Trouble building Qt

[Massi]

Hello
I ran qmake and try to build the project and I'm getting this. Can anybody explain me why I'm getting this error?

[Pl45m4]

@Massi

Try clean and re-build / run qmake again. Alternatively delete build folder.
That should fix this in most cases.

Just to be sure: Is your UI from type Ui::MainWindow or Ui::ImageReader? Therefore show your header and your *.pro file please. Also better post code as code block not as image

[Massi]

@Pl45m4 Thanks for your reply! I've tried to clean and rebuild but I got this error

:-1: error: No rule to make target '/usr/lib/qt5/bin/uic', needed by 'ui_ImageReader.h'.  Stop.

here is my simple code:

#ifndef IMAGEREADER_H
#define IMAGEREADER_H

#include <QMainWindow>
#include <memory>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow() = default;

private:
    std::unique_ptr<Ui::MainWindow> ui;
};
#endif // IMAGEREADER_H

cpp:

#include "ImageReader.h"
#include "ui_ImageReader.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

The objectName of the ui is MainWindow

.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 += \
    ImageReader.cpp \
    main.cpp

HEADERS += \
    ImageReader.h

FORMS += \
    ImageReader.ui

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

[SGaist]

Hi,

Did you just rename the files after having created them ? If so, that is not a good idea.

[Massi]

@SGaist Yes I did that, what should it be a problem if you don't mind asking?

[Massi]

@SGaist
I'm using Ubuntu 20.04 and I have installed qt5, I created a new empty project and I got this error again:

:-1: error: No rule to make target '/usr/lib/qt5/bin/uic', needed by 'ui_mainwindow.h'.  Stop.

something is wrong with my installation right?

[Massi]

@SGaist Get it worked
that was my problem: https://forum.qt.io/topic/127696/qt-qpa-plugin-could-not-load-the-qt-platform-plugin-xcb-in-even-though-it-was-found/28

[SGaist]

That's pretty surprising as the solution you link to is completely unrelated to your original problem.

[Massi]

@SGaist I restarted from scratch, deleted the build folder and created a new project. I ran qmake first and tried to build the project but this time I got this error:

qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

I just installed the xcb dependency and it built correctly. I still dont know/understand why I got the first error with the ui file?

[jsulm]

@Massi Set QT_DEBUG_PLUGINS env variable before starting your app and check its output to see why XCB plug-in can't be loaded. Is X server running?