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Qt 4.8 on 64-bit Windows using MinGW?



  • I've tried to get this working every way I can think of. I installed mingw-w64, but Qt didn't like it when I tried to install. I found a thread here that suggested that Qt 4.8 needed MinGW 4.4, with a link, so I downloaded that and everything seemed to work (minus a few missing dlls that I found online and having to manually edit the makefile because the path variable setting wasn't working), but the compiled program I made with Qt that way doesn't run (it just says the application failed to start). What am I missing?


  • Moderators

    Hi, and welcome to the Qt Dev Net!

    [quote author="faiuwle" date="1394775980"]I found a thread here that suggested that Qt 4.8 needed MinGW 4.4[/quote]Correct. Newer versions (MinGW 4.7 or 4.8) are incompatible.

    [quote]minus a few missing dlls that I found online[/quote]That's bad news. There should be no missing DLLs. Which ones were missing? Where did you get MinGW 4.4 from?

    Also, if you download them from somewhere else, you might get the wrong version of a DLL and it will crash.

    [quote]having to manually edit the makefile because the path variable setting wasn't working[/quote]PATH variable should work, and you shouldn't need to modify the Makefile. Did you reboot your PC after changing it?

    [quote]the compiled program I made with Qt that way doesn't run (it just says the application failed to start[/quote]Like I said, you probably downloaded the wrong versions of some DLLs.



  • Thanks for the welcome!

    The MinGW was from a linked blog post (that I can no longer find, apparently :/) saying that MinGW 4.4 had disappeared from the MinGW website and they were hosting it instead. The dlls I had to find were libgmp-3.dll (I found a post on another forum saying that this was missing from 4.4 and that it could be found on the MinGW sourceforge, which it could), and libmpfr-1.dll.

    EDIT: I believe this was the blog: http://nosymbolfound.blogspot.com/2012/12/since-until-now-qt-under-windows-is.html

    Is there a more sanctioned MinGW 4.4 somewhere?

    [quote author="JKSH" date="1394778238"]PATH variable should work, and you shouldn't need to modify the Makefile. Did you reboot your PC after changing it?[/quote]

    Ahh, no, I thought it would just work, like it does in linux.



  • Ok, so I copied over a MinGW installation from a saved hard disk that Qt 4 definitely worked on, no missing dlls, and the application still won't start. Of course, that was a 32-bit disk, if it matters.


  • Moderators

    [quote]The dlls I had to find were libgmp-3.dll... and libmpfr-1.dll.

    EDIT: I believe this was the blog: http://nosymbolfound.blogspot.com/2012/12/since-until-now-qt-under-windows-is.html
    Is there a more sanctioned MinGW 4.4 somewhere?[/quote]Hmm... I just downloaded that package. It has exactly the same number of files (and the same number of bytes) as the one in my system. It also contained libgmp-3.dll and libmpfr-1.dll.

    [quote]no missing dlls, and the application still won’t start. Of course, that was a 32-bit disk, if it matters.[/quote]Can you run it in Qt Creator? What does the debugger say?



  • Take a look on "unofficial Qt builds":http://sourceforge.net/projects/qtx64/files/qt-x64/4.8.5/

    They have 64 bit builds for Windows for various compilers.


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