Problem with linking to libQt6Network.so.6

[Perdrix]

I've got two executables, both built using CMake. Both specify:

target_link_libraries(${PROJECT_NAME} PRIVATE
    Qt6::Core
    Qt6::Gui
    Qt6::Widgets
    Qt6::Network
    Qt6::Charts
	DeepSkyStackerKernel
    ZClass
)

One runs just fine. The other gives me a nastygram:

/home/amonra/.vs/DSS/out/build/DeepSkyStackerLive/DeepSkyStackerLive: error while loading shared libraries: libQt6Network.so.6: cannot open shared object file: No such file or directory

Here's the result of running ldd on the two files:

amonra@styx:~/.vs/DSS/out/build/DeepSkyStackerLive$ ldd DeepSkyStackerLive
	linux-vdso.so.1 (0x00007ffe91193000)
	libQt6Charts.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Charts.so.6 (0x00007fa378953000)
	libcfitsio.so.10 => /usr/local/lib/libcfitsio.so.10 (0x00007fa378670000)
	libSmtpMime.so.2 => /usr/local/lib/libSmtpMime.so.2 (0x00007fa37862e000)
	libQt6Widgets.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Widgets.so.6 (0x00007fa377e85000)
	libQt6Gui.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Gui.so.6 (0x00007fa3773f5000)
	libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007fa3773bf000)
	libOpenGL.so.0 => /lib/x86_64-linux-gnu/libOpenGL.so.0 (0x00007fa377393000)
	libQt6Core.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Core.so.6 (0x00007fa376cbc000)
	libgomp.so.1 => /lib/x86_64-linux-gnu/libgomp.so.1 (0x00007fa376c68000)
	libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fa3769fb000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa376914000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fa3768ee000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa3766c5000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fa379643000)
	libQt6OpenGLWidgets.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGLWidgets.so.6 (0x00007fa3766b3000)
	libQt6OpenGL.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGL.so.6 (0x00007fa376606000)
	libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007fa37657f000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fa37657a000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fa37655c000)
	libQt6Network.so.6 => not found
	libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007fa376515000)
	libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007fa376502000)
	libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007fa3764b8000)
	libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007fa376376000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fa376371000)
	libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fa376237000)
	libQt6DBus.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6DBus.so.6 (0x00007fa376165000)
	libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007fa37609d000)
	libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fa376098000)
	libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007fa375fde000)
	libicui18n.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicui18n.so.73 (0x00007fa375c8f000)
	libicuuc.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicuuc.so.73 (0x00007fa375a77000)
	libicudata.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicudata.so.73 (0x00007fa373be9000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007fa373b1a000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fa373b15000)
	libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007fa373ae2000)
	libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007fa373ad9000)
	libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fa373aaf000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fa373a39000)
	libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007fa3739eb000)
	libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007fa3739ae000)
	libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007fa3739a0000)
	libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007fa37399a000)
	libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fa373992000)
	libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007fa3738cb000)
	libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007fa3738a6000)
	libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007fa37388e000)
	liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007fa373863000)
	liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007fa373843000)
	libcap.so.2 => /lib/x86_64-linux-gnu/libcap.so.2 (0x00007fa373838000)
	libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007fa3736fa000)
	libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x00007fa3736eb000)
	libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007fa3736c5000)
amonra@styx:~/.vs/DSS/out/build/DeepSkyStackerLive$ cd ../DeepSkyStacker
amonra@styx:~/.vs/DSS/out/build/DeepSkyStacker$ ldd DeepSkyStacker
	linux-vdso.so.1 (0x00007ffcd5164000)
	libcfitsio.so.10 => /usr/local/lib/libcfitsio.so.10 (0x00007f898db61000)
	libQt6Widgets.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Widgets.so.6 (0x00007f898d3b8000)
	libQt6Gui.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Gui.so.6 (0x00007f898c928000)
	libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f898c8f4000)
	libOpenGL.so.0 => /lib/x86_64-linux-gnu/libOpenGL.so.0 (0x00007f898c8c8000)
	libQt6Network.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so.6 (0x00007f898c6b5000)
	libQt6Core.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Core.so.6 (0x00007f898bfde000)
	libgomp.so.1 => /lib/x86_64-linux-gnu/libgomp.so.1 (0x00007f898bf8a000)
	libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f898bd1d000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f898bc36000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f898bc12000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f898b9e7000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f898eb95000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f898b9cb000)
	libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007f898b944000)
	libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007f898b8fd000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f898b8f8000)
	libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007f898b8e5000)
	libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f898b899000)
	libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007f898b759000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f898b754000)
	libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f898b61a000)
	libQt6DBus.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6DBus.so.6 (0x00007f898b548000)
	libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f898b480000)
	libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f898b479000)
	libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007f898b3c1000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f898b2f2000)
	libgssapi_krb5.so.2 => /lib/x86_64-linux-gnu/libgssapi_krb5.so.2 (0x00007f898b29e000)
	libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007f898b28a000)
	libicui18n.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicui18n.so.73 (0x00007f898af39000)
	libicuuc.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicuuc.so.73 (0x00007f898ad21000)
	libicudata.so.73 => /opt/Qt/6.8.0/gcc_64/lib/libicudata.so.73 (0x00007f8988e93000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8988e8e000)
	libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f8988e5d000)
	libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f8988e52000)
	libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f8988e28000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f8988db2000)
	libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f8988d64000)
	libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007f8988d29000)
	libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007f8988d19000)
	libkrb5.so.3 => /lib/x86_64-linux-gnu/libkrb5.so.3 (0x00007f8988c4e000)
	libk5crypto.so.3 => /lib/x86_64-linux-gnu/libk5crypto.so.3 (0x00007f8988c1f000)
	libcom_err.so.2 => /lib/x86_64-linux-gnu/libcom_err.so.2 (0x00007f8988c19000)
	libkrb5support.so.0 => /lib/x86_64-linux-gnu/libkrb5support.so.0 (0x00007f8988c0b000)
	libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007f8988c03000)
	libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f8988bfb000)
	libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007f8988b34000)
	libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007f8988b11000)
	libkeyutils.so.1 => /lib/x86_64-linux-gnu/libkeyutils.so.1 (0x00007f8988b0a000)
	libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007f8988af0000)
	liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f8988ac5000)
	liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f8988aa5000)
	libcap.so.2 => /lib/x86_64-linux-gnu/libcap.so.2 (0x00007f8988a9a000)
	libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007f898895c000)
	libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x00007f898894f000)
	libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f8988927000)
amonra@styx:~/.vs/DSS/out/build/DeepSkyStacker$ 

Am I missing something blindingly obvious?

[JonB]

@Perdrix
I don't see "much" what this has to do with cmake. Link time is over, we are now talking about runtime. One of your outputs shows libQt6Network.so.6 => not found, hence the error, while the other shows libQt6Network.so.6 => /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so.6, so it works. Find out why one of them looks there and not the other. First check their environments (e.g. LD_LIBRARY_PATH) Maybe check the linker lines if you use the -Wl,-rpath=... linker thing for telling it where to look at runtime, see if they differ.

[Perdrix]

Well given that they were build using pretty much identical incantations, all under the same top level CMakeLists.txt file ... The environment should be identical as they are both from the same terminal session. I'm in no way skilled in the Linux world.

LD_LIBRARY_PATH is not set in the environment.

I don't specify any linker options for Linux build, should I?

ldconfig -p | grep Qt6

reports nothing
D.

[JonB]

@Perdrix

I would want to look at the full linker command line issued.

In this case I'm not sure whether rpath is the issue since other libraries are found in /opt/Qt/6.8.0/gcc_64/lib/.

I would save the output of the two ldds to separate files and diff them.

In the failing case you have libQt6OpenGL stuff but in the succeeding case you do not. Is that expected or relevant? Do you have multiple libQt6Network.so.6 files on your system. I would run ldd on the existing /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so.6 and look at its dependencies, could they be incompatible where it fails? Does ldd have an option to tell you why it fails, like where it looks and why it didn't find a file or failed its dependencies?

In the working case you are using OpenGL but not in the bad case?

[Perdrix]

I suspect that this may be a problem of library order - ISTR seeing somewhere that the Linux loader is a bit "quirky" about this. There's only ONE copy of libQt6Network.so in the system and that's in the expected location of /opt/Qt/6.8.0/gcc_64/lib.

Re: OpenGL, I have no clue why that's getting picked up, I don't call any OpenGL stuff from my code. Does Widgets use it under the covers for some things?

The difference is that DeepSkyStacker calls stuff that's in Qt6Network directly, while DeepSkyStackerLive doesn't: The calls to stuff in Qt6Network are made from code in another shared library libSmtpMime.so.2.

Is the loader so "brain dead" that it can't re-traverse the library list. If so how to specify the order of shared libraries when I link the application.

A PS to this: If I want to ship the Qt6 .so files in the same directory as my application do I need to specify -Wl,-rpath,"\$ORIGIN"?

Here's the lines snipped from ninja.build for DeepSkyStackerLive:

  LINK_LIBRARIES = -Wl,-rpath,/opt/Qt/6.8.0/gcc_64/lib  CMakeFiles/DeepSkyStackerKernel_resources_1.dir/./out/build/.qt/rcc/qrc_DeepSkyStackerKernel_translations_init.cpp.o  /opt/Qt/6.8.0/gcc_64/lib/libQt6Charts.so.6.8.0  DeepSkyStackerKernel/libDeepSkyStackerKernel.a  ZClass/libZClass.a  vcpkg_installed/x64-linux/debug/lib/libboost_container.a  vcpkg_installed/x64-linux/debug/lib/libexiv2.a  vcpkg_installed/x64-linux/debug/lib/libexpat.a  vcpkg_installed/x64-linux/debug/lib/libraw_r.a  vcpkg_installed/x64-linux/debug/lib/libtiffd.a  vcpkg_installed/x64-linux/debug/lib/libz.a  -lcfitsio  -lSmtpMime  /opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGLWidgets.so.6.8.0  /opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGL.so.6.8.0  /opt/Qt/6.8.0/gcc_64/lib/libQt6Widgets.so.6.8.0  /opt/Qt/6.8.0/gcc_64/lib/libQt6Gui.so.6.8.0  /usr/lib/x86_64-linux-gnu/libGLX.so  /usr/lib/x86_64-linux-gnu/libOpenGL.so  /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so.6.8.0  vcpkg_installed/x64-linux/debug/lib/libINIReader.a  vcpkg_installed/x64-linux/debug/lib/libinih.a  vcpkg_installed/x64-linux/debug/lib/liblcms2.a  vcpkg_installed/x64-linux/debug/lib/libjasperd.a  vcpkg_installed/x64-linux/debug/lib/libjpeg.a  -lm  vcpkg_installed/x64-linux/debug/lib/liblzma.a  vcpkg_installed/x64-linux/debug/lib/libjpeg.a  /opt/Qt/6.8.0/gcc_64/lib/libQt6Core.so.6.8.0  /usr/lib/gcc/x86_64-linux-gnu/13/libgomp.so  /usr/lib/x86_64-linux-gnu/libpthread.a  -Wl,-rpath-link,/opt/Qt/6.8.0/gcc_64/lib

The equivalent stuff for DeepSkyStacker reads:

  LINK_LIBRARIES = -Wl,-rpath,/opt/Qt/6.8.0/gcc_64/lib  CMakeFiles/DeepSkyStackerKernel_resources_1.dir/./out/build/.qt/rcc/qrc_DeepSkyStackerKernel_translations_init.cpp.o  DeepSkyStackerKernel/libDeepSkyStackerKernel.a  ZClass/libZClass.a  vcpkg_installed/x64-linux/debug/lib/libboost_container.a  vcpkg_installed/x64-linux/debug/lib/libexiv2.a  vcpkg_installed/x64-linux/debug/lib/libexpat.a  vcpkg_installed/x64-linux/debug/lib/libraw_r.a  vcpkg_installed/x64-linux/debug/lib/libtiffd.a  vcpkg_installed/x64-linux/debug/lib/libz.a  -lcfitsio  /opt/Qt/6.8.0/gcc_64/lib/libQt6Widgets.so.6.8.0  /opt/Qt/6.8.0/gcc_64/lib/libQt6Gui.so.6.8.0  /usr/lib/x86_64-linux-gnu/libGLX.so  /usr/lib/x86_64-linux-gnu/libOpenGL.so  /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so.6.8.0  vcpkg_installed/x64-linux/debug/lib/libINIReader.a  vcpkg_installed/x64-linux/debug/lib/libinih.a  vcpkg_installed/x64-linux/debug/lib/liblcms2.a  vcpkg_installed/x64-linux/debug/lib/libjasperd.a  vcpkg_installed/x64-linux/debug/lib/libjpeg.a  -lm  vcpkg_installed/x64-linux/debug/lib/liblzma.a  vcpkg_installed/x64-linux/debug/lib/libjpeg.a  /opt/Qt/6.8.0/gcc_64/lib/libQt6Core.so.6.8.0  /usr/lib/gcc/x86_64-linux-gnu/13/libgomp.so  /usr/lib/x86_64-linux-gnu/libpthread.a  -Wl,-rpath-link,/opt/Qt/6.8.0/gcc_64/lib

Hmmm...

LD_DEBUG=libs ./DeepSkyStackerLive
      9693:     find library=libQt6Charts.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib/glibc-hwcaps/x86-64-v3:/opt/Qt/6.8.0/gcc_64/lib/glibc-hwcaps/x86-64-v2:/opt/Qt/6.8.0/gcc_64/lib/tls/haswell/x86_64:/opt/Qt/6.8.0/gcc_64/lib/tls/haswell:/opt/Qt/6.8.0/gcc_64/lib/tls/x86_64:/opt/Qt/6.8.0/gcc_64/lib/tls:/opt/Qt/6.8.0/gcc_64/lib/haswell/x86_64:/opt/Qt/6.8.0/gcc_64/lib/haswell:/opt/Qt/6.8.0/gcc_64/lib/x86_64:/opt/Qt/6.8.0/gcc_64/lib          (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/glibc-hwcaps/x86-64-v3/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/glibc-hwcaps/x86-64-v2/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/tls/haswell/x86_64/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/tls/haswell/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/tls/x86_64/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/tls/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/haswell/x86_64/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/haswell/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/x86_64/libQt6Charts.so.6
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6Charts.so.6
      9693:
      9693:     find library=libcfitsio.so.10 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libcfitsio.so.10
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/usr/local/lib/libcfitsio.so.10
      9693:
      9693:     find library=libSmtpMime.so.2 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libSmtpMime.so.2
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/usr/local/lib/libSmtpMime.so.2
      9693:
      9693:     find library=libQt6Widgets.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6Widgets.so.6
      9693:
      9693:     find library=libQt6Gui.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6Gui.so.6
      9693:
      9693:     find library=libGLX.so.0 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libGLX.so.0
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libGLX.so.0
      9693:
      9693:     find library=libOpenGL.so.0 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libOpenGL.so.0
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libOpenGL.so.0
      9693:
      9693:     find library=libQt6Core.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6Core.so.6
      9693:
      9693:     find library=libgomp.so.1 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libgomp.so.1
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libgomp.so.1
      9693:
      9693:     find library=libstdc++.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libstdc++.so.6
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libstdc++.so.6
      9693:
      9693:     find library=libm.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libm.so.6
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libm.so.6
      9693:
      9693:     find library=libgcc_s.so.1 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libgcc_s.so.1
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libgcc_s.so.1
      9693:
      9693:     find library=libc.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libc.so.6
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libc.so.6
      9693:
      9693:     find library=libQt6OpenGLWidgets.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGLWidgets.so.6
      9693:
      9693:     find library=libQt6OpenGL.so.6 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libQt6OpenGL.so.6
      9693:
      9693:     find library=libGL.so.1 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libGL.so.1
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libGL.so.1
      9693:
      9693:     find library=libpthread.so.0 [0]; searching
      9693:      search path=/opt/Qt/6.8.0/gcc_64/lib           (RUNPATH from file ./DeepSkyStackerLive)
      9693:       trying file=/opt/Qt/6.8.0/gcc_64/lib/libpthread.so.0
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libpthread.so.0
      9693:
      9693:     find library=libz.so.1 [0]; searching
      9693:      search cache=/etc/ld.so.cache
      9693:       trying file=/lib/x86_64-linux-gnu/libz.so.1
      9693:
      9693:     find library=libQt6Network.so.6 [0]; searching
      9693:      search cache=/etc/ld.so.cache
      9693:      search path=/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v3:/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v2:/lib/x86_64-linux-gnu/tls/haswell/x86_64:/lib/x86_64-linux-gnu/tls/haswell:/lib/x86_64-linux-gnu/tls/x86_64:/lib/x86_64-linux-gnu/tls:/lib/x86_64-linux-gnu/haswell/x86_64:/lib/x86_64-linux-gnu/haswell:/lib/x86_64-linux-gnu/x86_64:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v3:/usr/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v2:/usr/lib/x86_64-linux-gnu/tls/haswell/x86_64:/usr/lib/x86_64-linux-gnu/tls/haswell:/usr/lib/x86_64-linux-gnu/tls/x86_64:/usr/lib/x86_64-linux-gnu/tls:/usr/lib/x86_64-linux-gnu/haswell/x86_64:/usr/lib/x86_64-linux-gnu/haswell:/usr/lib/x86_64-linux-gnu/x86_64:/usr/lib/x86_64-linux-gnu:/lib/glibc-hwcaps/x86-64-v3:/lib/glibc-hwcaps/x86-64-v2:/lib/tls/haswell/x86_64:/lib/tls/haswell:/lib/tls/x86_64:/lib/tls:/lib/haswell/x86_64:/lib/haswell:/lib/x86_64:/lib:/usr/lib/glibc-hwcaps/x86-64-v3:/usr/lib/glibc-hwcaps/x86-64-v2:/usr/lib/tls/haswell/x86_64:/usr/lib/tls/haswell:/usr/lib/tls/x86_64:/usr/lib/tls:/usr/lib/haswell/x86_64:/usr/lib/haswell:/usr/lib/x86_64:/usr/lib              (system search path)
      9693:       trying file=/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v3/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v2/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/tls/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/tls/haswell/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/tls/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/tls/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/haswell/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/x86_64-linux-gnu/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v3/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/glibc-hwcaps/x86-64-v2/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/tls/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/tls/haswell/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/tls/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/tls/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/haswell/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64-linux-gnu/libQt6Network.so.6
      9693:       trying file=/lib/glibc-hwcaps/x86-64-v3/libQt6Network.so.6
      9693:       trying file=/lib/glibc-hwcaps/x86-64-v2/libQt6Network.so.6
      9693:       trying file=/lib/tls/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/tls/haswell/libQt6Network.so.6
      9693:       trying file=/lib/tls/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/tls/libQt6Network.so.6
      9693:       trying file=/lib/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/haswell/libQt6Network.so.6
      9693:       trying file=/lib/x86_64/libQt6Network.so.6
      9693:       trying file=/lib/libQt6Network.so.6
      9693:       trying file=/usr/lib/glibc-hwcaps/x86-64-v3/libQt6Network.so.6
      9693:       trying file=/usr/lib/glibc-hwcaps/x86-64-v2/libQt6Network.so.6
      9693:       trying file=/usr/lib/tls/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/tls/haswell/libQt6Network.so.6
      9693:       trying file=/usr/lib/tls/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/tls/libQt6Network.so.6
      9693:       trying file=/usr/lib/haswell/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/haswell/libQt6Network.so.6
      9693:       trying file=/usr/lib/x86_64/libQt6Network.so.6
      9693:       trying file=/usr/lib/libQt6Network.so.6
      9693:
./DeepSkyStackerLive: error while loading shared libraries: libQt6Network.so.6: cannot open shared object file: No such file or directory
amonra@styx:~/.vs/DSS/out/build/DeepSkyStackerLive$

Thanks, David

[JonB]

@Perdrix said in Problem with linking to libQt6Network.so.6:

The difference is that DeepSkyStacker calls stuff that's in Qt6Network directly, while DeepSkyStackerLive doesn't: The calls to stuff in Qt6Network are made from code in another shared library libSmtpMime.so.2.

Hmmm...

I'm not sure what your "Hmmm" means?! From the output I see that most libraries are sought in search path=/opt/Qt/6.8.0/gcc_64/lib via RUNPATH. But libQt6Network.so.6 (and libz.so.1) is not. That is the root of your error. Presumably when you use it it respects your -Wl,-rpath. But when it is wanted from libSmtpMime.so.2 it is not, presumably because that was not linked with the same -Wl,-rpath. If you compare against the case where it does work, called for from your own code, I presume you would see it using the same RUNPATH as the other libraries.

So what is libSmtpMime.so.2, and why does it want a Qt library anyway? There is basically nothing about it on Google, so I can only guess it's a library internal to DeepSkyStacker? Did you build that, so that you in control of its -Wl,-rpath? Does it require "deploying"?

For now you could ln -s /opt/Qt/6.8.0/gcc_64/lib/libQt6Network.so to either the executable directory or wherever libSmtpMime.so.2 is and verify that makes it work.

I don't know what you are supposed to do or what this tells us. I don't think Linux (unlike Windows) searches the executable or current directories for shared libraries, but I may be wrong. (I wonder what linuxdeployqt does about this?) Either -Wl,-rpath,"\$ORIGIN" or a "wrapper" at runtime for the executable which sets LD_LIBRARY_PATH.

[Perdrix]

SmtpMime.so is Qt related, see: https://github.com/bluetiger9/SmtpClient-for-Qt/ and builds as a .so.

If I remove the calls in my code that use it by ifdef-ing them away, my code links and loads OK.

[JonB]

@Perdrix
Then my guess is that if maybe libSmtpMime.so is built with -Wl,-rpath= to find libQt6Network.so.6 like your one that works does it would find it at runtime? I think when you build it behoves you to ensure your code and any libraries it uses use the same and a consistent set of where to find libraries. The SmtpMime stuff looks like it was written a long time ago, it won't know (during its build) about /opt/Qt/6.8.0/gcc_64/lib/ that you use for your part of the code?

[Perdrix]

Quoting from their CMakeLists.txt file:

find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Network REQUIRED)

qt_add_library(${PROJECT_NAME} SHARED
    emailaddress.cpp
    : omitted
)
target_link_libraries(${PROJECT_NAME} PRIVATE Qt${QT_VERSION_MAJOR}::Core)
target_link_libraries(${PROJECT_NAME} PRIVATE Qt${QT_VERSION_MAJOR}::Network)

set(CMAKE_SKIP_BUILD_RPATH FALSE)
set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)
set(CMAKE_INSTALL_RPATH “${ORIGIN}”)

I built it using:

cmake -B ./build -G Ninja -DQT_VERSION_MAJOR=6 -DCMAKE_INSTALL_PREFIX:STRING="/usr/local" -DCMAKE_MODULE_PATH:STRING="/usr/share/cmake-3.30/Modules" -DCMAKE_PREFIX_PATH:STRING="/opt/Qt/6.8.0/gcc_64"
cd build
ninja
sudo ninja install

it may behove me etc. but as I said I'm not a Linux guru - more a beginner.

This is clearly rpath related but way beyond my current understanding. Maybe I should ask the CMake folks how to work round this problem.

D.