Fuzzing: Add fuzz target for QRegularExpression::optimize

Change-Id: I693af83caed60cdffc83af368a15567d72524844
Reviewed-by: Albert Astals Cid <albert.astals.cid@kdab.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

tests/libfuzzer/corelib/text/qregularexpression/optimize/main.cpp

@@ -0,0 +1,35 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QRegularExpression>
+
+extern "C" int LLVMFuzzerTestOneInput(const char *Data, size_t Size) {
+    QRegularExpression qre(QByteArray::fromRawData(Data, Size));
+    qre.optimize();
+    return 0;
+}

tests/libfuzzer/corelib/text/qregularexpression/optimize/optimize.pro

@@ -0,0 +1,8 @@
+QT -= gui
+SOURCES += main.cpp
+FUZZ_ENGINE = $$(LIB_FUZZING_ENGINE)
+isEmpty(FUZZ_ENGINE) {
+    QMAKE_LFLAGS += -fsanitize=fuzzer
+} else {
+    LIBS += $$FUZZ_ENGINE
+}