doc: Fix remaining qdoc warmings for Vulkan stuff

Several uses of #if QT_CONFIG(vulkan) were modified to
for classes QVulkanFunctions and QVulkanDeviceFunctions
was added to qplatformvulkaninstance.h, because the
include file that contains them doesn't exist when
vulkan isn't there.

Change-Id: I392202ab5fe9bb4c558a991870e6ebf79254aec0
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

src/gui/kernel/qplatformintegration.cpp

@@ -629,7 +629,7 @@ void QPlatformIntegration::setApplicationIcon(const QIcon &icon) const
     Q_UNUSED(icon);
 }
 
-#if QT_CONFIG(vulkan)
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
 
 /*!
     Factory function for QPlatformVulkanInstance. The \a instance parameter is a

src/gui/kernel/qplatformintegration.h

@@ -192,7 +192,7 @@ public:
 
     virtual void beep() const;
 
-#if QT_CONFIG(vulkan)
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
     virtual QPlatformVulkanInstance *createPlatformVulkanInstance(QVulkanInstance *instance) const;
 #endif
 

src/gui/kernel/qwindow.cpp

@@ -2841,7 +2841,7 @@ QDebug operator<<(QDebug debug, const QWindow *window)
 }
 #endif // !QT_NO_DEBUG_STREAM
 
-#if QT_CONFIG(vulkan)
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
 
 /*!
     Associates this window with the specified Vulkan \a instance.

src/gui/kernel/qwindow.h

@@ -88,7 +88,7 @@ class QWindowContainer;
 #ifndef QT_NO_DEBUG_STREAM
 class QDebug;
 #endif
-#if QT_CONFIG(vulkan)
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
 class QVulkanInstance;
 #endif
 
@@ -270,7 +270,7 @@ public:
 
     static QWindow *fromWinId(WId id);
 
-#if QT_CONFIG(vulkan)
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
     void setVulkanInstance(QVulkanInstance *instance);
     QVulkanInstance *vulkanInstance() const;
 #endif
@@ -378,6 +378,7 @@ private:
 };
 
 #ifndef Q_QDOC
+// should these be seen by clang-qdoc?
 template <> inline QWindow *qobject_cast<QWindow*>(QObject *o)
 {
     if (!o || !o->isWindowType()) return nullptr;

src/gui/vulkan/qplatformvulkaninstance.h

@@ -88,4 +88,65 @@ QT_END_NAMESPACE
 
 #endif // QT_CONFIG(vulkan)
 
+#if defined(Q_CLANG_QDOC)
+/*
+  The following include file did not exist for clang-qdoc running
+  in macOS, but the classes are documented in qvulkanfunctions.cpp.
+  clang-qdoc must parse the class declarations in an include file,
+  or else it can't find a place to put the documentation for the
+  classes. Apparently these classes are created at build time if
+  Vulkan is present.
+ */
+#ifndef QVULKANFUNCTIONS_H
+#define QVULKANFUNCTIONS_H
+
+#include <QtGui/qtguiglobal.h>
+
+#if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
+
+#ifndef VK_NO_PROTOTYPES
+#define VK_NO_PROTOTYPES
+#endif
+#include <vulkan/vulkan.h>
+
+#include <QtCore/qscopedpointer.h>
+
+QT_BEGIN_NAMESPACE
+
+class QVulkanInstance;
+class QVulkanFunctionsPrivate;
+class QVulkanDeviceFunctionsPrivate;
+
+class Q_GUI_EXPORT QVulkanFunctions
+{
+public:
+    ~QVulkanFunctions();
+
+private:
+    Q_DISABLE_COPY(QVulkanFunctions)
+    QVulkanFunctions(QVulkanInstance *inst);
+
+    QScopedPointer<QVulkanFunctionsPrivate> d_ptr;
+    friend class QVulkanInstance;
+};
+
+class Q_GUI_EXPORT QVulkanDeviceFunctions
+{
+public:
+    ~QVulkanDeviceFunctions();
+
+private:
+    Q_DISABLE_COPY(QVulkanDeviceFunctions)
+    QVulkanDeviceFunctions(QVulkanInstance *inst, VkDevice device);
+
+    QScopedPointer<QVulkanDeviceFunctionsPrivate> d_ptr;
+    friend class QVulkanInstance;
+};
+
+QT_END_NAMESPACE
+
+#endif // QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
+#endif // QVULKANFUNCTIONS_H;
+#endif // Q_CLANG_QDOC
+
 #endif // QPLATFORMVULKANINSTANCE_H