[Mingw-notify] [ mingw-Support Requests-860173 ] Complicated problem

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Support Requests item #860173, was opened at 2003-12-15 14:29
Message generated for change (Comment added) made by infidel
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=202435&aid=860173&group_id=2435

Category: None
Group: None
Status: Open
Priority: 5
Submitted By: Marcelo Taube (marcelouy)
Assigned to: Nobody/Anonymous (nobody)
Summary: Complicated problem

Initial Comment:
Dear Sir,
I'm facing a difficult  situation while coding a program, 
and i really need your help.

Sometimes my program behaves great, then i make a 
little change to the program and it starts doing strange 
things, so i change another little thing and it starts 
working great again. It seems to me that there is a bug 
hided too deep and that i can't find it.

I'm starting to think that the bug is not in my code but 
in the standard C++ library but of course I'm not sure, I 
beg u help me

I finnally got a version of my programm that instead of 
doing strange things it simply crashes.
Analyzing what's happening i found that there is a string 
object that changes its value suddenly with no reason.
I needed to trace the value of that string in the whole 
program to know the exact moment when it changes.
So i created a class called TraceObjCaller that in whose 
constructor it writes to a file the value of that string. 
When i want to trace the value i build one object of 
that class.

Using that technique i traced down the bug to the 
construction of a deque. As shown in the next piece of 
code i've placed a trace before an after the 
construction of the deque.

**************************************
class msg_lnklist : public TraceObjCaller, public 
std::deque<mensaje>
{  
    private:
    TraceObjCaller toca;
**************************************

during that construction the value of the string changes 
for no reason
Here is the output (the trace file)
**************************************
TraceName():228.255.255.255
TraceName():|Q= l= l= n= |Q=  
**************************************

The first time the string has its correct value(an ip 
address), the second time it seems to show random 
chars.

From this evidence i suspect that in some conditions the 
deque class is modifying memory which doesn't belong 
to it. Could this be possible????
Thank you very much in advance for your help,
Marcelo Taube

PD: Some details: I'm using gcc version 3.2 (mingw 
special 20020817-1) (which comes with the last version 
of Dev-Cpp).

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>Comment By: Luke Dunstan (infidel)
Date: 2003-12-15 19:43

Message:
Logged In: YES 
user_id=30442

It is very unlikely that your problem is caused by a bug in 
libstdc++, but the only way for us to check is if you post a 
complete example program that demonstrates the problem. 
Ideally you should reduce the code as much as possible but it 
is not essential. You may use the file attachment feature on 
this bug tracker, or if it is too big then preferably you can 
make it available on the web and post a link here.


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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=202435&aid=860173&group_id=2435