How to compile just a specific module from the qt source?

[Christian Ehrlicher]

Configure Qt and then go into the subdir you want to have to get recompiled (when you use NMake Makefiles) or simply tell ninja what module it should build (e.g. ninja Widgets) when you use Ninja.

[Roberrt]

@Christian-Ehrlicher If i modify a single line in any file inside qtbase\src\widgets\kernel i need to recompile the entire widgets module? isn't possible somehow to recompile just the kernel folder?

[Christian Ehrlicher]

@Roberrt said in How to compile just a specific module from the qt source?:

? isn't possible somehow to recompile just the kernel folder?

I don't understand your question - every useful build system I'm aware of only re-builds the source files which were modified.

[Roberrt]

@Christian-Ehrlicher Then im doing something wrong because its recompiling everything instead of just the modified file. I will delete everything and try again.

[Roberrt]

I have modified a kernel file and when i run

D:\Qt\qt-everywhere-src-6.4.0>cmake --build . --target Widgets
ninja: no work to do.

It just say "no work to do" what im missing?

[Christian Ehrlicher]

I would use ninja Widgets but it should be the same. I would guess you did not modify anything inside the source dir for this build directory but somewhere else.

[SGaist]

Hi,

The kernel subfolder is not a module in itself. Depending on what you modified there, there will likely be several classes that need to be rebuilt, possibly through several modules.

That said, if you are only working on the widgets module, you can simply build only qtbase.

[Roberrt]

It worked after calling the configure command again

configure.bat -debug -platform win32-msvc -opensource -confirm-license -prefix "D:\Qt\Debug"

But now i'm getting tons of compile errors like:

@HPEAPEAX@Z)
1>moc_MainWindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: static struct QMetaObject const QMainWindow::staticMetaObject" (__imp_?staticMetaObject@QMainWindow@@2UQMetaObject@@B) referenced in function "public: static struct QMetaObject const * __cdecl QMetaObject::staticMetaObject<&public: static struct QMetaObject const

I also tried rebuild solution/clean solution, still getting the errors.
I'm getting these errors on all existing projects i have.
When i create a new project i get no error.

I'm building on vs 2022.

[JoeCFD]

@Roberrt
http://bin.ceicer.com/qt/Windows/Qt5.15.9_msvc_shared_64-bit/readme.txt
https://forum.qt.io/topic/144231/qt5-15-9-linux-and-windows-compiled-source-code?_=1681152916124

[Lightshadown]

Hi i got a similar situation but im compiling on rpi3, i did follow this tutorial tutorial rpi3 Qt, its posible to just compile and add a platform instead of recompile all the framework?, forgot to add -eglfs meabe something like
./configure -eglfs ? is that posible or do i need to start all over from scracht, last time took me like 30h just to compile

my compile command was as follow

../qt-everywhere-src-5.12.10/configure -platform linux-rpi-g++ \
-v \
-no-gtk \
-opensource -confirm-license -release \
-reduce-exports \
-force-pkg-config \
-nomake examples -no-compile-examples \
-skip qtwayland \
-skip qtwebengine \
-no-feature-geoservices_mapboxgl \
-qt-pcre \
-no-pch \
-ssl \
-evdev \
-system-freetype \
-fontconfig \
-glib \
-prefix /opt/Qt/5.12.10 \
-qpa eglfs

[Roberrt]

I found the cause of the errors, i compiled the new source using the x86 Native Tools Command Prompt for VS 2022 instead of the x64, it end up generating x32 exe.

Whenever I modify a source file and call ninja Widgets to it get compiled, it get compiled quickly < 1min
afterward i'm calling npm --install . to get the recompiled file copied from the qt-everywhere-src-6.4.0 folder to the D:\Qt\Debug

But this task is taking a lot of time, it is iterating through thousand files checking which are not updated:

-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_formeditorcommand_p.h
-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_formwindowcommand_p.h
-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_formwindowmanager_p.h
-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_introspection_p.h
-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_membersheet_p.h
-- Up-to-date: D:/Qt/Debug/include/QtDesigner/6.4.0/QtDesigner/private/qdesigner_menu_p.h
...

Am i doing this correctly?
There's another way to copy directly the file that got modified/recompiled instead of checking one by one which the command --install .?