QDebug: add operator<<(const char16_t *)

Avoids the conversion from UTF-8 for uses that are not dumping a string.

Mass conversion of Qt sources left for future opportunity.

Fixes: QTBUG-85811
Change-Id: I4ca4a35b687b46c39030fffd1626ae6c3294cacf
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/io/qdebug.cpp

@@ -597,9 +597,24 @@ QDebug &QDebug::resetFormat()
 /*!
     \fn QDebug &QDebug::operator<<(const char *t)
 
-    Writes the '\\0'-terminated string, \a t, to the stream and returns a
-    reference to the stream. The string is never quoted nor transformed to the
-    output, but note that some QDebug backends might not be 8-bit clean.
+    Writes the '\\0'-terminated UTF-8 string, \a t, to the stream and returns a
+    reference to the stream. The string is never quoted or escaped for the
+    output. Note that QDebug buffers internally as UTF-16 and may need to
+    transform to 8-bit using the locale's codec in order to use some backends,
+    which may cause garbled output (mojibake). Restricting to US-ASCII strings
+    is recommended.
+*/
+
+/*!
+    \fn QDebug &QDebug::operator<<(const char16_t *t)
+    \since 6.0
+
+    Writes the u'\\0'-terminated UTF-16 string, \a t, to the stream and returns
+    a reference to the stream. The string is never quoted or escaped for the
+    output. Note that QDebug buffers internally as UTF-16 and may need to
+    transform to 8-bit using the locale's codec in order to use some backends,
+    which may cause garbled output (mojibake). Restricting to US-ASCII strings
+    is recommended.
 */
 
 /*!
@@ -950,18 +965,18 @@ QDebug qt_QMetaEnum_debugOperator(QDebug &dbg, int value, const QMetaObject *met
     const int verbosity = dbg.verbosity();
     if (verbosity >= QDebug::DefaultVerbosity) {
         if (const char *scope = me.scope())
-            dbg << scope << "::";
+            dbg << scope << u"::";
     }
 
     const char *key = me.valueToKey(value);
     const bool scoped = me.isScoped() || verbosity & 1;
     if (scoped || !key)
-        dbg << me.enumName() << (!key ? "(" : "::");
+        dbg << me.enumName() << (!key ? u"(" : u"::");
 
     if (key)
         dbg << key;
     else
-        dbg << value << ")";
+        dbg << value << ')';
 
     return dbg;
 }
@@ -1008,18 +1023,18 @@ QDebug qt_QMetaEnum_flagDebugOperator(QDebug &debug, quint64 value, const QMetaO
 
     const bool classScope = verbosity >= QDebug::DefaultVerbosity;
     if (classScope) {
-        debug << "QFlags<";
+        debug << u"QFlags<";
 
         if (const char *scope = me.scope())
-            debug << scope << "::";
+            debug << scope << u"::";
     }
 
     const bool enumScope = me.isScoped() || verbosity > QDebug::MinimumVerbosity;
     if (enumScope) {
         debug << me.enumName();
         if (classScope)
-            debug << ">";
-        debug << "(";
+            debug << '>';
+        debug << '(';
     }
 
     debug << me.valueToKeys(value);

src/corelib/io/qdebug.h

@@ -155,6 +155,7 @@ public:
     inline QDebug &operator<<(float t) { stream->ts << t; return maybeSpace(); }
     inline QDebug &operator<<(double t) { stream->ts << t; return maybeSpace(); }
     inline QDebug &operator<<(const char* t) { stream->ts << QString::fromUtf8(t); return maybeSpace(); }
+    inline QDebug &operator<<(const char16_t *t)  { stream->ts << QStringView(t); return maybeSpace(); }
 #if QT_STRINGVIEW_LEVEL < 2
     inline QDebug &operator<<(const QString & t) { putString(t.constData(), uint(t.length())); return maybeSpace(); }
 #endif

tests/auto/corelib/io/qdebug/tst_qdebug.cpp

@@ -49,6 +49,7 @@ private slots:
     void assignment() const;
     void warningWithoutDebug() const;
     void criticalWithoutDebug() const;
+    void basics() const;
     void debugWithBool() const;
     void debugSpaceHandling() const;
     void debugNoQuotes() const;
@@ -156,6 +157,46 @@ void tst_QDebug::criticalWithoutDebug() const
     QCOMPARE(QString::fromLatin1(s_function), function);
 }
 
+void tst_QDebug::basics() const
+{
+    // test simple types, without quoting or other modifications
+    // (bool tested in the next function)
+    MessageHandlerSetter mhs(myMessageHandler);
+
+    qDebug() << 'X';
+    QCOMPARE(s_msg, "X");
+
+    qDebug() << 123;
+    QCOMPARE(s_msg, "123");
+
+    qDebug() << 456U;
+    QCOMPARE(s_msg, "456");
+
+    qDebug() << -123L;
+    QCOMPARE(s_msg, "-123");
+
+    qDebug() << 456UL;
+    QCOMPARE(s_msg, "456");
+
+    qDebug() << Q_INT64_C(-123);
+    QCOMPARE(s_msg, "-123");
+
+    qDebug() << Q_UINT64_C(456);
+    QCOMPARE(s_msg, "456");
+
+    qDebug() << "Hello";
+    QCOMPARE(s_msg, "Hello");
+
+    qDebug() << u"World";
+    QCOMPARE(s_msg, "World");
+
+    qDebug() << (void *)0xfff;
+    QCOMPARE(s_msg, "0xfff");
+
+    qDebug() << nullptr;
+    QCOMPARE(s_msg, "(nullptr)");
+}
+
 void tst_QDebug::debugWithBool() const
 {
     QString file, function;