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Improve error reporting when requesting unsupported native interface

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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>
This commit is contained in:
Tor Arne Vestbø 2021-07-13 23:52:13 +02:00
parent 149b5425d8
commit 1ef305de15
10 changed files with 115 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
src/corelib/global/qnativeinterface.h
View File

@ -61,11 +61,21 @@ QT_BEGIN_NAMESPACE
#define QT_DECLARE_NATIVE_INTERFACE_3(NativeInterface, Revision, BaseType) \
protected: \
virtual ~NativeInterface(); \
\
struct TypeInfo { \
using baseType = BaseType; \
static constexpr char const *name = QT_STRINGIFY(NativeInterface); \
static constexpr int revision = Revision; \
}; \
\
template <typename, typename> \
friend struct QNativeInterface::Private::has_type_info; \
\
template <typename> \
friend bool constexpr QNativeInterface::Private::hasTypeInfo(); \
\
template <typename> \
friend struct QNativeInterface::Private::TypeInfo; \
public: \
// Revisioned interfaces only make sense when exposed through a base
@ -81,35 +91,97 @@ QT_BEGIN_NAMESPACE
QT_OVERLOADED_MACRO(QT_DECLARE_NATIVE_INTERFACE, __VA_ARGS__)
namespace QNativeInterface::Private {
template <typename NativeInterface>
struct TypeInfo : private NativeInterface
{
static constexpr char const *name() { return NativeInterface::TypeInfo::name; }
static constexpr int revision() { return NativeInterface::TypeInfo::revision; }
template<typename BaseType>
static constexpr bool isCompatibleWith =
std::is_base_of<typename NativeInterface::TypeInfo::baseType, BaseType>::value;
// Basic type-trait to verify that a given native interface has
// all the required type information for us to evaluate it.
template <typename NativeInterface, typename = void>
struct has_type_info : std::false_type {};
// The type-trait is friended by TypeInfo, so that we can
// evaluate TypeInfo in the template arguments.
template <typename NativeInterface>
struct has_type_info<NativeInterface, std::void_t<
typename NativeInterface::TypeInfo,
typename NativeInterface::TypeInfo::baseType,
decltype(&NativeInterface::TypeInfo::name),
decltype(&NativeInterface::TypeInfo::revision)
>> : std::true_type {};
// We need to wrap the instantiation of has_type_info in a
// function friended by TypeInfo, otherwise MSVC will not
// let us evaluate TypeInfo in the template arguments.
template <typename NativeInterface>
bool constexpr hasTypeInfo()
{
return has_type_info<NativeInterface>::value;
}
template <typename NativeInterface>
struct TypeInfo
{
// To ensure SFINAE works for hasTypeInfo we can't use it in a constexpr
// variable that also includes an expression that relies on the type
// info. This helper variable is okey, as it it self contained.
static constexpr bool haveTypeInfo = hasTypeInfo<NativeInterface>();
// We can then use the helper variable in a constexpr condition in a
// function, which does not break SFINAE if haveTypeInfo is false.
template <typename BaseType>
static constexpr bool isCompatibleHelper()
{
if constexpr (haveTypeInfo)
return std::is_base_of<typename NativeInterface::TypeInfo::baseType, BaseType>::value;
else
return false;
}
// MSVC however doesn't like constexpr functions in enable_if_t conditions,
// so we need to wrap it yet again in a constexpr variable. This is fine,
// as all the SFINAE magic has been resolved at this point.
template <typename BaseType>
static constexpr bool isCompatibleWith = isCompatibleHelper<BaseType>();
// The revision and name accessors are not used in enable_if_t conditions,
// so we can leave them as constexpr functions. As this class template is
// friended by TypeInfo we can access the protected members of TypeInfo.
static constexpr int revision()
{
if constexpr (haveTypeInfo)
return NativeInterface::TypeInfo::revision;
else
return 0;
}
static constexpr char const *name()
{
if constexpr (haveTypeInfo)
return NativeInterface::TypeInfo::name;
else
return nullptr;
}
};
// Wrapper type to make the error message in case
// of incompatible interface types read better.
template <typename I>
struct NativeInterface : TypeInfo<I> {};
template <typename T>
Q_NATIVE_INTERFACE_IMPORT void *resolveInterface(const T *that, const char *name, int revision);
Q_CORE_EXPORT Q_DECLARE_LOGGING_CATEGORY(lcNativeInterface)
}
} // QNativeInterface::Private
// Declares an accessor for the native interface
#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR \
template <typename I> \
I *nativeInterface() const \
#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(T) \
template <typename NativeInterface, typename TypeInfo = QNativeInterface::Private::NativeInterface<NativeInterface>, \
typename BaseType = T, std::enable_if_t<TypeInfo::template isCompatibleWith<T>, bool> = true> \
NativeInterface *nativeInterface() const \
{ \
using T = std::decay_t<decltype(*this)>; \
using NativeInterface = QNativeInterface::Private::TypeInfo<I>; \
static_assert(NativeInterface::template isCompatibleWith<T>, \
"T::nativeInterface<I>() requires that native interface I is compatible with T"); \
\
return static_cast<I*>(QNativeInterface::Private::resolveInterface(this, \
NativeInterface::name(), NativeInterface::revision())); \
return static_cast<NativeInterface*>( \
QNativeInterface::Private::resolveInterface(this, \
TypeInfo::name(), TypeInfo::revision())); \
}
// Provides a definition for the interface destructor
@ -134,6 +206,8 @@ namespace QNativeInterface::Private {
revision, TypeInfo<NativeInterface>::revision(), name); \
return nullptr; \
} \
} else { \
qCDebug(lcNativeInterface, "No match for requested interface name %s", name); \
}
QT_END_NAMESPACE

2
src/corelib/kernel/qcoreapplication.h
View File

@ -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)

2
src/gui/kernel/qguiapplication.h
View File

@ -173,7 +173,7 @@ public:
bool isSavingSession() const;
#endif
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QGuiApplication)
static void sync();
Q_SIGNALS:

2
src/gui/kernel/qkeymapper_p.h
View File

@ -73,7 +73,7 @@ public:
static void changeKeyboard();
static QList<int> possibleKeys(QKeyEvent *e);
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QKeyMapper)
private:
friend QKeyMapperPrivate *qt_keymapper_private();

2
src/gui/kernel/qoffscreensurface.h
View File

@ -80,7 +80,7 @@ public:
QPlatformOffscreenSurface *handle() const;
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QOffscreenSurface)
Q_SIGNALS:
void screenChanged(QScreen *screen);

2
src/gui/kernel/qopenglcontext.h
View File

@ -154,7 +154,7 @@ public:
static bool supportsThreadedOpenGL();
static QOpenGLContext *globalShareContext();
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QOpenGLContext)
Q_SIGNALS:
void aboutToBeDestroyed();

2
src/gui/kernel/qscreen.h
View File

@ -153,7 +153,7 @@ public:
qreal refreshRate() const;
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QScreen)
Q_SIGNALS:
void geometryChanged(const QRect &geometry);

2
src/gui/kernel/qwindow.h
View File

@ -289,7 +289,7 @@ public:
QVulkanInstance *vulkanInstance() const;
#endif
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QWindow)
public Q_SLOTS:
Q_REVISION(2, 1) void requestActivate();

2
src/widgets/kernel/qapplication.h
View File

@ -154,7 +154,7 @@ public:
static Qt::NavigationMode navigationMode();
#endif
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(QApplication)
Q_SIGNALS:
void focusChanged(QWidget *old, QWidget *now);

15
tests/auto/corelib/global/qnativeinterface/tst_qnativeinterface.cpp
View File

@ -44,7 +44,7 @@ struct InterfaceImplementation;
struct PublicClass
{
PublicClass();
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR
QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(PublicClass)
std::unique_ptr<InterfaceImplementation> m_implementation;
};
@ -66,6 +66,15 @@ QT_DEFINE_NATIVE_INTERFACE(Interface);
QT_DEFINE_NATIVE_INTERFACE(OtherInterface);
QT_END_NAMESPACE
struct NotInterface {};
struct AlmostInterface
{
struct TypeInfo {
// Missing required members
};
};
using namespace QNativeInterface;
struct InterfaceImplementation : public Interface
@ -89,6 +98,10 @@ void tst_QNativeInterface::typeInfo() const
{
using namespace QNativeInterface::Private;
QCOMPARE(TypeInfo<Interface>::haveTypeInfo, true);
QCOMPARE(TypeInfo<NotInterface>::haveTypeInfo, false);
QCOMPARE(TypeInfo<AlmostInterface>::haveTypeInfo, false);
QCOMPARE(TypeInfo<Interface>::isCompatibleWith<PublicClass>, true);
QCOMPARE(TypeInfo<Interface>::isCompatibleWith<QObject>, false);
QCOMPARE(TypeInfo<Interface>::isCompatibleWith<int>, false);