Why does QMap together with QtConcurrent::blockingMapped() not works?

[PowerNow]

I want to use QMap together with QtConcurrent::blockingMapped(). Unfortunately I get an error.

"main.cpp:490: error: no match for 'operator=' (operand types are 'QList<QList<Place>>..."

QMap<QString, QList<Place>> m_plcs;

QList<Place> setAlt(QList<Place> places);
...
QList<QList<Place>> m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

tried also

QMap<QString, QList<Place>> m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

What I'm doing wrong or is QMap not supported?

[Christian Ehrlicher]

What's the type of 'Place'?
Also show the complete error message.

[PowerNow]

Hi it's an 'stuct', but seems not to be the problem because it worked with

QList<Place> m_plcs;

Place setAlt(QList<Place> places);
...
QList<Place> m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

Here the complete error message

main.cpp:490: error: no match for 'operator=' (operand types are 'QList<QList<Place> >' and 'QtPrivate::MapResultType<QMap<QString, QList<Place> >, QList<Place> (*)(QList<Place>)>::ResultType {aka void}')
     m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

[Christian Ehrlicher]

So as you can see the return value of QtConcurrent::blockingMapped(m_plcs, setAlt); is QMap<QString, QList<Place>

[PowerNow]

@Christian-Ehrlicher Yea, but as I wrote before I tried aready

QMap<QString, QList<Place>> m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

Then I get

main.cpp:490: error: no match for 'operator=' (operand types are 'QMap<QString, QList<Place> >' and 'QtPrivate::MapResultType<QMap<QString, QList<Place> >, QList<Place> (*)(QList<Place>)>::ResultType {aka void}')
     m_plcsAlt = QtConcurrent::blockingMapped(m_plcs, setAlt);

I don't understand the error message. Whats going wrong here?

[Christian Ehrlicher]

Sorry I did read something wrong.
Please see the documentation:
"The QtConcurrent::map(), QtConcurrent::mapped() and QtConcurrent::mappedReduced() functions run computations in parallel on the items in a sequence such as a QList or a QVector."

QMap is no sequence.

[PowerNow]

@Christian-Ehrlicher Yea, it seems so that QMap is not a sequence. Thxs!