QLayout: unify the constructors

Drive-by, make QLayout constructor explicit, as it should have
always been.

[ChangeLog][QtWidgets][QLayout] The QLayout constructor taking
a QWidget pointer is now explicit.

Change-Id: If6accfb2e7e810fa08adacea9e674c99121f6bc6
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 6 insertions, 13 deletions

diff --git a/src/widgets/kernel/qlayout.cpp b/src/widgets/kernel/qlayout.cpp
index c62c8fae41..6dce2da969 100644
--- a/src/widgets/kernel/qlayout.cpp
+++ b/src/widgets/kernel/qlayout.cpp
@@ -106,11 +106,16 @@ static int menuBarHeightForWidth(QWidget *menubar, int w)
 
 /*!
     Constructs a new top-level QLayout, with parent \a parent.
-    \a parent may not be \nullptr.
 
     The layout is set directly as the top-level layout for
     \a parent. There can be only one top-level layout for a
     widget. It is returned by QWidget::layout().
+
+    If \a parent is \nullptr, then you must insert this layout
+    into another layout, or set it as a widget's layout using
+    QWidget::setLayout().
+
+    \sa QWidget::setLayout()
 */
 QLayout::QLayout(QWidget *parent)
     : QObject(*new QLayoutPrivate, parent)
@@ -120,18 +125,6 @@ QLayout::QLayout(QWidget *parent)
     parent->setLayout(this);
 }
 
-/*!
-    Constructs a new child QLayout.
-
-    This layout has to be inserted into another layout before geometry
-    management will work.
-*/
-QLayout::QLayout()
-    : QObject(*new QLayoutPrivate, nullptr)
-{
-}
-
-
 /*! \internal
  */
 QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)