QVector::contains fails with checks against constants

Environment as stated in the tags too:

GCC 64bit, Qt 5.12

I have the following example code:

// test.h

#include <QVector>

class Test 
{
    Test();

    // Same results with QSet
    const QVector<int> things = {
        BANANA,
        RASPBERRY,
        APPLE,
        -2500,
    };

    const int BANANA = -1000;
    const int RASPBERRY = -2000;
    const int APPLE = -3000;
};

// test.cpp

#include <QDebug>
#include "test.h"

Test::Test()
{
    qDebug() << things.contains(APPLE); // false, expected true
    qDebug() << things.contains(-3000); // false, expected true
    qDebug() << things.contains(-2500); // true, expected true
}

I don't understand if I've done something wrong in the definitions or I encountered a bug in Qt.

Seems I was trying to use constant variables not defined yet

// test.h

#include <QVector>

class Test 
{
    Test();

    // Moved them above QVector
    const int BANANA = -1000;
    const int RASPBERRY = -2000;
    const int APPLE = -3000;

    const QVector<int> things = {
        BANANA,
        RASPBERRY,
        APPLE,
        -2500,
    };
};

// test.cpp

#include <QDebug>
#include "test.h"

Test::Test()
{
    // Now the tests pass as expected
    qDebug() << things.contains(APPLE); // true, expected true
    qDebug() << things.contains(-3000); // true, expected true
    qDebug() << things.contains(-2500); // true, expected true
}

Not a bug in QT!