Document how to use CMake on Qt Core, Qt GUI's central pages

Add documentation on how to use a module from CMake, alongside
the existing documentation about qmake. Separate generic info
from module-specific examples, to make it possible to use one
include file in all modules.

While at it, also remove the mentioning of the central include;
it is not something we should actively advocate anymore. Instead,
the documentation of every class gives the correct include to use.

Task-number: QTBUG-73058
Change-Id: I6b3c0e5ea218dd9c06a491c8fb799a7fcf42dd92
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

4 files changed, 14 insertions, 71 deletions

diff --git a/src/corelib/doc/snippets/code/doc_src_qtcore.cpp b/src/corelib/doc/snippets/code/doc_src_qtcore.cpp
deleted file mode 100644
index 61b71d993e..0000000000
--- a/src/corelib/doc/snippets/code/doc_src_qtcore.cpp
+++ /dev/null
@@ -1,53 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2016 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the documentation of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:BSD$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** BSD License Usage
-** Alternatively, you may use this file under the terms of the BSD license
-** as follows:
-**
-** "Redistribution and use in source and binary forms, with or without
-** modification, are permitted provided that the following conditions are
-** met:
-**   * Redistributions of source code must retain the above copyright
-**     notice, this list of conditions and the following disclaimer.
-**   * Redistributions in binary form must reproduce the above copyright
-**     notice, this list of conditions and the following disclaimer in
-**     the documentation and/or other materials provided with the
-**     distribution.
-**   * Neither the name of The Qt Company Ltd nor the names of its
-**     contributors may be used to endorse or promote products derived
-**     from this software without specific prior written permission.
-**
-**
-** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-//! [0]
-#include <QtCore>
-//! [0]
diff --git a/src/corelib/doc/snippets/overview/using-qt-core.cmake b/src/corelib/doc/snippets/overview/using-qt-core.cmake
new file mode 100644
index 0000000000..a5f43c1472
--- /dev/null
+++ b/src/corelib/doc/snippets/overview/using-qt-core.cmake
@@ -0,0 +1,2 @@
+find_package(Qt5 COMPONENTS Core REQUIRED)
+target_link_libraries(mytarget Qt5::Core)
diff --git a/src/corelib/doc/src/qtcore-index.qdoc b/src/corelib/doc/src/qtcore-index.qdoc
index 04af0e9416..40a6584af0 100644
--- a/src/corelib/doc/src/qtcore-index.qdoc
+++ b/src/corelib/doc/src/qtcore-index.qdoc
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the documentation of the Qt Toolkit.
@@ -31,17 +31,9 @@
 
     \brief The Qt Core module is part of Qt's essential modules.
 
-    \section1 Getting Started
-    All other Qt modules rely on this module. To include the
-    definitions of the module's classes, use the following directive:
-
-    \snippet code/doc_src_qtcore.cpp 0
-
-    If you use \l qmake to build your projects, Qt Core is included by default.
-
     \section1 Core Functionalities
 
-    Qt adds these features to C++:
+    Qt Core adds these features to C++:
 
     \list
     \li a very powerful mechanism for seamless object communication called
@@ -61,6 +53,15 @@
     \li \l{Signals & Slots}
     \endlist
 
+    \include module-use.qdocinc using qt module
+    \quotefile overview/using-qt-core.cmake
+
+    See also the \l[QtDoc]{Building with CMake} overview.
+
+    \section2 Building with qmake
+
+    If you use \l qmake to build your projects, Qt5Core is linked by default.
+
     \section1 Threading and Concurrent Programming
 
     Qt provides thread support in the form of platform-independent \l{Threading
diff --git a/src/corelib/doc/src/qtcore.qdoc b/src/corelib/doc/src/qtcore.qdoc
index 047ea621ca..5d63af3b18 100644
--- a/src/corelib/doc/src/qtcore.qdoc
+++ b/src/corelib/doc/src/qtcore.qdoc
@@ -33,12 +33,5 @@
 
     \brief Provides core non-GUI functionality.
 
-    All other Qt modules rely on this module. To include the
-    definitions of the module's classes, use the following directive:
-
-    \snippet code/doc_src_qtcore.cpp 0
-
-    If you use \l qmake to build your projects, \l{Qt Core} is included by
-    default.
-
+    All other Qt modules rely on this module.
 */