Adapt to QString::utf16() now returning char16_t *

Make the code agnostic of the exact return type. In one case, were
filling a C# IntPtr, drop the cast and use .data(), as IntPtr has a
ctor from void* and the code stores an explicit string length, so we
don't need the NUL-termination that utf16() guarantees.

There are a handful of casts remaining, so write a small helper that
allows to comment on certain aspects of the conversion.

Done-with: Marc Mutz <marc.mutz@kdab.com>
Change-Id: I16227077b31f02fbbefe1a83e4dfbd2d5333a0f7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

4 files changed, 29 insertions, 18 deletions

diff --git a/src/activeqt/axbase/qaxutils_p.h b/src/activeqt/axbase/qaxutils_p.h
index f56644b..5324dc5 100644
--- a/src/activeqt/axbase/qaxutils_p.h
+++ b/src/activeqt/axbase/qaxutils_p.h
@@ -66,6 +66,7 @@
 #include <QtCore/qmetatype.h>
 #include <QtCore/qpair.h>
 #include <QtCore/qrect.h>
+#include <QtCore/qstring.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -107,6 +108,12 @@ static inline RECT qaxContentRect(const QSize &size)  // Size with topleft = 0,0
     return result;
 }
 
+static inline wchar_t *qaxQString2MutableOleChars(QString &s) // must be passed an lvalue
+{
+    // using utf16() to force NUL-termination:
+    return const_cast<wchar_t *>(reinterpret_cast<const wchar_t *>(s.utf16()));
+}
+
 #ifdef QT_WIDGETS_LIB
 SIZEL qaxMapPixToLogHiMetrics(const QSize &s, const QWidget *widget);
 QSize qaxMapLogHiMetricsToPix(const SIZEL &s, const QWidget *widget);
diff --git a/src/activeqt/container/qaxbase.cpp b/src/activeqt/container/qaxbase.cpp
index 53fbe81..cb4893f 100644
--- a/src/activeqt/container/qaxbase.cpp
+++ b/src/activeqt/container/qaxbase.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the ActiveQt framework of the Qt Toolkit.
@@ -220,7 +220,7 @@ inline DISPID QMetaObjectExtra::dispIDofName(const QByteArray &name, IDispatch *
     if (dispid == DISPID_UNKNOWN) {
         // get the Dispatch ID from the object
         QString unicodeName = QLatin1String(name);
-        OLECHAR *names = reinterpret_cast<wchar_t *>(const_cast<ushort *>(unicodeName.utf16()));
+        OLECHAR *names = qaxQString2MutableOleChars(unicodeName);
         disp->GetIDsOfNames(IID_NULL, &names, 1, LOCALE_USER_DEFAULT, &dispid);
         if (dispid != DISPID_UNKNOWN)
             dispIDs.insert(name, dispid);
@@ -1377,6 +1377,14 @@ bool QAxBase::initializeFromFile(IUnknown** ptr)
 #define COAUTHIDENTITY AUTH_IDENTITY
 #endif
 
+// Set string values to COAUTHIDENTITY fields. Use data(), no need for 0-termination.
+static inline void setIdentityString(const QString &v, ULONG &length, USHORT *&target)
+{
+    length = ULONG(v.size());
+    target = length > 0
+        ? const_cast<USHORT *>(reinterpret_cast<const USHORT *>(v.data()))
+        : nullptr;
+}
 
 /*!
     Creates the instance on a remote server, and returns the IUnknown interface
@@ -1429,15 +1437,9 @@ bool QAxBase::initializeRemote(IUnknown** ptr)
         d->ctrl = d->ctrl + QChar::fromLatin1(':') + key;
 
     COAUTHIDENTITY authIdentity;
-    authIdentity.UserLength = ULONG(user.length());
-    authIdentity.User = authIdentity.UserLength
-        ? const_cast<ushort *>(user.utf16()) : nullptr;
-    authIdentity.DomainLength = ULONG(domain.length());
-    authIdentity.Domain = authIdentity.DomainLength
-        ? const_cast<ushort *>(domain.utf16()) : nullptr;
-    authIdentity.PasswordLength = ULONG(passwd.length());
-    authIdentity.Password = authIdentity.PasswordLength
-        ? const_cast<ushort *>(passwd.utf16()) : nullptr;
+    setIdentityString(user, authIdentity.UserLength, authIdentity.User);
+    setIdentityString(domain, authIdentity.DomainLength,  authIdentity.Domain);
+    setIdentityString(passwd, authIdentity.PasswordLength, authIdentity.Password);
     authIdentity.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;
 
     COAUTHINFO authInfo;
@@ -1453,7 +1455,7 @@ bool QAxBase::initializeRemote(IUnknown** ptr)
     serverInfo.dwReserved1 = 0;
     serverInfo.dwReserved2 = 0;
     serverInfo.pAuthInfo = &authInfo;
-    serverInfo.pwszName = reinterpret_cast<wchar_t *>(const_cast<ushort *>(server.utf16()));
+    serverInfo.pwszName = qaxQString2MutableOleChars(server);
 
     IClassFactory *factory = nullptr;
     HRESULT res = CoGetClassObject(QUuid(clsid), CLSCTX_REMOTE_SERVER, &serverInfo,
diff --git a/src/activeqt/control/qaxserver.cpp b/src/activeqt/control/qaxserver.cpp
index 7e85158..7932b1d 100644
--- a/src/activeqt/control/qaxserver.cpp
+++ b/src/activeqt/control/qaxserver.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the ActiveQt framework of the Qt Toolkit.
@@ -51,6 +51,8 @@
 #include "qaxbindable.h"
 #include "qaxfactory.h"
 
+#include <QtAxBase/private/qaxutils_p.h>
+
 #include <qapplication.h>
 #include <qdatetime.h>
 #include <qdir.h>
@@ -437,7 +439,7 @@ HRESULT UpdateRegistry(bool bRegister, bool perUser)
     QString file = QString::fromWCharArray(qAxModuleFilename);
     const QString module = QFileInfo(file).baseName();
 
-    const QString libFile = qAxInit();
+    QString libFile = qAxInit();
     auto libFile_cleanup = qScopeGuard([] { qAxCleanup(); });
 
     TLIBATTR *libAttr = nullptr;
@@ -449,7 +451,7 @@ HRESULT UpdateRegistry(bool bRegister, bool perUser)
 
     if (bRegister) {
         if (!perUser) {
-            HRESULT hr = RegisterTypeLib(qAxTypeLibrary, reinterpret_cast<wchar_t *>(const_cast<ushort *>(libFile.utf16())), nullptr);
+            HRESULT hr = RegisterTypeLib(qAxTypeLibrary, qaxQString2MutableOleChars(libFile), nullptr);
             if (FAILED(hr)) {
                 qWarning("Failing to register %s due to insufficient permission.", qPrintable(module));
                 return hr;
@@ -457,7 +459,7 @@ HRESULT UpdateRegistry(bool bRegister, bool perUser)
         } else {
 #ifndef Q_CC_MINGW
             // MinGW does not have RegisterTypeLibForUser() implemented so we cannot fallback in this case
-            RegisterTypeLibForUser(qAxTypeLibrary, reinterpret_cast<wchar_t *>(const_cast<ushort *>(libFile.utf16())), nullptr);
+            RegisterTypeLibForUser(qAxTypeLibrary, qaxQString2MutableOleChars(libFile), nullptr);
 #endif
         }
     } else {
diff --git a/src/activeqt/control/qaxserverbase.cpp b/src/activeqt/control/qaxserverbase.cpp
index eb07d2b..99a6bf0 100644
--- a/src/activeqt/control/qaxserverbase.cpp
+++ b/src/activeqt/control/qaxserverbase.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the ActiveQt framework of the Qt Toolkit.
@@ -2003,7 +2003,7 @@ int QAxServerBase::qt_metacall(QMetaObject::Call call, int index, void **argv)
                 qAxTypeLibrary->GetTypeInfoOfGuid(qAxFactory()->eventsID(class_name), &eventInfo);
                 if (eventInfo) {
                     QString uni_name = QLatin1String(name);
-                    OLECHAR *olename = reinterpret_cast<OLECHAR *>(const_cast<ushort *>(uni_name.utf16()));
+                    OLECHAR *olename = qaxQString2MutableOleChars(uni_name);
                     eventInfo->GetIDsOfNames(&olename, 1, &eventId);
                     eventInfo->Release();
                 }