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>

0 files changed, 0 insertions, 0 deletions