QCryptographicHash: Add getter for algorithm()

This can be helpful when you calculate multiple hashes, store them in a
vector and you want to know which result belongs to which algorithm.

[ChangeLog][QtCore][QCryptographicHash] Added getter algorithm().

Change-Id: Ifcf78536f215619a6e2e3035a95598327d0ed733
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/corelib/tools/qcryptographichash.cpp

@@ -364,6 +364,16 @@ void QCryptographicHash::reset() noexcept
     d->reset();
 }
 
+/*!
+    Returns the algorithm used to generate the cryptographic hash.
+
+    \since 6.5
+*/
+QCryptographicHash::Algorithm QCryptographicHash::algorithm() const noexcept
+{
+    return d->method;
+}
+
 void QCryptographicHashPrivate::reset() noexcept
 {
     switch (method) {

src/corelib/tools/qcryptographichash.h

@@ -71,6 +71,7 @@ public:
     void swap(QCryptographicHash &other) noexcept { qt_ptr_swap(d, other.d); }
 
     void reset() noexcept;
+    [[nodiscard]] Algorithm algorithm() const noexcept;
 
 #if QT_DEPRECATED_SINCE(6, 4)
     QT_DEPRECATED_VERSION_X_6_4("Use the QByteArrayView overload instead")

tests/auto/corelib/tools/qcryptographichash/tst_qcryptographichash.cpp

@@ -51,6 +51,8 @@ void tst_QCryptographicHash::repeated_result()
     QCryptographicHash::Algorithm _algo = QCryptographicHash::Algorithm(algo);
     QCryptographicHash hash(_algo);
 
+    QCOMPARE_EQ(hash.algorithm(), _algo);
+
     QFETCH(QByteArray, first);
     hash.addData(first);