From 4fc539bd846f08c5e448810e263f3850593b8dc2 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Fri, 3 Jul 2020 01:58:26 +0200
Subject: [PATCH] QMap: fix insert() rvalue overloads

Receiving an rvalue still requires to check whether the parameter
is detached, otherwise we can't steal its backing std::map.

Change-Id: Ie88dbf39fd777112ad7bb20a46d5c2d65be8eb3d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qmap.h                   | 12 +++
 tests/auto/corelib/tools/qmap/tst_qmap.cpp | 97 ++++++++++++++++++++++
 2 files changed, 109 insertions(+)

diff --git a/src/corelib/tools/qmap.h b/src/corelib/tools/qmap.h
index 2a87912c4a..9db8981bf5 100644
--- a/src/corelib/tools/qmap.h
+++ b/src/corelib/tools/qmap.h
@@ -655,6 +655,12 @@ public:
         if (!map.d || map.d->m.empty())
             return;
 
+        if (map.d.isShared()) {
+            // fall back to a regular copy
+            insert(map);
+            return;
+        }
+
         detach();
 
 #ifdef __cpp_lib_node_extract
@@ -1292,6 +1298,12 @@ public:
         if (!map.d || map.d->m.empty())
             return;
 
+        if (map.d.isShared()) {
+            // fall back to a regular copy
+            insert(map);
+            return;
+        }
+
         detach();
 
 #ifdef __cpp_lib_node_extract
diff --git a/tests/auto/corelib/tools/qmap/tst_qmap.cpp b/tests/auto/corelib/tools/qmap/tst_qmap.cpp
index c8a228f8dd..4f7ac08c2d 100644
--- a/tests/auto/corelib/tools/qmap/tst_qmap.cpp
+++ b/tests/auto/corelib/tools/qmap/tst_qmap.cpp
@@ -1205,6 +1205,100 @@ void tst_QMap::insert()
     }
 }
 
+template <template <typename K, typename T> typename Map>
+void testDetachWhenInsert()
+{
+    const Map<int, int> referenceSource = {
+        { 0, 0 },
+        { 1, 1 },
+        { 2, 2 }
+    };
+
+    const Map<int, int> referenceDestination = {
+        { 0, 0 },
+        { 1, 1 },
+        { 2, 2 },
+        { 3, 3 }
+    };
+
+    // copy insertion of non-shared map
+    {
+        Map<int, int> source;
+        source.insert(0, 0);
+        source.insert(1, 1);
+        source.insert(2, 2);
+
+        Map<int, int> dest;
+        dest.insert(3, 3);
+        Map<int, int> destCopy = dest;
+
+        dest.insert(source);
+
+        QCOMPARE(source, referenceSource);
+        QCOMPARE(dest, referenceDestination);
+
+        QCOMPARE(destCopy.count(), 1); // unchanged
+    }
+
+    // copy insertion of shared map
+    {
+        Map<int, int> source;
+        source.insert(0, 0);
+        source.insert(1, 1);
+        source.insert(2, 2);
+        Map<int, int> sourceCopy = source;
+
+        Map<int, int> dest;
+        dest.insert(3, 3);
+        Map<int, int> destCopy = dest;
+
+        dest.insert(source);
+
+        QCOMPARE(source, referenceSource);
+        QCOMPARE(sourceCopy, referenceSource);
+
+        QCOMPARE(dest, referenceDestination);
+        QCOMPARE(destCopy.count(), 1); // unchanged
+    }
+
+    // move insertion of non-shared map
+    {
+        Map<int, int> source;
+        source.insert(0, 0);
+        source.insert(1, 1);
+        source.insert(2, 2);
+
+        Map<int, int> dest;
+        dest.insert(3, 3);
+        Map<int, int> destCopy = dest;
+
+        dest.insert(source);
+
+        QCOMPARE(dest, referenceDestination);
+        QCOMPARE(destCopy.count(), 1); // unchanged
+    }
+
+    // move insertion of shared map
+    {
+        Map<int, int> source;
+        source.insert(0, 0);
+        source.insert(1, 1);
+        source.insert(2, 2);
+        Map<int, int> sourceCopy = source;
+
+        Map<int, int> dest;
+        dest.insert(3, 3);
+        Map<int, int> destCopy = dest;
+
+        dest.insert(std::move(source));
+
+        QCOMPARE(sourceCopy, referenceSource);
+
+        QCOMPARE(dest, referenceDestination);
+        QCOMPARE(destCopy.count(), 1); // unchanged
+    }
+};
+
 void tst_QMap::insertMap()
 {
     {
@@ -1298,6 +1392,9 @@ void tst_QMap::insertMap()
 
         QCOMPARE(map.count(), 1);
     }
+
+    testDetachWhenInsert<QMap>();
+    testDetachWhenInsert<QMultiMap>();
 }
 
 void tst_QMap::checkMostLeftNode()