Add const overload for QLoggingCategory::operator()()

Change 85e57653 caused a compile error for code that does

  Q_DECLARE_LOGGING_CATEGORY(cat);
  //..
  qCDebug(cat()) << // ...

error: C3848: expression having type 'const QLoggingCategory' would lose
some const-volatile qualifiers in order to call 'QLoggingCategory
&QLoggingCategory::operator ()(void)'

This is a regression from Qt 5.2. Fix the error by adding a const version
of operator()().

Change-Id: I2fb04f2e155962adee0f98089fc5a159000bef56
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
index 168087659f..f37b9575aa 100644
--- a/src/corelib/io/qloggingcategory.cpp
+++ b/src/corelib/io/qloggingcategory.cpp
@@ -274,6 +274,14 @@ void QLoggingCategory::setEnabled(QtMsgType type, bool enable)
  */
 
 /*!
+    \fn const QLoggingCategory &QLoggingCategory::operator()() const
+
+    Returns the object itself. This allows both a QLoggingCategory variable, and
+    a factory method returning a QLoggingCategory, to be used in \l qCDebug(),
+    \l qCWarning(), \l qCCritical() macros.
+ */
+
+/*!
     Returns a pointer to the global category \c "default" that
     is used e.g. by qDebug(), qWarning(), qCritical(), qFatal().