Add rvalue-ref qualified overload of QByteArray::to{Upper,Lower}

Those operations aren't very common with QByteArray but this is easy to
optimize.

                Qt                   Qt Creator
        const &         &&      const &         &&
toLower      34         10            0          1
toUpper       3          1            0          0

Change-Id: I2097955f4c889ea5a21903c35ddbc0ff27bf62c5
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

src/corelib/tools/qbytearray.cpp

@@ -2777,10 +2777,10 @@ static QByteArray toCase_template(T &input, const uchar * table)
     }
 
     if (firstBad == e)
-        return input;
+        return qMove(input);
 
     // transform the rest
-    QByteArray s = input;
+    QByteArray s = qMove(input);    // will copy if T is const QByteArray
     char *b = s.begin();            // will detach if necessary
     char *p = b + (firstBad - orig_begin);
     e = b + s.size();
@@ -2790,13 +2790,19 @@ static QByteArray toCase_template(T &input, const uchar * table)
     return s;
 }
 
-
-QByteArray QByteArray::toLower() const
+QByteArray QByteArray::toLower_helper(const QByteArray &a)
 {
-    return toCase_template(*this, latin1_lowercased);
+    return toCase_template(a, latin1_lowercased);
+}
+
+QByteArray QByteArray::toLower_helper(QByteArray &a)
+{
+    return toCase_template(a, latin1_lowercased);
 }
 
 /*!
+    \fn QByteArray QByteArray::toUpper() const
+
     Returns an uppercase copy of the byte array. The bytearray is
     interpreted as a Latin-1 encoded string.
 
@@ -2805,9 +2811,15 @@ QByteArray QByteArray::toLower() const
 
     \sa toLower(), {8-bit Character Comparisons}
 */
-QByteArray QByteArray::toUpper() const
+
+QByteArray QByteArray::toUpper_helper(const QByteArray &a)
 {
-    return toCase_template(*this, latin1_uppercased);
+    return toCase_template(a, latin1_uppercased);
+}
+
+QByteArray QByteArray::toUpper_helper(QByteArray &a)
+{
+    return toCase_template(a, latin1_uppercased);
 }
 
 /*! \fn void QByteArray::clear()

src/corelib/tools/qbytearray.h

@@ -264,8 +264,29 @@ public:
     void truncate(int pos);
     void chop(int n);
 
+#if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP)
+#  if defined(Q_CC_GNU)
+    // required due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61941
+#    pragma push_macro("Q_REQUIRED_RESULT")
+#    undef Q_REQUIRED_RESULT
+#    define Q_REQUIRED_RESULT
+#    define Q_REQUIRED_RESULT_pushed
+#  endif
+    QByteArray toLower() const & Q_REQUIRED_RESULT
+    { return toLower_helper(*this); }
+    QByteArray toLower() && Q_REQUIRED_RESULT
+    { return toLower_helper(*this); }
+    QByteArray toUpper() const & Q_REQUIRED_RESULT
+    { return toUpper_helper(*this); }
+    QByteArray toUpper() && Q_REQUIRED_RESULT
+    { return toUpper_helper(*this); }
+#  ifdef Q_REQUIRED_RESULT_pushed
+#    pragma pop_macro("Q_REQUIRED_RESULT")
+#  endif
+#else
     QByteArray toLower() const Q_REQUIRED_RESULT;
     QByteArray toUpper() const Q_REQUIRED_RESULT;
+#endif
 
     QByteArray trimmed() const Q_REQUIRED_RESULT;
     QByteArray simplified() const Q_REQUIRED_RESULT;
@@ -422,6 +443,10 @@ private:
     void expand(int i);
     QByteArray nulTerminated() const;
 
+    static QByteArray toLower_helper(const QByteArray &a);
+    static QByteArray toLower_helper(QByteArray &a);
+    static QByteArray toUpper_helper(const QByteArray &a);
+    static QByteArray toUpper_helper(QByteArray &a);
     friend class QByteRef;
     friend class QString;
     friend Q_CORE_EXPORT QByteArray qUncompress(const uchar *data, int nbytes);

src/corelib/tools/qstring_compat.cpp

@@ -39,11 +39,12 @@
 **
 ****************************************************************************/
 
-#if defined(QSTRING_H)
+#if defined(QSTRING_H) || defined(QBYTEARRAY_H)
 #  error "This file cannot be compiled with pre-compiled headers"
 #endif
 #define QT_COMPILING_QSTRING_COMPAT_CPP
 
+#include "qbytearray.h"
 #include "qstring.h"
 
 QT_BEGIN_NAMESPACE
@@ -64,4 +65,15 @@ QByteArray QString::toUtf8() const
     return toUtf8_helper(*this);
 }
 
+// ditto, for qbytearray.h (because we're lazy)
+QByteArray QByteArray::toLower() const
+{
+    return toLower_helper(*this);
+}
+
+QByteArray QByteArray::toUpper() const
+{
+    return toUpper_helper(*this);
+}
+
 QT_END_NAMESPACE

tests/auto/corelib/tools/qbytearray/tst_qbytearray.cpp

@@ -2008,6 +2008,9 @@ void tst_QByteArray::toUpperLower_data()
     QTest::addColumn<QByteArray>("lower");
 
     QTest::newRow("empty") << QByteArray() << QByteArray() << QByteArray();
+    QTest::newRow("literal") << QByteArrayLiteral("Hello World")
+                             << QByteArrayLiteral("HELLO WORLD")
+                             << QByteArrayLiteral("hello world");
     QTest::newRow("ascii") << QByteArray("Hello World, this is a STRING")
                            << QByteArray("HELLO WORLD, THIS IS A STRING")
                            << QByteArray("hello world, this is a string");
@@ -2026,6 +2029,30 @@ void tst_QByteArray::toUpperLower()
     QCOMPARE(upper.toUpper(), upper);
     QCOMPARE(input.toUpper(), upper);
     QCOMPARE(input.toLower(), lower);
+
+    QByteArray copy = input;
+    QCOMPARE(qMove(copy).toUpper(), upper);
+    copy = input;
+    copy.detach();
+    QCOMPARE(qMove(copy).toUpper(), upper);
+
+    copy = input;
+    QCOMPARE(qMove(copy).toLower(), lower);
+    copy = input;
+    copy.detach();
+    QCOMPARE(qMove(copy).toLower(), lower);
+
+    copy = lower;
+    QCOMPARE(qMove(copy).toLower(), lower);
+    copy = lower;
+    copy.detach();
+    QCOMPARE(qMove(copy).toLower(), lower);
+
+    copy = upper;
+    QCOMPARE(qMove(copy).toUpper(), upper);
+    copy = upper;
+    copy.detach();
+    QCOMPARE(qMove(copy).toUpper(), upper);
 }
 
 void tst_QByteArray::macTypes()