c++/3194: to many calls to copy ctor

[pere at hungry dot com]

>Number:         3194
>Category:       c++
>Synopsis:       to many calls to copy ctor
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 15 05:56:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Petter Reinholdtsen
>Release:        gcc 2.95.2 and 3.0 2001-06-15
>Organization:
>Environment:
Debian 2.2
>Description:
Given the following test program, gcc 2.95.2 behaves very different
with and without an explicit copy constructor.

  Without                  With
  ------------------------------------------------
  ctor default 0xbffff628  ctor default 0xbffff628
  foo ctor 1 dtor 0        foo ctor 1 dtor 0
  dtor default 0xbffff604  dtor default 0xbffff628
  dtor default 0xbffff628  ctor temp 0xbffff628
  ctor temp 0xbffff624     foo ctor 2 dtor 1
  foo ctor 2 dtor 2        dtor temp 0xbffff628
  dtor temp 0xbffff604     ctor live 0xbffff628
  dtor temp 0xbffff624     cctor live 0xbffff624
  ctor live 0xbffff620     foo ctor 4 dtor 2
  foo ctor 3 dtor 4        dtor live 0xbffff624
  dtor live 0xbffff604     dtor live 0xbffff628
  dtor live 0xbffff61c
  dtor live 0xbffff620

Notice how the default copy constructor is called even if it isn't
needed.
>How-To-Repeat:
Compile and run the enclosed test program.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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Content-Disposition: attachment; filename="defaultparm.cpp"

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