Re: c++/7981: -Wsequence-point broken for C++

Re: c++/7981: -Wsequence-point broken for C++

[neroden]

Synopsis: -Wsequence-point broken for C++

State-Changed-From-To: feedback->closed
State-Changed-By: neroden
State-Changed-When: Fri Mar 21 05:43:48 2003
State-Changed-Why:
    Seems fixed, no feedback 3 mo.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7981

Re: c++/7981: -Wsequence-point broken for C++

[bangerth]

Synopsis: -Wsequence-point broken for C++

State-Changed-From-To: open->feedback
State-Changed-By: bangerth
State-Changed-When: Thu Dec 19 17:31:51 2002
State-Changed-Why:
    In the documentation on TOT, the standard is always referenced
    as the "C standard", and there is now a sentence
    
    "The present implementation of this option only works for C programs.  A
    future implementation may also work for C++ programs."
    
    Is this something in the direction you request, Matt?
    
    W.
    
    
    PS: I like the sentence that follows the above:
    "The C standard is worded confusingly, therefore there is some debate
    over the precise meaning of the sequence point rules in subtle cases."

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7981

Re: c++/7981: -Wsequence-point broken for C++

[Joseph S. Myers]

The following reply was made to PR c++/7981; it has been noted by GNATS.

From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: <austern@apple.com>
Cc: <gcc-gnats@gcc.gnu.org>,  <gcc-bugs@gcc.gnu.org>
Subject: Re: c++/7981: -Wsequence-point broken for C++
Date: Fri, 20 Sep 2002 00:22:39 +0100 (BST)

 On 19 Sep 2002 austern@apple.com wrote:
 
 > The documentation doesn't list -Wsequence-point as a C-only option.  
 
 The manual says:
 
     The present implementation of this option only works for C programs.  A
     future implementation may also work for C++ programs.
 
 -- 
 Joseph S. Myers
 jsm28@cam.ac.uk
 

c++/7981: -Wsequence-point broken for C++

[austern]

>Number:         7981
>Category:       c++
>Synopsis:       -Wsequence-point broken for C++
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 19 16:16:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     austern@apple.com
>Release:        3.1, 3.2, and TOT
>Organization:
>Environment:
Linux, OS X
>Description:
The documentation doesn't list -Wsequence-point as a C-only option.  However, it turns out that this warning doesn't work for C++.  In 3.1 and 3.2 the option fails silently; in TOT we get a warning saying (in contradiction to the documentation) that this option isn't available for C++.

Either the compiler or the documentation should be fixed.



>How-To-Repeat:
bash-2.05$ cat > foo.c
int main() {
  int a = 0;
  a = a++;
  return a;
}
bash-2.05$ /usr/local/gcc-3.1/bin/gcc -Wsequence-point foo.c
foo.c: In function `main':
foo.c:3: warning: operation on `a' may be undefined
bash-2.05$ /usr/local/gcc-3.1/bin/g++ -Wsequence-point foo.c
bash-2.05$ /usr/local/gcc-3.2/bin/g++ -Wsequence-point foo.c
bash-2.05$ ~/root/bin/g++ -Wsequence-point foo.c
cc1plus: warning: "-Wsequence-point" is valid for C/ObjC but not for C++
bash-2.05$ 
>Fix:

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