QByteArrayList: add join(QByteArrayView)

Since QByteArray/QByteArrayView don't overload nicely, we need to make
the existing QByteArray overload a Q_WEAK_OVERLOAD (= a template) as a
tie breaker. This automatically prefers the QByteArrayView version
over the QByteArray overload, transparently optimizing existing users
passing char string literals to avoid the implicit creation of a
QByteArray just for passing the separator.

None of our modules exports a subclass of QByteArrayList, so turning
join(QByteArray) into a function template should be ok.

[ChangeLog][QtCore][QByteArrayList] Added join(QByteArrayView)
overload.

Change-Id: I090671d9b94c30b63a986f17e966d124c22b5c54
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

3 files changed, 42 insertions, 1 deletions

diff --git a/src/corelib/text/qbytearraylist.cpp b/src/corelib/text/qbytearraylist.cpp
index c815e766ab..5142869c72 100644
--- a/src/corelib/text/qbytearraylist.cpp
+++ b/src/corelib/text/qbytearraylist.cpp
@@ -116,6 +116,14 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
+    \fn QByteArray QByteArrayList::join(QByteArrayView separator) const
+    \since 6.3
+
+    Joins all the byte arrays into a single byte array with each
+    element separated by the given \a separator.
+*/
+
+/*!
     \fn QByteArray QByteArrayList::join(char separator) const
 
     Joins all the byte arrays into a single byte array with each
diff --git a/src/corelib/text/qbytearraylist.h b/src/corelib/text/qbytearraylist.h
index e00586291f..7e8fe89bab 100644
--- a/src/corelib/text/qbytearraylist.h
+++ b/src/corelib/text/qbytearraylist.h
@@ -77,8 +77,13 @@ public:
 
     inline QByteArray join() const
     { return QtPrivate::QByteArrayList_join(self(), nullptr, 0); }
+    inline QByteArray join(QByteArrayView sep) const // ### Qt 7: merge with the () overload
+    {
+        return QtPrivate::QByteArrayList_join(self(), sep.data(), sep.size());
+    }
+    Q_WEAK_OVERLOAD
     inline QByteArray join(const QByteArray &sep) const
-    { return QtPrivate::QByteArrayList_join(self(), sep.constData(), sep.size()); }
+    { return join(QByteArrayView{sep}); }
     inline QByteArray join(char sep) const
     { return QtPrivate::QByteArrayList_join(self(), &sep, 1); }
 };
diff --git a/tests/auto/corelib/text/qbytearraylist/tst_qbytearraylist.cpp b/tests/auto/corelib/text/qbytearraylist/tst_qbytearraylist.cpp
index 29e5b947f6..82459f21ea 100644
--- a/tests/auto/corelib/text/qbytearraylist/tst_qbytearraylist.cpp
+++ b/tests/auto/corelib/text/qbytearraylist/tst_qbytearraylist.cpp
@@ -27,10 +27,13 @@
 **
 ****************************************************************************/
 
+#define QT_USE_QSTRINGBUILDER
+
 #include <QTest>
 #include <qbytearraylist.h>
 
 #include <qmetatype.h>
+#include <qproperty.h>
 
 Q_DECLARE_METATYPE(QByteArrayList)
 
@@ -38,6 +41,7 @@ class tst_QByteArrayList : public QObject
 {
     Q_OBJECT
 private slots:
+    void join_overloads() const;
     void join() const;
     void join_data() const;
     void joinByteArray() const;
@@ -55,12 +59,34 @@ private slots:
     void initializerList() const;
 };
 
+void tst_QByteArrayList::join_overloads() const
+{
+    // Checks that there are no ambiguities between the different join() overloads:
+
+    const QByteArrayList list = {"a", "b", "c"};
+    const QByteArray expected = "aXbXc";
+
+    QCOMPARE(list.join('X'), expected);
+    QCOMPARE(list.join("X"), expected);
+    QCOMPARE(list.join(QByteArrayLiteral("X")), expected);
+    QCOMPARE(list.join(QByteArray("X")), expected);
+    QCOMPARE(list.join(QByteArrayView("X")), expected);
+    const char *sep = "X";
+    QCOMPARE(list.join(sep), expected);
+    QCOMPARE(list.join(QByteArray() % "X"), expected); // QStringBuilder expression
+    QProperty<QByteArray> prop("X"); // implicitly convertible to QByteArray
+    QCOMPARE(list.join(prop), expected);
+    QCOMPARE(list.join(std::as_const(prop)), expected);
+}
+
 void tst_QByteArrayList::join() const
 {
     QFETCH(QByteArrayList, input);
     QFETCH(QByteArray, expectedResult);
 
     QCOMPARE(input.join(), expectedResult);
+    QCOMPARE(input.join(QByteArrayView{}), expectedResult);
+    QCOMPARE(input.join(QByteArray{}), expectedResult);
 }
 
 void tst_QByteArrayList::join_data() const
@@ -88,6 +114,7 @@ void tst_QByteArrayList::joinByteArray() const
     QFETCH(QByteArray, expectedResult);
 
     QCOMPARE(input.join(separator), expectedResult);
+    QCOMPARE(input.join(QByteArrayView{separator}), expectedResult);
 }
 
 void tst_QByteArrayList::joinByteArray_data() const
@@ -132,6 +159,7 @@ void tst_QByteArrayList::joinChar() const
     QFETCH(QByteArray, expectedResult);
 
     QCOMPARE(input.join(separator), expectedResult);
+    QCOMPARE(input.join(QByteArrayView{&separator, 1}), expectedResult);
 }
 
 void tst_QByteArrayList::joinChar_data() const