Improve error reporting when requesting unsupported native interface

By switching out the static_assert for an enable_if we end up producing
a clearer error, at the call site:

/qt/qtbase/examples/gui/rasterwindow/main.cpp:69:9: error: no matching member
      function for call to 'nativeInterface'
    app.nativeInterface<QNativeInterface::QCocoaGLContext>();
    ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/qt/qtbase/src/gui/kernel/qguiapplication.h:176:5: note:
      candidate template ignored: requirement
      'NativeInterface<QNativeInterface::QCocoaGLContext>::isCompatibleWith<QGuiApplication>'
      was not satisfied [with NativeInterface = QNativeInterface::QCocoaGLContext, TypeInfo =
      QNativeInterface::Private::NativeInterface<QNativeInterface::QCocoaGLContext>, BaseType =
      QGuiApplication]
    QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QGuiApplication)
    ^
By using SFINAE for the TypeInfo we can also ensure that it works for
types that are not native interfaces, such as if the user tries to
call nativeInterface<QString>().

Since we can no longer use decltype(*this) to resolve the base type
we need to change QT_DECLARE_NATIVE_INTERFACE_ACCESSOR to take the
type as an argument, as we do for other QT_DECLARE_FOO macros.

Pick-to: 6.2
Change-Id: Ie3f7e01ab7c3eb3dcc2ef730834f268bb9e81e0c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/corelib/kernel/qcoreapplication.h b/src/corelib/kernel/qcoreapplication.h
index cbb9d12040..873c0acf1f 100644
--- a/src/corelib/kernel/qcoreapplication.h
+++ b/src/corelib/kernel/qcoreapplication.h
@@ -164,7 +164,7 @@ public:
                              const char * disambiguation = nullptr,
                              int n = -1);
 
-    QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
+    QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QCoreApplication)
 
 #ifndef QT_NO_QOBJECT
 #if QT_CONFIG(future)