QLatin1String: Add a constructor taking QByteArrayView

Change-Id: Ie90645486431d7af3fe8128417b0fb6bd02a88b5
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/text/qstring.cpp

@@ -8910,6 +8910,20 @@ QString &QString::setRawData(const QChar *unicode, qsizetype size)
     \sa latin1()
 */
 
+/*! \fn QLatin1String::QLatin1String(QByteArrayView str)
+    \since 6.3
+
+    Constructs a QLatin1String object that stores \a str.
+
+    The string data is \e not copied. The caller must be able to
+    guarantee that the data which \a str is pointing to will not
+    be deleted or modified as long as the QLatin1String object
+    exists. The size is obtained from \a str as-is, without checking
+    for a null-terminator.
+
+    \sa latin1()
+*/
+
 /*!
     \fn QString QLatin1String::toString() const
     \since 6.0

src/corelib/text/qstring.h

@@ -89,6 +89,7 @@ public:
         : QLatin1String(f, qsizetype(l - f)) {}
     constexpr inline explicit QLatin1String(const char *s, qsizetype sz) noexcept : m_size(sz), m_data(s) {}
     explicit QLatin1String(const QByteArray &s) noexcept : m_size(qsizetype(qstrnlen(s.constData(), s.size()))), m_data(s.constData()) {}
+    constexpr explicit QLatin1String(QByteArrayView s) noexcept : m_size(s.size()), m_data(s.data()) {}
 
     inline QString toString() const;
 

tests/auto/corelib/text/qlatin1string/tst_qlatin1string.cpp

@@ -44,6 +44,7 @@ class tst_QLatin1String : public QObject
     Q_OBJECT
 
 private Q_SLOTS:
+    void construction();
     void at();
     void arg() const;
     void midLeftRight();
@@ -54,6 +55,36 @@ private Q_SLOTS:
     void relationalOperators();
 };
 
+void tst_QLatin1String::construction()
+{
+    {
+        const char str[6] = "hello";
+        QLatin1String l1s(str);
+        QCOMPARE(l1s.size(), 5);
+        QCOMPARE(l1s.latin1(), reinterpret_cast<const void *>(&str[0]));
+        QCOMPARE(l1s.latin1(), "hello");
+
+        QByteArrayView helloView(str);
+        helloView = helloView.first(4);
+        l1s = QLatin1String(helloView);
+        QCOMPARE(l1s.latin1(), helloView.data());
+        QCOMPARE(l1s.latin1(), reinterpret_cast<const void *>(helloView.data()));
+        QCOMPARE(l1s.size(), helloView.size());
+    }
+
+    {
+        const QByteArray helloArray("hello");
+        QLatin1String l1s(helloArray);
+        QCOMPARE(l1s.latin1(), helloArray.data());
+        QCOMPARE(l1s.size(), helloArray.size());
+
+        QByteArrayView helloView(helloArray);
+        helloView = helloView.first(4);
+        l1s = QLatin1String(helloView);
+        QCOMPARE(l1s.latin1(), helloView.data());
+        QCOMPARE(l1s.size(), helloView.size());
+    }
+}
 
 void tst_QLatin1String::at()
 {