[Bug c/11751] New: wrong evaluation of an expression

[Bug c/11751] New: wrong evaluation of an expression

[me at elitsa dot net]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

           Summary: wrong evaluation of an expression
           Product: gcc
           Version: 3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: me at elitsa dot net
                CC: gcc-bugs at gcc dot gnu dot org

bellow is simple code that express this bug:

/************
 * File : b.C
 ************/

#include <stdio.h>

int main()
        {
        int a = 1;
        printf(" a = %i \n",(a++)+(++a));               //4

        a = 1;
        printf(" a = %i \n",(a++)+(a++)+(++a));         //4

        return 0;
        }






After compilation in a following way:

c++ -o b b.C

The result was:

 a = 4 
 a = 4

[Bug c/11751] wrong evaluation of an expression

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-31 17:55 -------
Not a bug in gcc but rather in your code.  Read about sequence points and modifying variables 
between them.

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-05 15:01 -------
*** Bug 15012 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mdeluigi at student dot ethz
                   |                            |dot ch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-05 15:01 -------
*** Bug 13403 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc at lantiainen dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-05 15:01 -------
*** Bug 15103 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |musicman529 at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-05 15:01 -------
*** Bug 14417 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mcvick_e at iname dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-05 15:02 -------
*** Bug 12552 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |devnull at frogshit dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 15:39 -------
*** Bug 11363 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |qyang at media dot lbl dot
                   |                            |gov


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 15:40 -------
*** Bug 17018 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |svetozarmarkov at netscape
                   |                            |dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 15:46 -------
*** Bug 16887 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |krs at home dot se


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 15:45 -------
*** Bug 14951 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zshao at acm dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:03 -------
*** Bug 816 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |super dot aorta at ntlworld
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:03 -------
*** Bug 5724 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |raoulgough at dial dot pipex
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:03 -------
*** Bug 4978 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ggs at homer dot att dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:04 -------
*** Bug 9693 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lxg8906 at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:04 -------
*** Bug 16309 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nakkore at libero dot it


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:03 -------
*** Bug 6790 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |horsh at mail dot ru


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:05 -------
*** Bug 10947 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bmead15 at cox dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-13 16:04 -------
*** Bug 7135 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lindahlb at hotmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[reichelt at gcc dot gnu dot org]

------- Additional Comments From reichelt at gcc dot gnu dot org  2004-08-19 08:01 -------
*** Bug 17095 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |asokumar at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-08-31 20:46 -------
*** Bug 17253 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vanveghel at home dot nl


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at suse dot de]

------- Additional Comments From schwab at suse dot de  2004-09-02 12:36 -------
*** Bug 17282 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gaurav_har at rediffmail dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-09-02 13:00 -------
Volker recently added a small paragraph about this very common non-bug to our 
non-bug page:

http://gcc.gnu.org/bugs.html#nonbugs_c

You can read here about this bug.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-09-03 05:23 -------
*** Bug 17282 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[reichelt at gcc dot gnu dot org]

------- Additional Comments From reichelt at gcc dot gnu dot org  2004-09-15 19:51 -------
*** Bug 17507 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |work at paul dot dubuc dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-09-23 20:54 -------
*** Bug 17639 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |barnarr at cc dot wwu dot
                   |                            |edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[bangerth at dealii dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|3.4.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pcarlini at suse dot de]

------- Additional Comments From pcarlini at suse dot de  2005-02-07 00:19 -------
*** Bug 19798 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ceniza666 at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-23 20:26 -------
*** Bug 20181 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |d_picco at hotmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[d_picco at hotmail dot com]

------- Additional Comments From d_picco at hotmail dot com  2005-02-23 20:38 -------
The point I was making with my example is that the native types (int, long,
char, etc...) have different behaviour than a user-defined class with the
operator++.  If it is compiler dependent which way the expression is evaluated,
why not at least make them both agree?  GCC is also the only compiler out of the
5 that I've tested that exhibits this behaviour... all others unify the
behaviour of native and user-defined operator++. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-23 20:41 -------
(In reply to comment #28)
The code is undefined, which means we should be able to do system("rm -Rf /");, note we don't.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[d_picco at hotmail dot com]

------- Additional Comments From d_picco at hotmail dot com  2005-02-23 20:46 -------
Here is a better clarification:

Case 1
======
int a = 0;
int b = a++ + a++;
printf("b = %d\n", b);  // output is 0


Case 2
======
class A
{
  int a_;
public:
  A() : a_(0) {}

  int operator++() { return a_++; }
};

A a;
int b = a++ + a++;
printf("b = %d\n", b);  // output is 1

This is a simple case that shows how the behaviour of the operator++ should be
united.

I'm not sure what you mean by the system(...) call... I understand that the code
is undefined (meaning its up to the compiler vendor to implement as they see
fit).  I think the most fitting way is to have the above two cases unified in
behaviour... isn't one of the reasons that operators were added to C++ was to
allow user-defined types to mimic the functionality and usability of the native
C types?

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-23 20:51 -------
(In reply to comment #30)
> I'm not sure what you mean by the system(...) call... I understand that the code
> is undefined (meaning its up to the compiler vendor to implement as they see
> fit).  I think the most fitting way is to have the above two cases unified in
> behaviour... isn't one of the reasons that operators were added to C++ was to
> allow user-defined types to mimic the functionality and usability of the native
> C types?

Undefined means that we can do anything.  Which where the system call comes from.  The point is that 
this undefined, there does not even have be a constancy in the behavior across optimization levels, 
types or anything else.



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[d_picco at hotmail dot com]

------- Additional Comments From d_picco at hotmail dot com  2005-02-23 23:27 -------
I won't press the issue further because I have other things more pressing ;)

But I think the decision to not change the behaviour here is wrong.  I cannot
create an Integer class that acts as an int due to the operator++.  Just because
it is undefined does not mean that we have to arbitrarily have to choose a
method that adds no value over one that adds good value.  Nearly all other
compiler vendors have adopted this method since it has an element of
common-sense in the face of an undefined process.  I get the feeling that the
only reason it isn't changed is simply because no-one wants to do it.  If there
is another reason, what is it?  

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schlie at comcast dot net]

------- Additional Comments From schlie at comcast dot net  2005-02-24 10:34 -------
Although I can confidently say that I've been less than enthusiastic with
some of GCC's standards interpretations; here GCC's results in each of the
examples you cite are within the set of semantically consent values which
should be expected to result from an unspecified evaluation and/or value
assignment order. (Although do agree that GCC has no license to return any
value other than those which would result from these ordering ambiguities).

(Although do believe that GCC should adopt an lr evaluation order; as
expressions which are otherwise ambitious are useless, and those which are
unaffected are insensitive to it; resulting in no harm, only benefit; and with a
little luck may lead to the C/C++ committees coming to their senses in time.)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:42 -------
*** Bug 3165 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tczarnecki at abc dot com
                   |                            |dot pl


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:47 -------
*** Bug 1039 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lid at ecn dot purdue dot
                   |                            |edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:55 -------
*** Bug 3324 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |arminu at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:59 -------
*** Bug 6409 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |suan at cs dot wisc dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:56 -------
*** Bug 5159 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |robc at free dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:57 -------
*** Bug 5494 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |carpman at voidptr dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:58 -------
*** Bug 5516 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smartmouse714 at yahoo dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 02:54 -------
*** Bug 2550 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikaldaz at unavarra dot es


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 03:03 -------
*** Bug 9334 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bala at rentec dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 03:05 -------
*** Bug 9675 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rjvbertin at hotmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-21 04:58 -------
*** Bug 6409 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2005-04-27 11:40 -------
*** Bug 21246 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jandres at dsic dot upv dot
                   |                            |es


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-05 18:12 -------
*** Bug 21404 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |janis at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-30 13:26 -------
*** Bug 22248 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |algorithmus at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-30 13:37 -------
*** Bug 22248 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-01 14:29 -------
*** Bug 22248 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-22 17:07 -------
*** Bug 24015 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |buergel at limmat dot ch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[elizbathjames at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

Elizbath Martin <elizbathjames at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |elizbathjames at gmail dot com

--- Comment #87 from Elizbath Martin <elizbathjames at gmail dot com> ---
For the good expansion order make a step by step working Like when go for the
buying of the juicer/blender 
http://zinch.zendesk.com/entries/31114770-Locating-Smoothie-Makers-In-Low-price
customer feedback is the key of the success. So For the right order of the
expansion an expert advice can work better for you.

[Bug c/11751] wrong evaluation order of an expression

[schwab at linux-m68k dot org]

------- Comment #86 from schwab at linux-m68k dot org  2010-01-12 16:24 -------
*** Bug 42711 has been marked as a duplicate of this bug. ***


-- 

schwab at linux-m68k dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aonebeam at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at linux-m68k dot org]

------- Comment #85 from schwab at linux-m68k dot org  2009-06-07 09:04 -------
*** Bug 40366 has been marked as a duplicate of this bug. ***


-- 

schwab at linux-m68k dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ashutosh dot sharma dot 0204
                   |                            |at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #84 from pinskia at gcc dot gnu dot org  2009-02-09 18:45 -------
*** Bug 39143 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |edulix at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at suse dot de]

------- Comment #83 from schwab at suse dot de  2008-12-13 18:26 -------
*** Bug 38516 has been marked as a duplicate of this bug. ***


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schwab at suse dot de changed:

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                 CC|                            |calliari at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[paolo dot carlini at oracle dot com]

------- Comment #82 from paolo dot carlini at oracle dot com  2008-10-10 16:33 -------
*** Bug 37800 has been marked as a duplicate of this bug. ***


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paolo dot carlini at oracle dot com changed:

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                 CC|                            |terrix at wp dot pl


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #81 from pinskia at gcc dot gnu dot org  2007-08-31 16:09 -------
*** Bug 33270 has been marked as a duplicate of this bug. ***


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pinskia at gcc dot gnu dot org changed:

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at suse dot de]

------- Comment #80 from schwab at suse dot de  2007-08-30 16:10 -------
*** Bug 33248 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[rguenth at gcc dot gnu dot org]

------- Comment #79 from rguenth at gcc dot gnu dot org  2007-08-30 12:33 -------
*** Bug 33248 has been marked as a duplicate of this bug. ***


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rguenth at gcc dot gnu dot org changed:

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[gjasny at web dot de]

------- Comment #78 from gjasny at web dot de  2007-08-10 12:02 -------
*** Bug 33043 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at suse dot de]

------- Comment #77 from schwab at suse dot de  2007-06-28 16:54 -------
*** Bug 32536 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #76 from pinskia at gcc dot gnu dot org  2007-05-28 22:47 -------
*** Bug 32133 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #75 from pinskia at gcc dot gnu dot org  2007-05-24 16:21 -------
*** Bug 32067 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[rguenth at gcc dot gnu dot org]

------- Comment #74 from rguenth at gcc dot gnu dot org  2007-03-30 13:03 -------
*** Bug 31398 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[rguenth at gcc dot gnu dot org]

------- Comment #73 from rguenth at gcc dot gnu dot org  2007-02-23 15:36 -------
*** Bug 30935 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #72 from pinskia at gcc dot gnu dot org  2006-05-17 19:06 -------
*** Bug 27646 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #71 from pinskia at gcc dot gnu dot org  2006-04-28 00:00 -------
*** Bug 27344 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #70 from pinskia at gcc dot gnu dot org  2006-04-21 00:40 -------
*** Bug 27233 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #69 from pinskia at gcc dot gnu dot org  2006-04-14 16:54 -------
*** Bug 27153 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #68 from pinskia at gcc dot gnu dot org  2006-04-14 02:50 -------
*** Bug 27153 has been marked as a duplicate of this bug. ***


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #67 from pinskia at gcc dot gnu dot org  2006-04-14 02:31 -------
*** Bug 27153 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #66 from pinskia at gcc dot gnu dot org  2006-03-29 19:26 -------
*** Bug 26923 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #65 from pinskia at gcc dot gnu dot org  2006-03-23 06:30 -------
*** Bug 26820 has been marked as a duplicate of this bug. ***


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pinskia at gcc dot gnu dot org changed:

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #64 from pinskia at gcc dot gnu dot org  2006-03-17 16:59 -------
*** Bug 26730 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[dberlin at gcc dot gnu dot org]

------- Comment #63 from dberlin at gcc dot gnu dot org  2006-03-11 16:49 -------
(In reply to comment #61)
> referring to duplicate 26642: 
> 
> The behavior changed between gcc3 and gcc4 and the comment is "there is no
> reason the result should not change"?

There is simply no guarantee at all that the behavior of this will or won't
change.
It's undefined code.  It could change depending on the phase of the moon.
> 
> Sorry, but I think that's a really bad way to handle things. When a update
> changes behavior, there should be et least an appropriate warning.

Unfortunately, it is impossible to warn for every permuation of undefined code
at compilation time.
However, in general, if you write code whose semantics are undefined, you are
going to get burned.  This is just the way the ball bounces.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #62 from pinskia at gcc dot gnu dot org  2006-03-11 16:14 -------
(In reply to comment #61)
> referring to duplicate 26642: 
> 
> The behavior changed between gcc3 and gcc4 and the comment is "there is no
> reason the result should not change"?

Why this is undefined code :).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[nobs at tigress dot com]

------- Comment #61 from nobs at tigress dot com  2006-03-11 16:10 -------
referring to duplicate 26642: 

The behavior changed between gcc3 and gcc4 and the comment is "there is no
reason the result should not change"?

Sorry, but I think that's a really bad way to handle things. When a update
changes behavior, there should be et least an appropriate warning.

And another comment says "look at the warning you got". If you'd read the
warnings you would have seen it refers to that part of the code that didn't
change its behavior. So a code that only uses the array-version (that behaves
differently) wouldn't get the warning.

I really doubt that there is any good reason that simple variables and array
variables should differ in the order their expressions are solved.

Please, think about it. At least give a warning at the right place!


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #60 from pinskia at gcc dot gnu dot org  2006-03-11 15:09 -------
*** Bug 26642 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #59 from pinskia at gcc dot gnu dot org  2006-02-22 14:04 -------
*** Bug 26418 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[schwab at suse dot de]

------- Comment #58 from schwab at suse dot de  2006-02-01 10:34 -------
*** Bug 26060 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #57 from pinskia at gcc dot gnu dot org  2005-12-12 20:23 -------
*** Bug 2673 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #55 from pinskia at gcc dot gnu dot org  2005-11-10 03:49 -------
*** Bug 6765 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #56 from pinskia at gcc dot gnu dot org  2005-11-10 03:49 -------
*** Bug 6891 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #54 from pinskia at gcc dot gnu dot org  2005-11-10 03:48 -------
*** Bug 8175 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #53 from pinskia at gcc dot gnu dot org  2005-11-10 03:18 -------
*** Bug 5051 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #52 from pinskia at gcc dot gnu dot org  2005-11-10 03:17 -------
*** Bug 762 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11751

[Bug c/11751] wrong evaluation order of an expression

[pinskia at gcc dot gnu dot org]

------- Comment #51 from pinskia at gcc dot gnu dot org  2005-11-10 03:17 -------
*** Bug 1570 has been marked as a duplicate of this bug. ***


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