C++: code completion for lambda calls

support for lambdas, e.g.:
struct S { int bar; };
[]() { return new S; } ()->bar;
[] { return new S; } ()->bar;
[]() ->S* { return new S(); } ()->bar;
[]() throw() { return new S(); } ()->bar;
[]() throw()->S* { return new S(); } ()->bar;

Task-number: QTCREATORBUG-9523
Change-Id: I43fbf6f0ee0bb11411c53c984df75ef33a276466
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/libs/cplusplus/ExpressionUnderCursor.cpp

@@ -176,6 +176,30 @@ int ExpressionUnderCursor::startOfExpression_helper(BackwardsScanner &tk, int in
                     else if (tk[lessIndex - 1].is(T_SLOT))
                         return startOfExpression(tk, lessIndex);
                 }
+            } else if (tk[matchingBraceIndex - 1].is(T_RBRACE)) {
+                // lambda: [](){} ()
+                int leftBraceIndex = tk.startOfMatchingBrace(matchingBraceIndex);
+                if (matchingBraceIndex != leftBraceIndex) {
+                    int currentIndex = leftBraceIndex;
+                    while (currentIndex >= 0) {
+                        if (tk[currentIndex-1].is(T_RPAREN)) {
+                            int leftParenIndex = tk.startOfMatchingBrace(currentIndex);
+                            if (tk[leftParenIndex-1].is(T_THROW)) {
+                                currentIndex = leftParenIndex-1;
+                            } else if (tk[leftParenIndex-1].is(T_RBRACKET)) {
+                                int leftBracketIndex = tk.startOfMatchingBrace(leftParenIndex);
+                                if (leftBracketIndex != leftParenIndex-1)
+                                    return leftBracketIndex;
+                            }
+                        } else if (tk[currentIndex-1].is(T_RBRACKET)) {
+                            int leftBracketIndex = tk.startOfMatchingBrace(currentIndex);
+                            if (leftBracketIndex != currentIndex-1)
+                                return leftBracketIndex;
+                        } else {
+                            --currentIndex;
+                        }
+                    }
+                }
             }
             return startOfExpression(tk, matchingBraceIndex);
         }

src/libs/cplusplus/ResolveExpression.cpp

@@ -366,6 +366,18 @@ bool ResolveExpression::visit(CompoundExpressionAST *ast)
     return false;
 }
 
+bool ResolveExpression::visit(LambdaExpressionAST *ast)
+{
+    accept(ast->statement);
+    return false;
+}
+
+bool ResolveExpression::visit(ReturnStatementAST *ast)
+{
+    accept(ast->expression);
+    return false;
+}
+
 bool ResolveExpression::visit(NestedExpressionAST *ast)
 {
     accept(ast->expression);
@@ -626,6 +638,11 @@ bool ResolveExpression::visit(CallAST *ast)
 {
     const QList<LookupItem> baseResults = resolve(ast->base_expression, _scope);
 
+    if (ast->base_expression->asLambdaExpression()) {
+        _results = baseResults;
+        return false;
+    }
+
     // Compute the types of the actual arguments.
     unsigned actualArgumentCount = 0;
 

src/libs/cplusplus/ResolveExpression.h

@@ -104,6 +104,8 @@ protected:
     virtual bool visit(UnaryExpressionAST *ast);
     virtual bool visit(CompoundLiteralAST *ast);
     virtual bool visit(CompoundExpressionAST *ast);
+    virtual bool visit(LambdaExpressionAST *ast);
+    virtual bool visit(ReturnStatementAST *ast);
 
     //names
     virtual bool visit(QualifiedNameAST *ast);

src/plugins/cpptools/cppcompletion_test.cpp

@@ -2690,3 +2690,138 @@ void CppToolsPlugin::test_completion_enum_inside_function_QTCREATORBUG5456()
     QVERIFY(completions.contains(QLatin1String("e2")));
     QVERIFY(completions.contains(QLatin1String("e3")));
 }
+
+void CppToolsPlugin::test_completion_lambdaCalls_1()
+{
+    TestData data;
+    data.srcText =
+            "struct S { int bar; };\n"
+            "void foo()\n"
+            "{\n"
+            "   @\n"
+            "   // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("[](){ return new S; } ()->");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 2);
+    QVERIFY(completions.contains(QLatin1String("S")));
+    QVERIFY(completions.contains(QLatin1String("bar")));
+}
+
+void CppToolsPlugin::test_completion_lambdaCalls_2()
+{
+    TestData data;
+    data.srcText =
+            "struct S { int bar; };\n"
+            "void foo()\n"
+            "{\n"
+            "   @\n"
+            "   // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("[] { return new S; } ()->");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 2);
+    QVERIFY(completions.contains(QLatin1String("S")));
+    QVERIFY(completions.contains(QLatin1String("bar")));
+}
+
+void CppToolsPlugin::test_completion_lambdaCalls_3()
+{
+    TestData data;
+    data.srcText =
+            "struct S { int bar; };\n"
+            "void foo()\n"
+            "{\n"
+            "   @\n"
+            "   // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("[]() ->S* { return new S; } ()->");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 2);
+    QVERIFY(completions.contains(QLatin1String("S")));
+    QVERIFY(completions.contains(QLatin1String("bar")));
+}
+
+void CppToolsPlugin::test_completion_lambdaCalls_4()
+{
+    TestData data;
+    data.srcText =
+            "struct S { int bar; };\n"
+            "void foo()\n"
+            "{\n"
+            "   @\n"
+            "   // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("[]() throw() { return new S; } ()->");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 2);
+    QVERIFY(completions.contains(QLatin1String("S")));
+    QVERIFY(completions.contains(QLatin1String("bar")));
+}
+
+void CppToolsPlugin::test_completion_lambdaCalls_5()
+{
+    TestData data;
+    data.srcText =
+            "struct S { int bar; };\n"
+            "void foo()\n"
+            "{\n"
+            "   @\n"
+            "   // padding so we get the scope right\n"
+            "}\n"
+            ;
+    setup(&data);
+
+    Utils::ChangeSet change;
+    QString txt = QLatin1String("[]() throw()->S* { return new S; } ()->");
+    change.insert(data.pos, txt);
+    QTextCursor cursor(data.doc);
+    change.apply(&cursor);
+    data.pos += txt.length();
+
+    QStringList completions = getCompletions(data);
+
+    QCOMPARE(completions.size(), 2);
+    QVERIFY(completions.contains(QLatin1String("S")));
+    QVERIFY(completions.contains(QLatin1String("bar")));
+}

src/plugins/cpptools/cpptoolsplugin.h

@@ -156,6 +156,13 @@ private slots:
     void test_completion_enum_inside_block_inside_function_QTCREATORBUG5456();
     void test_completion_enum_inside_function_QTCREATORBUG5456();
 
+    //lambda
+    void test_completion_lambdaCalls_1();
+    void test_completion_lambdaCalls_2();
+    void test_completion_lambdaCalls_3();
+    void test_completion_lambdaCalls_4();
+    void test_completion_lambdaCalls_5();
+
     void test_format_pointerdeclaration_in_simpledeclarations();
     void test_format_pointerdeclaration_in_simpledeclarations_data();
     void test_format_pointerdeclaration_in_controlflowstatements();