Built Qt6 from sources, problem with xcb plugin

[SGaist]

Don't you have some CMakeError.log files around ?

[mnesarco]

The compilation has no errors, the problem is that platform plugin for xcb is not generated.

➜  build ls -al
total 37248
drwxr-xr-x 17 mnesarco mnesarco     4096 Dec  2 14:26 .
drwxrwxr-x  5 mnesarco mnesarco     4096 Dec  2 11:50 ..
-rw-r--r--  1 mnesarco mnesarco 18076483 Dec  2 14:26 build.ninja
-rw-r--r--  1 mnesarco mnesarco   320652 Dec  2 14:26 CMakeCache.txt
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 CMakeFiles
-rw-r--r--  1 mnesarco mnesarco     4430 Dec  2 13:19 cmake_install.cmake
-rw-r--r--  1 mnesarco mnesarco      129 Dec  2 14:26 config.opt
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 11:55 config.tests
-rw-r--r--  1 mnesarco mnesarco      633 Dec  2 12:56 CTestTestfile.cmake
-rw-r--r--  1 mnesarco mnesarco   977889 Dec  2 12:25 install_manifest.txt
-rw-r--r--  1 mnesarco mnesarco 17585308 Dec  2 14:35 .ninja_deps
-rw-r--r--  1 mnesarco mnesarco  1082507 Dec  2 14:35 .ninja_log
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qt5compat
drwxr-xr-x 14 mnesarco mnesarco     4096 Dec  2 14:26 qtbase
drwxr-xr-x  5 mnesarco mnesarco     4096 Dec  2 14:26 qtdeclarative
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qtdoc
drwxr-xr-x  3 mnesarco mnesarco     4096 Dec  2 14:26 qtqa
drwxr-xr-x  5 mnesarco mnesarco     4096 Dec  2 14:26 qtquick3d
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qtquickcontrols2
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qtquicktimeline
drwxr-xr-x  5 mnesarco mnesarco     4096 Dec  2 14:26 qtshadertools
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qtsvg
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qttools
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 14:26 qttranslations
drwxr-xr-x  4 mnesarco mnesarco     4096 Dec  2 12:00 qtwaylan

[Christian Ehrlicher]

@mnesarco said in Built Qt6 from sources, problem with xcb plugin:

XCB Xlib ............................. no

Apart from what you're saying but it looks like some of the required xcb stuff is not found.

[mnesarco]

@Christian-Ehrlicher It is obvious, some xcb stuff is not found, the question is what. Because ./configure reports a lot of crap like this:

-- Found XCB: /usr/lib/x86_64-linux-gnu/libxcb.so;/usr/lib/x86_64-lin...

[mnesarco]

I have found CMakeError.log and CMakeOutput.log, they have a lot of things but nothing related with xcb.

[Christian Ehrlicher]

According to the config file XCB xlib needs:

        "xcb_xlib": {
            "label": "XCB Xlib",
            "test": {
                "main": "(void) XGetXCBConnection((Display *)0);"
            },
            "headers": "X11/Xlib-xcb.h",
            "sources": [
                { "type": "pkgConfig", "args": "x11-xcb" },
                "-lX11-xcb"
            ],
            "use": "xcb xlib"

[mnesarco]

It is installed:

➜  qtbase dpkg -la | grep Xlib
ii  libx11-xcb-dev:amd64                       2:1.6.4-3ubuntu0.3                                              amd64        Xlib/XCB interface library (development headers)
ii  libx11-xcb1:amd64                          2:1.6.4-3ubuntu0.3                                              amd64        Xlib/XCB interface library

[Christian Ehrlicher]

Try to search for some output of those values inside CMakeFiles subdir and try to compile this

#include <X11/Xlib-xcb.h>

int main(int, char**)
{
  (void) XGetXCBConnection((Display *)0);
  return 0;
}

g++ main.cpp -lX11-xcb

[mnesarco]

@Christian-Ehrlicher said in Built Qt6 from sources, problem with xcb plugin:

#include <X11/Xlib-xcb.h>

int main(int, char**)
{
(void) XGetXCBConnection((Display *)0);
return 0;
}

➜  test99 vi test.cpp 
➜  test99 c++ test.cpp -lX11-xcb
➜  test99 ./a.out 
[1]    12914 segmentation fault (core dumped)  ./a.out
➜  test99 
It compiles, but segfault on run.

[Christian Ehrlicher]

Doesn't matter that it does not execute - cmake only checks if it compiles and links. Sorry you have to dig though the CMakeFiles directory.

[mnesarco]

Apparently it was some kind of cache problem. Because I deleted the build folder, opened a new terminal a build from scratch and:

Features used by QPA backends:
  evdev .................................. yes
  libinput ............................... yes
  INTEGRITY HID .......................... no
  mtdev .................................. yes
  tslib .................................. no
  xkbcommon .............................. yes
  X11 specific:
    XLib ................................. yes
    XCB Xlib ............................. yes
    EGL on X11 ........................... yes
    xkbcommon-x11 ........................ yes
QPA backends:
  DirectFB ............................... no
  EGLFS .................................. yes
  EGLFS details:
    EGLFS OpenWFD ........................ no
    EGLFS i.Mx6 .......................... no
    EGLFS i.Mx6 Wayland .................. no
    EGLFS RCAR ........................... no
    EGLFS EGLDevice ...................... yes
    EGLFS GBM ............................ no
    EGLFS VSP2 ........................... no
    EGLFS Mali ........................... no
    EGLFS Raspberry Pi ................... no
    EGLFS X11 ............................ yes
  LinuxFB ................................ yes
  VNC .................................... yes
  QNX:
    lgmon ................................ no
    IMF .................................. no
  XCB:
    Using system-provided xcb-xinput ..... yes
    Native painting (experimental) ....... no
    GL integrations:
      GLX Plugin ......................... yes
        XCB GLX .......................... yes
      EGL-X11 Plugin ..................... yes
  Windows:
    Direct 2D ............................ no
    Direct 2D 1.1 ........................ no
    DirectWrite .......................... no
    DirectWrite 3 ........................ no

It is building, so I will report if succeed.

[mnesarco]

I can confirm that it worked. So which was exactly the missing dependency I don't know. But after installing all the mentioned libraries and build from scratch on an empty build directory, it worked.

[SGaist]

As the configure scripts prints at the end: if you re-run configure, you have to clean first. Otherwise you may have leftovers from your previous configure/build attempt that will make it so that not all tests are rerun.

[extollIT Enterprises]

@mnesarco I think it's worth mentioning (on an old thread) that in my case the (erroneously) missing dependencies included XCB GLX and xcb-sm (maybe others). It's important to pay careful attention to the output from ./configure and compare.