New Qt installation, simple QWidget App does not compile

Andy314 · 5 Apr 2025, 11:00

@HQ2000 said in New Qt installation, simple QWidget App does not compile:

Hi @Andy314 ,
As a Qt Beginner I do wonder why your path is "D:..." instead of "C:..." since you say you have you have set up Qt at the C: directory...
When searching for this path ("D" replaced with "C") in my own Qt6.9.0 installation, I flawlessly find this file.
Correct me if I didn't understand your problem correctly.

My old working installation is on C: and my new on D:
I must remain able to work for my job. Only when the new version works correctly will I delete the old one.
Since years I make the update in this way and had never problems with it.

HQ2000 · 5 Apr 2025, 11:02

@Andy314
Ah, ok. I'm still a beginner as mentioned before, but aren't there some other settings in QtCreator you need to change if you want to use another installation? Or do you use the QTCreator you potentially installed with the new installation in D:?

Andy314 · 5 Apr 2025, 13:01

@HQ2000 said in New Qt installation, simple QWidget App does not compile:

@Andy314
Ah, ok. I'm still a beginner as mentioned before, but aren't there some other settings in QtCreator you need to change if you want to use another installation? Or do you use the QTCreator you potentially installed with the new installation in D:?

Switching to a newer Qt version is unproblematic. You install additional new kits (Qt Version) in the Creator an try it out.
But from time to time I make a complete new full installation inclusive a new creator. (Of course the creator itself is updatable too but this is to much risk for me and sometimes its better to start from the scatch to get rid of old stuff)
The new Creator copys most settings from the old installation automatically. So parallel working with 2 versions of the Creator+Qt is umproblematic.
The maintaince tool for every version installs the packages for in correct creator in its corrosponding pathes.

Axel Spoerl

Can you post you CMakeLists.txt or .pro file?

Andy314

@Axel-Spoerl said in New Qt installation, simple QWidget App does not compile:

Can you post you CMakeLists.txt or .pro file?

Her is the pro file:

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++17

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    MainWindow.cpp

HEADERS += \
    MainWindow.h

FORMS += \
    MainWindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

hskoglund

Maybe you need to delete your .pro.user file when switching your project from one QtCreator to another QtCreator.

Andy314

@hskoglund said in New Qt installation, simple QWidget App does not compile:

Maybe you need to delete your .pro.user file when switching your project from one QtCreator to another QtCreator.

Done multiple time. Deleting complete build folder. No effect !

jsulm

@Andy314 said in New Qt installation, simple QWidget App does not compile:

Deleting complete build folder

Not the build folder, the .pro.user file in the project directory.

Andy314

@jsulm said in New Qt installation, simple QWidget App does not compile:

@Andy314 said in New Qt installation, simple QWidget App does not compile:

Deleting complete build folder

Not the build folder, the .pro.user file in the project directory.

Yes I did it too.

Andy314

Some effects I found. I can compile all my old projects with Qt 5.15.2 with qmake.
A new qmake test project or additional kid for my old projects do run never !
So the problem seem to be creation a new projekt independent of Qt version.

On the other side cmake projects work all.

The error occurs befor real compiling of a cpp-file starts. If it put an error in the first line of a file and compile this, I dont get this error. I get only :

-1: Fehler: dependent '..\..\..\..\..\..\Qt\6.5.3\msvc2019_64\include\QtWidgets\QMainWindow'
 does not exist

For some projects I get:

:-1: Fehler: dependent '..\..\..\..\..\Qt\6.8.3\msvc2022_64\include\QtWidgets\QWidget' does not exist.

What kind of errors are this. It is not a compiler nor a linker error. It seem a "project-build-error".

aha_1980

@Andy314 I have seen this kind of error when the build directory is below the source directory, and it does not happen when the build directory is parallel to the source directory (as QtCreator forced it for a long time).

So the project: C:\Users\user\projects\foo should have a build dir C:\Users\user\projects\build-foo.

Please try to setup the project again, and change the path to the build directory in the project settings before compiling.

Andy314

@aha_1980 said in New Qt installation, simple QWidget App does not compile:

@Andy314 I have seen this kind of error when the build directory is below the source directory, and it does not happen when the build directory is parallel to the source directory (as QtCreator forced it for a long time).

So the project: C:\Users\user\projects\foo should have a build dir C:\Users\user\projects\build-foo.

Please try to setup the project again, and change the path to the build directory in the project settings before compiling.

Oh man, thank you very much. This is the solution !
I am happy.

In my old projects I configure it always in that way, because I hate to mix source and target -> complicated (large) repository/backup etc.

But how stupid is that bug of the buildsysthem - default configuration creates a brocken project.
I assume this is not a inescapable bug, other condition may contribute their part.

aha_1980

@Andy314 I agree this is a stupid bug, but as qmake gets lower and lower support I doubt there will be a fix.

If you like, you can still report a bug but I don't think it will be high priority.

lijihong

@aha_1980 :

-1: error: dependent '..\..\..\..\..\..\qt\QT\6.9.0\msvc2022_64\include\QtWidgets\QMainWindow' does not exist.

Hello, may I ask my question is also this, what do I need to change?

jsulm

@lijihong said in New Qt installation, simple QWidget App does not compile:

what do I need to change?

Did you read what @aha_1980 wrote?
Make sure your build folder is NOT inside the source folder.

lijihong

@jsulm
Nice, thank you, I tried to build the MSVC2022 project in QtCreaator, this problem has been bothering me, and now it has finally been solved, the same project Visual Studio can run, I want to switch the IDE, hahahahaha