ClangTools: Add automatic clang tool runner for open documents

Fixes: QTCREATORBUG-23349
Change-Id: I81197180c9d69c7df6184f8fcbf05f2256eaf7f6
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/clangtools/virtualfilesystemoverlay.h

@@ -0,0 +1,59 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** 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.
+**
+****************************************************************************/
+
+#pragma once
+
+#include <utils/fileutils.h>
+#include <utils/temporarydirectory.h>
+
+namespace Core { class IDocument; }
+
+namespace ClangTools {
+namespace Internal {
+
+class VirtualFileSystemOverlay
+{
+public:
+    VirtualFileSystemOverlay(const QString &rootPattern);
+
+    void update();
+
+    Utils::FilePath overlayFilePath();
+    Utils::FilePath filePath(Core::IDocument *doc);
+
+private:
+    Utils::TemporaryDirectory m_root;
+    Utils::FilePath m_overlayFilePath;
+    struct AutoSavedPath
+    {
+        int revision = -1;
+        Utils::FilePath path;
+    };
+
+    QMap<Core::IDocument *, AutoSavedPath> m_saved;
+};
+
+} // namespace Internal
+} // namespace ClangTools