destructor called twice when a virtual method is called in virtual inherited class
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 13 18:26:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Jamie Painter <jamie@turboabs.com:>
>Release:        gcc version 3.0.2
>Organization:
>Environment:
Linux
>Description:
When a method is called with a class argument passed by value, under certain conditions the value is destructed twice.  The conditions seem to be related to the use of virtual inheritance, as demonstrated in the attached source.

>How-To-Repeat:
Compile (g++ gccbug.cpp), 
run (./a.out).

Observe the output:

constructing  ValueType 0xbffffa34
destructing   ValueType 0xbffffa34
destructing   ValueType 0xbffffa34

Note that the value parameter is constructed once and deconstructed twice.

Gcc 2.95.2 produces the correct output:

constructing  ValueType 0xbffff8a4
destructing   ValueType 0xbffff8a4

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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