Add a clear method to QAuthenticator

Provide an alternative for
*auth = QAuthenticator();

[ChangeLog][QtNetwork][QAuthenticator] Add a new method to clear all
credentials.

Fixes: QTBUG-139124
Change-Id: Ia33b5dcb8eb6961f5daa5bc78addd8c78dd10e9a
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/kernel/qauthenticator.cpp

@@ -358,6 +358,19 @@ bool QAuthenticator::isNull() const
     return !d;
 }
 
+/*!
+    \since 6.11
+
+    Clears all credentials and resets the object to its default uninitialized
+    state.
+*/
+
+void QAuthenticator::clear() noexcept
+{
+    *d = QAuthenticatorPrivate();
+    d->phase = QAuthenticatorPrivate::Done;
+}
+
 #if QT_CONFIG(sspi) // SSPI
 class QSSPIWindowsHandles
 {

src/network/kernel/qauthenticator.h

@@ -43,6 +43,8 @@ public:
 
     bool isNull() const;
     void detach();
+
+    void clear() noexcept;
 private:
     friend class QAuthenticatorPrivate;
     QAuthenticatorPrivate *d;

src/network/kernel/qauthenticator_p.h

@@ -40,6 +40,30 @@ class Q_NETWORK_EXPORT QAuthenticatorPrivate
 public:
     enum Method { None, Basic, Negotiate, Ntlm, DigestMd5, };
     QAuthenticatorPrivate();
+
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QAuthenticatorPrivate)
+    void swap(QAuthenticatorPrivate &other) noexcept
+    {
+        user.swap(other.user);
+        extractedUser.swap(other.extractedUser);
+        password.swap(other.password);
+        options.swap(other.options);
+        std::swap(method, other.method);
+        realm.swap(other.realm);
+        challenge.swap(other.challenge);
+#if QT_CONFIG(sspi) // SSPI
+        sspiWindowsHandles.swap(other.sspiWindowsHandles);
+#elif QT_CONFIG(gssapi) // GSSAPI
+        gssApiHandles.swap(other.gssApiHandles);
+#endif
+        std::swap(hasFailed, other.hasFailed);
+        std::swap(phase, other.phase);
+        cnonce.swap(other.cnonce);
+        std::swap(nonceCount, other.nonceCount);
+        workstation.swap(other.workstation);
+        userDomain.swap(other.userDomain);
+    }
+
     ~QAuthenticatorPrivate();
 
     QString user;

tests/auto/network/kernel/qauthenticator/tst_qauthenticator.cpp

@@ -29,6 +29,8 @@ private Q_SLOTS:
     void equalityOperators();
 
     void isMethodSupported();
+
+    void testClear();
 };
 
 tst_QAuthenticator::tst_QAuthenticator()
@@ -188,6 +190,27 @@ void tst_QAuthenticator::isMethodSupported()
     QVERIFY(!QAuthenticatorPrivate::isMethodSupported("Bearer"));
 }
 
+void tst_QAuthenticator::testClear()
+{
+    QAuthenticator qauth;
+    QVERIFY(qauth.isNull());
+
+    qauth.setUser("User");
+    qauth.setPassword("Password");
+    qauth.setRealm("Nether");
+
+    QVERIFY(!qauth.isNull());
+    QCOMPARE(qauth.user(), "User");
+    QCOMPARE(qauth.password(), "Password");
+    QCOMPARE(qauth.realm(), "Nether");
+
+    qauth.clear();
+    QVERIFY(!qauth.isNull());
+    QCOMPARE(qauth.user(), QString());
+    QCOMPARE(qauth.password(), QString());
+    QCOMPARE(qauth.realm(), QString());
+}
+
 QTEST_MAIN(tst_QAuthenticator);
 
 #include "tst_qauthenticator.moc"