From 8aff3d0bed78c64496178480af0545ec206e9938 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Sun, 28 Apr 2013 21:23:53 -0700
Subject: [PATCH] Add a pair of constructor/assignment function pairs to QPair

To allow copying one QPair of two types to a QPair of two different
types.

Change-Id: Ie7aa84cf5a361be6b7d242517578172c35bcacfd
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
---
 src/corelib/tools/qpair.h    | 13 +++++++++++++
 src/corelib/tools/qpair.qdoc | 20 ++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/src/corelib/tools/qpair.h b/src/corelib/tools/qpair.h
index 96b1b65e33..9b8691a3d8 100644
--- a/src/corelib/tools/qpair.h
+++ b/src/corelib/tools/qpair.h
@@ -57,6 +57,19 @@ struct QPair
     QPair(const T1 &t1, const T2 &t2) : first(t1), second(t2) {}
     // compiler-generated copy/move ctor/assignment operators are fine!
 
+    template <typename TT1, typename TT2>
+    QPair(const QPair<TT1, TT2> &p) : first(p.first), second(p.second) {}
+    template <typename TT1, typename TT2>
+    QPair &operator=(const QPair<TT1, TT2> &p)
+    { first = p.first; second = p.second; return *this; }
+#ifdef Q_COMPILER_RVALUE_REFS
+    template <typename TT1, typename TT2>
+    QPair(QPair<TT1, TT2> &&p) : first(std::move(p.first)), second(std::move(p.second)) {}
+    template <typename TT1, typename TT2>
+    QPair &operator=(QPair<TT1, TT2> &&p)
+    { first = std::move(p.first); second = std::move(p.second); return *this; }
+#endif
+
     T1 first;
     T2 second;
 };
diff --git a/src/corelib/tools/qpair.qdoc b/src/corelib/tools/qpair.qdoc
index b0caf1aaf0..dd3df8c464 100644
--- a/src/corelib/tools/qpair.qdoc
+++ b/src/corelib/tools/qpair.qdoc
@@ -96,6 +96,26 @@
     \sa qMakePair()
 */
 
+/*!
+    \fn QPair::QPair(const QPair<TT1, TT2> &p)
+    \since 5.2
+
+    Constructs a pair from the other pair \a p, of types TT1 and TT2. This
+    constructor will fail if \c first cannot be initialized from \c p.first or
+    if \c second cannot be initialized from \c p.second.
+
+    \sa qMakePair()
+*/
+
+/*!
+    \fn QPair &QPair::operator=(const QPair<TT1, TT2> &p)
+    \since 5.2
+
+    Copies the pair \a p onto this pair.
+
+    \sa qMakePair()
+*/
+
 /*! \fn bool operator==(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
 
     \relates QPair