Re: [Qt-creator] What's the crash?

[Jason H]

Yes!! I wonder why I don't get that anymore?


> Sent: Monday, July 16, 2018 at 10:37 AM
> From: "Nikos Chantziaras" 
> To: qt-creator@qt-project.org
> Subject: Re: [Qt-creator] What's the crash?
>
> Seems to be working fine here:
> 
>https://i.imgur.com/OfFSAk5.png
> 
> 
> On 16/07/18 17:05, Jason H wrote:
> > 
> >> There's nothing more the debugger or C++ can do for you here.
> > 
> > But it does at the command line:
> > Process 79112 launched: '/Users/jhihn/Projects/test_crash/a.out' (x86_64)
> > Process 79112 stopped
> > * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC 
> > (code=EXC_I386_DIV, subcode=0x0)
> >  frame #0: 0x00010fad a.out`main at main.c:7
> > 4   {
> > 5   int a = 2;
> > 6   int b = 0;
> > -> 7return a/b;
> > 
> > 
> > I'm pretty sure I remember some dialog appearing saying something about 
> > SIGSEGV (or in this case EXC_ARITHMETIC)?
> > 
> > MS gives this: 
> > https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png
> > I thought earlier versions of QtC had something simular.
> > 
> > The difference is:
> > 
> > int *a, *b; *b=0;
> > return *a / *b;
> > 
> > Here, the problem could be that 'a' is out of process space, or 'b' is 0. 
> > If 'a' is a pointer, I don't necessarily know what my address range is. I 
> > have to deduce (and risk being wrong) what the actual crash was, meaning I 
> > could waste time going down the wrong path.
> > 
> 
> 
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Re: [Qt-creator] What's the crash?

[André Hartmann]

Hi Jason,


There's nothing more the debugger or C++ can do for you here.

My comment refered to something like this in your code:

QList data;
data[0] = 123;

That will crash in qlist.cpp with index out of range, and not in your 
code. Therefore it is not immediately obvious what causes the crash. But 
with the stack trace you can find the guilty function.


It's up to you to inspect the stack though. If global variables are 
involved, things might get more complicated.


> MS gives this: 
https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png

> I thought earlier versions of QtC had something simular.

Are you working with a debug version of your program?

Regards,
André


But it does at the command line:
Process 79112 launched: '/Users/jhihn/Projects/test_crash/a.out' (x86_64)
Process 79112 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC 
(code=EXC_I386_DIV, subcode=0x0)
 frame #0: 0x00010fad a.out`main at main.c:7
4   {
5   int a = 2;
6   int b = 0;
-> 7 return a/b;


I'm pretty sure I remember some dialog appearing saying something about SIGSEGV 
(or in this case EXC_ARITHMETIC)?

MS gives this: 
https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png
I thought earlier versions of QtC had something simular.

The difference is:

int *a, *b; *b=0;
return *a / *b;

Here, the problem could be that 'a' is out of process space, or 'b' is 0. If 
'a' is a pointer, I don't necessarily know what my address range is. I have to 
deduce (and risk being wrong) what the actual crash was, meaning I could waste 
time going down the wrong path.
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Re: [Qt-creator] What's the crash?

[Andy]

FWIW I do (sometimes?) get a dialog like Nikos (MSVC 2017):

[image: 2018-07-16 10_29_04-Exception Triggered.jpg]

(What's "The inferior"?)

Once that's dismissed, however, the only place I can find the info is
digging through the debugger log.

It would be useful to indicate in the thread menu which thread crashed
along with the reason. Maybe add to the menu entry:

  "#0 - crashed (division by zero)"

or something like that.

---
Andy Maloney  //  https://asmaloney.com
twitter ~ @asmaloney 



On Mon, Jul 16, 2018 at 10:37 AM Nikos Chantziaras  wrote:

> Seems to be working fine here:
>
>https://i.imgur.com/OfFSAk5.png
>
>
> On 16/07/18 17:05, Jason H wrote:
> >
> >> There's nothing more the debugger or C++ can do for you here.
> >
> > But it does at the command line:
> > Process 79112 launched: '/Users/jhihn/Projects/test_crash/a.out' (x86_64)
> > Process 79112 stopped
> > * thread #1, queue = 'com.apple.main-thread', stop reason =
> EXC_ARITHMETIC (code=EXC_I386_DIV, subcode=0x0)
> >  frame #0: 0x00010fad a.out`main at main.c:7
> > 4 {
> > 5 int a = 2;
> > 6 int b = 0;
> > -> 7  return a/b;
> >
> >
> > I'm pretty sure I remember some dialog appearing saying something about
> SIGSEGV (or in this case EXC_ARITHMETIC)?
> >
> > MS gives this:
> https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png
> > I thought earlier versions of QtC had something simular.
> >
> > The difference is:
> >
> > int *a, *b; *b=0;
> > return *a / *b;
> >
> > Here, the problem could be that 'a' is out of process space, or 'b' is
> 0. If 'a' is a pointer, I don't necessarily know what my address range is.
> I have to deduce (and risk being wrong) what the actual crash was, meaning
> I could waste time going down the wrong path.
> >
>
>
> ___
> Qt-creator mailing list
> Qt-creator@qt-project.org
> http://lists.qt-project.org/mailman/listinfo/qt-creator
>
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Re: [Qt-creator] What's the crash?

[Nikos Chantziaras]

Seems to be working fine here:

  https://i.imgur.com/OfFSAk5.png


On 16/07/18 17:05, Jason H wrote:



There's nothing more the debugger or C++ can do for you here.


But it does at the command line:
Process 79112 launched: '/Users/jhihn/Projects/test_crash/a.out' (x86_64)
Process 79112 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC 
(code=EXC_I386_DIV, subcode=0x0)
 frame #0: 0x00010fad a.out`main at main.c:7
4   {
5   int a = 2;
6   int b = 0;
-> 7 return a/b;


I'm pretty sure I remember some dialog appearing saying something about SIGSEGV 
(or in this case EXC_ARITHMETIC)?

MS gives this: 
https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png
I thought earlier versions of QtC had something simular.

The difference is:

int *a, *b; *b=0;
return *a / *b;

Here, the problem could be that 'a' is out of process space, or 'b' is 0. If 
'a' is a pointer, I don't necessarily know what my address range is. I have to 
deduce (and risk being wrong) what the actual crash was, meaning I could waste 
time going down the wrong path.




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Re: [Qt-creator] What's the crash?

[Jason H]

> There's nothing more the debugger or C++ can do for you here. 

But it does at the command line:
Process 79112 launched: '/Users/jhihn/Projects/test_crash/a.out' (x86_64)
Process 79112 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC 
(code=EXC_I386_DIV, subcode=0x0)
frame #0: 0x00010fad a.out`main at main.c:7
   4{
   5int a = 2;
   6int b = 0;
-> 7return a/b;


I'm pretty sure I remember some dialog appearing saying something about SIGSEGV 
(or in this case EXC_ARITHMETIC)? 

MS gives this: 
https://user-images.githubusercontent.com/10531631/36583169-c65d48ea-1874-11e8-90db-1a651cfd09f5.png
I thought earlier versions of QtC had something simular.

The difference is:

int *a, *b; *b=0;
return *a / *b;

Here, the problem could be that 'a' is out of process space, or 'b' is 0. If 
'a' is a pointer, I don't necessarily know what my address range is. I have to 
deduce (and risk being wrong) what the actual crash was, meaning I could waste 
time going down the wrong path.
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Re: [Qt-creator] What's the crash?

[aha_1980]

Hi all,

> Yes, but how do you get the actual crash reason?


You need to inspect the backtrace. You have the local variables for each 
function on the stack, and this should give you some insight.

There's nothing more the debugger or C++ can do for you here.

Regards, Andre
> 
> On Sat, Jul 14, 2018 at 6:27 AM Nikos Chantziaras  wrote:
> 
> > On 12/07/18 18:16, Jason H wrote:
> > > When my program seg faults, bus errors, or divides by zero, I'm left at
> > the offending line in the debugger. Is there a way to tell what exactly
> > caused the crash without having to guess?
> >
> > You need to do a debug build of your application and then start it in
> > the debugger (just press F5.) This will give you the line of the crash
> > but also a backtrace to see how you got to that current line.
> >
> > ___
> > Qt-creator mailing list
> > Qt-creator@qt-project.org
> > http://lists.qt-project.org/mailman/listinfo/qt-creator
> >
>

-- 
Von meinem Jolla gesendet
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Re: [Qt-creator] What's the crash?

[Vadim Peretokin]

Yes, but how do you get the actual crash reason?

On Sat, Jul 14, 2018 at 6:27 AM Nikos Chantziaras  wrote:

> On 12/07/18 18:16, Jason H wrote:
> > When my program seg faults, bus errors, or divides by zero, I'm left at
> the offending line in the debugger. Is there a way to tell what exactly
> caused the crash without having to guess?
>
> You need to do a debug build of your application and then start it in
> the debugger (just press F5.) This will give you the line of the crash
> but also a backtrace to see how you got to that current line.
>
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> Qt-creator@qt-project.org
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Re: [Qt-creator] What's the crash?

[Nikos Chantziaras]

On 12/07/18 18:16, Jason H wrote:

When my program seg faults, bus errors, or divides by zero, I'm left at the 
offending line in the debugger. Is there a way to tell what exactly caused the 
crash without having to guess?


You need to do a debug build of your application and then start it in 
the debugger (just press F5.) This will give you the line of the crash 
but also a backtrace to see how you got to that current line.


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Re: [Qt-creator] What's the crash?

[Jason H]

Didn't there used to be some simple dialog that presented that information?

> Sent: Thursday, July 12, 2018 at 11:16 AM
> From: "Jason H" 
> To: qt-creator 
> Subject: [Qt-creator] What's the crash?
>
> When my program seg faults, bus errors, or divides by zero, I'm left at the 
> offending line in the debugger. Is there a way to tell what exactly caused 
> the crash without having to guess?
> ___
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> Qt-creator@qt-project.org
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