QLogging: fix potential missing NUL-terminator when calling OutputDebugString

The string returned from QStringView::utf16() is, in general, not
NUL-terminated, as OutputDebugString() requires. Though we only ever
call win_outputDebugString_helper() with an actual QString, it's not
100% clear said QString doesn't originate from, say, a QStringLiteral,
in which case QString::utf16() would have to (an does) detach() to
ensure the NUL-termination.

So, take by const QString&, but use QStringView::mid() to avoid
copying the substring content twice.

Amends a049325cc708b483ed1aadc6589419f4d74b19f3.

Change-Id: Ie42a6000c75c6a55d629621d89e0cf498b174d29
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit 7ef614017091d7b56ac905c43da035259583c077)

1 files changed, 2 insertions, 2 deletions

diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 9708ab75da..877831cc8b 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -1669,7 +1669,7 @@ static bool android_default_message_handler(QtMsgType type,
 #endif //Q_OS_ANDROID
 
 #ifdef Q_OS_WIN
-static void win_outputDebugString_helper(QStringView message)
+static void win_outputDebugString_helper(const QString &message)
 {
     const int maxOutputStringLength = 32766;
     static QBasicMutex m;
@@ -1681,7 +1681,7 @@ static void win_outputDebugString_helper(QStringView message)
         wchar_t *messagePart = new wchar_t[maxOutputStringLength + 1];
         for (int i = 0; i < message.length(); i += maxOutputStringLength ) {
             const int length = std::min(message.length() - i, maxOutputStringLength );
-            const int len = message.mid(i, length).toWCharArray(messagePart);
+            const int len = QStringView{message}.mid(i, length).toWCharArray(messagePart);
             Q_ASSERT(len == length);
             messagePart[len] = 0;
             OutputDebugString(messagePart);