Deprecate QString::null

It's a Qt 3 compatibility vehicle, and as such inherits the now-alien
property to distinguish empty and null strings. Particularly worrisome
is the following asymmetry:

   QString("") == QString::null          // false
   QString("") == QString(QString::null) // true

Instead of fixing this behavior, recognize that people might use it as
a weird way to call isNull(), albeit one that once was idiomatic, and
simply deprecate everything that deals with QString::null.

[ChangeLog][QtCore][QString] QString::null is now deprecated. When
used to construct a QString, use QString() instead. When used to
compare to a QString, replace with QString::isNull().

Change-Id: I9f7e84a92522c75666da15f49324c500ae93af42
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/auto/sql/kernel/qsqldatabase/tst_qsqldatabase.cpp b/tests/auto/sql/kernel/qsqldatabase/tst_qsqldatabase.cpp
index 8126e72ad2..d7772f5c34 100644
--- a/tests/auto/sql/kernel/qsqldatabase/tst_qsqldatabase.cpp
+++ b/tests/auto/sql/kernel/qsqldatabase/tst_qsqldatabase.cpp
@@ -2191,7 +2191,7 @@ void tst_QSqlDatabase::sqlStatementUseIsNull_189093()
     CHECK_DATABASE(db);
 
     // select a record with NULL value
-    QSqlQuery q(QString::null, db);
+    QSqlQuery q(QString(), db);
     QVERIFY_SQL(q, exec("select * from " + qTableName("qtest", __FILE__, db) + " where id = 4"));
     QVERIFY_SQL(q, next());