4. Static Qt with static MSVC C++ library

Static Qt with static MSVC C++ library


  • Hi,

    I am compiling an application statically with no problem but I would like to use the static version of the MSVC C++ library. To do so I use:
    QMAKE_CFLAGS_RELEASE += /MT
    QMAKE_CXXFLAGS_RELEASE += /MT

    But I get multiple definitions of the same symbol:
    ...
    MSVCRT.lib(MSVCR100.dll) : error LNK2005: __open_osfhandle already defined in LIBCMT.lib(osfinfo.obj)

    Is there an easy solution or should I tell the linker to accept multiple symbols?

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  • Since you are refering to MSVC C++ I would assume that you are also using visual studio. You could install "vsaddin ":http://developer.qt.nokia.com/wiki/QtVSAddin
    There is no need to use qmake explicitely.

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  • One way or the other the actual flag to accept multiple symbols is:
    QMAKE_LFLAGS_RELEASE += /FORCE:MULTIPLE

    But it still creates an executable relying on:
    MSVCP100.dll
    MSVCR100.dll

    And I would like to get rid of those DLL dependencies.

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  • I have just compiled a small project with /MT option. I was compiling with dlls before.
    First recompilation it complaint that I need to specify /NODEFAULTIB
    Second recompilation gave loads of error messages. Probable I would need to adjust more settings, which I can't do today.

    BTW: I am using Win 7 64 bit and msvc2005.

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  • Any luck?

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  • It looks like with MSVC you need to tell at compile-time DLL or LIB dependencies. This means you need to rebuild QT to use static VC libraries. Go to ${QtDir}\mkspecs\win32-msvc2010\qmake.conf, and replace

    QMAKE_CFLAGS_RELEASE = -O2 -MD
    QMAKE_CFLAGS_RELEASE_WITH_DEBUGINFO += -O2 -MD -Zi
    QMAKE_CFLAGS_DEBUG = -Zi -MDd

    with

    QMAKE_CFLAGS_RELEASE = -O2 -MT
    QMAKE_CFLAGS_RELEASE_WITH_DEBUGINFO += -O2 -MT -Zi
    QMAKE_CFLAGS_DEBUG = -Zi -MTd

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  • I was able to setup a small "hello world" application with -MT. When I add Qt it will require dlls, because I do not have a static Qt compilation. So, that is logical.
    Did you succeed with your application?

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  • I need to rebuild the Qt libraries using the settings previously mentioned, so it'll take me another 2 hours. I might as well add the following compilation flag: /Gy and link the final executable with /OPT:REF. This way it'll remove unused functions. And voila!

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  • Just for the records I found a nmake clone that uses all the available cores on the system... just like "-jX" of make:
    http://labs.qt.nokia.com/2009/03/27/speeding-up-visual-c-qt-builds/

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  • [quote author="philippeb8" date="1310852943"]Just for the records I found a nmake clone that uses all the available cores on the system... just like "-jX" of make:
    http://labs.qt.nokia.com/2009/03/27/speeding-up-visual-c-qt-builds/[/quote]

    Yes, jom may reduce your overall compilation time cosiderably.

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  • [quote author="philippeb8" date="1310747680"]
    MSVCRT.lib(MSVCR100.dll) : error LNK2005: __open_osfhandle already defined in LIBCMT.lib(osfinfo.obj)

    Is there an easy solution or should I tell the linker to accept multiple symbols?[/quote]
    As answer to your initial question: You may also exclude LIBCMT (option: NODEFAULTLIB:LIBCMT). This is eliminating the multiple definitions warning/error.

    However, for msvc2005 there is an error:
    @
    error LNK2019: unresolved external symbol _WSAAsyncSelect@16 referenced in function "public: void __thiscall EventDispatcherWin32Private::doWsaAsyncSelect(int)" (?doWsaAsyncSelect@QEventDispatcherWin32Private@@QAEXH@Z)
    @
    This error is there also when LIBCMT has not been ignored, respectively, also accepting multiple definitions does not help. Could be an msvc2005 specific problem.

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