From 68c4449d2fc9bd18499b885e3a04d0464ba51d6c Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@qt.io>
Date: Fri, 10 Jul 2020 14:36:58 +0200
Subject: [PATCH] Cleanup v_construct and friends

Streamline code using if constexpr and remove some unused code paths.

Change-Id: I602acffab4b3e53fab9e2433856f6b7e8210cc60
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/kernel/qvariant_p.h | 82 ++++-----------------------------
 1 file changed, 9 insertions(+), 73 deletions(-)

diff --git a/src/corelib/kernel/qvariant_p.h b/src/corelib/kernel/qvariant_p.h
index 833e1c6adb..1094ee6c2b 100644
--- a/src/corelib/kernel/qvariant_p.h
+++ b/src/corelib/kernel/qvariant_p.h
@@ -63,34 +63,19 @@ QT_BEGIN_NAMESPACE
 template<typename T>
 struct QVariantIntegrator
 {
-    static const bool CanUseInternalSpace = sizeof(T) <= sizeof(QVariant::Private::Data);
+    static constexpr bool CanUseInternalSpace = sizeof(T) <= sizeof(QVariant::Private::Data);
     typedef std::integral_constant<bool, CanUseInternalSpace> CanUseInternalSpace_t;
 };
 static_assert(QVariantIntegrator<double>::CanUseInternalSpace);
 static_assert(QVariantIntegrator<long int>::CanUseInternalSpace);
 static_assert(QVariantIntegrator<qulonglong>::CanUseInternalSpace);
 
-#ifdef Q_CC_SUN // Sun CC picks the wrong overload, so introduce awful hack
-
-// takes a type, returns the internal void* pointer cast
-// to a pointer of the input type
-template <typename T>
-inline T *v_cast(const QVariant::Private *nd, T * = 0)
-{
-    QVariant::Private *d = const_cast<QVariant::Private *>(nd);
-    return !QVariantIntegrator<T>::CanUseInternalSpace
-            ? static_cast<T *>(d->data.shared->ptr)
-            : static_cast<T *>(static_cast<void *>(&d->data.c));
-}
-
-#else // every other compiler in this world
-
 template <typename T>
 inline const T *v_cast(const QVariant::Private *d, T * = nullptr)
 {
     return !QVariantIntegrator<T>::CanUseInternalSpace
             ? static_cast<const T *>(d->data.shared->data())
-            : static_cast<const T *>(static_cast<const void *>(&d->data.c));
+            : static_cast<const T *>(static_cast<const void *>(&d->data));
 }
 
 template <typename T>
@@ -98,69 +83,20 @@ inline T *v_cast(QVariant::Private *d, T * = nullptr)
 {
     return !QVariantIntegrator<T>::CanUseInternalSpace
             ? static_cast<T *>(d->data.shared->data())
-            : static_cast<T *>(static_cast<void *>(&d->data.c));
-}
-
-#endif
-
-template <class T>
-inline void v_construct_helper(QVariant::Private *x, const T &t, std::true_type)
-{
-    new (&x->data) T(t);
-    x->is_shared = false;
-}
-
-template <class T>
-inline void v_construct_helper(QVariant::Private *x, const T &t, std::false_type)
-{
-    x->data.shared = QVariant::PrivateShared::create(QMetaType::fromType<T>());
-    new (x->data.shared->data()) T(t);
-    x->is_shared = true;
-}
-
-template <class T>
-inline void v_construct_helper(QVariant::Private *x, std::true_type)
-{
-    new (&x->data) T();
-    x->is_shared = false;
-}
-
-template <class T>
-inline void v_construct_helper(QVariant::Private *x, std::false_type)
-{
-    x->data.shared = QVariant::PrivateShared::create(QMetaType::fromType<T>());
-    new (x->data.shared->data()) T();
-    x->is_shared = true;
+            : static_cast<T *>(static_cast<void *>(&d->data));
 }
 
 template <class T>
 inline void v_construct(QVariant::Private *x, const T &t)
 {
-    // dispatch
-    v_construct_helper(x, t, typename QVariantIntegrator<T>::CanUseInternalSpace_t());
-}
-
-// constructs a new variant if copy is 0, otherwise copy-constructs
-template <class T>
-inline void v_construct(QVariant::Private *x, const void *copy, T * = nullptr)
-{
-    if (copy)
-        v_construct<T>(x, *static_cast<const T *>(copy));
-    else
-        v_construct_helper<T>(x, typename QVariantIntegrator<T>::CanUseInternalSpace_t());
-}
-
-// deletes the internal structures
-template <class T>
-inline void v_clear(QVariant::Private *d, T* = nullptr)
-{
-
-    if (!QVariantIntegrator<T>::CanUseInternalSpace) {
-        delete static_cast<T *>(d->data.shared->data());
+    if constexpr (QVariantIntegrator<T>::CanUseInternalSpace) {
+        new (&x->data) T(t);
+        x->is_shared = false;
     } else {
-        v_cast<T>(d)->~T();
+        x->data.shared = QVariant::PrivateShared::create(QMetaType::fromType<T>());
+        new (x->data.shared->data()) T(t);
+        x->is_shared = true;
     }
-
 }
 
 Q_CORE_EXPORT const QVariant::Handler *qcoreVariantHandler();