Qt5 and Visual Studion 2022

**d_stranz** · 7th March 2023, 18:12

OK, here's what you do to build an out-of-source Qt on Windows with VS 2022:

0 - Download the Qt 5 source distribution and unzip it where you want it to be.
1 - Open a Visual Studio command prompt window. (Start Menu: Programs -> Visual Studio 2022 -> Visual Studio Tools -> Developer Command Prompt)
2 - CD to your Qt5 "src" directory, then go up one level.
3 - At this level, create a "build" directory and CD to it
4 - Run "..\src\configure -opensource" and reply "y" to the prompt when asked to accept the open source terms.
5 - When this completes, run "nmake" from within the build directory. It will take an hour or more to build Qt.
6 - Optionally, run "nmake install" after this finishes. By default, this will install the binaries to a directory under C:\Qt. There is probably a configure option to change this location; check the Qt documentation.

If you get an error when running the configure script:

"msvc-version.conf loaded but QMAKE_MSC_VER isn't set"

then open the file in the src\qtbase\mkspecs\common\msvc-version.conf and add this line at the top of the file (above where you will see the error message):

Qt Code:

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QMAKE_MSC_VER = 1920

QMAKE_MSC_VER = 1920

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(This is for my Qt 5.14.2 distribution. A later Qt5 distribution could have support for Visual Studio 2022 already - look towards the bottom of this file for the last entry of the form below that has something like this:

Qt Code:

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greaterThan(QMAKE_MSC_VER, 1909) {
    # Visual Studio 2017 (15.0) / Visual C++ 19.10 and up
    MSVC_VER            = 15.0
    COMPAT_MKSPEC       = win32-msvc2017
    QMAKE_CXXFLAGS     += -Zc:referenceBinding
 
    # Only Visual Studio 2017 version 15.3 / Visual C++ 19.11 & up have support
    # for AVX-512. We enable the switches anyway and let configure check if they
    # work.
    QMAKE_CFLAGS_AVX512F   = -arch:AVX512
    QMAKE_CFLAGS_AVX512ER  = -arch:AVX512
    QMAKE_CFLAGS_AVX512CD  = -arch:AVX512
    QMAKE_CFLAGS_AVX512PF  = -arch:AVX512
    QMAKE_CFLAGS_AVX512DQ  = -arch:AVX512
    QMAKE_CFLAGS_AVX512BW  = -arch:AVX512
    QMAKE_CFLAGS_AVX512VL  = -arch:AVX512
    QMAKE_CFLAGS_AVX512IFMA = -arch:AVX512
    QMAKE_CFLAGS_AVX512VBMI = -arch:AVX512
 
    # For now permissive fails as soon as UWP API comes into play. In qtbase this
    # API is used in direct2d, but also in multimedia, positioning and sensors.
    # We can try again with a later version of Visual Studio.
    # QMAKE_CXXFLAGS_STRICTCXX = -permissive-
 
    # MSVC partially supports the following, but '__cplusplus' definition is set
    # as for C++98 until MSVC fully conforms with C++14, see
    # https://developercommunity.visualstudio.com/content/problem/139261/msvc-incorrectly-defines-cplusplus.html
    # Support became available in MSVC 2017 15.7:
    greaterThan(QMAKE_MSC_VER, 1913) {
        QMAKE_CXXFLAGS      += -Zc:__cplusplus
        QMAKE_CXXFLAGS_CXX14 = -std:c++14
        QMAKE_CXXFLAGS_CXX1Z = -std:c++17
    }
}

greaterThan(QMAKE_MSC_VER, 1909) {
    # Visual Studio 2017 (15.0) / Visual C++ 19.10 and up
    MSVC_VER            = 15.0
    COMPAT_MKSPEC       = win32-msvc2017
    QMAKE_CXXFLAGS     += -Zc:referenceBinding

    # Only Visual Studio 2017 version 15.3 / Visual C++ 19.11 & up have support
    # for AVX-512. We enable the switches anyway and let configure check if they
    # work.
    QMAKE_CFLAGS_AVX512F   = -arch:AVX512
    QMAKE_CFLAGS_AVX512ER  = -arch:AVX512
    QMAKE_CFLAGS_AVX512CD  = -arch:AVX512
    QMAKE_CFLAGS_AVX512PF  = -arch:AVX512
    QMAKE_CFLAGS_AVX512DQ  = -arch:AVX512
    QMAKE_CFLAGS_AVX512BW  = -arch:AVX512
    QMAKE_CFLAGS_AVX512VL  = -arch:AVX512
    QMAKE_CFLAGS_AVX512IFMA = -arch:AVX512
    QMAKE_CFLAGS_AVX512VBMI = -arch:AVX512

    # For now permissive fails as soon as UWP API comes into play. In qtbase this
    # API is used in direct2d, but also in multimedia, positioning and sensors.
    # We can try again with a later version of Visual Studio.
    # QMAKE_CXXFLAGS_STRICTCXX = -permissive-

    # MSVC partially supports the following, but '__cplusplus' definition is set
    # as for C++98 until MSVC fully conforms with C++14, see
    # https://developercommunity.visualstudio.com/content/problem/139261/msvc-incorrectly-defines-cplusplus.html
    # Support became available in MSVC 2017 15.7:
    greaterThan(QMAKE_MSC_VER, 1913) {
        QMAKE_CXXFLAGS      += -Zc:__cplusplus
        QMAKE_CXXFLAGS_CXX14 = -std:c++14
        QMAKE_CXXFLAGS_CXX1Z = -std:c++17
    }
}

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In my case (Qt 5.14.2), the last entry is the above, with an entry after that that references the VS 2019 version and modifies a couple of the variables defined above:

Qt Code:

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greaterThan(QMAKE_MSC_VER, 1919) {
    # Visual Studio 2019 (16.0) / Visual C++ 19.20 and up
    MSVC_VER            = 16.0
    QMAKE_CXXFLAGS_CXX2A = -std:c++latest
 
}

greaterThan(QMAKE_MSC_VER, 1919) {
    # Visual Studio 2019 (16.0) / Visual C++ 19.20 and up
    MSVC_VER            = 16.0
    QMAKE_CXXFLAGS_CXX2A = -std:c++latest

}

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Setting QMAKE_MSVC_VER to 1920 will ensure that at least the VS 2019 compiler will be used with the latest C++ version.