Qt issue in Kubuntu

ChrisW67

@SGaist Good point:

Kubuntu 24.10 Beta ships with Qt6 6.6.12 and KDE Frameworks 6 version 6.5.0.
For applications that are still based on Qt5/KF5, Qt5 5.15.13 and Frameworks 5.116.0 are still in the archive.

So possibly the Qt5/KF5-based executable is missing a KDE 5 framework library or resource that is not present out-of-the-box. For example, KDEPlasmaPlatformTheme5.so or libKF5Solid.so.5 in stack trace above.

I will check when I get back to the machine with the VM.

ChrisW67

Nothing seems to be out of order in terms of mixed Qt5/6 or KDE dependencies missing.

BTW, the apt-supplied privacybrowser fails for me:

Kubuntu 24.04 with KDE Frameworks 5.115.0, Qt 5.15.3
Kubuntu 24.10 with KDE Frameworks 6.5.0, Qt 6.6.2 and what looks to be KDE Frameworks 5.116

This issue with Wireshark looks to be the same thing. Essentially, the impossible happens :(
That leads to QTBUG-86173 and that rabbit hole is more detail than I am willing to wade into and understand.

There is a suggestion that, "disabling -reduce-relocations by default is the best option."

Soren Stoutner

Given the discussion about -fPIC and -fPIE on the Wireshark bug, do you think that lines 45-52 in CMakeLists.txt could be the issue:

  45 # Include the Position Independent Executable checker.  <https://cmake.org/cmake/help/latest/policy/CMP0083.html>
  46 include(CheckPIESupported)
  47 
  48 # Check to see if Position Independent Executable is supported in the current linker and environment.
  49 check_pie_supported()
  50 
  51 # Add the Position Independent Executable compiler flag if it is supported in the current linker and environment.  <https://cmake.org/cmake/help/latest/variable/CMAKE_POSITION_INDEPENDENT_CODE.html>
  52 set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)

ChrisW67

Possibly. This snippet derived from the CMake manual:

include(CheckPIESupported)
check_pie_supported(OUTPUT_VARIABLE output LANGUAGES CXX)
set_property(TARGET mmmm_pie PROPERTY POSITION_INDEPENDENT_CODE TRUE)
if(NOT CMAKE_C_LINK_PIE_SUPPORTED)
  message(WARNING "PIE is not supported at link time: ${output}.\n"
                  "PIE link options will not be passed to linker.")
endif()

Added to the CMakeLists.txt for a basic empty-widget project generates this:

[cmake] Running /usr/bin/cmake -S /tmp/mmmm_pie -B /tmp/mmmm_pie/build/Desktop_Qt_6_7_2-Debug in /tmp/mmmm_pie/build/Desktop_Qt_6_7_2-Debug.
[cmake] CMake Warning at CMakeLists.txt:51 (message):
[cmake]   PIE is not supported at link time: .
[cmake] 
[cmake]   PIE link options will not be passed to linker.
[cmake]

It nevertheless adds -fPIE to the g++ calls for source compile and linking.
Kubuntu 24.04, Qt 5.15.3 or 6.7.2, CMake 3.28.3

Could be worth removing the option as an experiment. I expect that support for ASLR is a desirable in a browser though.

Soren Stoutner

@qt_usr, could you please install the .deb from the upstream website in your testing environment (assuming it will install) and check to see if you get the same error?

That .deb was built against Debian unstable. Assuming you do get the same error, I can produce another version for testing with the PIE linking code removed.

qt_usr

@Soren-Stoutner Hello,
using the .deb from the website (0.6.1) it starts!

Soren Stoutner

That is very interesting (and not what I was expecting). I think I will move this conversation back to the Launchpad bug as it appears to be some issue with how it was built for Ubuntu.

qt_usr

@Soren-Stoutner Fine. I noticed the Ubuntu repository's version is 0.6 while the website's version is 0.6.1. Let's go "back" to the launchpad bug for this.

Soren Stoutner

For exactness of comparison, you can load 0.6 from the upstream website. Although I don't expect any difference from 0.6.1.

qt_usr

@Soren-Stoutner Yes, I confirm. Also the v0.6 starts correctly if installed using the .deb pacakge from the website.