How to debug with release libaries?

[jmj]

Hello!
I want to speed up debuger start, and reduce memory consumption when I debug my applications. So, I want compile my program in debug mode, but when Qt Creator start debuger I want force it to load release Qt dlls instead debug dlls.

How to do that with Qt Creatort???

[tbscope]

I guess from reading your post you have two versions of Qt installed. One with debugging symbols, and one without?

If so, go to your configuration panel (projects button on the left) in Qt Creator, select the "debug" profile and see which qt version is used to link your program. If the qt library with debugging symbols is used, change it to the one without debugging symbols.

[jmj]

Thank you for your reply.

I use Qt SDK 2010.04 for Windows. And in QtCreator->Projects i can choose Qt version, but in combo I have only two options:
1. Qt in path
2. 4.6.3
But above of this I have combo "build configuration" with four options:
1. Qt in path debug
2. Qt in path release
3. 4.6.3 debug
4. 4.6.3 release
I use this combo to swich between debug and reelase mode (I use only "Qt in path" options).

I can't find way to choose option "compile program in debug" and "use Qt release".

[Zlatomir]

I can't find way to choose option "compile program in debug" and "use Qt release".

That won't be possible, you need to have "debugging information" in both your application (witch use the library) and the library itself (or release configuration again for both).

But you can use the debugger on the "release" build of your application, just that it doesn't contain so mutch "debugging information" and it contains the optimisations.

[jmj]

I was thinking that it is possible when I read answer for bug:

http://bugreports.qt.nokia.com/brows...s:all-tabpanel

That bug report debug memory consumption, and (as far as I understood) they claims that it is possible... But maybe I don't fully understand them.

[tbscope]

You can perfectly debug applications and libraries without debugging information (symbols). BUT!!! It will be very difficult as you don't see what is what at first sight.

You also do not need a debug version of Qt to be able to debug your own program.

If you want to have a lot of information, compile everything with the -g option (even Qt), but this will result in a lot of disk space being used and slower compile times (Webkit with the -g option is a pain to link because of its size). But it will give you a very clear picture when tracing (like backtraces).

How the memory consumption in that bug report was measured is unknown to me though.

[jmj]

@tbscope
Thanks for your reply. But you do not answer how I can compile my program with debug informations but run it with Qt release libraries under Qt Creator? - This is my problem posted in this thread.

[tbscope]

1. Open your project in Qt Creator
2. Go to the projects page (it's the fourth button from the top on the left side of the window)
3. Select the debug configuration
4. In the build settings, you can see which Qt version is used. For me that is, for the project I have open, "Default Qt Version (Qt in PATH)"
Here you want to change it to a non debug version of Qt. To do this, click on show details, and then select the version you want.
5. When you now compile your program, you have a debug version of your program using a non debug version of Qt. As noted several times above, this might not be the preference since backtraces get more abstract.


Now, if you want all the information, use the -g flag.
Alter your .pro file and add the following line

QMAKE_CXXFLAGS += -g

QMAKE_CXXFLAGS += -g

To copy to clipboard, switch view to plain text mode 

This last line is especially useful when using dtrace or systemtap since you can just monitor variables by their actual name etc...

[jmj]

4. In the build settings, you can see which Qt version is used. For me that is, for the project I have open, "Default Qt Version (Qt in PATH)"
Here you want to change it to a non debug version of Qt. To do this, click on show details, and then select the version you want.

I am a little confused... I found "Qt version" combo in "Build settings" but it have only two options: "Qt in PATH" and "4.6.3" which are perfectly the same (because former is searched in PATH and later was written in configuration by Qt SDK instaler). So I haven't option "Qt in PATH Debug" which should be.
Even worst: I don't known whether "Qt in PATH" and "4.6.3" mind "Debug" or "Release"???
I think this is very weird...

Now, if you want all the information, use the -g flag.

Do you mind all debug information for my program? (Not for Qt library - I am not intend to compile Qt library)