From 4b6c1448047362b8c38d265e6414f0e3e59b8d37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Mon, 25 Sep 2017 14:11:00 +0200
Subject: Revert "Revert "macOS: Deduplicate QNSWindow/QNSPanel code""
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This reverts commit 3ad8295451aa30a212eb6efe6330b5bfccd9f599.

The fix for the issue was landed in 5.10 as 1be1ed014b1deacb51fef4,
and will be merged into dev as a followup.

Change-Id: Id7773d1cc2caecbe358aadd9ade427a9c1eed9ef
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
---
 src/plugins/platforms/cocoa/qcocoahelpers.h | 129 ++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)

(limited to 'src/plugins/platforms/cocoa/qcocoahelpers.h')

diff --git a/src/plugins/platforms/cocoa/qcocoahelpers.h b/src/plugins/platforms/cocoa/qcocoahelpers.h
index 4478895538..1f4f9cd276 100644
--- a/src/plugins/platforms/cocoa/qcocoahelpers.h
+++ b/src/plugins/platforms/cocoa/qcocoahelpers.h
@@ -55,6 +55,9 @@
 #include <QtGui/qpalette.h>
 #include <QtGui/qscreen.h>
 
+#include <objc/runtime.h>
+#include <objc/message.h>
+
 Q_FORWARD_DECLARE_OBJC_CLASS(QT_MANGLE_NAMESPACE(QNSView));
 
 QT_BEGIN_NAMESPACE
@@ -188,5 +191,131 @@ QT_END_NAMESPACE
 
 QT_NAMESPACE_ALIAS_OBJC_CLASS(QNSPanelContentsWrapper);
 
+// -------------------------------------------------------------------------
+
+// Depending on the ABI of the platform, we may need to use objc_msgSendSuper_stret:
+// - http://www.sealiesoftware.com/blog/archive/2008/10/30/objc_explain_objc_msgSend_stret.html
+// - https://lists.apple.com/archives/cocoa-dev/2008/Feb/msg02338.html
+template <typename T>
+struct objc_msgsend_requires_stret
+{ static const bool value =
+#if defined(Q_PROCESSOR_X86)
+    // Any return value larger than two registers on i386/x86_64
+    sizeof(T) > sizeof(void*) * 2;
+#elif defined(Q_PROCESSOR_ARM_32)
+    // Any return value larger than a single register on arm
+    sizeof(T) >  sizeof(void*);
+#elif defined(Q_PROCESSOR_ARM_64)
+    // Stret not used on arm64
+    false;
+#endif
+};
+
+template <>
+struct objc_msgsend_requires_stret<void>
+{ static const bool value = false; };
+
+template <typename ReturnType, typename... Args>
+ReturnType qt_msgSendSuper(id receiver, SEL selector, Args... args)
+{
+    static_assert(!objc_msgsend_requires_stret<ReturnType>::value,
+        "The given return type requires stret on this platform");
+
+    typedef ReturnType (*SuperFn)(objc_super *, SEL, Args...);
+    SuperFn superFn = reinterpret_cast<SuperFn>(objc_msgSendSuper);
+    objc_super sup = { receiver, class_getSuperclass(object_getClass(receiver)) };
+    return superFn(&sup, selector, args...);
+}
+
+template <typename ReturnType, typename... Args>
+ReturnType qt_msgSendSuper_stret(id receiver, SEL selector, Args... args)
+{
+    static_assert(objc_msgsend_requires_stret<ReturnType>::value,
+        "The given return type does not use stret on this platform");
+
+    typedef void (*SuperStretFn)(ReturnType *, objc_super *, SEL, Args...);
+    SuperStretFn superStretFn = reinterpret_cast<SuperStretFn>(objc_msgSendSuper_stret);
+
+    objc_super sup = { receiver, class_getSuperclass(object_getClass(receiver)) };
+    ReturnType ret;
+    superStretFn(&ret, &sup, selector, args...);
+    return ret;
+}
+
+template<typename... Args>
+class QSendSuperHelper {
+public:
+    QSendSuperHelper(id receiver, SEL sel, Args... args)
+        : m_receiver(receiver), m_selector(sel), m_args(std::make_tuple(args...)), m_sent(false)
+    {
+    }
+
+    ~QSendSuperHelper()
+    {
+        if (!m_sent)
+            msgSendSuper<void>(m_args);
+    }
+
+    template <typename ReturnType>
+    operator ReturnType()
+    {
+#if defined(QT_DEBUG)
+        Method method = class_getInstanceMethod(object_getClass(m_receiver), m_selector);
+        char returnTypeEncoding[256];
+        method_getReturnType(method, returnTypeEncoding, sizeof(returnTypeEncoding));
+        NSUInteger alignedReturnTypeSize = 0;
+        NSGetSizeAndAlignment(returnTypeEncoding, nullptr, &alignedReturnTypeSize);
+        Q_ASSERT(alignedReturnTypeSize == sizeof(ReturnType));
+#endif
+        m_sent = true;
+        return msgSendSuper<ReturnType>(m_args);
+    }
+
+private:
+    template <std::size_t... Ts>
+    struct index {};
+
+    template <std::size_t N, std::size_t... Ts>
+    struct gen_seq : gen_seq<N - 1, N - 1, Ts...> {};
+
+    template <std::size_t... Ts>
+    struct gen_seq<0, Ts...> : index<Ts...> {};
+
+    template <typename ReturnType, bool V>
+    using if_requires_stret = typename std::enable_if<objc_msgsend_requires_stret<ReturnType>::value == V, ReturnType>::type;
+
+    template <typename ReturnType, std::size_t... Is>
+    if_requires_stret<ReturnType, false> msgSendSuper(std::tuple<Args...>& args, index<Is...>)
+    {
+        return qt_msgSendSuper<ReturnType>(m_receiver, m_selector, std::get<Is>(args)...);
+    }
+
+    template <typename ReturnType, std::size_t... Is>
+    if_requires_stret<ReturnType, true> msgSendSuper(std::tuple<Args...>& args, index<Is...>)
+    {
+        return qt_msgSendSuper_stret<ReturnType>(m_receiver, m_selector, std::get<Is>(args)...);
+    }
+
+    template <typename ReturnType>
+    ReturnType msgSendSuper(std::tuple<Args...>& args)
+    {
+        return msgSendSuper<ReturnType>(args, gen_seq<sizeof...(Args)>{});
+    }
+
+    id m_receiver;
+    SEL m_selector;
+    std::tuple<Args...> m_args;
+    bool m_sent;
+};
+
+template<typename... Args>
+QSendSuperHelper<Args...> qt_objcDynamicSuperHelper(id receiver, SEL selector, Args... args)
+{
+    return QSendSuperHelper<Args...>(receiver, selector, args...);
+}
+
+// Same as calling super, but the super_class field resolved at runtime instead of compile time
+#define qt_objcDynamicSuper(...) qt_objcDynamicSuperHelper(self, _cmd, ##__VA_ARGS__)
+
 #endif //QCOCOAHELPERS_H
 
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