False constParameterPointer flag for QMap::insert

[Long Huang]

Minimal reproduction:

#ifdef KNOWN_MAP_DECLARATION
template<typename Key, typename Value>
class QMap
{
public:
   void insert(const Key&, const Value&);
   Value value(const Key&) const;
};
#else
#include <QMap>
#endif

struct Client
{
   void Update();
};

class Registry
{
public:
   void Add(unsigned id, Client* client);
   void Update(unsigned id) const;

private:
   QMap<unsigned, Client*> Clients;
};

void Registry::Add(unsigned id, Client* client)
{
   Clients.insert(id, client);
}

void Registry::Update(unsigned id) const
{
   Clients.value(id)->Update();
}

Save as repro.cpp, then run:

cppcheck --enable=style --inconclusive --library=qt --std=c++14 repro.cpp

Actual:

style: Parameter 'client' can be declared as pointer to const [constParameterPointer]

Expected:

No warning. The suggestion is invalid: the map stores Client*, not const Client*. For QMap::insert(const Key&, const T&), substituting T = Client* makes the second parameter Client* const&. It does not permit a pointer to a const client. The stored clients are subsequently used for non-const calls.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/15185