QString: fix append(const QStringRef &str)

Use QStringRef::isNull instead of QStringRef::string()
for validation. Non-NULL str.string() may yet leave us
with a useless str.unicode(), which is the actual problem here;
whereas !str.isNull() does really confirm that str.unicode()
is sensible.

Such test prevents situation like:

const QString a;
QString b;
b.append(a); // b.isNull() == true
b.append(QStringRef(&a)); // b.isNull() == false

Auto test updated: create QStringRef from QString directly, without
any condition.

Change-Id: I082cd58ef656d8a53e3c1223aca01feea82fffb9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/auto/corelib/tools/qstring/tst_qstring.cpp b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
index da6cdddd4f..db4c33afde 100644
--- a/tests/auto/corelib/tools/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
@@ -131,7 +131,7 @@ template <>
 class Arg<QStringRef> : ArgBase
 {
     QStringRef ref() const
-    { return this->pinned.isNull() ? QStringRef() : this->pinned.midRef(0) ; }
+    { return QStringRef(&pinned); }
 public:
     explicit Arg(const char *str) : ArgBase(str) {}