C++: Handle recursive auto declarations

Remember auto declarations we have already looked up and stop if we try
it again.

Task-number: QTCREATORBUG-9503

Change-Id: I989b11609c98bf197ce916d79c9d452294355053
Reviewed-by: Przemyslaw Gorszkowski <pgorszkowski@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
(cherry picked from commit 8f1b6656677344e9ca4b6798ddd900725c478b16)

6 files changed, 82 insertions, 10 deletions

diff --git a/src/libs/cplusplus/ResolveExpression.cpp b/src/libs/cplusplus/ResolveExpression.cpp
index b547c22d68..32dcbeb4e6 100644
--- a/src/libs/cplusplus/ResolveExpression.cpp
+++ b/src/libs/cplusplus/ResolveExpression.cpp
@@ -75,11 +75,13 @@ static QList<_Tp> removeDuplicates(const QList<_Tp> &results)
 /////////////////////////////////////////////////////////////////////
 // ResolveExpression
 /////////////////////////////////////////////////////////////////////
-ResolveExpression::ResolveExpression(const LookupContext &context)
+ResolveExpression::ResolveExpression(const LookupContext &context,
+                                     const QSet<const Declaration *> &autoDeclarationsBeingResolved)
     : ASTVisitor(context.expressionDocument()->translationUnit()),
       _scope(0),
       _context(context),
       bind(context.expressionDocument()->translationUnit()),
+      _autoDeclarationsBeingResolved(autoDeclarationsBeingResolved),
       _reference(false)
 { }
 
@@ -519,6 +521,10 @@ bool ResolveExpression::visit(SimpleNameAST *ast)
             if (!decl)
                 continue;
 
+            // Stop on recursive auto declarations
+            if (_autoDeclarationsBeingResolved.contains(decl))
+                continue;
+
             const StringLiteral *initializationString = decl->getInitializer();
             if (initializationString == 0)
                 continue;
@@ -533,7 +539,8 @@ bool ResolveExpression::visit(SimpleNameAST *ast)
 
             TypeOfExpression exprTyper;
             Document::Ptr doc = _context.snapshot().document(QString::fromLocal8Bit(decl->fileName()));
-            exprTyper.init(doc, _context.snapshot(), _context.bindings());
+            exprTyper.init(doc, _context.snapshot(), _context.bindings(),
+                           QSet<const Declaration* >(_autoDeclarationsBeingResolved) << decl);
 
             Document::Ptr exprDoc =
                     documentForExpression(exprTyper.preprocessedExpression(initializer));
@@ -543,8 +550,8 @@ bool ResolveExpression::visit(SimpleNameAST *ast)
             if (deduceAuto._block)
                 continue;
 
-            const QList<LookupItem> &typeItems =
-                    exprTyper(extractExpressionAST(exprDoc), exprDoc, decl->enclosingScope());
+            const QList<LookupItem> &typeItems = exprTyper(extractExpressionAST(exprDoc), exprDoc,
+                                                           decl->enclosingScope());
             if (typeItems.empty())
                 continue;
 
diff --git a/src/libs/cplusplus/ResolveExpression.h b/src/libs/cplusplus/ResolveExpression.h
index e6ce50dde4..922d1b6bf0 100644
--- a/src/libs/cplusplus/ResolveExpression.h
+++ b/src/libs/cplusplus/ResolveExpression.h
@@ -42,7 +42,9 @@ namespace CPlusPlus {
 class CPLUSPLUS_EXPORT ResolveExpression: protected ASTVisitor
 {
 public:
-    ResolveExpression(const LookupContext &context);
+    ResolveExpression(const LookupContext &context,
+                      const QSet<const Declaration *> &autoDeclarationsBeingResolved
+                        = QSet<const Declaration *>());
     virtual ~ResolveExpression();
 
     QList<LookupItem> operator()(ExpressionAST *ast, Scope *scope);
@@ -125,6 +127,7 @@ private:
     const LookupContext& _context;
     Bind bind;
     QList<LookupItem> _results;
+    QSet<const Declaration *> _autoDeclarationsBeingResolved;
     bool _reference;
 };
 
diff --git a/src/libs/cplusplus/TypeOfExpression.cpp b/src/libs/cplusplus/TypeOfExpression.cpp
index ac813fa873..7025c474c1 100644
--- a/src/libs/cplusplus/TypeOfExpression.cpp
+++ b/src/libs/cplusplus/TypeOfExpression.cpp
@@ -58,7 +58,8 @@ void TypeOfExpression::reset()
 }
 
 void TypeOfExpression::init(Document::Ptr thisDocument, const Snapshot &snapshot,
-                            QSharedPointer<CreateBindings> bindings)
+                            QSharedPointer<CreateBindings> bindings,
+                            const QSet<const Declaration *> &autoDeclarationsBeingResolved)
 {
     m_thisDocument = thisDocument;
     m_snapshot = snapshot;
@@ -67,6 +68,7 @@ void TypeOfExpression::init(Document::Ptr thisDocument, const Snapshot &snapshot
     m_lookupContext = LookupContext();
     m_bindings = bindings;
     m_environment.clear();
+    m_autoDeclarationsBeingResolved = autoDeclarationsBeingResolved;
 }
 
 QList<LookupItem> TypeOfExpression::operator()(const QByteArray &utf8code,
@@ -111,7 +113,7 @@ QList<LookupItem> TypeOfExpression::operator()(ExpressionAST *expression,
     m_lookupContext.setBindings(m_bindings);
     m_lookupContext.setExpandTemplates(m_expandTemplates);
 
-    ResolveExpression resolve(m_lookupContext);
+    ResolveExpression resolve(m_lookupContext, m_autoDeclarationsBeingResolved);
     const QList<LookupItem> items = resolve(m_ast, scope);
 
     if (! m_bindings)
@@ -133,7 +135,7 @@ QList<LookupItem> TypeOfExpression::reference(ExpressionAST *expression,
     m_lookupContext.setBindings(m_bindings);
     m_lookupContext.setExpandTemplates(m_expandTemplates);
 
-    ResolveExpression resolve(m_lookupContext);
+    ResolveExpression resolve(m_lookupContext, m_autoDeclarationsBeingResolved);
     const QList<LookupItem> items = resolve.reference(m_ast, scope);
 
     if (! m_bindings)
diff --git a/src/libs/cplusplus/TypeOfExpression.h b/src/libs/cplusplus/TypeOfExpression.h
index adeb1d9644..a6743e3989 100644
--- a/src/libs/cplusplus/TypeOfExpression.h
+++ b/src/libs/cplusplus/TypeOfExpression.h
@@ -58,8 +58,11 @@ public:
      * Also clears the lookup context, so can be used to make sure references
      * to the documents previously used are removed.
      */
-    void init(Document::Ptr thisDocument, const Snapshot &snapshot,
-              QSharedPointer<CreateBindings> bindings = QSharedPointer<CreateBindings>());
+    void init(Document::Ptr thisDocument,
+              const Snapshot &snapshot,
+              QSharedPointer<CreateBindings> bindings = QSharedPointer<CreateBindings>(),
+              const QSet<const Declaration *> &autoDeclarationsBeingResolved
+                = QSet<const Declaration *>());
 
     void reset();
 
@@ -151,6 +154,8 @@ private:
     // Keep the expression documents and thus all the symbols and
     // their types alive until they are not needed any more.
     QList<Document::Ptr> m_documents;
+
+    QSet<const Declaration *> m_autoDeclarationsBeingResolved;
 };
 
 ExpressionAST CPLUSPLUS_EXPORT *extractExpressionAST(Document::Ptr doc);
diff --git a/src/plugins/cpptools/cppcompletion_test.cpp b/src/plugins/cpptools/cppcompletion_test.cpp
index 11e380092b..44f9178cdb 100644
--- a/src/plugins/cpptools/cppcompletion_test.cpp
+++ b/src/plugins/cpptools/cppcompletion_test.cpp
@@ -1832,3 +1832,56 @@ void CppToolsPlugin::test_completion_crash_cloning_template_class_QTCREATORBUG93
     QVERIFY(completions.contains(QLatin1String("Templ")));
     QVERIFY(completions.contains(QLatin1String("f")));
 }
+
+void CppToolsPlugin::test_completion_recursive_auto_declarations1_QTCREATORBUG9503()
+{
+    TestData data;
+    data.srcText =
+            "void f()\n"
+            "{\n"
+            "    auto object2 = object1;\n"
+            "    auto object1 = object2;\n"
+            "    @;\n"
+            "    // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("object1.");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 0);
+}
+
+void CppToolsPlugin::test_completion_recursive_auto_declarations2_QTCREATORBUG9503()
+{
+    TestData data;
+    data.srcText =
+            "void f()\n"
+            "{\n"
+            "    auto object3 = object1;\n"
+            "    auto object2 = object3;\n"
+            "    auto object1 = object2;\n"
+            "    @;\n"
+            "    // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("object1.");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 0);
+}
diff --git a/src/plugins/cpptools/cpptoolsplugin.h b/src/plugins/cpptools/cpptoolsplugin.h
index bf9c9b67a5..0b3998c9e6 100644
--- a/src/plugins/cpptools/cpptoolsplugin.h
+++ b/src/plugins/cpptools/cpptoolsplugin.h
@@ -128,6 +128,8 @@ private slots:
     void test_completion_typedef_using_templates2();
     void test_completion_namespace_alias_with_many_namespace_declarations();
     void test_completion_crash_cloning_template_class_QTCREATORBUG9329();
+    void test_completion_recursive_auto_declarations1_QTCREATORBUG9503();
+    void test_completion_recursive_auto_declarations2_QTCREATORBUG9503();
 
     void test_format_pointerdeclaration_in_simpledeclarations();
     void test_format_pointerdeclaration_in_simpledeclarations_data();