path: root/libsolidity/ast/Types.cpp

/*
    This file is part of cpp-ethereum.

    cpp-ethereum is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    cpp-ethereum is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity data types
 */

#include <libsolidity/ast/Types.h>
#include <limits>
#include <boost/range/adaptor/reversed.hpp>
#include <libdevcore/CommonIO.h>
#include <libdevcore/CommonData.h>
#include <libdevcore/SHA3.h>
#include <libsolidity/interface/Utils.h>
#include <libsolidity/ast/AST.h>

using namespace std;
using namespace dev;
using namespace dev::solidity;

void StorageOffsets::computeOffsets(TypePointers const& _types)
{
    bigint slotOffset = 0;
    unsigned byteOffset = 0;
    map<size_t, pair<u256, unsigned>> offsets;
    for (size_t i = 0; i < _types.size(); ++i)
    {
        TypePointer const& type = _types[i];
        if (!type->canBeStored())
            continue;
        if (byteOffset + type->storageBytes() > 32)
        {
            // would overflow, go to next slot
            ++slotOffset;
            byteOffset = 0;
        }
        if (slotOffset >= bigint(1) << 256)
            BOOST_THROW_EXCEPTION(Error(Error::Type::TypeError) << errinfo_comment("Object too large for storage."));
        offsets[i] = make_pair(u256(slotOffset), byteOffset);
        solAssert(type->storageSize() >= 1, "Invalid storage size.");
        if (type->storageSize() == 1 && byteOffset + type->storageBytes() <= 32)
            byteOffset += type->storageBytes();
        else
        {
            slotOffset += type->storageSize();
            byteOffset = 0;
        }
    }
    if (byteOffset > 0)
        ++slotOffset;
    if (slotOffset >= bigint(1) << 256)
        BOOST_THROW_EXCEPTION(Error(Error::Type::TypeError) << errinfo_comment("Object too large for storage."));
    m_storageSize = u256(slotOffset);
    swap(m_offsets, offsets);
}

pair<u256, unsigned> const* StorageOffsets::offset(size_t _index) const
{
    if (m_offsets.count(_index))
        return &m_offsets.at(_index);
    else
        return nullptr;
}

MemberList& MemberList::operator=(MemberList&& _other)
{
    assert(&_other != this);

    m_memberTypes = move(_other.m_memberTypes);
    m_storageOffsets = move(_other.m_storageOffsets);
    return *this;
}

void MemberList::combine(MemberList const & _other)
{
    m_memberTypes += _other.m_memberTypes;
}

pair<u256, unsigned> const* MemberList::memberStorageOffset(string const& _name) const
{
    if (!m_storageOffsets)
    {
        TypePointers memberTypes;
        memberTypes.reserve(m_memberTypes.size());
        for (auto const& member: m_memberTypes)
            memberTypes.push_back(member.type);
        m_storageOffsets.reset(new StorageOffsets());
        m_storageOffsets->computeOffsets(memberTypes);
    }
    for (size_t index = 0; index < m_memberTypes.size(); ++index)
        if (m_memberTypes[index].name == _name)
            return m_storageOffsets->offset(index);
    return nullptr;
}

u256 const& MemberList::storageSize() const
{
    // trigger lazy computation
    memberStorageOffset("");
    return m_storageOffsets->storageSize();
}

TypePointer Type::fromElementaryTypeName(Token::Value _typeToken)
{
    char const* tokenCstr = Token::toString(_typeToken);
    solAssert(Token::isElementaryTypeName(_typeToken),
        "Expected an elementary type name but got " + ((tokenCstr) ? string(Token::toString(_typeToken)) : ""));

    if (Token::Int <= _typeToken && _typeToken <= Token::Bytes32)
    {
        int offset = _typeToken - Token::Int;
        int bytes = offset % 33;
        if (bytes == 0 && _typeToken != Token::Bytes1)
            bytes = 32;
        int modifier = offset / 33;
        switch(modifier)
        {
        case 0:
            return make_shared<IntegerType>(bytes * 8, IntegerType::Modifier::Signed);
        case 1:
            return make_shared<IntegerType>(bytes * 8, IntegerType::Modifier::Unsigned);
        case 2:
            return make_shared<FixedBytesType>(bytes + 1);
        default:
            solAssert(false, "Unexpected modifier value. Should never happen");
            return TypePointer();
        }
    }
    else if (_typeToken == Token::Byte)
        return make_shared<FixedBytesType>(1);
    else if (_typeToken == Token::Address)
        return make_shared<IntegerType>(0, IntegerType::Modifier::Address);
    else if (_typeToken == Token::Bool)
        return make_shared<BoolType>();
    else if (_typeToken == Token::Bytes)
        return make_shared<ArrayType>(DataLocation::Storage);
    else if (_typeToken == Token::String)
        return make_shared<ArrayType>(DataLocation::Storage, true);
    else
        BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment(
            "Unable to convert elementary typename " + string(Token::toString(_typeToken)) + " to type."
        ));
}

TypePointer Type::fromElementaryTypeName(string const& _name)
{
    return fromElementaryTypeName(Token::fromIdentifierOrKeyword(_name));
}

TypePointer Type::forLiteral(Literal const& _literal)
{
    switch (_literal.token())
    {
    case Token::TrueLiteral:
    case Token::FalseLiteral:
        return make_shared<BoolType>();
    case Token::Number:
        if (!IntegerConstantType::isValidLiteral(_literal))
            return TypePointer();
        return make_shared<IntegerConstantType>(_literal);
    case Token::StringLiteral:
        return make_shared<StringLiteralType>(_literal);
    default:
        return shared_ptr<Type>();
    }
}

TypePointer Type::commonType(TypePointer const& _a, TypePointer const& _b)
{
    if (_b->isImplicitlyConvertibleTo(*_a))
        return _a;
    else if (_a->isImplicitlyConvertibleTo(*_b))
        return _b;
    else
        return TypePointer();
}

MemberList const& Type::members(ContractDefinition const* _currentScope) const
{
    if (!m_members[_currentScope])
    {
        MemberList::MemberMap members = nativeMembers(_currentScope);
        if (_currentScope)
            members +=  boundFunctions(*this, *_currentScope);
        m_members[_currentScope] = unique_ptr<MemberList>(new MemberList(move(members)));
    }
    return *m_members[_currentScope];
}

MemberList::MemberMap Type::boundFunctions(Type const& _type, ContractDefinition const& _scope)
{
    // Normalise data location of type.
    TypePointer type = ReferenceType::copyForLocationIfReference(DataLocation::Storage, _type.shared_from_this());
    set<Declaration const*> seenFunctions;
    MemberList::MemberMap members;
    for (ContractDefinition const* contract: _scope.annotation().linearizedBaseContracts)
        for (UsingForDirective const* ufd: contract->usingForDirectives())
        {
            if (ufd->typeName() && *type != *ReferenceType::copyForLocationIfReference(
                DataLocation::Storage,
                ufd->typeName()->annotation().type
            ))
                continue;
            auto const& library = dynamic_cast<ContractDefinition const&>(
                *ufd->libraryName().annotation().referencedDeclaration
            );
            for (auto const& it: library.interfaceFunctions())
            {
                FunctionType const& funType = *it.second;
                solAssert(funType.hasDeclaration(), "Tried to bind function without declaration.");
                if (seenFunctions.count(&funType.declaration()))
                    continue;
                seenFunctions.insert(&funType.declaration());
                if (auto fun = funType.asMemberFunction(true, true))
                    members.push_back(MemberList::Member(
                        funType.declaration().name(),
                        fun,
                        &funType.declaration()
                    ));
            }
        }
    return members;
}

IntegerType::IntegerType(int _bits, IntegerType::Modifier _modifier):
    m_bits(_bits), m_modifier(_modifier)
{
    if (isAddress())
        m_bits = 160;
    solAssert(
        m_bits > 0 && m_bits <= 256 && m_bits % 8 == 0,
        "Invalid bit number for integer type: " + dev::toString(_bits)
    );
}

bool IntegerType::isImplicitlyConvertibleTo(Type const& _convertTo) const
{
    if (_convertTo.category() != category())
        return false;
    IntegerType const& convertTo = dynamic_cast<IntegerType const&>(_convertTo);
    if (convertTo.m_bits < m_bits)
        return false;
    if (isAddress())
        return convertTo.isAddress();
    else if (isSigned())
        return convertTo.isSigned();
    else
        return !convertTo.isSigned() || convertTo.m_bits > m_bits;
}

bool IntegerType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    return _convertTo.category() == category() ||
        _convertTo.category() == Category::Contract ||
        _convertTo.category() == Category::Enum ||
        _convertTo.category() == Category::FixedBytes;
}

TypePointer IntegerType::unaryOperatorResult(Token::Value _operator) const
{
    // "delete" is ok for all integer types
    if (_operator == Token::Delete)
        return make_shared<TupleType>();
    // no further unary operators for addresses
    else if (isAddress())
        return TypePointer();
    // for non-address integers, we allow +, -, ++ and --
    else if (_operator == Token::Add || _operator == Token::Sub ||
            _operator == Token::Inc || _operator == Token::Dec ||
            _operator == Token::After || _operator == Token::BitNot)
        return shared_from_this();
    else
        return TypePointer();
}

bool IntegerType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    IntegerType const& other = dynamic_cast<IntegerType const&>(_other);
    return other.m_bits == m_bits && other.m_modifier == m_modifier;
}

string IntegerType::toString(bool) const
{
    if (isAddress())
        return "address";
    string prefix = isSigned() ? "int" : "uint";
    return prefix + dev::toString(m_bits);
}

TypePointer IntegerType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
{
    if (_other->category() != Category::IntegerConstant && _other->category() != category())
        return TypePointer();
    auto commonType = dynamic_pointer_cast<IntegerType const>(Type::commonType(shared_from_this(), _other));

    if (!commonType)
        return TypePointer();

    // All integer types can be compared
    if (Token::isCompareOp(_operator))
        return commonType;
    if (Token::isBooleanOp(_operator))
        return TypePointer();
    // Nothing else can be done with addresses
    if (commonType->isAddress())
        return TypePointer();

    return commonType;
}

MemberList::MemberMap IntegerType::nativeMembers(ContractDefinition const*) const
{
    if (isAddress())
        return {
            {"balance", make_shared<IntegerType >(256)},
            {"call", make_shared<FunctionType>(strings(), strings{"bool"}, FunctionType::Location::Bare, true)},
            {"callcode", make_shared<FunctionType>(strings(), strings{"bool"}, FunctionType::Location::BareCallCode, true)},
            {"send", make_shared<FunctionType>(strings{"uint"}, strings{"bool"}, FunctionType::Location::Send)}
        };
    else
        return MemberList::MemberMap();
}

bool IntegerConstantType::isValidLiteral(const Literal& _literal)
{
    try
    {
        bigint x(_literal.value());
    }
    catch (...)
    {
        return false;
    }
    return true;
}

IntegerConstantType::IntegerConstantType(Literal const& _literal)
{
    m_value = bigint(_literal.value());

    switch (_literal.subDenomination())
    {
    case Literal::SubDenomination::Wei:
    case Literal::SubDenomination::Second:
    case Literal::SubDenomination::None:
        break;
    case Literal::SubDenomination::Szabo:
        m_value *= bigint("1000000000000");
        break;
    case Literal::SubDenomination::Finney:
        m_value *= bigint("1000000000000000");
        break;
    case Literal::SubDenomination::Ether:
        m_value *= bigint("1000000000000000000");
        break;
    case Literal::SubDenomination::Minute:
        m_value *= bigint("60");
        break;
    case Literal::SubDenomination::Hour:
        m_value *= bigint("3600");
        break;
    case Literal::SubDenomination::Day:
        m_value *= bigint("86400");
        break;
    case Literal::SubDenomination::Week:
        m_value *= bigint("604800");
        break;
    case Literal::SubDenomination::Year:
        m_value *= bigint("31536000");
        break;
    }
}

bool IntegerConstantType::isImplicitlyConvertibleTo(Type const& _convertTo) const
{
    if (auto targetType = dynamic_cast<IntegerType const*>(&_convertTo))
    {
        if (m_value == 0)
            return true;
        int forSignBit = (targetType->isSigned() ? 1 : 0);
        if (m_value > 0)
        {
            if (m_value <= (u256(-1) >> (256 - targetType->numBits() + forSignBit)))
                return true;
        }
        else if (targetType->isSigned() && -m_value <= (u256(1) << (targetType->numBits() - forSignBit)))
            return true;
        return false;
    }
    else if (_convertTo.category() == Category::FixedBytes)
    {
        FixedBytesType const& fixedBytes = dynamic_cast<FixedBytesType const&>(_convertTo);
        return fixedBytes.numBytes() * 8 >= integerType()->numBits();
    }
    else
        return false;
}

bool IntegerConstantType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    TypePointer intType = integerType();
    return intType && intType->isExplicitlyConvertibleTo(_convertTo);
}

TypePointer IntegerConstantType::unaryOperatorResult(Token::Value _operator) const
{
    bigint value;
    switch (_operator)
    {
    case Token::BitNot:
        value = ~m_value;
        break;
    case Token::Add:
        value = m_value;
        break;
    case Token::Sub:
        value = -m_value;
        break;
    case Token::After:
        return shared_from_this();
    default:
        return TypePointer();
    }
    return make_shared<IntegerConstantType>(value);
}

TypePointer IntegerConstantType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
{
    if (_other->category() == Category::Integer)
    {
        shared_ptr<IntegerType const> intType = integerType();
        if (!intType)
            return TypePointer();
        return intType->binaryOperatorResult(_operator, _other);
    }
    else if (_other->category() != category())
        return TypePointer();

    IntegerConstantType const& other = dynamic_cast<IntegerConstantType const&>(*_other);
    if (Token::isCompareOp(_operator))
    {
        shared_ptr<IntegerType const> thisIntegerType = integerType();
        shared_ptr<IntegerType const> otherIntegerType = other.integerType();
        if (!thisIntegerType || !otherIntegerType)
            return TypePointer();
        return thisIntegerType->binaryOperatorResult(_operator, otherIntegerType);
    }
    else
    {
        bigint value;
        switch (_operator)
        {
        case Token::BitOr:
            value = m_value | other.m_value;
            break;
        case Token::BitXor:
            value = m_value ^ other.m_value;
            break;
        case Token::BitAnd:
            value = m_value & other.m_value;
            break;
        case Token::Add:
            value = m_value + other.m_value;
            break;
        case Token::Sub:
            value = m_value - other.m_value;
            break;
        case Token::Mul:
            value = m_value * other.m_value;
            break;
        case Token::Div:
            if (other.m_value == 0)
                return TypePointer();
            value = m_value / other.m_value;
            break;
        case Token::Mod:
            if (other.m_value == 0)
                return TypePointer();
            value = m_value % other.m_value;
            break;
        case Token::Exp:
            if (other.m_value < 0)
                return TypePointer();
            else if (other.m_value > numeric_limits<unsigned int>::max())
                return TypePointer();
            else
                value = boost::multiprecision::pow(m_value, other.m_value.convert_to<unsigned int>());
            break;
        default:
            return TypePointer();
        }
        return make_shared<IntegerConstantType>(value);
    }
}

bool IntegerConstantType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    return m_value == dynamic_cast<IntegerConstantType const&>(_other).m_value;
}

string IntegerConstantType::toString(bool) const
{
    return "int_const " + m_value.str();
}

u256 IntegerConstantType::literalValue(Literal const*) const
{
    u256 value;
    // we ignore the literal and hope that the type was correctly determined
    solAssert(m_value <= u256(-1), "Integer constant too large.");
    solAssert(m_value >= -(bigint(1) << 255), "Integer constant too small.");

    if (m_value >= 0)
        value = u256(m_value);
    else
        value = s2u(s256(m_value));

    return value;
}

TypePointer IntegerConstantType::mobileType() const
{
    auto intType = integerType();
    solAssert(!!intType, "mobileType called with invalid integer constant " + toString(false));
    return intType;
}

shared_ptr<IntegerType const> IntegerConstantType::integerType() const
{
    bigint value = m_value;
    bool negative = (value < 0);
    if (negative) // convert to positive number of same bit requirements
        value = ((-value) - 1) << 1;
    if (value > u256(-1))
        return shared_ptr<IntegerType const>();
    else
        return make_shared<IntegerType>(
            max(bytesRequired(value), 1u) * 8,
            negative ? IntegerType::Modifier::Signed : IntegerType::Modifier::Unsigned
        );
}

StringLiteralType::StringLiteralType(Literal const& _literal):
    m_value(_literal.value())
{
}

bool StringLiteralType::isImplicitlyConvertibleTo(Type const& _convertTo) const
{
    if (auto fixedBytes = dynamic_cast<FixedBytesType const*>(&_convertTo))
        return size_t(fixedBytes->numBytes()) >= m_value.size();
    else if (auto arrayType = dynamic_cast<ArrayType const*>(&_convertTo))
        return
            arrayType->isByteArray() &&
            !(arrayType->dataStoredIn(DataLocation::Storage) && arrayType->isPointer());
    else
        return false;
}

bool StringLiteralType::operator==(const Type& _other) const
{
    if (_other.category() != category())
        return false;
    return m_value == dynamic_cast<StringLiteralType const&>(_other).m_value;
}

TypePointer StringLiteralType::mobileType() const
{
    return make_shared<ArrayType>(DataLocation::Memory, true);
}

shared_ptr<FixedBytesType> FixedBytesType::smallestTypeForLiteral(string const& _literal)
{
    if (_literal.length() <= 32)
        return make_shared<FixedBytesType>(_literal.length());
    return shared_ptr<FixedBytesType>();
}

FixedBytesType::FixedBytesType(int _bytes): m_bytes(_bytes)
{
    solAssert(m_bytes >= 0 && m_bytes <= 32,
              "Invalid byte number for fixed bytes type: " + dev::toString(m_bytes));
}

bool FixedBytesType::isImplicitlyConvertibleTo(Type const& _convertTo) const
{
    if (_convertTo.category() != category())
        return false;
    FixedBytesType const& convertTo = dynamic_cast<FixedBytesType const&>(_convertTo);
    return convertTo.m_bytes >= m_bytes;
}

bool FixedBytesType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    return _convertTo.category() == Category::Integer ||
        _convertTo.category() == Category::Contract ||
        _convertTo.category() == category();
}

TypePointer FixedBytesType::unaryOperatorResult(Token::Value _operator) const
{
    // "delete" and "~" is okay for FixedBytesType
    if (_operator == Token::Delete)
        return make_shared<TupleType>();
    else if (_operator == Token::BitNot)
        return shared_from_this();

    return TypePointer();
}

TypePointer FixedBytesType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
{
    auto commonType = dynamic_pointer_cast<FixedBytesType const>(Type::commonType(shared_from_this(), _other));
    if (!commonType)
        return TypePointer();

    // FixedBytes can be compared and have bitwise operators applied to them
    if (Token::isCompareOp(_operator) || Token::isBitOp(_operator))
        return commonType;

    return TypePointer();
}

MemberList::MemberMap FixedBytesType::nativeMembers(const ContractDefinition*) const
{
    return MemberList::MemberMap{MemberList::Member{"length", make_shared<IntegerType>(8)}};
}

bool FixedBytesType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    FixedBytesType const& other = dynamic_cast<FixedBytesType const&>(_other);
    return other.m_bytes == m_bytes;
}

bool BoolType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    // conversion to integer is fine, but not to address
    // this is an example of explicit conversions being not transitive (though implicit should be)
    if (_convertTo.category() == category())
    {
        IntegerType const& convertTo = dynamic_cast<IntegerType const&>(_convertTo);
        if (!convertTo.isAddress())
            return true;
    }
    return isImplicitlyConvertibleTo(_convertTo);
}

u256 BoolType::literalValue(Literal const* _literal) const
{
    solAssert(_literal, "");
    if (_literal->token() == Token::TrueLiteral)
        return u256(1);
    else if (_literal->token() == Token::FalseLiteral)
        return u256(0);
    else
        BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Bool type constructed from non-boolean literal."));
}

TypePointer BoolType::unaryOperatorResult(Token::Value _operator) const
{
    if (_operator == Token::Delete)
        return make_shared<TupleType>();
    return (_operator == Token::Not) ? shared_from_this() : TypePointer();
}

TypePointer BoolType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
{
    if (category() != _other->category())
        return TypePointer();
    if (Token::isCompareOp(_operator) || _operator == Token::And || _operator == Token::Or)
        return _other;
    else
        return TypePointer();
}

bool ContractType::isImplicitlyConvertibleTo(Type const& _convertTo) const
{
    if (*this == _convertTo)
        return true;
    if (_convertTo.category() == Category::Integer)
        return dynamic_cast<IntegerType const&>(_convertTo).isAddress();
    if (_convertTo.category() == Category::Contract)
    {
        auto const& bases = contractDefinition().annotation().linearizedBaseContracts;
        if (m_super && bases.size() <= 1)
            return false;
        return find(m_super ? ++bases.begin() : bases.begin(), bases.end(),
                    &dynamic_cast<ContractType const&>(_convertTo).contractDefinition()) != bases.end();
    }
    return false;
}

bool ContractType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    return
        isImplicitlyConvertibleTo(_convertTo) ||
        _convertTo.category() == Category::Integer ||
        _convertTo.category() == Category::Contract;
}

TypePointer ContractType::unaryOperatorResult(Token::Value _operator) const
{
    return _operator == Token::Delete ? make_shared<TupleType>() : TypePointer();
}

TypePointer ReferenceType::unaryOperatorResult(Token::Value _operator) const
{
    if (_operator != Token::Delete)
        return TypePointer();
    // delete can be used on everything except calldata references or storage pointers
    // (storage references are ok)
    switch (location())
    {
    case DataLocation::CallData:
        return TypePointer();
    case DataLocation::Memory:
        return make_shared<TupleType>();
    case DataLocation::Storage:
        return m_isPointer ? TypePointer() : make_shared<TupleType>();
    default:
        solAssert(false, "");
    }
    return TypePointer();
}

TypePointer ReferenceType::copyForLocationIfReference(DataLocation _location, TypePointer const& _type)
{
    if (auto type = dynamic_cast<ReferenceType const*>(_type.get()))
        return type->copyForLocation(_location, false);
    return _type;
}

TypePointer ReferenceType::copyForLocationIfReference(TypePointer const& _type) const
{
    return copyForLocationIfReference(m_location, _type);
}

string ReferenceType::stringForReferencePart() const
{
    switch (m_location)
    {
    case DataLocation::Storage:
        return string("storage ") + (m_isPointer ? "pointer" : "ref");
    case DataLocation::CallData:
        return "calldata";
    case DataLocation::Memory:
        return "memory";
    }
    solAssert(false, "");
    return "";
}

bool ArrayType::isImplicitlyConvertibleTo(const Type& _convertTo) const
{
    if (_convertTo.category() != category())
        return false;
    auto& convertTo = dynamic_cast<ArrayType const&>(_convertTo);
    if (convertTo.isByteArray() != isByteArray() || convertTo.isString() != isString())
        return false;
    // memory/calldata to storage can be converted, but only to a direct storage reference
    if (convertTo.location() == DataLocation::Storage && location() != DataLocation::Storage && convertTo.isPointer())
        return false;
    if (convertTo.location() == DataLocation::CallData && location() != convertTo.location())
        return false;
    if (convertTo.location() == DataLocation::Storage && !convertTo.isPointer())
    {
        // Less restrictive conversion, since we need to copy anyway.
        if (!baseType()->isImplicitlyConvertibleTo(*convertTo.baseType()))
            return false;
        if (convertTo.isDynamicallySized())
            return true;
        return !isDynamicallySized() && convertTo.length() >= length();
    }
    else
    {
        // Conversion to storage pointer or to memory, we de not copy element-for-element here, so
        // require that the base type is the same, not only convertible.
        // This disallows assignment of nested dynamic arrays from storage to memory for now.
        if (
            *copyForLocationIfReference(location(), baseType()) !=
            *copyForLocationIfReference(location(), convertTo.baseType())
        )
            return false;
        if (isDynamicallySized() != convertTo.isDynamicallySized())
            return false;
        // We also require that the size is the same.
        if (!isDynamicallySized() && length() != convertTo.length())
            return false;
        return true;
    }
}

bool ArrayType::isExplicitlyConvertibleTo(const Type& _convertTo) const
{
    if (isImplicitlyConvertibleTo(_convertTo))
        return true;
    // allow conversion bytes <-> string
    if (_convertTo.category() != category())
        return false;
    auto& convertTo = dynamic_cast<ArrayType const&>(_convertTo);
    if (convertTo.location() != location())
        return false;
    if (!isByteArray() || !convertTo.isByteArray())
        return false;
    return true;
}

bool ArrayType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    ArrayType const& other = dynamic_cast<ArrayType const&>(_other);
    if (
        !ReferenceType::operator==(other) ||
        other.isByteArray() != isByteArray() ||
        other.isString() != isString() ||
        other.isDynamicallySized() != isDynamicallySized()
    )
        return false;
    if (*other.baseType() != *baseType())
        return false;
    return isDynamicallySized() || length()  == other.length();
}

unsigned ArrayType::calldataEncodedSize(bool _padded) const
{
    if (isDynamicallySized())
        return 32;
    bigint size = bigint(length()) * (isByteArray() ? 1 : baseType()->calldataEncodedSize(_padded));
    size = ((size + 31) / 32) * 32;
    solAssert(size <= numeric_limits<unsigned>::max(), "Array size does not fit unsigned.");
    return unsigned(size);
}

u256 ArrayType::storageSize() const
{
    if (isDynamicallySized())
        return 1;

    bigint size;
    unsigned baseBytes = baseType()->storageBytes();
    if (baseBytes == 0)
        size = 1;
    else if (baseBytes < 32)
    {
        unsigned itemsPerSlot = 32 / baseBytes;
        size = (bigint(length()) + (itemsPerSlot - 1)) / itemsPerSlot;
    }
    else
        size = bigint(length()) * baseType()->storageSize();
    if (size >= bigint(1) << 256)
        BOOST_THROW_EXCEPTION(Error(Error::Type::TypeError) << errinfo_comment("Array too large for storage."));
    return max<u256>(1, u256(size));
}

unsigned ArrayType::sizeOnStack() const
{
    if (m_location == DataLocation::CallData)
        // offset [length] (stack top)
        return 1 + (isDynamicallySized() ? 1 : 0);
    else
        // storage slot or memory offset
        // byte offset inside storage value is omitted
        return 1;
}

string ArrayType::toString(bool _short) const
{
    string ret;
    if (isString())
        ret = "string";
    else if (isByteArray())
        ret = "bytes";
    else
    {
        ret = baseType()->toString(_short) + "[";
        if (!isDynamicallySized())
            ret += length().str();
        ret += "]";
    }
    if (!_short)
        ret += " " + stringForReferencePart();
    return ret;
}

string ArrayType::canonicalName(bool _addDataLocation) const
{
    string ret;
    if (isString())
        ret = "string";
    else if (isByteArray())
        ret = "bytes";
    else
    {
        ret = baseType()->canonicalName(false) + "[";
        if (!isDynamicallySized())
            ret += length().str();
        ret += "]";
    }
    if (_addDataLocation && location() == DataLocation::Storage)
        ret += " storage";
    return ret;
}

MemberList::MemberMap ArrayType::nativeMembers(ContractDefinition const*) const
{
    MemberList::MemberMap members;
    if (!isString())
    {
        members.push_back({"length", make_shared<IntegerType>(256)});
        if (isDynamicallySized() && location() == DataLocation::Storage)
            members.push_back({"push", make_shared<FunctionType>(
                TypePointers{baseType()},
                TypePointers{make_shared<IntegerType>(256)},
                strings{string()},
                strings{string()},
                isByteArray() ? FunctionType::Location::ByteArrayPush : FunctionType::Location::ArrayPush
            )});
    }
    return members;
}

TypePointer ArrayType::encodingType() const
{
    if (location() == DataLocation::Storage)
        return make_shared<IntegerType>(256);
    else
        return this->copyForLocation(DataLocation::Memory, true);
}

TypePointer ArrayType::decodingType() const
{
    if (location() == DataLocation::Storage)
        return make_shared<IntegerType>(256);
    else
        return shared_from_this();
}

TypePointer ArrayType::interfaceType(bool _inLibrary) const
{
    if (_inLibrary && location() == DataLocation::Storage)
        return shared_from_this();

    if (m_arrayKind != ArrayKind::Ordinary)
        return this->copyForLocation(DataLocation::Memory, true);
    TypePointer baseExt = m_baseType->interfaceType(_inLibrary);
    if (!baseExt)
        return TypePointer();
    if (m_baseType->category() == Category::Array && m_baseType->isDynamicallySized())
        return TypePointer();

    if (isDynamicallySized())
        return make_shared<ArrayType>(DataLocation::Memory, baseExt);
    else
        return make_shared<ArrayType>(DataLocation::Memory, baseExt, m_length);
}

u256 ArrayType::memorySize() const
{
    solAssert(!isDynamicallySized(), "");
    solAssert(m_location == DataLocation::Memory, "");
    bigint size = bigint(m_length) * m_baseType->memoryHeadSize();
    solAssert(size <= numeric_limits<unsigned>::max(), "Array size does not fit u256.");
    return u256(size);
}

TypePointer ArrayType::copyForLocation(DataLocation _location, bool _isPointer) const
{
    auto copy = make_shared<ArrayType>(_location);
    copy->m_isPointer = _isPointer;
    copy->m_arrayKind = m_arrayKind;
    copy->m_baseType = copy->copyForLocationIfReference(m_baseType);
    copy->m_hasDynamicLength = m_hasDynamicLength;
    copy->m_length = m_length;
    return copy;
}

bool ContractType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    ContractType const& other = dynamic_cast<ContractType const&>(_other);
    return other.m_contract == m_contract && other.m_super == m_super;
}

string ContractType::toString(bool) const
{
    return
        string(m_contract.isLibrary() ? "library " : "contract ") +
        string(m_super ? "super " : "") +
        m_contract.name();
}

string ContractType::canonicalName(bool) const
{
    return m_contract.annotation().canonicalName;
}

MemberList::MemberMap ContractType::nativeMembers(ContractDefinition const*) const
{
    // All address members and all interface functions
    MemberList::MemberMap members(IntegerType(120, IntegerType::Modifier::Address).nativeMembers(nullptr));
    if (m_super)
    {
        // add the most derived of all functions which are visible in derived contracts
        for (ContractDefinition const* base: m_contract.annotation().linearizedBaseContracts)
            for (FunctionDefinition const* function: base->definedFunctions())
            {
                if (!function->isVisibleInDerivedContracts())
                    continue;
                auto functionType = make_shared<FunctionType>(*function, true);
                bool functionWithEqualArgumentsFound = false;
                for (auto const& member: members)
                {
                    if (member.name != function->name())
                        continue;
                    auto memberType = dynamic_cast<FunctionType const*>(member.type.get());
                    solAssert(!!memberType, "Override changes type.");
                    if (!memberType->hasEqualArgumentTypes(*functionType))
                        continue;
                    functionWithEqualArgumentsFound = true;
                    break;
                }
                if (!functionWithEqualArgumentsFound)
                    members.push_back(MemberList::Member(
                        function->name(),
                        functionType,
                        function
                    ));
            }
    }
    else
    {
        for (auto const& it: m_contract.interfaceFunctions())
            members.push_back(MemberList::Member(
                it.second->declaration().name(),
                it.second->asMemberFunction(m_contract.isLibrary()),
                &it.second->declaration()
            ));
    }
    return members;
}

shared_ptr<FunctionType const> const& ContractType::constructorType() const
{
    if (!m_constructorType)
    {
        FunctionDefinition const* constructor = m_contract.constructor();
        if (constructor)
            m_constructorType = make_shared<FunctionType>(*constructor);
        else
            m_constructorType = make_shared<FunctionType>(TypePointers(), TypePointers());
    }
    return m_constructorType;
}

vector<tuple<VariableDeclaration const*, u256, unsigned>> ContractType::stateVariables() const
{
    vector<VariableDeclaration const*> variables;
    for (ContractDefinition const* contract: boost::adaptors::reverse(m_contract.annotation().linearizedBaseContracts))
        for (VariableDeclaration const* variable: contract->stateVariables())
            if (!variable->isConstant())
                variables.push_back(variable);
    TypePointers types;
    for (auto variable: variables)
        types.push_back(variable->annotation().type);
    StorageOffsets offsets;
    offsets.computeOffsets(types);

    vector<tuple<VariableDeclaration const*, u256, unsigned>> variablesAndOffsets;
    for (size_t index = 0; index < variables.size(); ++index)
        if (auto const* offset = offsets.offset(index))
            variablesAndOffsets.push_back(make_tuple(variables[index], offset->first, offset->second));
    return variablesAndOffsets;
}

bool StructType::isImplicitlyConvertibleTo(const Type& _convertTo) const
{
    if (_convertTo.category() != category())
        return false;
    auto& convertTo = dynamic_cast<StructType const&>(_convertTo);
    // memory/calldata to storage can be converted, but only to a direct storage reference
    if (convertTo.location() == DataLocation::Storage && location() != DataLocation::Storage && convertTo.isPointer())
        return false;
    if (convertTo.location() == DataLocation::CallData && location() != convertTo.location())
        return false;
    return this->m_struct == convertTo.m_struct;
}

bool StructType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    StructType const& other = dynamic_cast<StructType const&>(_other);
    return ReferenceType::operator==(other) && other.m_struct == m_struct;
}

unsigned StructType::calldataEncodedSize(bool _padded) const
{
    unsigned size = 0;
    for (auto const& member: members(nullptr))
        if (!member.type->canLiveOutsideStorage())
            return 0;
        else
        {
            unsigned memberSize = member.type->calldataEncodedSize(_padded);
            if (memberSize == 0)
                return 0;
            size += memberSize;
        }
    return size;
}

u256 StructType::memorySize() const
{
    u256 size;
    for (auto const& member: members(nullptr))
        if (member.type->canLiveOutsideStorage())
            size += member.type->memoryHeadSize();
    return size;
}

u256 StructType::storageSize() const
{
    return max<u256>(1, members(nullptr).storageSize());
}

string StructType::toString(bool _short) const
{
    string ret = "struct " + m_struct.name();
    if (!_short)
        ret += " " + stringForReferencePart();
    return ret;
}

MemberList::MemberMap StructType::nativeMembers(ContractDefinition const*) const
{
    MemberList::MemberMap members;
    for (ASTPointer<VariableDeclaration> const& variable: m_struct.members())
    {
        TypePointer type = variable->annotation().type;
        // Skip all mapping members if we are not in storage.
        if (location() != DataLocation::Storage && !type->canLiveOutsideStorage())
            continue;
        members.push_back(MemberList::Member(
            variable->name(),
            copyForLocationIfReference(type),
            variable.get())
        );
    }
    return members;
}

TypePointer StructType::interfaceType(bool _inLibrary) const
{
    if (_inLibrary && location() == DataLocation::Storage)
        return shared_from_this();
    else
        return TypePointer();
}

TypePointer StructType::copyForLocation(DataLocation _location, bool _isPointer) const
{
    auto copy = make_shared<StructType>(m_struct, _location);
    copy->m_isPointer = _isPointer;
    return copy;
}

string StructType::canonicalName(bool _addDataLocation) const
{
    string ret = m_struct.annotation().canonicalName;
    if (_addDataLocation && location() == DataLocation::Storage)
        ret += " storage";
    return ret;
}

FunctionTypePointer StructType::constructorType() const
{
    TypePointers paramTypes;
    strings paramNames;
    for (auto const& member: members(nullptr))
    {
        if (!member.type->canLiveOutsideStorage())
            continue;
        paramNames.push_back(member.name);
        paramTypes.push_back(copyForLocationIfReference(DataLocation::Memory, member.type));
    }
    return make_shared<FunctionType>(
        paramTypes,
        TypePointers{copyForLocation(DataLocation::Memory, false)},
        paramNames,
        strings(),
        FunctionType::Location::Internal
    );
}

pair<u256, unsigned> const& StructType::storageOffsetsOfMember(string const& _name) const
{
    auto const* offsets = members(nullptr).memberStorageOffset(_name);
    solAssert(offsets, "Storage offset of non-existing member requested.");
    return *offsets;
}

u256 StructType::memoryOffsetOfMember(string const& _name) const
{
    u256 offset;
    for (auto const& member: members(nullptr))
        if (member.name == _name)
            return offset;
        else
            offset += member.type->memoryHeadSize();
    solAssert(false, "Member not found in struct.");
    return 0;
}

set<string> StructType::membersMissingInMemory() const
{
    set<string> missing;
    for (ASTPointer<VariableDeclaration> const& variable: m_struct.members())
        if (!variable->annotation().type->canLiveOutsideStorage())
            missing.insert(variable->name());
    return missing;
}

TypePointer EnumType::unaryOperatorResult(Token::Value _operator) const
{
    return _operator == Token::Delete ? make_shared<TupleType>() : TypePointer();
}

bool EnumType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    EnumType const& other = dynamic_cast<EnumType const&>(_other);
    return other.m_enum == m_enum;
}

unsigned EnumType::storageBytes() const
{
    size_t elements = m_enum.members().size();
    if (elements <= 1)
        return 1;
    else
        return dev::bytesRequired(elements - 1);
}

string EnumType::toString(bool) const
{
    return string("enum ") + m_enum.name();
}

string EnumType::canonicalName(bool) const
{
    return m_enum.annotation().canonicalName;
}

bool EnumType::isExplicitlyConvertibleTo(Type const& _convertTo) const
{
    return _convertTo.category() == category() || _convertTo.category() == Category::Integer;
}

unsigned int EnumType::memberValue(ASTString const& _member) const
{
    unsigned int index = 0;
    for (ASTPointer<EnumValue> const& decl: m_enum.members())
    {
        if (decl->name() == _member)
            return index;
        ++index;
    }
    BOOST_THROW_EXCEPTION(m_enum.createTypeError("Requested unknown enum value ." + _member));
}

bool TupleType::isImplicitlyConvertibleTo(Type const& _other) const
{
    if (auto tupleType = dynamic_cast<TupleType const*>(&_other))
    {
        TypePointers const& targets = tupleType->components();
        if (targets.empty())
            return components().empty();
        if (components().size() != targets.size() && !targets.front() && !targets.back())
            return false; // (,a,) = (1,2,3,4) - unable to position `a` in the tuple.
        size_t minNumValues = targets.size();
        if (!targets.back() || !targets.front())
            --minNumValues; // wildcards can also match 0 components
        if (components().size() < minNumValues)
            return false;
        if (components().size() > targets.size() && targets.front() && targets.back())
            return false; // larger source and no wildcard
        bool fillRight = !targets.back() || targets.front();
        for (size_t i = 0; i < min(targets.size(), components().size()); ++i)
        {
            auto const& s = components()[fillRight ? i : components().size() - i - 1];
            auto const& t = targets[fillRight ? i : targets.size() - i - 1];
            if (!s && t)
                return false;
            else if (s && t && !s->isImplicitlyConvertibleTo(*t))
                return false;
        }
        return true;
    }
    else
        return false;
}

bool TupleType::operator==(Type const& _other) const
{
    if (auto tupleType = dynamic_cast<TupleType const*>(&_other))
        return components() == tupleType->components();
    else
        return false;
}

string TupleType::toString(bool _short) const
{
    if (components().empty())
        return "tuple()";
    string str = "tuple(";
    for (auto const& t: components())
        str += (t ? t->toString(_short) : "") + ",";
    str.pop_back();
    return str + ")";
}

u256 TupleType::storageSize() const
{
    BOOST_THROW_EXCEPTION(
        InternalCompilerError() <<
        errinfo_comment("Storage size of non-storable tuple type requested.")
    );
}

unsigned TupleType::sizeOnStack() const
{
    unsigned size = 0;
    for (auto const& t: components())
        size += t ? t->sizeOnStack() : 0;
    return size;
}

TypePointer TupleType::mobileType() const
{
    TypePointers mobiles;
    for (auto const& c: components())
        mobiles.push_back(c ? c->mobileType() : TypePointer());
    return make_shared<TupleType>(mobiles);
}

TypePointer TupleType::closestTemporaryType(TypePointer const& _targetType) const
{
    solAssert(!!_targetType, "");
    TypePointers const& targetComponents = dynamic_cast<TupleType const&>(*_targetType).components();
    bool fillRight = !targetComponents.empty() && (!targetComponents.back() || targetComponents.front());
    TypePointers tempComponents(targetComponents.size());
    for (size_t i = 0; i < min(targetComponents.size(), components().size()); ++i)
    {
        size_t si = fillRight ? i : components().size() - i - 1;
        size_t ti = fillRight ? i : targetComponents.size() - i - 1;
        if (components()[si] && targetComponents[ti])
            tempComponents[ti] = components()[si]->closestTemporaryType(targetComponents[ti]);
    }
    return make_shared<TupleType>(tempComponents);
}

FunctionType::FunctionType(FunctionDefinition const& _function, bool _isInternal):
    m_location(_isInternal ? Location::Internal : Location::External),
    m_isConstant(_function.isDeclaredConst()),
    m_declaration(&_function)
{
    TypePointers params;
    vector<string> paramNames;
    TypePointers retParams;
    vector<string> retParamNames;

    params.reserve(_function.parameters().size());
    paramNames.reserve(_function.parameters().size());
    for (ASTPointer<VariableDeclaration> const& var: _function.parameters())
    {
        paramNames.push_back(var->name());
        params.push_back(var->annotation().type);
    }
    retParams.reserve(_function.returnParameters().size());
    retParamNames.reserve(_function.returnParameters().size());
    for (ASTPointer<VariableDeclaration> const& var: _function.returnParameters())
    {
        retParamNames.push_back(var->name());
        retParams.push_back(var->annotation().type);
    }
    swap(params, m_parameterTypes);
    swap(paramNames, m_parameterNames);
    swap(retParams, m_returnParameterTypes);
    swap(retParamNames, m_returnParameterNames);
}

FunctionType::FunctionType(VariableDeclaration const& _varDecl):
    m_location(Location::External), m_isConstant(true), m_declaration(&_varDecl)
{
    TypePointers paramTypes;
    vector<string> paramNames;
    auto returnType = _varDecl.annotation().type;

    while (true)
    {
        if (auto mappingType = dynamic_cast<MappingType const*>(returnType.get()))
        {
            paramTypes.push_back(mappingType->keyType());
            paramNames.push_back("");
            returnType = mappingType->valueType();
        }
        else if (auto arrayType = dynamic_cast<ArrayType const*>(returnType.get()))
        {
            if (arrayType->isByteArray())
                // Return byte arrays as as whole.
                break;
            returnType = arrayType->baseType();
            paramNames.push_back("");
            paramTypes.push_back(make_shared<IntegerType>(256));
        }
        else
            break;
    }

    TypePointers retParams;
    vector<string> retParamNames;
    if (auto structType = dynamic_cast<StructType const*>(returnType.get()))
    {
        for (auto const& member: structType->members(nullptr))
            if (member.type->category() != Category::Mapping)
            {
                if (auto arrayType = dynamic_cast<ArrayType const*>(member.type.get()))
                    if (!arrayType->isByteArray())
                        continue;
                retParams.push_back(member.type);
                retParamNames.push_back(member.name);
            }
    }
    else
    {
        retParams.push_back(ReferenceType::copyForLocationIfReference(
            DataLocation::Memory,
            returnType
        ));
        retParamNames.push_back("");
    }

    swap(paramTypes, m_parameterTypes);
    swap(paramNames, m_parameterNames);
    swap(retParams, m_returnParameterTypes);
    swap(retParamNames, m_returnParameterNames);
}

FunctionType::FunctionType(const EventDefinition& _event):
    m_location(Location::Event), m_isConstant(true), m_declaration(&_event)
{
    TypePointers params;
    vector<string> paramNames;
    params.reserve(_event.parameters().size());
    paramNames.reserve(_event.parameters().size());
    for (ASTPointer<VariableDeclaration> const& var: _event.parameters())
    {
        paramNames.push_back(var->name());
        params.push_back(var->annotation().type);
    }
    swap(params, m_parameterTypes);
    swap(paramNames, m_parameterNames);
}

vector<string> FunctionType::parameterNames() const
{
    if (!bound())
        return m_parameterNames;
    return vector<string>(m_parameterNames.cbegin() + 1, m_parameterNames.cend());
}

TypePointers FunctionType::parameterTypes() const
{
    if (!bound())
        return m_parameterTypes;
    return TypePointers(m_parameterTypes.cbegin() + 1, m_parameterTypes.cend());
}

bool FunctionType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    FunctionType const& other = dynamic_cast<FunctionType const&>(_other);

    if (m_location != other.m_location)
        return false;
    if (m_isConstant != other.isConstant())
        return false;

    if (m_parameterTypes.size() != other.m_parameterTypes.size() ||
            m_returnParameterTypes.size() != other.m_returnParameterTypes.size())
        return false;
    auto typeCompare = [](TypePointer const& _a, TypePointer const& _b) -> bool { return *_a == *_b; };

    if (!equal(m_parameterTypes.cbegin(), m_parameterTypes.cend(),
               other.m_parameterTypes.cbegin(), typeCompare))
        return false;
    if (!equal(m_returnParameterTypes.cbegin(), m_returnParameterTypes.cend(),
               other.m_returnParameterTypes.cbegin(), typeCompare))
        return false;
    //@todo this is ugly, but cannot be prevented right now
    if (m_gasSet != other.m_gasSet || m_valueSet != other.m_valueSet)
        return false;
    if (bound() != other.bound())
        return false;
    if (bound() && *selfType() != *other.selfType())
        return false;
    return true;
}

string FunctionType::toString(bool _short) const
{
    string name = "function (";
    for (auto it = m_parameterTypes.begin(); it != m_parameterTypes.end(); ++it)
        name += (*it)->toString(_short) + (it + 1 == m_parameterTypes.end() ? "" : ",");
    name += ") returns (";
    for (auto it = m_returnParameterTypes.begin(); it != m_returnParameterTypes.end(); ++it)
        name += (*it)->toString(_short) + (it + 1 == m_returnParameterTypes.end() ? "" : ",");
    return name + ")";
}

u256 FunctionType::storageSize() const
{
    BOOST_THROW_EXCEPTION(
        InternalCompilerError()
            << errinfo_comment("Storage size of non-storable function type requested."));
}

unsigned FunctionType::sizeOnStack() const
{
    Location location = m_location;
    if (m_location == Location::SetGas || m_location == Location::SetValue)
    {
        solAssert(m_returnParameterTypes.size() == 1, "");
        location = dynamic_cast<FunctionType const&>(*m_returnParameterTypes.front()).m_location;
    }

    unsigned size = 0;
    if (location == Location::External || location == Location::CallCode)
        size = 2;
    else if (location == Location::Bare || location == Location::BareCallCode)
        size = 1;
    else if (location == Location::Internal)
        size = 1;
    else if (location == Location::ArrayPush || location == Location::ByteArrayPush)
        size = 1;
    if (m_gasSet)
        size++;
    if (m_valueSet)
        size++;
    if (bound())
        size += m_parameterTypes.front()->sizeOnStack();
    return size;
}

FunctionTypePointer FunctionType::interfaceFunctionType() const
{
    // Note that m_declaration might also be a state variable!
    solAssert(m_declaration, "Declaration needed to determine interface function type.");
    bool isLibraryFunction = dynamic_cast<ContractDefinition const&>(*m_declaration->scope()).isLibrary();

    TypePointers paramTypes;
    TypePointers retParamTypes;

    for (auto type: m_parameterTypes)
    {
        if (auto ext = type->interfaceType(isLibraryFunction))
            paramTypes.push_back(ext);
        else
            return FunctionTypePointer();
    }
    for (auto type: m_returnParameterTypes)
    {
        if (auto ext = type->interfaceType(isLibraryFunction))
            retParamTypes.push_back(ext);
        else
            return FunctionTypePointer();
    }
    auto variable = dynamic_cast<VariableDeclaration const*>(m_declaration);
    if (variable && retParamTypes.empty())
        return FunctionTypePointer();

    return make_shared<FunctionType>(paramTypes, retParamTypes, m_parameterNames, m_returnParameterNames, m_location, m_arbitraryParameters);
}

MemberList::MemberMap FunctionType::nativeMembers(ContractDefinition const*) const
{
    switch (m_location)
    {
    case Location::External:
    case Location::Creation:
    case Location::ECRecover:
    case Location::SHA256:
    case Location::RIPEMD160:
    case Location::Bare:
    case Location::BareCallCode:
    {
        MemberList::MemberMap members{
            {
                "value",
                make_shared<FunctionType>(
                    parseElementaryTypeVector({"uint"}),
                    TypePointers{copyAndSetGasOrValue(false, true)},
                    strings(),
                    strings(),
                    Location::SetValue,
                    false,
                    nullptr,
                    m_gasSet,
                    m_valueSet
                )
            }
        };
        if (m_location != Location::Creation)
            members.push_back(
                MemberList::Member(
                    "gas",
                    make_shared<FunctionType>(
                        parseElementaryTypeVector({"uint"}),
                        TypePointers{copyAndSetGasOrValue(true, false)},
                        strings(),
                        strings(),
                        Location::SetGas,
                        false,
                        nullptr,
                        m_gasSet,
                        m_valueSet
                    )
                )
            );
        return members;
    }
    default:
        return MemberList::MemberMap();
    }
}

bool FunctionType::canTakeArguments(TypePointers const& _argumentTypes, TypePointer const& _selfType) const
{
    solAssert(!bound() || _selfType, "");
    if (bound() && !_selfType->isImplicitlyConvertibleTo(*selfType()))
        return false;
    TypePointers paramTypes = parameterTypes();
    if (takesArbitraryParameters())
        return true;
    else if (_argumentTypes.size() != paramTypes.size())
        return false;
    else
        return equal(
            _argumentTypes.cbegin(),
            _argumentTypes.cend(),
            paramTypes.cbegin(),
            [](TypePointer const& argumentType, TypePointer const& parameterType)
            {
                return argumentType->isImplicitlyConvertibleTo(*parameterType);
            }
        );
}

bool FunctionType::hasEqualArgumentTypes(FunctionType const& _other) const
{
    if (m_parameterTypes.size() != _other.m_parameterTypes.size())
        return false;
    return equal(
        m_parameterTypes.cbegin(),
        m_parameterTypes.cend(),
        _other.m_parameterTypes.cbegin(),
        [](TypePointer const& _a, TypePointer const& _b) -> bool { return *_a == *_b; }
    );
}

bool FunctionType::isBareCall() const
{
    switch (m_location)
    {
    case Location::Bare:
    case Location::BareCallCode:
    case Location::ECRecover:
    case Location::SHA256:
    case Location::RIPEMD160:
        return true;
    default:
        return false;
    }
}

string FunctionType::externalSignature() const
{
    solAssert(m_declaration != nullptr, "External signature of function needs declaration");

    bool _inLibrary = dynamic_cast<ContractDefinition const&>(*m_declaration->scope()).isLibrary();

    string ret = m_declaration->name() + "(";

    FunctionTypePointer external = interfaceFunctionType();
    solAssert(!!external, "External function type requested.");
    TypePointers externalParameterTypes = external->parameterTypes();
    for (auto it = externalParameterTypes.cbegin(); it != externalParameterTypes.cend(); ++it)
    {
        solAssert(!!(*it), "Parameter should have external type");
        ret += (*it)->canonicalName(_inLibrary) + (it + 1 == externalParameterTypes.cend() ? "" : ",");
    }

    return ret + ")";
}

u256 FunctionType::externalIdentifier() const
{
    return FixedHash<4>::Arith(FixedHash<4>(dev::sha3(externalSignature())));
}

TypePointers FunctionType::parseElementaryTypeVector(strings const& _types)
{
    TypePointers pointers;
    pointers.reserve(_types.size());
    for (string const& type: _types)
        pointers.push_back(Type::fromElementaryTypeName(type));
    return pointers;
}

TypePointer FunctionType::copyAndSetGasOrValue(bool _setGas, bool _setValue) const
{
    return make_shared<FunctionType>(
        m_parameterTypes,
        m_returnParameterTypes,
        m_parameterNames,
        m_returnParameterNames,
        m_location,
        m_arbitraryParameters,
        m_declaration,
        m_gasSet || _setGas,
        m_valueSet || _setValue,
        m_bound
    );
}

FunctionTypePointer FunctionType::asMemberFunction(bool _inLibrary, bool _bound) const
{
    TypePointers parameterTypes;
    for (auto const& t: m_parameterTypes)
    {
        auto refType = dynamic_cast<ReferenceType const*>(t.get());
        if (refType && refType->location() == DataLocation::CallData)
            parameterTypes.push_back(refType->copyForLocation(DataLocation::Memory, false));
        else
            parameterTypes.push_back(t);
    }

    // Removes dynamic types.
    TypePointers returnParameterTypes;
    vector<string> returnParameterNames;
    for (size_t i = 0; i < m_returnParameterTypes.size(); ++i)
        if (!m_returnParameterTypes[i]->isDynamicallySized())
        {
            returnParameterTypes.push_back(m_returnParameterTypes[i]);
            returnParameterNames.push_back(m_returnParameterNames[i]);
        }
    return make_shared<FunctionType>(
        parameterTypes,
        returnParameterTypes,
        m_parameterNames,
        returnParameterNames,
        _inLibrary ? Location::CallCode : m_location,
        m_arbitraryParameters,
        m_declaration,
        m_gasSet,
        m_valueSet,
        _bound
    );
}

vector<string> const FunctionType::parameterTypeNames(bool _addDataLocation) const
{
    vector<string> names;
    for (TypePointer const& t: parameterTypes())
        names.push_back(t->canonicalName(_addDataLocation));

    return names;
}

vector<string> const FunctionType::returnParameterTypeNames(bool _addDataLocation) const
{
    vector<string> names;
    for (TypePointer const& t: m_returnParameterTypes)
        names.push_back(t->canonicalName(_addDataLocation));

    return names;
}

TypePointer FunctionType::selfType() const
{
    solAssert(bound(), "");
    return m_parameterTypes.at(0);
}

ASTPointer<ASTString> FunctionType::documentation() const
{
    auto function = dynamic_cast<Documented const*>(m_declaration);
    if (function)
        return function->documentation();

    return ASTPointer<ASTString>();
}

bool MappingType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    MappingType const& other = dynamic_cast<MappingType const&>(_other);
    return *other.m_keyType == *m_keyType && *other.m_valueType == *m_valueType;
}

string MappingType::toString(bool _short) const
{
    return "mapping(" + keyType()->toString(_short) + " => " + valueType()->toString(_short) + ")";
}

string MappingType::canonicalName(bool) const
{
    return "mapping(" + keyType()->canonicalName(false) + " => " + valueType()->canonicalName(false) + ")";
}

bool TypeType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    TypeType const& other = dynamic_cast<TypeType const&>(_other);
    return *actualType() == *other.actualType();
}

u256 TypeType::storageSize() const
{
    BOOST_THROW_EXCEPTION(
        InternalCompilerError()
            << errinfo_comment("Storage size of non-storable type type requested."));
}

unsigned TypeType::sizeOnStack() const
{
    if (auto contractType = dynamic_cast<ContractType const*>(m_actualType.get()))
        if (contractType->contractDefinition().isLibrary())
            return 1;
    return 0;
}

MemberList::MemberMap TypeType::nativeMembers(ContractDefinition const* _currentScope) const
{
    MemberList::MemberMap members;
    if (m_actualType->category() == Category::Contract)
    {
        ContractDefinition const& contract = dynamic_cast<ContractType const&>(*m_actualType).contractDefinition();
        bool isBase = false;
        if (_currentScope != nullptr)
        {
            auto const& currentBases = _currentScope->annotation().linearizedBaseContracts;
            isBase = (find(currentBases.begin(), currentBases.end(), &contract) != currentBases.end());
        }
        if (contract.isLibrary())
            for (auto const& it: contract.interfaceFunctions())
                members.push_back(MemberList::Member(
                    it.second->declaration().name(),
                    it.second->asMemberFunction(true), // use callcode
                    &it.second->declaration()
                ));
        if (isBase)
        {
            // We are accessing the type of a base contract, so add all public and protected
            // members. Note that this does not add inherited functions on purpose.
            for (Declaration const* decl: contract.inheritableMembers())
                members.push_back(MemberList::Member(decl->name(), decl->type(), decl));
        }
        else
        {
            for (auto const& stru: contract.definedStructs())
                members.push_back(MemberList::Member(stru->name(), stru->type(), stru));
            for (auto const& enu: contract.definedEnums())
                members.push_back(MemberList::Member(enu->name(), enu->type(), enu));
        }
    }
    else if (m_actualType->category() == Category::Enum)
    {
        EnumDefinition const& enumDef = dynamic_cast<EnumType const&>(*m_actualType).enumDefinition();
        auto enumType = make_shared<EnumType>(enumDef);
        for (ASTPointer<EnumValue> const& enumValue: enumDef.members())
            members.push_back(MemberList::Member(enumValue->name(), enumType));
    }
    return members;
}

ModifierType::ModifierType(const ModifierDefinition& _modifier)
{
    TypePointers params;
    params.reserve(_modifier.parameters().size());
    for (ASTPointer<VariableDeclaration> const& var: _modifier.parameters())
        params.push_back(var->annotation().type);
    swap(params, m_parameterTypes);
}

u256 ModifierType::storageSize() const
{
    BOOST_THROW_EXCEPTION(
        InternalCompilerError()
            << errinfo_comment("Storage size of non-storable type type requested."));
}

bool ModifierType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    ModifierType const& other = dynamic_cast<ModifierType const&>(_other);

    if (m_parameterTypes.size() != other.m_parameterTypes.size())
        return false;
    auto typeCompare = [](TypePointer const& _a, TypePointer const& _b) -> bool { return *_a == *_b; };

    if (!equal(m_parameterTypes.cbegin(), m_parameterTypes.cend(),
               other.m_parameterTypes.cbegin(), typeCompare))
        return false;
    return true;
}

string ModifierType::toString(bool _short) const
{
    string name = "modifier (";
    for (auto it = m_parameterTypes.begin(); it != m_parameterTypes.end(); ++it)
        name += (*it)->toString(_short) + (it + 1 == m_parameterTypes.end() ? "" : ",");
    return name + ")";
}

bool ModuleType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    return &m_sourceUnit == &dynamic_cast<ModuleType const&>(_other).m_sourceUnit;
}

MemberList::MemberMap ModuleType::nativeMembers(ContractDefinition const*) const
{
    MemberList::MemberMap symbols;
    for (auto const& symbolName: m_sourceUnit.annotation().exportedSymbols)
        for (Declaration const* symbol: symbolName.second)
            symbols.push_back(MemberList::Member(symbolName.first, symbol->type(), symbol));
    return symbols;
}

string ModuleType::toString(bool) const
{
    return string("module \"") + m_sourceUnit.annotation().path + string("\"");
}

bool MagicType::operator==(Type const& _other) const
{
    if (_other.category() != category())
        return false;
    MagicType const& other = dynamic_cast<MagicType const&>(_other);
    return other.m_kind == m_kind;
}

MemberList::MemberMap MagicType::nativeMembers(ContractDefinition const*) const
{
    switch (m_kind)
    {
    case Kind::Block:
        return MemberList::MemberMap({
            {"coinbase", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
            {"timestamp", make_shared<IntegerType>(256)},
            {"blockhash", make_shared<FunctionType>(strings{"uint"}, strings{"bytes32"}, FunctionType::Location::BlockHash)},
            {"difficulty", make_shared<IntegerType>(256)},
            {"number", make_shared<IntegerType>(256)},
            {"gaslimit", make_shared<IntegerType>(256)}
        });
    case Kind::Message:
        return MemberList::MemberMap({
            {"sender", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
            {"gas", make_shared<IntegerType>(256)},
            {"value", make_shared<IntegerType>(256)},
            {"data", make_shared<ArrayType>(DataLocation::CallData)},
            {"sig", make_shared<FixedBytesType>(4)}
        });
    case Kind::Transaction:
        return MemberList::MemberMap({
            {"origin", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
            {"gasprice", make_shared<IntegerType>(256)}
        });
    default:
        BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown kind of magic."));
    }
}

string MagicType::toString(bool) const
{
    switch (m_kind)
    {
    case Kind::Block:
        return "block";
    case Kind::Message:
        return "msg";
    case Kind::Transaction:
        return "tx";
    default:
        BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown kind of magic."));
    }
}