Merge pull request #2734 from ethereum/reject-create-interface

Reject the creation of interface with the new statement

4 files changed, 46 insertions, 1 deletions

diff --git a/Changelog.md b/Changelog.md
index 3574455b..39cbd44b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -15,6 +15,7 @@ Bugfixes:
  * Parser: Limit maximum recursion depth.
  * Type Checker: Crash fix related to ``using``.
  * Type Checker: Disallow constructors in libraries.
+ * Type Checker: Reject the creation of interface contracts using the ``new`` statement.
 
 ### 0.4.15 (2017-08-08)
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 32d078fd..99f3c64c 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -430,7 +430,11 @@ void TypeChecker::endVisit(InheritanceSpecifier const& _inheritance)
 		m_errorReporter.typeError(_inheritance.location(), "Libraries cannot be inherited from.");
 
 	auto const& arguments = _inheritance.arguments();
-	TypePointers parameterTypes = ContractType(*base).newExpressionType()->parameterTypes();
+	TypePointers parameterTypes;
+	if (base->contractKind() != ContractDefinition::ContractKind::Interface)
+		// Interfaces do not have constructors, so there are zero parameters.
+		parameterTypes = ContractType(*base).newExpressionType()->parameterTypes();
+
 	if (!arguments.empty() && parameterTypes.size() != arguments.size())
 	{
 		m_errorReporter.typeError(
@@ -1554,6 +1558,8 @@ void TypeChecker::endVisit(NewExpression const& _newExpression)
 
 		if (!contract)
 			m_errorReporter.fatalTypeError(_newExpression.location(), "Identifier is not a contract.");
+		if (contract->contractKind() == ContractDefinition::ContractKind::Interface)
+				m_errorReporter.fatalTypeError(_newExpression.location(), "Cannot instantiate an interface.");
 		if (!contract->annotation().unimplementedFunctions.empty())
 			m_errorReporter.typeError(
 				_newExpression.location(),
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index e6664895..adf41229 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -2140,6 +2140,8 @@ FunctionTypePointer FunctionType::newExpressionType(ContractDefinition const& _c
 	strings parameterNames;
 	StateMutability stateMutability = StateMutability::NonPayable;
 
+	solAssert(_contract.contractKind() != ContractDefinition::ContractKind::Interface, "");
+
 	if (constructor)
 	{
 		for (ASTPointer<VariableDeclaration> const& var: constructor->parameters())
@@ -2150,6 +2152,7 @@ FunctionTypePointer FunctionType::newExpressionType(ContractDefinition const& _c
 		if (constructor->isPayable())
 			stateMutability = StateMutability::Payable;
 	}
+
 	return make_shared<FunctionType>(
 		parameters,
 		TypePointers{make_shared<ContractType>(_contract)},
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index e349bf83..f5f607ca 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -6709,6 +6709,41 @@ BOOST_AUTO_TEST_CASE(experimental_pragma)
 //	CHECK_ERROR_ALLOW_MULTI(text, SyntaxError, "Duplicate experimental feature name.");
 }
 
+BOOST_AUTO_TEST_CASE(reject_interface_creation)
+{
+	char const* text = R"(
+		interface I {}
+		contract C {
+			function f() {
+				new I();
+			}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Cannot instantiate an interface.");
+}
+
+BOOST_AUTO_TEST_CASE(accept_library_creation)
+{
+	char const* text = R"(
+		library L {}
+		contract C {
+			function f() {
+				new L();
+			}
+		}
+	)";
+	CHECK_SUCCESS(text);
+}
+
+BOOST_AUTO_TEST_CASE(reject_interface_constructors)
+{
+	char const* text = R"(
+		interface I {}
+		contract C is I(2) {}
+	)";
+	CHECK_ERROR(text, TypeError, "Wrong argument count for constructor call: 1 arguments given but expected 0.");
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }