QVarLengthArray: add missing (size, value) ctor

Extend the corresponding test in tst_containerapisymmetry.

[ChangeLog][QtCore][QVarLengthArray] Added (size, value) constructor.

Fixes: QTBUG-102469
Change-Id: I4802eebe6ba1a6835e4d6f41e1d3db2a0d7c7894
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qvarlengtharray.h

@@ -286,6 +286,15 @@ public:
 
     inline explicit QVarLengthArray(qsizetype size);
 
+#ifndef Q_QDOC
+    template <typename U = T, if_copyable<U> = true>
+#endif
+    explicit QVarLengthArray(qsizetype sz, const T &v)
+        : QVarLengthArray{}
+    {
+        resize(sz, v);
+    }
+
     QVarLengthArray(const QVarLengthArray &other)
         : QVarLengthArray{}
     {

src/corelib/tools/qvarlengtharray.qdoc

@@ -105,6 +105,18 @@
     \l{default-constructed value}.
 */
 
+/*!
+    \fn template<class T, qsizetype Prealloc> QVarLengthArray<T, Prealloc>::QVarLengthArray(qsizetype size, const T &v)
+    \since 6.4
+
+    Constructs an array with an initial size of \a size elements filled with
+    copies of \a v.
+
+    \note This constructor is only available when \c T is copy-constructible.
+
+    \sa size(), squeeze()
+*/
+
 
 /*! \fn template<class T, qsizetype Prealloc> QVarLengthArray<T, Prealloc>::QVarLengthArray(std::initializer_list<T> args)
     \since 5.5

tests/auto/corelib/tools/containerapisymmetry/tst_containerapisymmetry.cpp

@@ -750,6 +750,18 @@ void tst_ContainerApiSymmetry::resize_impl() const
     c.resize(4, V(5));
     QCOMPARE(c.size(), S(4));
     QCOMPARE(c.back(), V(5));
+
+    // ctor/resize symmetry:
+    {
+        Container c1(S(5), V(4));
+        QCOMPARE(c1.size(), S(5));
+
+        Container c2;
+        c2.resize(S(5), V(4));
+        QCOMPARE(c2.size(), S(5));
+
+        QCOMPARE(c1, c2);
+    }
 }
 
 template <typename Container>