Error: no matching constructor for initialization, what should I do?

Question

Qt

There is a TemplateRequirement class, in another class, ReqTGroup, there is a vector whose elements are TemplateRequirement instances.
When I run it, it throws this error:
/Users/Mac/Qt/5.6/clang_64/lib/QtCore.framework/Headers/qvector.h:631: error: no matching constructor for initialization of 'TemplateRequirement'
T copy(t);
^ ~
As I understand it, the problem lies precisely in creating a vector, the elements of which are my class, but I can’t figure out how to fix it.
TemplateRequirement class:

class TemplateRequirement
{

public:
    TemplateRequirement();

    TemplateRequirement(TemplateRequirement &);

    TemplateRequirement(QString&,QString&, QString&);


    TemplateRequirement& operator=(TemplateRequirement&);

    QString getReq();

    QString getType();

    QString getHead();

    void save(std::ofstream &);

    void read(std::ifstream &);

    void setRequirement(QString&);


protected:
    QString head;

    QString requirement;

    QString type;

};

ReqTGroup class:

class ReqTGroup
{

public:
    ReqTGroup();

    ReqTGroup (int);


    void save();
    void read();

    int findByHead(QString&);

    void addItrm(QString, QString, QString);

protected:
   QVector<TemplateRequirement> requirements;

};

Answer 1

Incorrectly declared copy constructor and assignment operator:

TemplateRequirement(TemplateRequirement &);
TemplateRequirement& operator=(TemplateRequirement&);

It should be like this:

TemplateRequirement(const TemplateRequirement &);
TemplateRequirement& operator=(const TemplateRequirement&);

I also advise you to replace the type parameters QStringand QString&with const QString&.

Answer 2

Maybe the const is missing in the copy constructor .
TemplateRequirement(const TemplateRequirement &);