Qt utf-16 output shows question marks in Windows cmd and powershell -- with minimum reproducible example in C++

Question

Previously, I have asked Qt translations in C++ project are rendered as question marks in cmd and powershell question. The point of the question was that the help message of .\app -h, translated to Cyrillic, is rendered as ?????????.

Since then, I discovered that in https://github.com/RSATom/Qt/blob/master/qtbase/src/corelib/tools/qcommandlineparser.cpp, the Qt messages are printed with qInfo("%ls", qUtf16Printable(message)) on Windows.

In cmd.exe or poweshell.exe I get question marks ?????????, when trying to output a Cyrillic message this way.

I tried to change the font of cmd.exe and powershell.exe to Lucida Console and to execute chcp 10000 (as proposed here UTF-16 on cmd.exe), but this does not help.

Here is the minimum reproducible example:

// > cl main.cpp /I C:\Qt\5.12.12\msvc2017_64\include
// > link main.obj /LIBPATH C:\Qt\5.12.12\msvc2017_64\lib\Qt5Core.lib

#include "QtCore/QtGlobal"
#include "QtCore/QString"

int main()
{
    qInfo("%ls", qUtf16Printable("Привет"));
    return 0;
}

// > main.exe
// ?????? 

I would really appreciate any help. There are two problems here. The first: how can I use QCommandLineParser under Windows. The second: if QCommandLineParser (using qInfo("%ls", qUtf16Printable(message))) is okay and not a bug, then how can I make cmd show it all right.

Answer 1

I don't pretend on the answer, but on Windows for Unicode console output you should do something similar to:

#include <QDebug>
#include <iostream>
#include <string>

#include <fcntl.h>
#include <io.h>
#include <stdio.h>

void myMessageOutput( QtMsgType type, const QMessageLogContext & context, const QString & msg )
{
    Q_UNUSED( context );

    std::wcout << msg.toStdWString() << std::endl;

    if( type == QtFatalMsg )
        abort();
}

int main()
{
    _setmode( _fileno( stdout ), _O_U16TEXT );

    qInstallMessageHandler( myMessageOutput );

    const std::wstring rs = L"Привет";
    const auto s = QString::fromStdWString( rs );

    std::wcout << s.toStdWString() << std::endl;

    qDebug() << s;

    qInfo() << s;

    return 0;
}

Answer 2

Accidentally I found the solution. You should create following manifest file for your executable:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
    <application>
        <windowsSettings>
            <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
        </windowsSettings>
    </application>
</assembly>

Let it will be named as app.manifest. In CMake project just add app.manifest into sources of your executable.

In the main() function add two lines of code:

#include <Windows.h>

int main( int argc, char ** argv )
{
    SetConsoleCP( GetACP() );
    SetConsoleOutputCP( GetACP() );
}

And voila...

Printing should be done using UTF-8, so:

// 1 - works.
QTextStream s( stdout );
s << QString( "Вот оно!!!\n" ) << Qt::flush;

// 2 - works.
fputs( qPrintable( QString( "Опа-на...\n" ) ), stdout );

// 3 - works.
std::cout << u8"std::cout работает!!!\n";

// 4 - DOES NOT work.
std::wcout << L"wcout НЕ работает!!!\n";