Support explicit conversion of external function type to address

4 files changed, 25 insertions, 1 deletions

diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index dbabc8db..4a64b4c8 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -2158,6 +2158,17 @@ bool FunctionType::operator==(Type const& _other) const
 	return true;
 }
 
+bool FunctionType::isExplicitlyConvertibleTo(Type const& _convertTo) const
+{
+	if (m_location == Location::External && _convertTo.category() == Category::Integer)
+	{
+		IntegerType const& convertTo = dynamic_cast<IntegerType const&>(_convertTo);
+		if (convertTo.isAddress())
+			return true;
+	}
+	return _convertTo.category() == category();
+}
+
 TypePointer FunctionType::unaryOperatorResult(Token::Value _operator) const
 {
 	if (_operator == Token::Value::Delete)
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index a5147f17..3917dca2 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -922,6 +922,7 @@ public:
 
 	virtual std::string identifier() const override;
 	virtual bool operator==(Type const& _other) const override;
+	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual std::string canonicalName(bool /*_addDataLocation*/) const override;
 	virtual std::string toString(bool _short) const override;
diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index 477f021a..469bd0ed 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -787,6 +787,18 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 		if (_cleanupNeeded)
 			m_context << Instruction::ISZERO << Instruction::ISZERO;
 		break;
+	case Type::Category::Function:
+	{
+		solAssert(targetTypeCategory == Type::Category::Integer, "Invalid conversion for function type.");
+		IntegerType const& targetType = dynamic_cast<IntegerType const&>(_targetType);
+		solAssert(targetType.isAddress(), "Function type can only be converted to address.");
+		FunctionType const& typeOnStack = dynamic_cast<FunctionType const&>(_typeOnStack);
+		solAssert(typeOnStack.location() == FunctionType::Location::External, "Only external function type can be converted.");
+
+		// stack: <address> <function_id>
+		m_context << Instruction::POP;
+		break;
+	}
 	default:
 		// All other types should not be convertible to non-equal types.
 		solAssert(_typeOnStack == _targetType, "Invalid type conversion requested.");
diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 4d33927d..f4279906 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -42,7 +42,7 @@ class StackHeightChecker
 public:
 	StackHeightChecker(CompilerContext const& _context):
 		m_context(_context), stackHeight(m_context.stackHeight()) {}
-	void check() { solAssert(m_context.stackHeight() == stackHeight, "I sense a disturbance in the stack."); }
+	void check() { solAssert(m_context.stackHeight() == stackHeight, "I sense a disturbance in the stack. "); }
 private:
 	CompilerContext const& m_context;
 	unsigned stackHeight;