QtConcurrent::Mapped returns QFuture<void>

[DrZod]

I have a QList<T*> and my map functions takes T* and returns an object of U type, I don't understand why when calling QtConcurrent::Mapped returns QFuture<void> shouldn't it return QFuture<U>?. How is the return type of QtConcurrent::Mapped decided?

[jsulm]

@DrZod Please show how you call QtConcurrent::mapped

[DrZod]

@jsulm

QList<T*> list = ....
auto mapFunction = [std::biset<10U> bitset](const T* t)->U {return t->someFunction(bitset);}      //someFunction() return U

QFuture<U> futures = QtConcurrent::mapped(list,mapFunction)

[jsulm]

@DrZod But how do you know that it returns QFuture<void>?

[DrZod]

@jsulm

Because the code doesn't compile. I am using MSVC and the error message says that there is no conversion from QFuture<void> to QFuture<U>.

[Christian Ehrlicher]

Can you test it temporary with a static function and /or const ref instead pointer? What MSVC compiler do you use?