How to build the 3rd party libraries in Qt's source code?

Diracsbracket

Hi.
I am faced with bug QTBUG-86704 which prevents remote debugging in Qt 5.15.1.

It is suggested there that patching the code in
Qt/5.15.1/Src/qtbase/src/3rdparty/forkfd/forkfd_linux.c

works around this apparently known gdb bug.

Am I correct to assume that I only need to patch this on the remote Qt installation and not on the host?

My actual question is this: how do I build the forkfd library in the 3rdparty folder of Qt's sources?

Although this library is not mentioned in the Qt docs
https://doc.qt.io/qt-5/configure-options.html
nor in configure -help, I naively tried to add the following to my configure line:

-qt-forkfd

However, that does not work, and configure returns with:

ERROR: Unknown command line option '-qt-forkfd'.

Thanks for your help!

jsulm

@Diracsbracket said in How to build the 3rd party libraries in Qt's source code?:

My actual question is this: how do I build the forkfd library in the 3rdparty folder of Qt's sources?

I guess you simply apply the patch and build qtbase...

Diracsbracket

@jsulm said in How to build the 3rd party libraries in Qt's source code?:

I guess you simply apply the patch and build qtbase...

When I do the normal configure, the build shadow dir does not contain any folder nor file with reference to it, and just a few matches to 3rdparty

build$ grep -r "forkfd"
dirac@buster:~/raspi/qt-everywhere-src-5.15.1/build$ grep -r "3rdparty"
Binary file qtbase/qmake/qcborstreamwriter.o matches
Binary file qtbase/qmake/qcryptographichash.o matches
Binary file qtbase/qmake/qlocale_tools.o matches
qtbase/qmake/Makefile:	   -I$(SOURCE_PATH)/src/3rdparty/tinycbor/src \
Binary file qtbase/bin/qmake matches
dirac@buster:~/raspi/qt-everywhere-src-5.15.1/build$

Diracsbracket

@jsulm
I applied the patch and rebuild the whole thing (since I don't know how to build qtbase alone using configure), and that solves the problem.
Also, the patch seems to have been applied in version Qt5.15.2 as the updated comment of QTBUG-86704 indicates.

However, remote debugging on the Pi 4 is not really stable it seems, possibly due to a buggy PiOS/Raspbian GDB implementation.