path: root/libsolidity/analysis/ReferencesResolver.cpp

/*
    This file is part of solidity.

    solidity 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.

    solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Component that resolves type names to types and annotates the AST accordingly.
 */

#include <libsolidity/analysis/ReferencesResolver.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/analysis/NameAndTypeResolver.h>
#include <libsolidity/interface/Exceptions.h>
#include <libsolidity/analysis/ConstantEvaluator.h>
#include <libsolidity/inlineasm/AsmAnalysis.h>
#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libsolidity/interface/ErrorReporter.h>

#include <boost/algorithm/string.hpp>

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


bool ReferencesResolver::resolve(ASTNode const& _root)
{
    _root.accept(*this);
    return !m_errorOccurred;
}

bool ReferencesResolver::visit(Identifier const& _identifier)
{
    auto declarations = m_resolver.nameFromCurrentScope(_identifier.name());
    if (declarations.empty())
        declarationError(_identifier.location(), "Undeclared identifier.");
    else if (declarations.size() == 1)
        _identifier.annotation().referencedDeclaration = declarations.front();
    else
        _identifier.annotation().overloadedDeclarations =
            m_resolver.cleanedDeclarations(_identifier, declarations);
    return false;
}

bool ReferencesResolver::visit(ElementaryTypeName const& _typeName)
{
    _typeName.annotation().type = Type::fromElementaryTypeName(_typeName.typeName());
    return true;
}

bool ReferencesResolver::visit(FunctionDefinition const& _functionDefinition)
{
    m_returnParameters.push_back(_functionDefinition.returnParameterList().get());
    return true;
}

void ReferencesResolver::endVisit(FunctionDefinition const&)
{
    solAssert(!m_returnParameters.empty(), "");
    m_returnParameters.pop_back();
}

bool ReferencesResolver::visit(ModifierDefinition const&)
{
    m_returnParameters.push_back(nullptr);
    return true;
}

void ReferencesResolver::endVisit(ModifierDefinition const&)
{
    solAssert(!m_returnParameters.empty(), "");
    m_returnParameters.pop_back();
}

void ReferencesResolver::endVisit(UserDefinedTypeName const& _typeName)
{
    Declaration const* declaration = m_resolver.pathFromCurrentScope(_typeName.namePath());
    if (!declaration)
    {
        declarationError(_typeName.location(), "Identifier not found or not unique.");
        return;
    }

    _typeName.annotation().referencedDeclaration = declaration;

    if (StructDefinition const* structDef = dynamic_cast<StructDefinition const*>(declaration))
        _typeName.annotation().type = make_shared<StructType>(*structDef);
    else if (EnumDefinition const* enumDef = dynamic_cast<EnumDefinition const*>(declaration))
        _typeName.annotation().type = make_shared<EnumType>(*enumDef);
    else if (ContractDefinition const* contract = dynamic_cast<ContractDefinition const*>(declaration))
        _typeName.annotation().type = make_shared<ContractType>(*contract);
    else
        typeError(_typeName.location(), "Name has to refer to a struct, enum or contract.");
}

void ReferencesResolver::endVisit(FunctionTypeName const& _typeName)
{
    switch (_typeName.visibility())
    {
    case VariableDeclaration::Visibility::Internal:
    case VariableDeclaration::Visibility::External:
        break;
    default:
        typeError(_typeName.location(), "Invalid visibility, can only be \"external\" or \"internal\".");
        return;
    }

    if (_typeName.isPayable() && _typeName.visibility() != VariableDeclaration::Visibility::External)
    {
        typeError(_typeName.location(), "Only external function types can be payable.");
        return;
    }

    if (_typeName.visibility() == VariableDeclaration::Visibility::External)
        for (auto const& t: _typeName.parameterTypes() + _typeName.returnParameterTypes())
        {
            solAssert(t->annotation().type, "Type not set for parameter.");
            if (!t->annotation().type->canBeUsedExternally(false))
            {
                typeError(t->location(), "Internal type cannot be used for external function type.");
                return;
            }
        }

    _typeName.annotation().type = make_shared<FunctionType>(_typeName);
}

void ReferencesResolver::endVisit(Mapping const& _typeName)
{
    TypePointer keyType = _typeName.keyType().annotation().type;
    TypePointer valueType = _typeName.valueType().annotation().type;
    // Convert key type to memory.
    keyType = ReferenceType::copyForLocationIfReference(DataLocation::Memory, keyType);
    // Convert value type to storage reference.
    valueType = ReferenceType::copyForLocationIfReference(DataLocation::Storage, valueType);
    _typeName.annotation().type = make_shared<MappingType>(keyType, valueType);
}

void ReferencesResolver::endVisit(ArrayTypeName const& _typeName)
{
    TypePointer baseType = _typeName.baseType().annotation().type;
    if (baseType->storageBytes() == 0)
        fatalTypeError(_typeName.baseType().location(), "Illegal base type of storage size zero for array.");
    if (Expression const* length = _typeName.length())
    {
        TypePointer lengthTypeGeneric = length->annotation().type;
        if (!lengthTypeGeneric)
            lengthTypeGeneric = ConstantEvaluator(m_errorReporter).evaluate(*length);
        RationalNumberType const* lengthType = dynamic_cast<RationalNumberType const*>(lengthTypeGeneric.get());
        if (!lengthType || !lengthType->mobileType())
            fatalTypeError(length->location(), "Invalid array length, expected integer literal or constant expression.");
        else if (lengthType->isFractional())
            fatalTypeError(length->location(), "Array with fractional length specified.");
        else if (lengthType->isNegative())
            fatalTypeError(length->location(), "Array with negative length specified.");
        else
            _typeName.annotation().type = make_shared<ArrayType>(DataLocation::Storage, baseType, lengthType->literalValue(nullptr));
    }
    else
        _typeName.annotation().type = make_shared<ArrayType>(DataLocation::Storage, baseType);
}

bool ReferencesResolver::visit(InlineAssembly const& _inlineAssembly)
{
    m_resolver.warnVariablesNamedLikeInstructions();

    // Errors created in this stage are completely ignored because we do not yet know
    // the type and size of external identifiers, which would result in false errors.
    // The only purpose of this step is to fill the inline assembly annotation with
    // external references.
    ErrorList errors;
    ErrorReporter errorsIgnored(errors);
    julia::ExternalIdentifierAccess::Resolver resolver =
    [&](assembly::Identifier const& _identifier, julia::IdentifierContext, bool _crossesFunctionBoundary) {
        auto declarations = m_resolver.nameFromCurrentScope(_identifier.name);
        bool isSlot = boost::algorithm::ends_with(_identifier.name, "_slot");
        bool isOffset = boost::algorithm::ends_with(_identifier.name, "_offset");
        if (isSlot || isOffset)
        {
            // special mode to access storage variables
            if (!declarations.empty())
                // the special identifier exists itself, we should not allow that.
                return size_t(-1);
            string realName = _identifier.name.substr(0, _identifier.name.size() - (
                isSlot ?
                string("_slot").size() :
                string("_offset").size()
            ));
            declarations = m_resolver.nameFromCurrentScope(realName);
        }
        if (declarations.size() != 1)
            return size_t(-1);
        if (auto var = dynamic_cast<VariableDeclaration const*>(declarations.front()))
            if (var->isLocalVariable() && _crossesFunctionBoundary)
            {
                declarationError(_identifier.location, "Cannot access local Solidity variables from inside an inline assembly function.");
                return size_t(-1);
            }
        _inlineAssembly.annotation().externalReferences[&_identifier].isSlot = isSlot;
        _inlineAssembly.annotation().externalReferences[&_identifier].isOffset = isOffset;
        _inlineAssembly.annotation().externalReferences[&_identifier].declaration = declarations.front();
        return size_t(1);
    };

    // Will be re-generated later with correct information
    assembly::AsmAnalysisInfo analysisInfo;
    assembly::AsmAnalyzer(analysisInfo, errorsIgnored, assembly::AsmFlavour::Loose, resolver).analyze(_inlineAssembly.operations());
    return false;
}

bool ReferencesResolver::visit(Return const& _return)
{
    solAssert(!m_returnParameters.empty(), "");
    _return.annotation().functionReturnParameters = m_returnParameters.back();
    return true;
}

void ReferencesResolver::endVisit(VariableDeclaration const& _variable)
{
    if (_variable.annotation().type)
        return;

    TypePointer type;
    if (_variable.typeName())
    {
        type = _variable.typeName()->annotation().type;
        using Location = VariableDeclaration::Location;
        Location varLoc = _variable.referenceLocation();
        DataLocation typeLoc = DataLocation::Memory;
        // References are forced to calldata for external function parameters (not return)
        // and memory for parameters (also return) of publicly visible functions.
        // They default to memory for function parameters and storage for local variables.
        // As an exception, "storage" is allowed for library functions.
        if (auto ref = dynamic_cast<ReferenceType const*>(type.get()))
        {
            bool isPointer = true;
            if (_variable.isExternalCallableParameter())
            {
                auto const& contract = dynamic_cast<ContractDefinition const&>(
                    *dynamic_cast<Declaration const&>(*_variable.scope()).scope()
                );
                if (contract.isLibrary())
                {
                    if (varLoc == Location::Memory)
                        fatalTypeError(_variable.location(),
                            "Location has to be calldata or storage for external "
                            "library functions (remove the \"memory\" keyword)."
                        );
                }
                else
                {
                    // force location of external function parameters (not return) to calldata
                    if (varLoc != Location::Default)
                        fatalTypeError(_variable.location(),
                            "Location has to be calldata for external functions "
                            "(remove the \"memory\" or \"storage\" keyword)."
                        );
                }
                if (varLoc == Location::Default)
                    typeLoc = DataLocation::CallData;
                else
                    typeLoc = varLoc == Location::Memory ? DataLocation::Memory : DataLocation::Storage;
            }
            else if (_variable.isCallableParameter() && dynamic_cast<Declaration const&>(*_variable.scope()).isPublic())
            {
                auto const& contract = dynamic_cast<ContractDefinition const&>(
                    *dynamic_cast<Declaration const&>(*_variable.scope()).scope()
                );
                // force locations of public or external function (return) parameters to memory
                if (varLoc == Location::Storage && !contract.isLibrary())
                    fatalTypeError(_variable.location(),
                        "Location has to be memory for publicly visible functions "
                        "(remove the \"storage\" keyword)."
                    );
                if (varLoc == Location::Default || !contract.isLibrary())
                    typeLoc = DataLocation::Memory;
                else
                    typeLoc = varLoc == Location::Memory ? DataLocation::Memory : DataLocation::Storage;
            }
            else
            {
                if (_variable.isConstant())
                {
                    if (varLoc != Location::Default && varLoc != Location::Memory)
                        fatalTypeError(
                            _variable.location(),
                            "Storage location has to be \"memory\" (or unspecified) for constants."
                        );
                    typeLoc = DataLocation::Memory;
                }
                else if (varLoc == Location::Default)
                {
                    if (_variable.isCallableParameter())
                        typeLoc = DataLocation::Memory;
                    else
                    {
                        typeLoc = DataLocation::Storage;
                        if (_variable.isLocalVariable())
                        {
                            if (_variable.sourceUnit().annotation().experimentalFeatures.count(ExperimentalFeature::V050))
                                typeError(
                                    _variable.location(),
                                    "Storage location must be specified as either \"memory\" or \"storage\"."
                                );
                            else
                                m_errorReporter.warning(
                                    _variable.location(),
                                    "Variable is declared as a storage pointer. "
                                    "Use an explicit \"storage\" keyword to silence this warning."
                                );
                        }
                    }
                }
                else
                    typeLoc = varLoc == Location::Memory ? DataLocation::Memory : DataLocation::Storage;
                isPointer = !_variable.isStateVariable();
            }

            type = ref->copyForLocation(typeLoc, isPointer);
        }
        else if (varLoc != Location::Default && !ref)
            typeError(_variable.location(), "Storage location can only be given for array or struct types.");

        _variable.annotation().type = type;
    }
    else if (!_variable.canHaveAutoType())
        typeError(_variable.location(), "Explicit type needed.");
    // otherwise we have a "var"-declaration whose type is resolved by the first assignment
}

void ReferencesResolver::typeError(SourceLocation const& _location, string const& _description)
{
    m_errorOccurred = true;
    m_errorReporter.typeError(_location, _description);
}

void ReferencesResolver::fatalTypeError(SourceLocation const& _location, string const& _description)
{
    m_errorOccurred = true;
    m_errorReporter.fatalTypeError(_location, _description);
}

void ReferencesResolver::declarationError(SourceLocation const& _location, string const& _description)
{
    m_errorOccurred = true;
    m_errorReporter.declarationError(_location, _description);
}

void ReferencesResolver::fatalDeclarationError(SourceLocation const& _location, string const& _description)
{
    m_errorOccurred = true;
    m_errorReporter.fatalDeclarationError(_location, _description);
}