C++: Don't show unused mark for known RAII types

Change-Id: Id552539c6a2cf5d7558adf88bed61a11ab770516
Reviewed-by: Christian Kamm <christian.d.kamm@nokia.com>

src/plugins/cppeditor/cppeditor.cpp

@@ -68,6 +68,7 @@
 #include <cpptools/cppqtstyleindenter.h>
 #include <cpptools/cppcodestylesettings.h>
 #include <cpptools/cpprefactoringchanges.h>
+#include <cpptools/cpptoolsreuse.h>
 
 #include <coreplugin/icore.h>
 #include <coreplugin/actionmanager/actionmanager.h>
@@ -1776,6 +1777,11 @@ void CPPEditorWidget::updateSemanticInfo(const SemanticInfo &semanticInfo)
     m_renameSelections.clear();
     m_currentRenameSelection = NoCurrentRenameSelection;
 
+    // We can use the semanticInfo's snapshot (and avoid locking), but not its
+    // document, since it doesn't contain expanded macros.
+    LookupContext context(semanticInfo.snapshot.document(file()->fileName()),
+                          semanticInfo.snapshot);
+
     SemanticInfo::LocalUseIterator it(semanticInfo.localUses);
     while (it.hasNext()) {
         it.next();
@@ -1791,12 +1797,14 @@ void CPPEditorWidget::updateSemanticInfo(const SemanticInfo &semanticInfo)
             }
         }
 
-        if (uses.size() == 1)
-            // it's an unused declaration
-            highlightUses(uses, semanticInfo, &unusedSelections);
-
-        else if (good && m_renameSelections.isEmpty())
+        if (uses.size() == 1) {
+            if (!CppTools::isOwnershipRAIIType(it.key(), context)) {
+                // it's an unused declaration
+                highlightUses(uses, semanticInfo, &unusedSelections);
+            }
+        } else if (good && m_renameSelections.isEmpty()) {
             highlightUses(uses, semanticInfo, &m_renameSelections);
+        }
     }
 
     if (m_lastSemanticInfo.forced || previousSemanticInfo.revision != semanticInfo.revision) {

src/plugins/cpptools/cpptoolsreuse.cpp

@@ -32,9 +32,17 @@
 
 #include "cpptoolsreuse.h"
 
+#include <Symbols.h>
+#include <CoreTypes.h>
+#include <cplusplus/Overview.h>
+#include <cplusplus/LookupContext.h>
+
+#include <QtCore/QSet>
 #include <QtGui/QTextDocument>
 #include <QtGui/QTextCursor>
 
+using namespace CPlusPlus;
+
 namespace CppTools {
 
 void moveCursorToEndOfIdentifier(QTextCursor *tc) {
@@ -49,4 +57,50 @@ void moveCursorToEndOfIdentifier(QTextCursor *tc) {
     }
 }
 
+static bool isOwnershipRAIIName(const QString &name)
+{
+    static QSet<QString> knownNames;
+    if (knownNames.isEmpty()) {
+        // Qt
+        knownNames.insert(QLatin1String("QScopedPointer"));
+        knownNames.insert(QLatin1String("QScopedArrayPointer"));
+        knownNames.insert(QLatin1String("QMutexLocker"));
+        knownNames.insert(QLatin1String("QReadLocker"));
+        knownNames.insert(QLatin1String("QWriteLocker"));
+        // Standard C++
+        knownNames.insert(QLatin1String("auto_ptr"));
+        knownNames.insert(QLatin1String("unique_ptr"));
+        // Boost
+        knownNames.insert(QLatin1String("scoped_ptr"));
+        knownNames.insert(QLatin1String("scoped_array"));
+    }
+
+    return knownNames.contains(name);
+}
+
+bool isOwnershipRAIIType(CPlusPlus::Symbol *symbol, const LookupContext &context)
+{
+    if (!symbol)
+        return false;
+
+    // This is not a "real" comparison of types. What we do is to resolve the symbol
+    // in question and then try to match its name with already known ones.
+    if (symbol->isDeclaration()) {
+        Declaration *declaration = symbol->asDeclaration();
+        const NamedType *namedType = declaration->type()->asNamedType();
+        if (namedType) {
+            ClassOrNamespace *clazz = context.lookupType(namedType->name(),
+                                                         declaration->enclosingScope());
+            if (clazz && !clazz->symbols().isEmpty()) {
+                Overview overview;
+                Symbol *symbol = clazz->symbols().at(0);
+                return isOwnershipRAIIName(overview.prettyName(symbol->name()));
+            }
+        }
+    }
+
+    return false;
+}
+
+
 } // CppTools

src/plugins/cpptools/cpptoolsreuse.h

@@ -37,10 +37,18 @@
 
 QT_FORWARD_DECLARE_CLASS(QTextCursor)
 
+namespace CPlusPlus {
+class Symbol;
+class LookupContext;
+}
+
 namespace CppTools {
 
 void CPPTOOLS_EXPORT moveCursorToEndOfIdentifier(QTextCursor *tc);
 
+bool CPPTOOLS_EXPORT isOwnershipRAIIType(CPlusPlus::Symbol *symbol,
+                                         const CPlusPlus::LookupContext &context);
+
 } // CppTools
 
 #endif // CPPTOOLSREUSE_H