Clang: implement requestFollowSymbol plug-in side

Invoke follow symbol in clang backend
if env variable QTC_CLANG_FOLLOW_SYMBOL is 1.
Does not include backend implementation.

Change-Id: Ia20a677830ebdd7f24800af5c5d6e8b1bf579205
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cpptools/baseeditordocumentprocessor.h

@@ -27,6 +27,7 @@
 
 #include "baseeditordocumentparser.h"
 #include "cppcursorinfo.h"
+#include "cppsymbolinfo.h"
 #include "cppsemanticinfo.h"
 #include "cpptools_global.h"
 
@@ -75,6 +76,7 @@ public:
     virtual void setParserConfig(const BaseEditorDocumentParser::Configuration config);
 
     virtual QFuture<CursorInfo> cursorInfo(const CursorInfoParams &params) = 0;
+    virtual QFuture<SymbolInfo> requestFollowSymbol(int line, int column, bool resolveTarget) = 0;
 
 public:
     using HeaderErrorDiagnosticWidgetCreator = std::function<QWidget*()>;

src/plugins/cpptools/builtineditordocumentprocessor.h

@@ -52,6 +52,8 @@ public:
     bool isParserRunning() const override;
 
     QFuture<CursorInfo> cursorInfo(const CursorInfoParams &params) override;
+    QFuture<SymbolInfo> requestFollowSymbol(int, int, bool) override
+    { return QFuture<SymbolInfo>(); }
 
 private:
     void onParserFinished(CPlusPlus::Document::Ptr document, CPlusPlus::Snapshot snapshot);

src/plugins/cpptools/cppsymbolinfo.h

@@ -0,0 +1,45 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 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 "cpptools_global.h"
+
+#include <QString>
+
+namespace CppTools {
+
+class CPPTOOLS_EXPORT SymbolInfo
+{
+public:
+    int startLine = 0;
+    int startColumn = 0;
+    int endLine = 0;
+    int endColumn = 0;
+    QString fileName;
+    bool failedToFollow = false;
+};
+
+} // namespace CppTools

src/plugins/cpptools/cpptools.pro

@@ -87,6 +87,7 @@ HEADERS += \
     cppprojectfilecategorizer.h \
     clangcompileroptionsbuilder.h \
     cppprojectpartchooser.h \
+    cppsymbolinfo.h
 
 SOURCES += \
     abstracteditorsupport.cpp \