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belfegor

Strange bug in Release mode

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I am using VS2012. I have a bug in my code that i don't know how to overcome as it appears in bizarre situation. It works fine in Debug but crashes in Release mode.

 

I have  a class with couple of vectors and some pointers:

[code]class Foo { private:     Bla*                       pBla;        std::vector<shared_ptr<Node>> vBar1;      std::vector<shared_ptr<Node>> vBar2;      std::vector<shared_ptr<Node>> vBar3;      //std::vector<shared_ptr<Node>> vBar4; ... more data public: ... };[/code]

 

When i introduced one more vector (vBar4) to this class it crashes my app even if don't use it anywhere, if i comment it then everything works.

 

WTF is going on?

 

Thank you for your time.

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[quote]

We need to see code before we can try to debug it.

[/quote]

 

I think there is no need for more code because even if i just add vector declaration (and nothing else) it just crashes my app in Release build, comment it and everything works.

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I haven't used C++ on VS2012, only C#, but maybe solutions are handled the same way.

Are you using two or more projects in your solution, where one project contains node and the other one, the code your showing? If yes, check compilation options for those projects.

I recently had the same issue at work. Two projects set to "Any CPU" mode and one goes for "x86". Switching it to "Any CPU" didn't help either, so i usually switch all projects to x84 and make sure they are built on compilation Edited by Sollum

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I think there is no need for more code because even if i just add vector declaration (and nothing else) it just crashes my app in Release build, comment it and everything works.

 

I have recently seen some weird things happen when I use templates in VS2012. Have your tried to "Clean" up the .obj files and do a full rebuild of the project?

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When i introduced one more vector (vBar4) to this class it crashes my app even if don't use it anywhere, if i comment it then everything works.

WTF is going on?
Memory corruption is your best bet.

Try compiling your release mode with debugging symbols, and examine where the application crashes in release mode.

EDIT:
As simast suggested, try rebuilding your project before assuming memory corruption. Edited by fastcall22

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I'm not 100% certain, but maybe the clean/rebuild just moved the memory around and hid the bug, but did not fix it. I would take a look at every place you use the pBla variable. Make sure it's initialized at null, set back to null when deleted and always check for != null before using it. Also check static array before/after the places where you use your Foo class, because it might be a buffer overflow, it cause this kind of problems.

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I'm not 100% certain, but maybe the clean/rebuild just moved the memory around and hid the bug, but did not fix it. I would take a look at every place you use the pBla variable. Make sure it's initialized at null, set back to null when deleted and always check for != null before using it. Also check static array before/after the places where you use your Foo class, because it might be a buffer overflow, it cause this kind of problems.

 

Yup.

 

If it wasn't just a build error.

 

Adding a vector is not a bug unless you type it in wrong, but it can cause an existing bug to crash the program or give you heisenbergs.

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If i'm not mistaken, i believe it's actually because you don't use the vector.

Being in release mode you are not permitted to declare variables/methods without actually using them.

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If i'm not mistaken, i believe it's actually because you don't use the vector.

Being in release mode you are not permitted to declare variables/methods without actually using them.

That's just... wrong. You're absolutely allowed to have variables and methods that you never use. The compiler is free to remove them (to some degree), but merely having them itself is not an error in any way.

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If i'm not mistaken, i believe it's actually because you don't use the vector.

Being in release mode you are not permitted to declare variables/methods without actually using them.

That's just... wrong. You're absolutely allowed to have variables and methods that you never use. The compiler is free to remove them (to some degree), but merely having them itself is not an error in any way.

In most languages, at least. In Go, for instance, declaring unused variables is an error. But for C++, you can of course declare placeholder variables which you aren't actually using yet, the compiler will simply ignore them (usually). At least with correct code, adding extra unused variables should not change the program's observable behaviour.

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If i'm not mistaken, i believe it's actually because you don't use the vector.

Being in release mode you are not permitted to declare variables/methods without actually using them.

That's just... wrong. You're absolutely allowed to have variables and methods that you never use. The compiler is free to remove them (to some degree), but merely having them itself is not an error in any way.

In most languages, at least. In Go, for instance, declaring unused variables is an error. But for C++, you can of course declare placeholder variables which you aren't actually using yet, the compiler will simply ignore them (usually). At least with correct code, adding extra unused variables should not change the program's observable behaviour.

 

So long as their construction/destruction has no global side-effects.

Edited by Ameise

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The last time Ive had a bug like this it was becasuse the debug mode did additional things like initializing variables to NULL. ....in debug mode everything was fine but in "normal" mode it produced a weird error.

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Clean and Rebuild may have worked because the dependent library, that is associated with the class, might be built previously in debug mode, and since you just switched to Release and rebuilt, it might not have been picked up appropriately. For Release builds, all the dependencies should also be built in release mode, otherwise it won't work.

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