no matching function for call when migrating project from qt4 to qt5

Question

I am migrating a project from Qt4 to Qt5, in fact I have finished migrating it but now I have to migrate the libraries, and I have encountered a problem that I cant figure out:

..\qenc\ShapeLandPOI.cpp: In member function 'virtual void ShapeLandPOI::draw(QPainter*)':
..\qenc\ShapeLandPOI.cpp:74:92: error: no matching function for call to 'QMap<QString, ShapeAttribute>::iterator::iterator(QMap<QString, ShapeAttribute>::const_iterator)'
         AttributeSet::iterator vItPOI = (AttributeSet::iterator)attributes.at(i).find("POI");
note: candidates are:QMap<Key, T>::iterator::iterator(QMap<Key, T>::Node*) [with Key = QString; T = ShapeAttribute; QMap<Key, T>::Node = QMapNode<QString, ShapeAttribute>]
         inline iterator(Node *node) : i(node) { }
                ^

After that one I get another error below, but I think once the error above is solved this one wont be a problem, although it might help to know whats going on:

..\..\..\..\..\Qt5\5.2.1\mingw48_32\include\QtCore/qmap.h:423:16: note:   no known conversion for argument 1 from 'QMap<QString, ShapeAttribute>::const_iterator' to 'QMap<QString, ShapeAttribute>::Node* {aka QMapNode<QString, ShapeAttribute>*}'
..\..\..\..\..\Qt5\5.2.1\mingw48_32\include\QtCore/qmap.h:422:16: note: QMap<Key, T>::iterator::iterator() [with Key = QString; T = ShapeAttribute]
         inline iterator() : i(0) { }
                ^

these are the two lines giving problems:

AttributeSet::iterator vItPOI = (AttributeSet::iterator)attributes.at(i).find("POI");
AttributeSet::iterator vItPOI0 = (AttributeSet::iterator)attributes.at(i).find("POI0");

I honestly dont know how to correct these lines so they match the candidate functions suggested. I hope someone can throw some light on the subject. Thankyou.

EDIT: I have tried using static_cast instead but its still the same error.

Answer 1

I solved it by turning

AttributeSet::iterator vItPOI = (AttributeSet::iterator)attributes.at(i).find("POI");

into

ShapeAttribute vItPOI = attributes.at(i).find("POI").value();

and changing very little part of the code, for example I had

if (vItPOI  == attributes.at(i).end()) continue;

and changed it to

    if (attributes.at(i).find("POI") == attributes.at(i).end()) continue;

So the functionality should stay the same. I was lucky because the variable was only use to get the string value of the shape attribute, except for a few ifs I didnt have to do change much.