gnats/78: g++ 2.95.2 copies without constructor, then calls destructor

[pmorris]

>Number:         78
>Category:       gnats
>Synopsis:       g++ 2.95.2 copies without constructor, then calls destructor
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 26 15:34:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Paul Morris and Will Edgington
>Release:        g++-2.95.2 and earlier
>Organization:
>Environment:
Sun Ultra 2 SunOS 5.6 (Solaris)
>Description:
g++ compiles incorrectly.  Under certain circumstances, it
creates a copy without calling the copy constructor, and
later passes the copy to the destructor.  This can cause
reference-count schemes to prematurely release storage.
>How-To-Repeat:
Enclosed is a self-contained program that exercises the bug,
with print statements to illustrate the problem.
Note that the refCount goes to -1.(If the SUNWspro compiler
is used instead, the refCount correctly ends at 0.)

PRINTOUT FROM EXAMPLE PROGRAM

Created tag 1 item 
     refCount now 1
Created tag 2 item as copy of tag 1 item 
     refCount now 2
Created tag 3 item 
Assigned tag 3 item as copy of tag 2 item 
     refCount now 3
Descoped tag 2 item 
     refCount now 2
Created tag 4 item as copy of tag 3 item 
     refCount now 3
Created tag 5 item 
Assigned tag 5 item as copy of tag 4 impostor 
     refCount now 4
Descoped tag 4 impostor 
     refCount now 3
Descoped tag 4 item 
     refCount now 2
Descoped tag 5 item 
     refCount now 1
Descoped tag 3 item 
     refCount now 0
Descoped tag 1 item 
     refCount now -1
>Fix:
The compiler needs to be modified to call the copy
constructor when it makes the copy identified as the
"impostor" in the example printout.
>Release-Note:
>Audit-Trail:
>Unformatted:
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