QApplication: No such file or directory

[avnishsachar]

I have appropriately added QtWidgets to my CMakeLists.txt file but when I run make, it throws back the above-mentioned error. Everything works perfectly fine when I try the same with QGuiApplication though. Attaching the header file where I include QApplication (It works perfectly fine when I don't include QApplication). I don't understand where I am going wrong. Appreciate any help!

#ifndef IGNITION_GUI_QT_H_
#define IGNITION_GUI_QT_H_

#ifndef _MSC_VER
#pragma GCC system_header
#endif

#include <QtCore>
#include <QtGui>

#include <QGuiApplication>
#include <QApplication>

#include <QOffscreenSurface>
#include <QOpenGLFunctions>

#include <QQmlApplicationEngine>
#include <QQmlComponent>
#include <QQmlContext>
#include <QQmlEngine>

#include <QQuickItem>
#include <QQuickStyle>
#include <QQuickWindow>

#include <QSGSimpleTextureNode>
#include <QStandardItemModel>


#endif  // IGNITION_GUI_QT_H_

[avnishsachar]

There seems to be a problem with QtGui. As it cannot seem to locate QtGui either.

[SGaist]

Hi and welcome to devnet,

What version of Qt ?
What version of cmake ?
How did you install both ?
What OS ?
What is the content of your CMakeList.txt ?

[avnishsachar]

Hi, thanks for welcoming me!
Apologies for not sharing the information in the post.
Qt version 5.9.5
cmake version 3.10.2
I installed them using apt-get (used qt5-default)
I'm running Ubuntu Bionic
My CMakeLists.txt:

include_directories(
  ${Qt5Core_INCLUDE_DIRS}
  ${Qt5Widgets_INCLUDE_DIRS}
  ${tinyxml_INCLUDE_DIRS}
  ${Qt5Qml_INCLUDE_DIRS}
  ${Qt5Quick_INCLUDE_DIRS}
  ${Qt5QuickControls2_INCLUDE_DIRS}
)

set (CMAKE_AUTOMOC ON)

add_definitions(
  ${Qt5Core_DEFINITIONS}
  ${Qt5Widgets_DEFINITIONS}
  ${Qt5Qml_DEFINITIONS}
  ${Qt5Quick_DEFINITIONS}
  ${Qt5QuickControls2_DEFINITIONS}
)

set (qt_headers
  Application.hh
  Dialog.hh
  MainWindow.hh
  Plugin.hh
)

set (headers
  Conversions.hh
  DragDropModel.hh
  Enums.hh
  Helpers.hh
  ign.hh
  qt.h
  SearchModel.hh
  System.hh
)

set (resources resources.qrc)

QT5_WRAP_CPP(headers_MOC ${qt_headers})
QT5_ADD_RESOURCES(resources_RCC ${resources})

ign_create_core_library(SOURCES
  ${sources}
  ${headers_MOC}
  ${resources_RCC}
  CXX_STANDARD 17
)

target_link_libraries(${PROJECT_LIBRARY_TARGET_NAME}
  PUBLIC
    ${IGNITION-COMMON_LIBRARIES}
    ${IGNITION-MATH_LIBRARIES}
    ${IGNITION-MSGS_LIBRARIES}
    ignition-plugin${IGN_PLUGIN_VER}::loader
    ${IGNITION-TRANSPORT_LIBRARIES}
    ${Qt5Core_LIBRARIES}
    ${Qt5Widgets_LIBRARIES}
    ${Qt5Qml_LIBRARIES}
    ${Qt5Quick_LIBRARIES}
    ${Qt5QuickControls2_LIBRARIES}
    TINYXML2::TINYXML2
)

add_subdirectory(plugins)

ign_install_all_headers(EXCLUDE_DIRS plugins)

Please let me know in case more info. is needed. Thanks!

[avnishsachar]

Solved the issue. I had not added Qt5Widgets to find_package in a top-level CMakeLists.txt.

[ArantxaES]

I have the same issue but now with Qt6.

• OS: Ubuntu 24.0.1
• Qt: Creator 6.7.3
• Compiler: gcc/g++ 13.2
• IDE: MS Visual Studio Code (from snap)
• Extensions installed in MVSC: ms-vscode.cpptools, twxs.cmake, ms-vscode.cmake-tools, theqtcompany.qt, theqtcompany.qt-cpp-pack and tonka3000.qtvsctools
• Qt's installation folder: home/Qt/
• Qt example's folder: home/Qt/Examples/Qt-6.7.3/widgets/widgets/calculator/

I'm trying to run this example using CMakeLists.txt and c_cpp_properties.json.
c_cpp_properties.json in .vscode:

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/**",
                "/home/arantxa/Qt/6.7.3/gcc_64/include/**",
                "/home/arantxa/Qt/6.7.3/gcc_64/include/QtWidgets/"
            ],
            "defines": [],
            "compilerPath": "/usr/bin/gcc",
            "cStandard": "c17",
            "cppStandard": "gnu++17",
            "intelliSenseMode": "linux-gcc-x64"
        }
    ],
    "version": 4
}

The top-level CMakeLists.txt:

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

cmake_minimum_required(VERSION 3.16)
project(calculator LANGUAGES CXX)

find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets)

qt_standard_project_setup()

qt_add_executable(calculator
    button.cpp button.h
    calculator.cpp calculator.h
    main.cpp
)

set_target_properties(calculator PROPERTIES
    WIN32_EXECUTABLE TRUE
    MACOSX_BUNDLE TRUE
)

target_link_libraries(calculator PRIVATE
    Qt6::Core
    Qt6::Gui
    Qt6::Widgets
)

install(TARGETS calculator
    BUNDLE  DESTINATION .
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
)

qt_generate_deploy_app_script(
    TARGET calculator
    OUTPUT_SCRIPT deploy_script
    NO_UNSUPPORTED_PLATFORM_ERROR
)
install(SCRIPT ${deploy_script})

Everything that is required, every include, is listed! I'm not sure what should I do.