QSqlDatabase: Skip confusing thread warning on invalid QSqlDatabase

If the db isn't valid, then that's the actual issue, not the fact that we're
getting the same invalid db (with the same driver QSqlNullDriver) in
multiple threads.

Change-Id: I95490818ed78e741c3823e115f139c2cff01b0b1
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/sql/kernel/qsqldatabase.cpp b/src/sql/kernel/qsqldatabase.cpp
index 291b35f8a6..2c7b4b83db 100644
--- a/src/sql/kernel/qsqldatabase.cpp
+++ b/src/sql/kernel/qsqldatabase.cpp
@@ -229,12 +229,14 @@ QSqlDatabase QSqlDatabasePrivate::database(const QString& name, bool open)
     dict->lock.lockForRead();
     QSqlDatabase db = dict->value(name);
     dict->lock.unlock();
-    if (db.driver() && db.driver()->thread() != QThread::currentThread()) {
+    if (!db.isValid())
+        return db;
+    if (db.driver()->thread() != QThread::currentThread()) {
         qWarning("QSqlDatabasePrivate::database: requested database does not belong to the calling thread.");
         return QSqlDatabase();
     }
 
-    if (db.isValid() && !db.isOpen() && open) {
+    if (open && !db.isOpen()) {
         if (!db.open())
             qWarning() << "QSqlDatabasePrivate::database: unable to open database:" << db.lastError().text();