Disallow comparisons between some types.

Changelog.md

@@ -19,6 +19,7 @@ Bugfixes:
  * Type Checker: Fix address literals not being treated as compile-time constants.
  * Type Checker: Disallow invoking the same modifier multiple times.
  * Type Checker: Make UTF8-validation a bit more sloppy to include more valid sequences.
+ * Type Checker: Disallow comparisons between mapping and non-internal function types.
  * Type Checker: Do not treat strings that look like addresses as addresses.
  * Fixed crash concerning non-callable types.
  * Unused variable warnings no longer issued for variables used inside inline assembly.

libsolidity/ast/Types.cpp

@@ -2248,6 +2248,16 @@ TypePointer FunctionType::unaryOperatorResult(Token::Value _operator) const
 	return TypePointer();
 }
 
+TypePointer FunctionType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
+{
+	if (_other->category() != category() || !Token::isCompareOp(_operator))
+		return TypePointer();
+	FunctionType const& other = dynamic_cast<FunctionType const&>(*_other);
+	if (kind() == Kind::Internal && other.kind() == Kind::Internal && sizeOnStack() == 1 && other.sizeOnStack() == 1)
+		return commonType(shared_from_this(), _other);
+	return TypePointer();
+}
+
 string FunctionType::canonicalName(bool) const
 {
 	solAssert(m_kind == Kind::External, "");

libsolidity/ast/Types.h

@@ -933,6 +933,7 @@ public:
 	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 TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override;
 	virtual std::string canonicalName(bool /*_addDataLocation*/) const override;
 	virtual std::string toString(bool _short) const override;
 	virtual unsigned calldataEncodedSize(bool _padded) const override;
@@ -1038,6 +1039,7 @@ public:
 	virtual std::string toString(bool _short) const override;
 	virtual std::string canonicalName(bool _addDataLocation) const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
+	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual TypePointer encodingType() const override
 	{
 		return std::make_shared<IntegerType>(256);
@@ -1116,11 +1118,7 @@ public:
 
 	explicit ModuleType(SourceUnit const& _source): m_sourceUnit(_source) {}
 
-	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override
+	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
-	{
-		return TypePointer();
-	}
-
 	virtual std::string identifier() const override;
 	virtual bool operator==(Type const& _other) const override;
 	virtual bool canBeStored() const override { return false; }
@@ -1178,6 +1176,7 @@ public:
 	virtual std::string identifier() const override { return "t_inaccessible"; }
 	virtual bool isImplicitlyConvertibleTo(Type const&) const override { return false; }
 	virtual bool isExplicitlyConvertibleTo(Type const&) const override { return false; }
+	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual unsigned calldataEncodedSize(bool _padded) const override { (void)_padded; return 32; }
 	virtual bool canBeStored() const override { return false; }
 	virtual bool canLiveOutsideStorage() const override { return false; }

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1366,6 +1366,7 @@ void ExpressionCompiler::appendAndOrOperatorCode(BinaryOperation const& _binaryO
 
 void ExpressionCompiler::appendCompareOperatorCode(Token::Value _operator, Type const& _type)
 {
+	solAssert(_type.sizeOnStack() == 1, "Comparison of multi-slot types.");
 	if (_operator == Token::Equal || _operator == Token::NotEqual)
 	{
 		if (FunctionType const* funType = dynamic_cast<decltype(funType)>(&_type))