QByteArray/QVarLengthArray: add missing resize(n, v) overloads

QList and QString had them, so add them to QByteArray and
QVarLengthArray, too.

In the QVLA case, we need to jump though a hoop or two to avoid having
to duplicate all the reallocation logic. Nothing a few template tricks
cannot solve.

[ChangeLog][QtCore][QByteArray] Added resize(n, ch) overload.

[ChangeLog][QtCore][QVarLengthArray] Added resize(n, v) overload.

Fixes: QTBUG-102270
Change-Id: I0d281ae5b574f440f682e4a62427b434dcf5b687
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 35 insertions, 5 deletions

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index fd3d4ffbf2..2c9d0dd975 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -237,9 +237,9 @@ protected:
     }
 
     void append_impl(qsizetype prealloc, void *array, const T *buf, qsizetype n);
-    void reallocate_impl(qsizetype prealloc, void *array, qsizetype size, qsizetype alloc);
-    void resize_impl(qsizetype prealloc, void *array, qsizetype sz)
-    { reallocate_impl(prealloc, array, sz, qMax(sz, capacity())); }
+    void reallocate_impl(qsizetype prealloc, void *array, qsizetype size, qsizetype alloc, const T *v = nullptr);
+    void resize_impl(qsizetype prealloc, void *array, qsizetype sz, const T *v = nullptr)
+    { reallocate_impl(prealloc, array, sz, qMax(sz, capacity()), v); }
 
     bool isValidIterator(const const_iterator &i) const
     {
@@ -393,6 +393,14 @@ public:
     }
     bool isEmpty() const { return empty(); }
     void resize(qsizetype sz) { Base::resize_impl(Prealloc, this->array, sz); }
+#ifdef Q_QDOC
+    void
+#else
+    template <typename U = T>
+    std::enable_if_t<std::is_copy_constructible_v<U>>
+#endif
+    resize(qsizetype sz, const T &v)
+    { Base::resize_impl(Prealloc, this->array, sz, &v); }
     inline void clear() { resize(0); }
     void squeeze() { reallocate(size(), size()); }
 
@@ -720,7 +728,7 @@ Q_OUTOFLINE_TEMPLATE void QVLABase<T>::append_impl(qsizetype prealloc, void *arr
 }
 
 template <class T>
-Q_OUTOFLINE_TEMPLATE void QVLABase<T>::reallocate_impl(qsizetype prealloc, void *array, qsizetype asize, qsizetype aalloc)
+Q_OUTOFLINE_TEMPLATE void QVLABase<T>::reallocate_impl(qsizetype prealloc, void *array, qsizetype asize, qsizetype aalloc, const T *v)
 {
     Q_ASSERT(aalloc >= asize);
     Q_ASSERT(data());
@@ -765,7 +773,16 @@ Q_OUTOFLINE_TEMPLATE void QVLABase<T>::reallocate_impl(qsizetype prealloc, void
     if (oldPtr != reinterpret_cast<T *>(array) && oldPtr != data())
         free(oldPtr);
 
-    if constexpr (QTypeInfo<T>::isComplex) {
+    if (v) {
+        if constexpr (std::is_copy_constructible_v<T>) {
+            while (size() < asize) {
+                new (data() + size()) T(*v);
+                ++s;
+            }
+        } else {
+            Q_UNREACHABLE();
+        }
+    } else if constexpr (QTypeInfo<T>::isComplex) {
         // call default constructor for new objects (which can throw)
         while (size() < asize) {
             new (data() + size()) T;
diff --git a/src/corelib/tools/qvarlengtharray.qdoc b/src/corelib/tools/qvarlengtharray.qdoc
index de57daf4e4..12789b49b9 100644
--- a/src/corelib/tools/qvarlengtharray.qdoc
+++ b/src/corelib/tools/qvarlengtharray.qdoc
@@ -245,6 +245,19 @@
     \sa size(), squeeze()
 */
 
+/*!
+    \fn template<class T, qsizetype Prealloc> void QVarLengthArray<T, Prealloc>::resize(qsizetype size, const T &v)
+    \since 6.4
+
+    Sets the size of the array to \a size. If \a size is greater than
+    the current size, copies of \a v are added to the end. If \a size is
+    less than the current size, elements are removed from the end.
+
+    \note This function is only available when \c T is copy-constructible.
+
+    \sa size(), squeeze()
+*/
+
 /*! \fn template<class T, qsizetype Prealloc> qsizetype QVarLengthArray<T, Prealloc>::capacity() const
 
     Returns the maximum number of elements that can be stored in the