Fix warnings about size conversion in QList

Because difference_type is 64-bit on 64-bit systems, there's a
downconversion warning from MSVC and possibly other compilers when it
gets passed to functions taking simply int.

Task-number: QTBUG-41092
Change-Id: I46a710810f4a57b8b84c4933f419a1f1fdf6bb5a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 23 insertions, 20 deletions

diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index 8e2bed7a7c..fe5e0f33b4 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -1363,7 +1363,7 @@ void **QListData::erase(void **xi)
     \sa operator*()
 */
 
-/*! \fn T &QList::iterator::operator[](int j) const
+/*! \fn T &QList::iterator::operator[](difference_type j) const
 
     Returns a modifiable reference to the item at position *this +
     \a{j}.
@@ -1464,7 +1464,7 @@ void **QListData::erase(void **xi)
     current and returns an iterator to the previously current item.
 */
 
-/*! \fn QList::iterator &QList::iterator::operator+=(int j)
+/*! \fn QList::iterator &QList::iterator::operator+=(difference_type j)
 
     Advances the iterator by \a j items. (If \a j is negative, the
     iterator goes backward.)
@@ -1472,7 +1472,7 @@ void **QListData::erase(void **xi)
     \sa operator-=(), operator+()
 */
 
-/*! \fn QList::iterator &QList::iterator::operator-=(int j)
+/*! \fn QList::iterator &QList::iterator::operator-=(difference_type j)
 
     Makes the iterator go back by \a j items. (If \a j is negative,
     the iterator goes forward.)
@@ -1480,7 +1480,7 @@ void **QListData::erase(void **xi)
     \sa operator+=(), operator-()
 */
 
-/*! \fn QList::iterator QList::iterator::operator+(int j) const
+/*! \fn QList::iterator QList::iterator::operator+(difference_type j) const
 
     Returns an iterator to the item at \a j positions forward from
     this iterator. (If \a j is negative, the iterator goes backward.)
@@ -1488,7 +1488,7 @@ void **QListData::erase(void **xi)
     \sa operator-(), operator+=()
 */
 
-/*! \fn QList::iterator QList::iterator::operator-(int j) const
+/*! \fn QList::iterator QList::iterator::operator-(difference_type j) const
 
     Returns an iterator to the item at \a j positions backward from
     this iterator. (If \a j is negative, the iterator goes forward.)
@@ -1618,7 +1618,7 @@ void **QListData::erase(void **xi)
     \sa operator*()
 */
 
-/*! \fn const T &QList::const_iterator::operator[](int j) const
+/*! \fn const T &QList::const_iterator::operator[](difference_type j) const
 
     Returns the item at position *this + \a{j}.
 
@@ -1710,7 +1710,7 @@ void **QListData::erase(void **xi)
     current and returns an iterator to the previously current item.
 */
 
-/*! \fn QList::const_iterator &QList::const_iterator::operator+=(int j)
+/*! \fn QList::const_iterator &QList::const_iterator::operator+=(difference_type j)
 
     Advances the iterator by \a j items. (If \a j is negative, the
     iterator goes backward.)
@@ -1718,7 +1718,7 @@ void **QListData::erase(void **xi)
     \sa operator-=(), operator+()
 */
 
-/*! \fn QList::const_iterator &QList::const_iterator::operator-=(int j)
+/*! \fn QList::const_iterator &QList::const_iterator::operator-=(difference_type j)
 
     Makes the iterator go back by \a j items. (If \a j is negative,
     the iterator goes forward.)
@@ -1726,7 +1726,7 @@ void **QListData::erase(void **xi)
     \sa operator+=(), operator-()
 */
 
-/*! \fn QList::const_iterator QList::const_iterator::operator+(int j) const
+/*! \fn QList::const_iterator QList::const_iterator::operator+(difference_type j) const
 
     Returns an iterator to the item at \a j positions forward from
     this iterator. (If \a j is negative, the iterator goes backward.)
@@ -1734,7 +1734,7 @@ void **QListData::erase(void **xi)
     \sa operator-(), operator+=()
 */
 
-/*! \fn QList::const_iterator QList::const_iterator::operator-(int j) const
+/*! \fn QList::const_iterator QList::const_iterator::operator-(difference_type j) const
 
     Returns an iterator to the item at \a j positions backward from
     this iterator. (If \a j is negative, the iterator goes forward.)
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index 326a276f40..e33be9a2f1 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -188,6 +188,7 @@ public:
     public:
         Node *i;
         typedef std::random_access_iterator_tag  iterator_category;
+        // ### Qt6: use int
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef T *pointer;
@@ -198,7 +199,7 @@ public:
         inline iterator(const iterator &o): i(o.i){}
         inline T &operator*() const { return i->t(); }
         inline T *operator->() const { return &i->t(); }
-        inline T &operator[](int j) const { return i[j].t(); }
+        inline T &operator[](difference_type j) const { return i[j].t(); }
         inline bool operator==(const iterator &o) const { return i == o.i; }
         inline bool operator!=(const iterator &o) const { return i != o.i; }
         inline bool operator<(const iterator& other) const { return i < other.i; }
@@ -223,10 +224,10 @@ public:
         inline iterator operator++(int) { Node *n = i; ++i; return n; }
         inline iterator &operator--() { i--; return *this; }
         inline iterator operator--(int) { Node *n = i; i--; return n; }
-        inline iterator &operator+=(int j) { i+=j; return *this; }
-        inline iterator &operator-=(int j) { i-=j; return *this; }
-        inline iterator operator+(int j) const { return iterator(i+j); }
-        inline iterator operator-(int j) const { return iterator(i-j); }
+        inline iterator &operator+=(difference_type j) { i+=j; return *this; }
+        inline iterator &operator-=(difference_type j) { i-=j; return *this; }
+        inline iterator operator+(difference_type j) const { return iterator(i+j); }
+        inline iterator operator-(difference_type j) const { return iterator(i-j); }
         inline int operator-(iterator j) const { return int(i - j.i); }
     };
     friend class iterator;
@@ -235,6 +236,7 @@ public:
     public:
         Node *i;
         typedef std::random_access_iterator_tag  iterator_category;
+        // ### Qt6: use int
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef const T *pointer;
@@ -250,7 +252,7 @@ public:
 #endif
         inline const T &operator*() const { return i->t(); }
         inline const T *operator->() const { return &i->t(); }
-        inline const T &operator[](int j) const { return i[j].t(); }
+        inline const T &operator[](difference_type j) const { return i[j].t(); }
         inline bool operator==(const const_iterator &o) const { return i == o.i; }
         inline bool operator!=(const const_iterator &o) const { return i != o.i; }
         inline bool operator<(const const_iterator& other) const { return i < other.i; }
@@ -261,10 +263,10 @@ public:
         inline const_iterator operator++(int) { Node *n = i; ++i; return n; }
         inline const_iterator &operator--() { i--; return *this; }
         inline const_iterator operator--(int) { Node *n = i; i--; return n; }
-        inline const_iterator &operator+=(int j) { i+=j; return *this; }
-        inline const_iterator &operator-=(int j) { i-=j; return *this; }
-        inline const_iterator operator+(int j) const { return const_iterator(i+j); }
-        inline const_iterator operator-(int j) const { return const_iterator(i-j); }
+        inline const_iterator &operator+=(difference_type j) { i+=j; return *this; }
+        inline const_iterator &operator-=(difference_type j) { i-=j; return *this; }
+        inline const_iterator operator+(difference_type j) const { return const_iterator(i+j); }
+        inline const_iterator operator-(difference_type j) const { return const_iterator(i-j); }
         inline int operator-(const_iterator j) const { return int(i - j.i); }
     };
     friend class const_iterator;
@@ -316,6 +318,7 @@ public:
     typedef const value_type *const_pointer;
     typedef value_type &reference;
     typedef const value_type &const_reference;
+    // ### Qt6: use int
     typedef qptrdiff difference_type;
 
     // comfort