1 files changed, 39 insertions, 62 deletions

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index 6be695e317..f0e4342e06 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -49,6 +49,7 @@
 #include <algorithm>
 #include <initializer_list>
 #include <iterator>
+#include <memory>
 #include <new>
 #include <string.h>
 #include <stdlib.h>
@@ -152,30 +153,18 @@ public:
         if (s == a) {   // i.e. s != 0
             T copy(t);
             realloc(s, s<<1);
-            const int idx = s++;
-            if (QTypeInfo<T>::isComplex) {
-                new (ptr + idx) T(std::move(copy));
-            } else {
-                ptr[idx] = std::move(copy);
-            }
+            new (end()) T(std::move(copy));
         } else {
-            const int idx = s++;
-            if (QTypeInfo<T>::isComplex) {
-                new (ptr + idx) T(t);
-            } else {
-                ptr[idx] = t;
-            }
+            new (end()) T(t);
         }
+        ++s;
     }
 
     void append(T &&t) {
         if (s == a)
             realloc(s, s << 1);
-        const int idx = s++;
-        if (QTypeInfo<T>::isComplex)
-            new (ptr + idx) T(std::move(t));
-        else
-            ptr[idx] = std::move(t);
+        new (end()) T(std::move(t));
+        ++s;
     }
 
     void append(const T *buf, int size);
@@ -249,6 +238,20 @@ public:
 private:
     void realloc(int size, int alloc);
 
+    void resize_impl(int newSize, const T &t)
+    {
+        const auto increment = newSize - size();
+        if (increment > 0 && QtPrivate::q_points_into_range(&t, cbegin(), cend())) {
+            resize_impl(newSize, T(t));
+            return;
+        }
+        realloc(qMin(size(), newSize), qMax(newSize, capacity()));
+
+        if (increment > 0)
+            std::uninitialized_fill_n(end(), increment, t);
+        s = newSize;
+    }
+
     int a;      // capacity
     int s;      // size
     T *ptr;     // data
@@ -487,57 +490,25 @@ Q_OUTOFLINE_TEMPLATE typename QVarLengthArray<T, Prealloc>::iterator QVarLengthA
 {
     Q_ASSERT_X(isValidIterator(before), "QVarLengthArray::insert", "The specified const_iterator argument 'before' is invalid");
 
-    int offset = int(before - ptr);
-    reserve(s + 1);
-    if (!QTypeInfo<T>::isRelocatable) {
-        T *b = ptr + offset;
-        T *i = ptr + s;
-        T *j = i + 1;
-        // The new end-element needs to be constructed, the rest must be move assigned
-        if (i != b) {
-            new (--j) T(std::move(*--i));
-            while (i != b)
-                *--j = std::move(*--i);
-            *b = std::move(t);
-        } else {
-            new (b) T(std::move(t));
-        }
-    } else {
-        T *b = ptr + offset;
-        memmove(static_cast<void *>(b + 1), static_cast<const void *>(b), (s - offset) * sizeof(T));
-        new (b) T(std::move(t));
-    }
-    s += 1;
-    return ptr + offset;
+    const int offset = int(before - ptr);
+    append(std::move(t));
+    const auto b = begin() + offset;
+    const auto e = end();
+    QtPrivate::q_rotate(b, e - 1, e);
+    return b;
 }
 
 template <class T, int Prealloc>
-Q_OUTOFLINE_TEMPLATE typename QVarLengthArray<T, Prealloc>::iterator QVarLengthArray<T, Prealloc>::insert(const_iterator before, size_type n, const T &t)
+Q_OUTOFLINE_TEMPLATE typename QVarLengthArray<T, Prealloc>::iterator QVarLengthArray<T, Prealloc>::insert(const_iterator before, int n, const T &t)
 {
     Q_ASSERT_X(isValidIterator(before), "QVarLengthArray::insert", "The specified const_iterator argument 'before' is invalid");
 
-    int offset = int(before - ptr);
-    if (n != 0) {
-        resize(s + n);
-        const T copy(t);
-        if (!QTypeInfoQuery<T>::isRelocatable) {
-            T *b = ptr + offset;
-            T *j = ptr + s;
-            T *i = j - n;
-            while (i != b)
-                *--j = *--i;
-            i = b + n;
-            while (i != b)
-                *--i = copy;
-        } else {
-            T *b = ptr + offset;
-            T *i = b + n;
-            memmove(static_cast<void *>(i), static_cast<const void *>(b), (s - offset - n) * sizeof(T));
-            while (i != b)
-                new (--i) T(copy);
-        }
-    }
-    return ptr + offset;
+    const int offset = int(before - cbegin());
+    resize_impl(size() + n, t);
+    const auto b = begin() + offset;
+    const auto e = end();
+    QtPrivate::q_rotate(b, e - n, e);
+    return b;
 }
 
 template <class T, int Prealloc>
@@ -549,6 +520,12 @@ Q_OUTOFLINE_TEMPLATE typename QVarLengthArray<T, Prealloc>::iterator QVarLengthA
     int f = int(abegin - ptr);
     int l = int(aend - ptr);
     int n = l - f;
+
+    if (n == 0) // avoid UB in std::copy() below
+        return data() + f;
+
+    Q_ASSERT(n > 0); // aend must be reachable from abegin
+
     if (QTypeInfo<T>::isComplex) {
         std::copy(ptr + l, ptr + s, QT_MAKE_CHECKED_ARRAY_ITERATOR(ptr + f, s - f));
         T *i = ptr + s;