QJsonObject::erase: erase unnecessary and wrong code

Commit 35adb74ddd915831789f0175423660f8e898942e ("Reimplement JSON
support on top of Cbor") accidentally forgot to multiply by 2 the index
stored in the QJsonObject::iterator. The same mistake was propagated
when QJsonObject::iterator was converted to QJsonValueRef. This had no
ill effects because the o->elements container would always contain more
elements, but it meant the check was ineffective and meant nothing.

So instead of doing nothing when the iterator does not point to this
container, simply assume it does. Bad things will happen if you try to
erase an iterator that points to another container, but that's true for
almost all container/iterator mechanisms.

Drive-by modernization of some of the surrounding lines.

Change-Id: I89446ea06b5742efb194fffd16bb7c322c2fc4f2
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 62 insertions, 9 deletions

diff --git a/tests/auto/corelib/serialization/json/tst_qtjson.cpp b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
index 5a2ed0a85d..1b6148429f 100644
--- a/tests/auto/corelib/serialization/json/tst_qtjson.cpp
+++ b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
@@ -1040,14 +1040,37 @@ void tst_QtJson::testObjectIteration()
         QCOMPARE(object, object2);
 
         QJsonValue val = *object2.begin();
-        object2.erase(object2.begin());
+        auto next = object2.erase(object2.begin());
         QCOMPARE(object.size(), 10);
         QCOMPARE(object2.size(), 9);
+        QVERIFY(next == object2.begin());
 
-        for (QJsonObject::const_iterator it = object2.constBegin(); it != object2.constEnd(); ++it) {
+        double d = 1;   // we erased the first item
+        for (auto it = object2.constBegin(); it != object2.constEnd(); ++it, d += 1) {
             QJsonValue value = it.value();
             QVERIFY(it.value() != val);
-            QCOMPARE((double)it.key().toInt(), value.toDouble());
+            QCOMPARE(it.value(), d);
+            QCOMPARE(it.value().toDouble(), d);
+            QCOMPARE(it.key().toInt(), value.toDouble());
+        }
+    }
+
+    {
+        QJsonObject object2 = object;
+        QCOMPARE(object, object2);
+
+        QJsonValue val = *(object2.end() - 1);
+        auto next = object2.erase(object2.end() - 1);
+        QCOMPARE(object.size(), 10);
+        QCOMPARE(object2.size(), 9);
+        QVERIFY(next == object2.end());
+        double d = 0;
+        for (auto it = object2.constBegin(); it != object2.constEnd(); ++it, d += 1) {
+            QJsonValue value = it.value();
+            QVERIFY(it.value() != val);
+            QCOMPARE(it.value(), d);
+            QCOMPARE(it.value().toDouble(), d);
+            QCOMPARE(it.key().toInt(), value.toDouble());
         }
     }
 
@@ -1057,14 +1080,20 @@ void tst_QtJson::testObjectIteration()
 
         QJsonObject::iterator it = object2.find(QString::number(5));
         QJsonValue val = *it;
-        object2.erase(it);
+        auto next = object2.erase(it);
         QCOMPARE(object.size(), 10);
         QCOMPARE(object2.size(), 9);
+        QCOMPARE(*next, 6);
 
-        for (QJsonObject::const_iterator it = object2.constBegin(); it != object2.constEnd(); ++it) {
+        int i = 0;
+        for (auto it = object2.constBegin(); it != object2.constEnd(); ++it, ++i) {
+            if (i == 5)
+                ++i;
             QJsonValue value = it.value();
             QVERIFY(it.value() != val);
-            QCOMPARE((double)it.key().toInt(), value.toDouble());
+            QCOMPARE(it.value(), i);
+            QCOMPARE(it.value().toInt(), i);
+            QCOMPARE(it.key().toInt(), value.toDouble());
         }
     }
 
@@ -1120,14 +1149,38 @@ void tst_QtJson::testArrayIteration()
         QCOMPARE(array, array2);
 
         QJsonValue val = *array2.begin();
-        array2.erase(array2.begin());
+        auto next = array2.erase(array2.begin());
         QCOMPARE(array.size(), 10);
         QCOMPARE(array2.size(), 9);
+        QVERIFY(next == array2.begin());
 
         i = 1;
-        for (QJsonArray::const_iterator it = array2.constBegin(); it != array2.constEnd(); ++it, ++i) {
+        for (auto it = array2.constBegin(); it != array2.constEnd(); ++it, ++i) {
+            QJsonValue value = (*it);
+            QCOMPARE(value.toInt(), i);
+            QCOMPARE(value.toDouble(), i);
+            QCOMPARE(it->toInt(), i);
+            QCOMPARE(it->toDouble(), i);
+        }
+    }
+
+    {
+        QJsonArray array2 = array;
+        QCOMPARE(array, array2);
+
+        QJsonValue val = array2.last();
+        auto next = array2.erase(array2.end() - 1);
+        QCOMPARE(array.size(), 10);
+        QCOMPARE(array2.size(), 9);
+        QVERIFY(next == array2.end());
+
+        i = 0;
+        for (auto it = array2.constBegin(); it != array2.constEnd(); ++it, ++i) {
             QJsonValue value = (*it);
-            QCOMPARE((double)i, value.toDouble());
+            QCOMPARE(value.toInt(), i);
+            QCOMPARE(value.toDouble(), i);
+            QCOMPARE(it->toInt(), i);
+            QCOMPARE(it->toDouble(), i);
         }
     }