how to fix linker error in eclipse on linux

micha_eleric · 22 Feb 2022, 08:59

@JonB it seems i already installed qt5. just it is not showing up under /usr/include

jsulm · 22 Feb 2022, 09:05

@micha_eleric said in how to fix linker error in eclipse on linux:

i already installed qt5

What exactly? Which qt5 packages?
" just it is not showing up under /usr/include" - as I already told you b efore the libraries will NOT show up in that directory. Search for the qt5 libs like I suggested before:

find /usr/lib -name *qt5*
find /usr/lib64 -name *qt5*

Don't forget to also change include folders in your set-up as currently you use qt4 include folder.

micha_eleric · 22 Feb 2022, 09:06

@jsulm said in how to fix linker error in eclipse on linux:

find /usr/lib -name qt5

michaeleric@michaeleric-C7B250-CB-ML:/usr/lib$ find -name qt5
./qt5
./x86_64-linux-gnu/qt5
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib$ cd /
michaeleric@michaeleric-C7B250-CB-ML:/$ cd /usr/lib64
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib64$ find -name qt5
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib64$

jsulm · 22 Feb 2022, 09:11

@micha_eleric Please read again what I suggested (hint: * is important)...

micha_eleric · 22 Feb 2022, 09:13

@jsulm the * was used, copied, pasted, but did not show on post.

jsulm · 22 Feb 2022, 09:15

@micha_eleric Can you please answer questions?
I asked before: What exactly? Which qt5 packages?

micha_eleric · 22 Feb 2022, 09:21

@jsulm sudo apt-get install qt5-default
from:
https://wiki.qt.io/Install_Qt_5_on_Ubuntu

jsulm · wrote on 22 Feb 2022, 09:21

@micha_eleric On my Ubuntu machine Qt5 libs are in /lib/x86_64-linux-gnu
Like /lib/x86_64-linux-gnu/libQt5Widgets.so.5

JonB · 22 Feb 2022, 09:28

@micha_eleric said in how to fix linker error in eclipse on linux:

@jsulm the * was used, copied, pasted, but did not show on post.

find /usr/lib -name *qt5*
find /usr/lib64 -name *qt5*

You must quote these from the shell's expansion:

find /usr/lib -name '*Qt5*'
find /usr/lib64 -name '*Qt5*'

Or you might find this useful:

locate Qt5

jsulm · 22 Feb 2022, 09:33

@JonB It is Qt not qt in lib names, so was my mistake

JonB · 22 Feb 2022, 09:51

@jsulm
I have edited my response to use Qt5. But the quoting is still necessary!? https://man7.org/linux/man-pages/man1/find.1.html :

The filename matching is performed
with the use of the fnmatch(3) library function. Don't
forget to enclose the pattern in quotes in order to
protect it from expansion by the shell.

micha_eleric · 22 Feb 2022, 09:50

@jsulm michaeleric@michaeleric-C7B250-CB-ML:~$ find /usr/lib -name *Qt5 *
/usr/lib/python3/dist-packages/PyQt5
/usr/lib/python3/dist-packages/PyQt5-5.14.1.dist-info
/usr/lib/x86_64-linux-gnu/libQt5GlxSupport.a
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5LinuxAccessibilitySupport.a
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5
/usr/lib/x86_64-linux-gnu/libQt5ThemeSupport.a
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5AccessibilitySupport.a
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5EdidSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so
/usr/lib/x86_64-linux-gnu/libQt5PlatformCompositorSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so
/usr/lib/x86_64-linux-gnu/libQt5Network.so
/usr/lib/x86_64-linux-gnu/libQt5Xml.so
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5
/usr/lib/x86_64-linux-gnu/libQt5VulkanSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5ThemeSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5InputSupport.a
/usr/lib/x86_64-linux-gnu/libQt5GlxSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5
/usr/lib/x86_64-linux-gnu/libQt5VulkanSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5PluginTarget.cmake.in
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5BasicConfig.cmake.in
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5ConfigVersion.cmake.in
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5KmsSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5
/usr/lib/x86_64-linux-gnu/libQt5EventDispatcherSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Test.prl
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5.12.8
/usr/lib/x86_64-linux-gnu/cmake/Qt5TextToSpeech
/usr/lib/x86_64-linux-gnu/cmake/Qt5TextToSpeech/Qt5TextToSpeech_QTextToSpeechEngineFlite.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL/Qt5OpenGLConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupportConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupport_QCupsPrinterSupportPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupportConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql/Qt5SqlConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql/Qt5SqlConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions/Qt5OpenGLExtensionsConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions/Qt5OpenGLExtensionsConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevMousePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QTuioTouchPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevKeyboardPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSKmsGbmIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbEglIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSKmsEglDeviceIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QComposePlatformInputContextPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QIbusPlatformInputContextPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QVncIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevTouchScreenPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbGlxIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevTabletPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSX11IntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSEmulatorIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QGifPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QMinimalIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QOffscreenIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QICOPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QMinimalEglIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QLinuxFbIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QLibInputPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QJpegPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort/Qt5SerialPortConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort/Qt5SerialPortConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QGenericEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5NetworkConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QNetworkManagerEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QConnmanEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5NetworkConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CTestMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigExtrasMkspecDir.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent/Qt5ConcurrentConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent/Qt5ConcurrentConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml/Qt5XmlConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml/Qt5XmlConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5ConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5ModuleLocation.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5Config.cmake
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Xml.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Widgets.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Test.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Sql.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Core.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5SerialPort.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Concurrent.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Gui.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Network.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5DBus.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5PrintSupport.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5OpenGLExtensions.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5OpenGL.pc
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5
/usr/lib/x86_64-linux-gnu/libQt5Gui.prl
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DeviceDiscoverySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5
/usr/lib/x86_64-linux-gnu/libQt5EventDispatcherSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5EglSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so
/usr/lib/x86_64-linux-gnu/libQt5DBus.prl
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5
/usr/lib/x86_64-linux-gnu/libQt5Xml.prl
/usr/lib/x86_64-linux-gnu/libQt5AccessibilitySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5PlatformCompositorSupport.a
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.prl
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5FbSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5ServiceSupport.a
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.prl
/usr/lib/x86_64-linux-gnu/libQt5Test.so
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5FontDatabaseSupport.a
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Network.prl
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Gui.so
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.so
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so
/usr/lib/x86_64-linux-gnu/libQt5Sql.so
/usr/lib/x86_64-linux-gnu/libQt5EdidSupport.a
/usr/lib/x86_64-linux-gnu/libQt5DeviceDiscoverySupport.a
/usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5.212.0
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5
/usr/lib/x86_64-linux-gnu/libQt5InputSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5
/usr/lib/x86_64-linux-gnu/libQt5FontDatabaseSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5OpenGLExtensions.prl
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.prl
/usr/lib/x86_64-linux-gnu/libQt5Sql.prl
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.prl
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.so.5.212.0
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.prl
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5
/usr/lib/x86_64-linux-gnu/libQt5FbSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5ServiceSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5OpenGLExtensions.a
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Widgets.prl
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5LinuxAccessibilitySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DBus.so
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.prl
/usr/lib/x86_64-linux-gnu/libQt5KmsSupport.a
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.12
michaeleric@michaeleric-C7B250-CB-ML:~$

jsulm · wrote on 22 Feb 2022, 09:50

@micha_eleric So, now you know in which folder the Qt libs are located

jsulm · 22 Feb 2022, 09:59

@JonB said in how to fix linker error in eclipse on linux:

But the quoting is still necessary!?

For me both work on Ubuntu with GNU find (both have same amount of matches)

JonB · 23 Feb 2022, 00:02

@jsulm
Sorry I cannot leave this statement as-is! As we discussed privately, your unquoted behaviour of *Qt* will generate totally different results depending on whether the current directory does or does not contain any filenames matching *Qt*. Which is not what is desired for this search. ALWAYS quote wildcards (*, ?) you are passing to a command like find if you expect it to work correctly robustly.... :)

P.S.
If anyone does not believe me: before running the command do a touch Qt5 in the directory you run find /usr/lib -name '*Qt5*' versus find /usr/lib -name *Qt5* from., and compare the results...

micha_eleric · 23 Feb 2022, 09:45

@JonB for me, find /usr/lib -name'*Qt5 *', anr find /usr/lib -name *Qt5 * had same results. [note] no space between 5 and *

micha_eleric · 23 Feb 2022, 05:13

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/qt5
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/qt5

both have libraries, but no clue if i have to add a specific file, or just the dir it is in

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/libQtCore
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/libQtCore
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/libQtCore.so
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/libQtCore.so

it can not find a library, so i have to be doing something wrong

micha_eleric · wrote on 23 Feb 2022, 04:52

michaeleric@michaeleric-C7B250-CB-ML:~$ sudo find / -name '*MainWindow *'
[sudo] password for michaeleric:
/home/michaeleric/eclipse-workspace/GUI/CUi_MainWindow.h
find: ‘/run/user/1000/doc’: Permission denied
/usr/share/doc/HTML/ca/spectacle/MainWindow.png
/usr/share/doc/HTML/uk/spectacle/MainWindow.png
/usr/share/doc/HTML/en/spectacle/MainWindow.png
/usr/include/qt4/Qt3Support/Q3MainWindow
/usr/include/qt4/QtGui/QMainWindow
/usr/include/x86_64-linux-gnu/qt5/QtWidgets/QMainWindow
michaeleric@michaeleric-C7B250-CB-ML:~$

there are no .h files for QMainWindow under Qt5 anywhere, thus why i was using Qt4, and thought Qt4 was installed.
error is about undefined reference to `QMainWindow:
i am looking around for a needle in a haystack, but dont know what the needle looks like, nor which haystack

jsulm · 23 Feb 2022, 05:27

@micha_eleric said in how to fix linker error in eclipse on linux:

it can not find a library

Please post the error message.

"there are no .h files for QMainWindow under Qt5 anywhere" - of course there is if you installed qtwidgets module, see https://doc.qt.io/qt-5/qmainwindow.html

I'm wondering: why don't you use a proper build system like qmake or CMake instead hacking around with manual settings?

micha_eleric · 23 Feb 2022, 05:32

@jsulm

using eclipse on linux
error, i am mostly sure is an eclipse issue, and not a programming issue.

g++ -L/usr/include/qt4 -L/usr/include/qt4/QtSerialPort -L/usr/include/qt4/QtGui -o "GUI2" ./src/CGUI.o ./src/Main.o
/usr/bin/ld: ./src/CGUI.o: in function CGUI::CGUI()': /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:10: undefined reference toQMainWindow::QMainWindow(QWidget*, QFlagsQt::WindowType)'
/usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:10: undefined reference to vtable for CGUI' /usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:10: undefined reference tovtable for CGUI'
/usr/bin/ld: ./src/CGUI.o: in function CGUI::~CGUI()': /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:15: undefined reference tovtable for CGUI'
/usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:15: undefined reference to vtable for CGUI' /usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/CGUI.cpp:15: undefined reference toQMainWindow::~QMainWindow()'
/usr/bin/ld: ./src/Main.o: in function main': /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/Main.cpp:14: undefined reference toQApplication::QApplication(int&, char**, int)'
/usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/Main.cpp:17: undefined reference to QApplication::exec()' /usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/Main.cpp:14: undefined reference toQApplication::~QApplication()'
/usr/bin/ld: /home/michaeleric/eclipse-workspace/GUI2/Debug/../src/Main.cpp:14: undefined reference to `QApplication::~QApplication()'
collect2: error: ld returned 1 exit status
make: *** [makefile:47: GUI2] Error 1

based on https://forum.qt.io/topic/101400/qt-with-eclipse-c/5 , i added QtCore and QtWidgets, even though there were no errors with #include<>. same errors from compile.

https://stackoverflow.com/questions/6478317/eclipse-undefined-reference says it is a linker error

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->command: g++

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) [nothing]

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries search path (-L) /usr/include/qt4 /usr/include/qt4/QtWidgets /usr/include/qt4/QtCore /usr/include/qt4/QtSerialPort /usr/include/qt4/QtGui

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Miscellaneous->Linker flags [nothing]

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Miscellaneous->Other options (-Xlinker [option]) [nothing]

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Miscellaneous->Other objects [nothing]

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Shared Library Settings [nothing][nothing][nothing][nothing]

what is suppose to be added, and where?

if:
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/include/qt4/QtGui
error:
/usr/bin/ld: cannot find -l/usr/include/qt4/QtGui

if:
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Miscellaneous->Other options (-Xlinker [option]) /usr/include/qt4/QtGui
error:
/usr/bin/ld: cannot find /usr/include/qt4/QtGui: file format not recognized

if:
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Miscellaneous->Other objects /usr/include/qt4/QtGui
error:
/usr/bin/ld: cannot find /usr/include/qt4/QtGui: file format not recognized

if it is a virtual function that has to be defined, then what would it be, other than constructor/destructor?