Fix the __return keyword

fixes #7811

lib/config/config_parser.yy

@@ -652,9 +652,7 @@ lterm: T_LOCAL indexer combined_set_op rterm
 	}
 	| T_RETURN rterm
 	{
-		std::vector<Expression *> vname;
+		$$ = new ReturnExpression($2, DebugInfoRange(@1, @2));
-		vname.push_back(MakeLiteral("__result"));
-		$$ = new SetExpression(vname, OpSetLiteral, $2, false, DebugInfoRange(@1, @2));
 	}
 	| apply
 	{

lib/config/expression.cpp

@@ -45,6 +45,8 @@ Value Expression::Evaluate(VMFrame& frame, DebugHint *dhint) const
 #endif /* _DEBUG */
 
 		return DoEvaluate(frame, dhint);
+	} catch (const InterruptExecutionError&) {
+		throw;
 	} catch (const std::exception& ex) {
 		if (boost::get_error_info<boost::errinfo_nested_exception>(ex))
 			throw;
@@ -344,6 +346,11 @@ Value SetExpression::DoEvaluate(VMFrame& frame, DebugHint *dhint) const
 	return right;
 }
 
+Value ReturnExpression::DoEvaluate(VMFrame& frame, DebugHint *dhint) const
+{
+	BOOST_THROW_EXCEPTION(InterruptExecutionError(m_Operand->Evaluate(frame)));
+}
+
 Value IndexerExpression::DoEvaluate(VMFrame& frame, DebugHint *dhint) const
 {
 	return VMOps::Indexer(frame, m_Indexer);

lib/config/expression.hpp

@@ -101,6 +101,25 @@ enum CombinedSetOp
 	OpSetDivide
 };
 
+class InterruptExecutionError : virtual public std::exception, virtual public boost::exception
+{
+public:
+	InterruptExecutionError(const Value& result)
+		: m_Result(result)
+	{ }
+
+	~InterruptExecutionError(void) throw()
+	{ }
+
+	Value GetResult(void) const
+	{
+		return m_Result;
+	}
+
+private:
+	Value m_Result;
+};
+
 typedef std::map<String, String> DefinitionMap;
 
 /**
@@ -537,6 +556,17 @@ private:
 
 };
 
+class I2_CONFIG_API ReturnExpression : public UnaryExpression
+{
+public:
+	ReturnExpression(Expression *expression, const DebugInfo& debugInfo = DebugInfo())
+		: UnaryExpression(expression, debugInfo)
+	{ }
+
+protected:
+	virtual Value DoEvaluate(VMFrame& frame, DebugHint *dhint) const;
+};
+
 class I2_CONFIG_API IndexerExpression : public DebuggableExpression
 {
 public:

lib/config/vmframe.hpp

@@ -30,7 +30,6 @@ struct VMFrame
 {
 	Dictionary::Ptr Locals;
 	Object::Ptr Self;
-	Value Result;
 
 	VMFrame(void)
 		: Locals(new Dictionary()), Self(Locals)

lib/config/vmops.hpp

@@ -295,8 +295,14 @@ private:
 		for (std::vector<Value>::size_type i = 0; i < std::min(arguments.size(), funcargs.size()); i++)
 			frame.Locals->Set(funcargs[i], arguments[i]);
 
-		expr->Evaluate(frame);
+		Value result;
-		return frame.Result;
+		try {
+			result = expr->Evaluate(frame);
+		} catch (const InterruptExecutionError& iee) {
+			result = iee.GetResult();
+		}
+
+		return result;
 	}
 
 	static inline void SlotWrapper(const Value& funcName, const std::vector<Value>& arguments)

test/config-ops.cpp

@@ -226,6 +226,14 @@ BOOST_AUTO_TEST_CASE(advanced)
 
 	expr = ConfigCompiler::CompileText("<test>", "a = 3 b = 3");
 	BOOST_CHECK(expr == NULL);
+
+	expr = ConfigCompiler::CompileText("<test>", "__function() { 3 }()");
+	BOOST_CHECK(expr->Evaluate(frame) == 3);
+	delete expr;
+
+	expr = ConfigCompiler::CompileText("<test>", "__function() { __return 3, 5 }()");
+	BOOST_CHECK(expr->Evaluate(frame) == 3);
+	delete expr;
 }
 
 BOOST_AUTO_TEST_SUITE_END()