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

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

[nathan]

Synopsis: to many calls to copy ctor

State-Changed-From-To: open->closed
State-Changed-By: nathan
State-Changed-When: Fri Apr 26 03:52:40 2002
State-Changed-Why:
    appears fixed

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=3194

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

[pere]

>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:
----gnatsweb-attachment----
Content-Type: text/x-c++src; name="defaultparm.cpp"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="defaultparm.cpp"
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