Doc: Fix warnings and linking issues

Remove or replace links to examples that were removed or moved under
manual tests.

Replace code snippets that were quoting the now-missing examples.

Fix documentation of QSet::removeIf().

Add qtopengl, qtshadertools dependencies to Qt Widgets documentation
project to enable correct linking to those topics.

Pick-to: 6.5
Change-Id: I058cd5f2063aa933ea310bceff906f05422a7cb2
(cherry picked from commit dc33b0ca7a680713552063d7f74befea53f34814)
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/doc/src/resource-system.qdoc

@@ -130,9 +130,6 @@
 
     \snippet resource-system/main.cpp url
 
-    See the \l{mainwindows/mainwindow}{Mainwindow} example for an actual
-    application that uses Qt's resource system to store its icons.
-
     \section1 Advanced Topics
 
     \section2 Prefixes

src/corelib/doc/src/timers.qdoc

@@ -94,6 +94,5 @@
     optimization, you can use QBasicTimer instead of QTimer. With
     QBasicTimer, you must reimplement
     \l{QObject::timerEvent()}{timerEvent()} in your QObject subclass
-    and handle the timeout there. The \l{widgets/tetrix}{Tetrix}
-    example shows how to use QBasicTimer.
+    and handle the timeout there.
 */

src/corelib/global/qnamespace.qdoc

@@ -980,8 +980,7 @@
 
     \value WA_Hover Forces Qt to generate paint events when the mouse
     enters or leaves the widget. This feature is typically used when
-    implementing custom styles; see the \l{widgets/styles}{Styles}
-    example for details.
+    implementing custom styles.
 
     \value WA_InputMethodEnabled Enables input methods for Asian languages.
     Must be set when creating custom text editing widgets.

src/corelib/io/qsettings.cpp

@@ -2122,9 +2122,6 @@ void QConfFileSettingsPrivate::ensureSectionParsed(QConfFile *confFile,
     \codeline
     \snippet settings/settings.cpp 21
 
-    See the \l{mainwindows/application}{Application} example for a
-    self-contained example that uses QSettings.
-
     \section1 Accessing Settings from Multiple Threads or Processes Simultaneously
 
     QSettings is \l{reentrant}. This means that you can use

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -1743,7 +1743,13 @@ QAbstractItemModel::~QAbstractItemModel()
 
     For example:
 
-    \snippet ../widgets/itemviews/simpledommodel/dommodel.cpp 2
+    \code
+    int MyModel::columnCount(const QModelIndex &parent) const
+    {
+        Q_UNUSED(parent);
+        return 3;
+    }
+    \endcode
 
     \note When implementing a table based model, columnCount() should return 0
     when the parent is valid.

src/corelib/kernel/qbasictimer.cpp

@@ -33,9 +33,6 @@ QT_BEGIN_NAMESPACE
     can maintain a list of basic timers by holding them in container
     that supports move-only types, e.g. std::vector.
 
-    The \l{widgets/tetrix}{Tetrix} example uses QBasicTimer to control
-    the rate at which pieces fall.
-
     \sa QTimer, QTimerEvent, QObject::timerEvent(), Timers, {Affine Transformations}
 */
 

src/corelib/plugin/qpluginloader.cpp

@@ -71,7 +71,7 @@ using namespace Qt::StringLiterals;
     link to plugins statically. You can use QLibrary if you need to
     load dynamic libraries in a statically linked application.
 
-    \sa QLibrary, {Plug & Paint Example}
+    \sa QLibrary, {Echo Plugin Example}
 */
 
 static constexpr QLibrary::LoadHints defaultLoadHints = QLibrary::PreventUnloadHint;

src/corelib/tools/qset.qdoc

@@ -887,11 +887,9 @@
     any.
 */
 
-/*! \fn template <class T> template <class Predicate> qsizetype QSet<T>::removeIf(Predicate pred)
-    \relates QSet
+/*! \fn template <class T> template <class Pred> qsizetype QSet<T>::removeIf(Pred pred)
     \since 6.1
 
-    Removes all elements for which the predicate \a pred returns true
-    from the set \a set. Returns the number of elements removed, if
-    any.
+    Removes, from this set, all elements for which the predicate \a pred
+    returns \c true. Returns the number of elements removed, if any.
 */

src/gui/doc/src/dnd.qdoc

@@ -335,7 +335,9 @@
     For example, we can copy the contents of a QLineEdit to the clipboard
     with the following code:
 
-    \snippet ../widgets/widgets/charactermap/mainwindow.cpp 11
+    \code
+    QGuiApplication::clipboard()->setText(lineEdit->text(), QClipboard::Clipboard);
+    \endcode
 
     Data with different MIME types can also be put on the clipboard.
     Construct a QMimeData object and set data with setData() function in
@@ -364,8 +366,6 @@
     \li \l{draganddrop/draggableicons}{Draggable Icons}
     \li \l{draganddrop/draggabletext}{Draggable Text}
     \li \l{draganddrop/dropsite}{Drop Site}
-    \li \l{draganddrop/fridgemagnets}{Fridge Magnets}
-    \li \l{draganddrop/puzzle}{Drag and Drop Puzzle}
     \endlist
 
     \section1 Interoperating with Other Applications

src/gui/image/qicon.cpp

@@ -1154,7 +1154,7 @@ QStringList QIcon::themeSearchPaths()
 
     The fallback search paths are consulted for standalone
     icon files if the \l{themeName()}{current icon theme}
-    or \l{fallbackIconTheme()}{fallback icon theme} do
+    or \l{fallbackThemeName()}{fallback icon theme} do
     not provide results for an icon lookup.
 
     If not set, the fallback search paths will be defined
@@ -1174,7 +1174,7 @@ QStringList QIcon::fallbackSearchPaths()
 
     The fallback search paths are consulted for standalone
     icon files if the \l{themeName()}{current icon theme}
-    or \l{fallbackIconTheme()}{fallback icon theme} do
+    or \l{fallbackThemeName()}{fallback icon theme} do
     not provide results for an icon lookup.
 
     For example:

src/widgets/doc/qtwidgets.qdocconf

@@ -26,7 +26,20 @@ qhp.QtWidgets.subprojects.classes.sortPages = true
 
 tagfile                 = ../../../doc/qtwidgets/qtwidgets.tags
 
-depends                 += qtcore qtgui qtdoc qtsql qtdesigner qtquick qmake qtcmake qtsvg qtlinguist qthelp
+depends += \
+    qtcore \
+    qtgui \
+    qtdoc \
+    qtsql \
+    qtdesigner \
+    qtquick \
+    qmake \
+    qtcmake \
+    qtsvg \
+    qtlinguist \
+    qthelp \
+    qtopengl \
+    qtshadertools
 
 headerdirs  += ..