QMessageAuthenticationCode: port to QByteArrayView [1/3]: ctor/setKey()

The class is not used frequently enough to warrant the overhead of a
Q_WEAK_ QByteArray overload to fix the SiC Type A for users that pass
objects that implicitly convert to QByteArray. QCryptographicHash also
doesn't have it.

Also mark setKey() noexcept. Now that it takes a view instead of
an owning container, it only calls other noexcept functions.

ChangeLog will be on patch [3/3].

Task-number: QTBUG-111676
Task-number: QTBUG-111688
Change-Id: Ic2321d0d41ce8eb4d0390889f28b3fd4bd9af103
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/corelib/compat/removed_api.cpp

@@ -486,6 +486,17 @@ void QXmlStreamWriter::writeStartElement(const QString &namespaceUri, const QStr
 
 #if QT_CORE_REMOVED_SINCE(6, 6)
 
+#include "qmessageauthenticationcode.h"
+
+QMessageAuthenticationCode::QMessageAuthenticationCode(QCryptographicHash::Algorithm method,
+                                                       const QByteArray &key)
+    : QMessageAuthenticationCode(method, qToByteArrayViewIgnoringNull(key)) {}
+
+void QMessageAuthenticationCode::setKey(const QByteArray &key)
+{
+    setKey(qToByteArrayViewIgnoringNull(key));
+}
+
 #include "qstring.h"
 
 qsizetype QString::toUcs4_helper(const ushort *uc, qsizetype length, uint *out)

src/corelib/tools/qcryptographichash.cpp

@@ -1245,9 +1245,18 @@ void QMessageAuthenticationCodePrivate::initMessageHash() noexcept
 /*!
     Constructs an object that can be used to create a cryptographic hash from data
     using method \a method and key \a key.
+
+//! [qba-to-qbav-6.6]
+    \note In Qt versions prior to 6.6, this function took its arguments as
+    QByteArray, not QByteArrayView. If you experience compile errors, it's
+    because your code is passing objects that are implicitly convertible to
+    QByteArray, but not QByteArrayView. Wrap the corresponding argument in
+    \c{QByteArray{~~~}} to make the cast explicit. This is backwards-compatible
+    with old Qt versions.
+//! [qba-to-qbav-6.6]
 */
 QMessageAuthenticationCode::QMessageAuthenticationCode(QCryptographicHash::Algorithm method,
-                                                       const QByteArray &key)
+                                                       QByteArrayView key)
     : d(new QMessageAuthenticationCodePrivate(method))
 {
     d->setKey(key);
@@ -1334,8 +1343,10 @@ void QMessageAuthenticationCode::reset()
     mac.emplace(method, key);
     use(*mac);
     \endcode
+
+    \include qcryptographichash.cpp {qba-to-qbav-6.6}
 */
-void QMessageAuthenticationCode::setKey(const QByteArray &key)
+void QMessageAuthenticationCode::setKey(QByteArrayView key) noexcept
 {
     d->result.clear();
     d->messageHash.reset();

src/corelib/tools/qmessageauthenticationcode.h

@@ -16,8 +16,13 @@ class QIODevice;
 class Q_CORE_EXPORT QMessageAuthenticationCode
 {
 public:
+#if QT_CORE_REMOVED_SINCE(6, 6)
     explicit QMessageAuthenticationCode(QCryptographicHash::Algorithm method,
-                                        const QByteArray &key = QByteArray());
+                                        const QByteArray &key);
+#endif
+    explicit QMessageAuthenticationCode(QCryptographicHash::Algorithm method,
+                                        QByteArrayView key = {});
+
     QMessageAuthenticationCode(QMessageAuthenticationCode &&other) noexcept
         : d{std::exchange(other.d, nullptr)} {}
     ~QMessageAuthenticationCode();
@@ -28,7 +33,10 @@ public:
 
     void reset();
 
+#if QT_CORE_REMOVED_SINCE(6, 6)
     void setKey(const QByteArray &key);
+#endif
+    void setKey(QByteArrayView key) noexcept;
 
     void addData(const char *data, qsizetype length);
     void addData(const QByteArray &data);