3 files changed, 31 insertions, 17 deletions

diff --git a/AST.cpp b/AST.cpp
index bcaae0e1..90b9962c 100644
--- a/AST.cpp
+++ b/AST.cpp
@@ -228,8 +228,8 @@ void UnaryOperation::checkTypeRequirements()
 	m_subExpression->checkTypeRequirements();
 	if (m_operator == Token::Value::INC || m_operator == Token::Value::DEC || m_operator == Token::Value::DELETE)
 		m_subExpression->requireLValue();
-	m_type = m_subExpression->getType();
-	if (!m_type->acceptsUnaryOperator(m_operator))
+	m_type = m_subExpression->getType()->unaryOperatorResult(m_operator);
+	if (!m_type)
 		BOOST_THROW_EXCEPTION(createTypeError("Unary operator not compatible with type."));
 }
 
diff --git a/Types.cpp b/Types.cpp
index d1a3c7a7..ade196f2 100644
--- a/Types.cpp
+++ b/Types.cpp
@@ -156,18 +156,26 @@ bool IntegerType::isExplicitlyConvertibleTo(Type const& _convertTo) const
 	return _convertTo.getCategory() == getCategory() || _convertTo.getCategory() == Category::CONTRACT;
 }
 
-bool IntegerType::acceptsUnaryOperator(Token::Value _operator) const
+TypePointer IntegerType::unaryOperatorResult(Token::Value _operator) const
 {
+	// "delete" is ok for all integer types
 	if (_operator == Token::DELETE)
-		return true;
-	if (isAddress())
-		return false;
-	if (_operator == Token::BIT_NOT)
-		return true;
-	if (isHash())
-		return false;
-	return _operator == Token::ADD || _operator == Token::SUB ||
-		   _operator == Token::INC || _operator == Token::DEC;
+		return shared_from_this();
+	// no further unary operators for addresses
+	else if (isAddress())
+		return TypePointer();
+	// "~" is ok for all other types
+	else if (_operator == Token::BIT_NOT)
+		return shared_from_this();
+	// nothing else for hashes
+	else if (isHash())
+		return TypePointer();
+	// for non-hash integers, we allow +, -, ++ and --
+	else if (_operator == Token::ADD || _operator == Token::SUB ||
+			_operator == Token::INC || _operator == Token::DEC)
+		return shared_from_this();
+	else
+		return TypePointer();
 }
 
 bool IntegerType::operator==(Type const& _other) const
diff --git a/Types.h b/Types.h
index 3b416f40..36484451 100644
--- a/Types.h
+++ b/Types.h
@@ -99,7 +99,10 @@ public:
 	{
 		return isImplicitlyConvertibleTo(_convertTo);
 	}
-	virtual bool acceptsUnaryOperator(Token::Value) const { return false; }
+	/// @returns the resulting type of applying the given unary operator or an empty pointer if
+	/// this is not possible.
+	/// The default implementation does not allow any unary operator.
+	virtual TypePointer unaryOperatorResult(Token::Value) const { return TypePointer(); }
 	/// @returns the resulting type of applying the given binary operator or an empty pointer if
 	/// this is not possible.
 	/// The default implementation allows comparison operators if a common type exists
@@ -163,7 +166,7 @@ public:
 
 	virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
-	virtual bool acceptsUnaryOperator(Token::Value _operator) const override;
+	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;
 
 	virtual bool operator==(Type const& _other) const override;
@@ -225,9 +228,9 @@ public:
 	BoolType() {}
 	virtual Category getCategory() const { return Category::BOOL; }
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
-	virtual bool acceptsUnaryOperator(Token::Value _operator) const override
+	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override
 	{
-		return _operator == Token::NOT || _operator == Token::DELETE;
+		return (_operator == Token::NOT || _operator == Token::DELETE) ? shared_from_this() : TypePointer();
 	}
 	virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;
 
@@ -277,7 +280,10 @@ class StructType: public Type
 public:
 	virtual Category getCategory() const override { return Category::STRUCT; }
 	StructType(StructDefinition const& _struct): m_struct(_struct) {}
-	virtual bool acceptsUnaryOperator(Token::Value _operator) const override { return _operator == Token::DELETE; }
+	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override
+	{
+		return _operator == Token::DELETE ? shared_from_this() : TypePointer();
+	}
 
 	virtual bool operator==(Type const& _other) const override;
 	virtual u256 getStorageSize() const override;