Code generator for function types.

4 files changed, 46 insertions, 2 deletions

diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index 808b0c55..19a1b9d1 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -2065,6 +2065,16 @@ MemberList::MemberMap FunctionType::nativeMembers(ContractDefinition const*) con
 	}
 }
 
+TypePointer FunctionType::encodingType() const
+{
+	// Only external functions can be encoded, internal functions cannot leave code boundaries.
+	if (m_location == Location::External)
+		// This looks like bytes24, but bytes24 is stored differently on the stack.
+		return shared_from_this();
+	else
+		return TypePointer();
+}
+
 TypePointer FunctionType::interfaceType(bool _inLibrary) const
 {
 	if (m_location != Location::External && m_location != Location::Internal)
@@ -2072,7 +2082,7 @@ TypePointer FunctionType::interfaceType(bool _inLibrary) const
 	if (_inLibrary)
 		return shared_from_this();
 	else
-		return make_shared<FixedBytesType>(storageBytes());
+		return make_shared<IntegerType>(8 * storageBytes());
 }
 
 bool FunctionType::canTakeArguments(TypePointers const& _argumentTypes, TypePointer const& _selfType) const
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index 358c7efc..691ddf29 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -901,6 +901,7 @@ public:
 	virtual bool canLiveOutsideStorage() const override { return m_location == Location::Internal || m_location == Location::External; }
 	virtual unsigned sizeOnStack() const override;
 	virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override;
+	virtual TypePointer encodingType() const override;
 	virtual TypePointer interfaceType(bool _inLibrary) const override;
 
 	/// @returns TypePointer of a new FunctionType object. All input/return parameters are an
diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index 58d1caa9..38a7a23b 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -133,6 +133,17 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 			m_context << u256(str->value().size());
 		m_context << Instruction::ADD;
 	}
+	else if (
+		_type.category() == Type::Category::Function &&
+		dynamic_cast<FunctionType const&>(_type).location() == FunctionType::Location::External
+	)
+	{
+		solAssert(_padToWordBoundaries, "Non-padded store for function not implemented.");
+		m_context << u256(0xffffffffUL) << Instruction::AND << (u256(1) << 160) << Instruction::MUL << Instruction::SWAP1;
+		m_context << ((u256(1) << 160) - 1) << Instruction::AND << Instruction::OR;
+		m_context << Instruction::DUP2 << Instruction::MSTORE;
+		m_context << u256(_padToWordBoundaries ? 32 : 24) << Instruction::ADD;
+	}
 	else
 	{
 		unsigned numBytes = prepareMemoryStore(_type, _padToWordBoundaries);
@@ -206,7 +217,8 @@ void CompilerUtils::encodeToMemory(
 			else if (
 				_givenTypes[i]->dataStoredIn(DataLocation::Storage) ||
 				_givenTypes[i]->dataStoredIn(DataLocation::CallData) ||
-				_givenTypes[i]->category() == Type::Category::StringLiteral
+				_givenTypes[i]->category() == Type::Category::StringLiteral ||
+				_givenTypes[i]->category() == Type::Category::Function
 			)
 				type = _givenTypes[i]; // delay conversion
 			else
@@ -678,6 +690,14 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 
 void CompilerUtils::pushZeroValue(Type const& _type)
 {
+	if (auto const* funType = dynamic_cast<FunctionType const*>(&_type))
+	{
+		if (funType->location() == FunctionType::Location::Internal)
+		{
+			m_context << m_context.errorTag();
+			return;
+		}
+	}
 	auto const* referenceType = dynamic_cast<ReferenceType const*>(&_type);
 	if (!referenceType || referenceType->location() == DataLocation::Storage)
 	{
@@ -839,6 +859,18 @@ unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCallda
 		}
 	}
 
+	if (auto const* funType = dynamic_cast<FunctionType const*>(&_type))
+	{
+		if (funType->location() == FunctionType::Location::External)
+		{
+			// We have to split the right-aligned <function identifier><address> into two stack slots:
+			// address (right aligned), function identifier (right aligned)
+			m_context << Instruction::DUP1 << ((u256(1) << 160) - 1) << Instruction::AND << Instruction::SWAP1;
+			m_context << (u256(1) << 160) << Instruction::SWAP1 << Instruction::DIV;
+			m_context << u256(0xffffffffUL) << Instruction::AND;
+		}
+	}
+
 	return numBytes;
 }
 
diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 2aec3055..9cd893e8 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -293,6 +293,7 @@ void ContractCompiler::appendCalldataUnpacker(TypePointers const& _typeParameter
 	{
 		// stack: v1 v2 ... v(k-1) base_offset current_offset
 		TypePointer type = parameterType->decodingType();
+		solAssert(type, "No decoding type found.");
 		if (type->category() == Type::Category::Array)
 		{
 			auto const& arrayType = dynamic_cast<ArrayType const&>(*type);