Debugging step by step

Development
1

Hello,

I created a C++ extension, which works quite fine but i never managed to make to debugger work.

I tried with several IDE QtCreator, Kdevelop, Clion, I correctly set the CMAKE_BUILD_TYPE Flag to debug (for my extension and for 3D Slicer), and each time i can’t get breakpoints working. It seems that debug symbols are not generated.

Am I missing something ?

2

Did you have a chance to read through the following page: https://www.slicer.org/wiki/Documentation/Nightly/Developers/Tutorials/Debug_Instructions

3

Yes quite a lot of times.

4

Assuming you are using Linux, did you try to:

  • start Slicer
  • start ddd and attach to the running process
  • set breakpoints
5

I’m indeed on linux (ubuntu 18.04.3 , using Qt 5.11.0 GCC 64bit)

I tried this kind of thing using QtCreator when i attach to the process i get this :

This does not seem to be a “Debug” build.
Setting breakpoints by file name and line number may fail.
Section .debug_info: Not found.
Section .debug_abbrev: Not found.
Section .debug_line: Not found.
Section .debug_str: Not found.
Section .debug_loc: Not found.
Section .debug_range: Not found.
Section .gdb_index: Not found.
Section .note.gnu.build-id: Found.
Section .gnu.hash: Found.
Section .gnu_debuglink: Not found.

After googling it i just got advice to set BuilType to Debug, which was the first thing i did.
I though maybe the extension dependency to 3d slicer (which is also build in debug) was messing things up, but i did not found anything relevant.

6

For any futher user here how i fixed this :

The real process is not SlicerWith or Slicer but SlicerApp-real so you can’t debug at start, we need to attach to the process (ubuntu need some minor configuration to be able to do so, see below). From https://www.slicer.org/wiki/Documentation/Nightly/Developers/Tutorials/Debug_Instructions

GDB debug by attaching to running process: Starting with Ubuntu 10.10, ptracing of non-child processes by non-root users as been disabled -ie. only a process which is a parent of another process can ptrace it for normal users. You can temporarily disable this restriction by: $ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

To permanently allow it to edit /etc/sysctl.d/10-ptrace.conf and change the line: kernel.yama.ptrace_scope = 1 to read: kernel.yama.ptrace_scope = 0

Run SlicerWith*NameOfYourExtension, then attach to process SlicerApp-real

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