#define QT_NO_CAST_FROM_ASCII
#include <QString>
void func()
{
    auto f = [] () -> QString
    {
        QString a = QStringLiteral("Hello.");
        return a;
    };
    QString b = f();
}

1>example.cpp(7): error C2248: 'QString::QString' : cannot access private member declared in class 'QString'
1>          C:Qt5.1.1includeQtCore/qstring.h(691) : see declaration of 'QString::QString'
1>          C:Qt5.1.1includeQtCore/qstring.h(207) : see declaration of 'QString'

#undef QT_NO_CAST_FROM_ASCII  // Note the undef!
#include <QString>
void func()
{
    auto f = [] () -> QString
    {
        QString a = QStringLiteral("Hello.");
        return a;
    };
    QString b = f();
}

#define QT_NO_CAST_FROM_ASCII
#include <QString>
void func()
{
    auto f = [] () -> QString
    {
        QString a = QLatin1String("Hello."); // Note using QLatin1String() instead.
        return a;
    };
    QString b = f();
}

#define QT_NO_CAST_FROM_ASCII
#include <QString>
void func()
{
    QString a = QStringLiteral("Hello."); // Note QStringLiteral() used outside the lambda.
    auto f = [&a] () -> QString
    {
        return a;
    };
    QString b = f();
}

#define QT_NO_CAST_FROM_ASCII
#include <QString>
void func()
{
    auto f = [] () -> QString
    {
        QString a = (   []() -> QString
                        {
                            enum { Size = sizeof(L"Hello.")/2 - 1 };
                            static const QStaticStringData<Size> qstring_literal = { { { { (-1) } }, Size, 0, 0, sizeof(QStringData) }, L"Hello." };
                            QStringDataPtr holder = { qstring_literal.data_ptr() };
                            const QString s(holder);
                            return s;
                        }()
                    );
        return a;
    };
    QString b = f();
}

#define QT_NO_CAST_FROM_ASCII
#include <QString>
void func()
{
    auto f = [] () -> QString
    {
        auto qsl =  []() -> QString
                    {
                        enum { Size = sizeof(L"Hello.")/2 - 1 };
                        static const QStaticStringData<Size> qstring_literal = { { { { (-1) } }, Size, 0, 0, sizeof(QStringData) }, L"Hello." };
                        QStringDataPtr holder = { qstring_literal.data_ptr() };
                        const QString s(holder);
                        return s;
                    };
        QString a = qsl();
        return a;
    };
    QString b = f();
}