Suppress warning (MSVC, C4250)

This design decision was intentional and reflects the fact that we
cannot have inheritance tree 'linear' as before, since the base
interface is an abstract class without any data-members.
Also, fix a warning about size_t -> int implicit conversion.

Pick-to: dev
Fixes: QTBUG-91866
Change-Id: Icbc73c22d8adf72bbd8949125d4404ea6da69c6d
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/ssl/qdtls_openssl.cpp

@@ -1273,7 +1273,7 @@ unsigned QDtlsPrivateOpenSSL::pskClientCallback(const char *hint, char *identity
         }
 
         QTlsBackend::setupClientPskAuth(&authenticator, hint ? identityHint.constData() : nullptr,
-                                        hint ? std::strlen(hint) : 0, max_identity_len, max_psk_len);
+                                        hint ? int(std::strlen(hint)) : 0, max_identity_len, max_psk_len);
         pskAuthenticator.swap(authenticator);
     }
 

src/network/ssl/qdtls_openssl_p.h

@@ -58,6 +58,7 @@
 #include <QtNetwork/qhostaddress.h>
 
 #include <QtCore/qbytearray.h>
+#include <QtCore/qglobal.h>
 #include <QtCore/qlist.h>
 #include <QtCore/qsharedpointer.h>
 
@@ -134,6 +135,13 @@ private:
 
 } // namespace dtlsopenssl
 
+// The trick with 'right' ancestor in the tree overriding (only once) some shared
+// virtual functions is intentional. Too bad MSVC warns me about ... exactly the
+// feature of C++ that I want to use.
+
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_MSVC(4250)
+
 class QDtlsClientVerifierOpenSSL : public QTlsPrivate::DtlsCookieVerifier, public QDtlsBasePrivate
 {
 public:
@@ -236,6 +244,8 @@ private:
     QByteArray identityHint;
 };
 
+QT_WARNING_POP // C4250
+
 QT_END_NAMESPACE
 
 #endif // QDTLS_OPENSSL_P_H