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, 2 insertions, 2 deletions

diff --git a/tests/auto/corelib/tools/qstring/tst_qstring.cpp b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
index 48e856f406..03436375dd 100644
--- a/tests/auto/corelib/tools/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
@@ -3818,7 +3818,7 @@ void tst_QString::startsWith()
     QVERIFY( !a.startsWith(QLatin1Char('x')) );
     QVERIFY( !a.startsWith(QChar()) );
 
-    a = QString::null;
+    a = QString();
     QVERIFY( !a.startsWith("") );
     QVERIFY( a.startsWith(QString::null) );
     QVERIFY( !a.startsWith("ABC") );
@@ -3928,7 +3928,7 @@ void tst_QString::endsWith()
     QVERIFY( a.endsWith(QLatin1String(0)) );
     QVERIFY( !a.endsWith(QLatin1String("ABC")) );
 
-    a = QString::null;
+    a = QString();
     QVERIFY( !a.endsWith("") );
     QVERIFY( a.endsWith(QString::null) );
     QVERIFY( !a.endsWith("ABC") );