From 9f1e1eb5524fbf27a9fd2db4f1d98bb2bcd90077 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Thu, 15 Oct 2020 02:30:18 +0200
Subject: [PATCH] QHash: code tidies

Apply std::exchange. Remove a wrong comment about MultiNode
-- the compiler isn't generating any move operations, the
move constructor is user-provided and there isn't a move
assignment operator...

Change-Id: Idd69458c69cc93e4575c119daba564e0046452c1
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/corelib/tools/qhash.h | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index a1c1371e240..c6b82dbd338 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -185,9 +185,8 @@ struct MultiNode
 
     MultiNode(MultiNode &&other)
         : key(other.key),
-          value(other.value)
+          value(qExchange(other.value, nullptr))
     {
-        other.value = nullptr;
     }
 
     MultiNode(const MultiNode &other)
@@ -217,16 +216,13 @@ struct MultiNode
     void insertMulti(Args &&... args)
     {
         Chain *e = new Chain{ T(std::forward<Args>(args)...), nullptr };
-        e->next = value;
-        value = e;
+        e->next = qExchange(value, e);
     }
     template<typename ...Args>
     void emplaceValue(Args &&... args)
     {
         value->value = T(std::forward<Args>(args)...);
     }
-
-    // compiler generated move operators are fine
 };
 
 template<typename  Node>
@@ -1212,10 +1208,10 @@ public:
         }
         return *this;
     }
-    QMultiHash(QMultiHash &&other) noexcept : d(other.d), m_size(other.m_size)
+    QMultiHash(QMultiHash &&other) noexcept
+        : d(qExchange(other.d, nullptr)),
+          m_size(qExchange(other.m_size, 0))
     {
-        other.d = nullptr;
-        other.m_size = 0;
     }
     QMultiHash &operator=(QMultiHash &&other) noexcept(std::is_nothrow_destructible<Node>::value)
     {