Fix bugs in internal comparison operators

The comparison operators between QJsonPrivate::String
and QJsonPrivate::Latin1String weren't all correct, leading
to wrong sorting of keys in QJsonObjects when the keys were
outside of the latin1 range and resulting lookup errors.

Task-number: QTBUG-41100
Change-Id: Idceff615f85d7ab874ad2a8e4a6c1ce8c2aa0f65
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

src/corelib/json/qjson_p.h

@@ -354,7 +354,7 @@ public:
         return !memcmp(d->utf16, str.d->utf16, d->length*sizeof(ushort));
     }
     inline bool operator<(const String &other) const;
-    inline bool operator >=(const String &other) const { return other < *this; }
+    inline bool operator >=(const String &other) const { return !(*this < other); }
 
     inline QString toString() const {
 #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
@@ -414,12 +414,29 @@ public:
             val = d->length - str.d->length;
         return val >= 0;
     }
+    inline bool operator<(const String &str) const
+    {
+        const qle_ushort *uc = (qle_ushort *) str.d->utf16;
+        if (!uc || *uc == 0)
+            return false;
 
+        const uchar *c = (uchar *)d->latin1;
+        const uchar *e = c + qMin((int)d->length, (int)str.d->length);
+
+        while (c < e) {
+            if (*c != *uc)
+                break;
+            ++c;
+            ++uc;
+        }
+        return (c == e ? (int)d->length < (int)str.d->length : *c < *uc);
+
+    }
     inline bool operator ==(const String &str) const {
         return (str == *this);
     }
     inline bool operator >=(const String &str) const {
-        return (str < *this);
+        return !(*this < str);
     }
 
     inline QString toString() const {
@@ -456,7 +473,7 @@ inline bool String::operator <(const String &other) const
         a++,b++;
     if (l==-1)
         return (alen < blen);
-    return (ushort)*a - (ushort)*b;
+    return (ushort)*a < (ushort)*b;
 }
 
 inline bool String::operator<(const Latin1String &str) const

tests/auto/corelib/json/tst_qtjson.cpp

@@ -149,6 +149,8 @@ private Q_SLOTS:
 
     void arrayInitializerList();
     void objectInitializerList();
+
+    void unicodeKeys();
 private:
     QString testDataDir;
 };
@@ -2753,5 +2755,27 @@ void tst_QtJson::objectInitializerList()
 #endif
 }
 
+void tst_QtJson::unicodeKeys()
+{
+    QByteArray json = "{"
+                      "\"x\u2090_1\": \"hello_1\","
+                      "\"y\u2090_2\": \"hello_2\","
+                      "\"T\u2090_3\": \"hello_3\","
+                      "\"xyz_4\": \"hello_4\","
+                      "\"abc_5\": \"hello_5\""
+                      "}";
+
+    QJsonParseError error;
+    QJsonDocument doc = QJsonDocument::fromJson(json, &error);
+    QVERIFY(error.error == QJsonParseError::NoError);
+    QJsonObject o = doc.object();
+
+    QCOMPARE(o.keys().size(), 5);
+    Q_FOREACH (const QString &key, o.keys()) {
+        QString suffix = key.mid(key.indexOf(QLatin1Char('_')));
+        QCOMPARE(o[key].toString(), QString("hello") + suffix);
+    }
+}
+
 QTEST_MAIN(tst_QtJson)
 #include "tst_qtjson.moc"