path: root/libsolidity/analysis/ContractLevelChecker.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/>.
*/
/**
 * Component that verifies overloads, abstract contracts, function clashes and others
 * checks at contract or function level.
 */

#include <libsolidity/analysis/ContractLevelChecker.h>
#include <libsolidity/ast/AST.h>

#include <liblangutil/ErrorReporter.h>

#include <boost/range/adaptor/reversed.hpp>


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


bool ContractLevelChecker::check(ContractDefinition const& _contract)
{
    checkDuplicateFunctions(_contract);
    checkDuplicateEvents(_contract);
    checkIllegalOverrides(_contract);
    checkAbstractFunctions(_contract);
    checkBaseConstructorArguments(_contract);
    checkConstructor(_contract);
    checkFallbackFunction(_contract);
    checkExternalTypeClashes(_contract);
    checkHashCollisions(_contract);
    checkLibraryRequirements(_contract);

    return Error::containsOnlyWarnings(m_errorReporter.errors());
}

void ContractLevelChecker::checkDuplicateFunctions(ContractDefinition const& _contract)
{
    /// Checks that two functions with the same name defined in this contract have different
    /// argument types and that there is at most one constructor.
    map<string, vector<FunctionDefinition const*>> functions;
    FunctionDefinition const* constructor = nullptr;
    FunctionDefinition const* fallback = nullptr;
    for (FunctionDefinition const* function: _contract.definedFunctions())
        if (function->isConstructor())
        {
            if (constructor)
                m_errorReporter.declarationError(
                    function->location(),
                    SecondarySourceLocation().append("Another declaration is here:", constructor->location()),
                    "More than one constructor defined."
                );
            constructor = function;
        }
        else if (function->isFallback())
        {
            if (fallback)
                m_errorReporter.declarationError(
                    function->location(),
                    SecondarySourceLocation().append("Another declaration is here:", fallback->location()),
                    "Only one fallback function is allowed."
                );
            fallback = function;
        }
        else
        {
            solAssert(!function->name().empty(), "");
            functions[function->name()].push_back(function);
        }

    findDuplicateDefinitions(functions, "Function with same name and arguments defined twice.");
}

void ContractLevelChecker::checkDuplicateEvents(ContractDefinition const& _contract)
{
    /// Checks that two events with the same name defined in this contract have different
    /// argument types
    map<string, vector<EventDefinition const*>> events;
    for (EventDefinition const* event: _contract.events())
        events[event->name()].push_back(event);

    findDuplicateDefinitions(events, "Event with same name and arguments defined twice.");
}

template <class T>
void ContractLevelChecker::findDuplicateDefinitions(map<string, vector<T>> const& _definitions, string _message)
{
    for (auto const& it: _definitions)
    {
        vector<T> const& overloads = it.second;
        set<size_t> reported;
        for (size_t i = 0; i < overloads.size() && !reported.count(i); ++i)
        {
            SecondarySourceLocation ssl;

            for (size_t j = i + 1; j < overloads.size(); ++j)
                if (FunctionType(*overloads[i]).asCallableFunction(false)->hasEqualParameterTypes(
                    *FunctionType(*overloads[j]).asCallableFunction(false))
                )
                {
                    ssl.append("Other declaration is here:", overloads[j]->location());
                    reported.insert(j);
                }

            if (ssl.infos.size() > 0)
            {
                ssl.limitSize(_message);

                m_errorReporter.declarationError(
                    overloads[i]->location(),
                    ssl,
                    _message
                );
            }
        }
    }
}

void ContractLevelChecker::checkIllegalOverrides(ContractDefinition const& _contract)
{
    // TODO unify this at a later point. for this we need to put the constness and the access specifier
    // into the types
    map<string, vector<FunctionDefinition const*>> functions;
    map<string, ModifierDefinition const*> modifiers;

    // We search from derived to base, so the stored item causes the error.
    for (ContractDefinition const* contract: _contract.annotation().linearizedBaseContracts)
    {
        for (FunctionDefinition const* function: contract->definedFunctions())
        {
            if (function->isConstructor())
                continue; // constructors can neither be overridden nor override anything
            string const& name = function->name();
            if (modifiers.count(name))
                m_errorReporter.typeError(modifiers[name]->location(), "Override changes function to modifier.");

            for (FunctionDefinition const* overriding: functions[name])
                checkFunctionOverride(*overriding, *function);

            functions[name].push_back(function);
        }
        for (ModifierDefinition const* modifier: contract->functionModifiers())
        {
            string const& name = modifier->name();
            ModifierDefinition const*& override = modifiers[name];
            if (!override)
                override = modifier;
            else if (ModifierType(*override) != ModifierType(*modifier))
                m_errorReporter.typeError(override->location(), "Override changes modifier signature.");
            if (!functions[name].empty())
                m_errorReporter.typeError(override->location(), "Override changes modifier to function.");
        }
    }
}

void ContractLevelChecker::checkFunctionOverride(FunctionDefinition const& _function, FunctionDefinition const& _super)
{
    FunctionTypePointer functionType = FunctionType(_function).asCallableFunction(false);
    FunctionTypePointer superType = FunctionType(_super).asCallableFunction(false);

    if (!functionType->hasEqualParameterTypes(*superType))
        return;
    if (!functionType->hasEqualReturnTypes(*superType))
        overrideError(_function, _super, "Overriding function return types differ.");

    if (!_function.annotation().superFunction)
        _function.annotation().superFunction = &_super;

    if (_function.visibility() != _super.visibility())
    {
        // Visibility change from external to public is fine.
        // Any other change is disallowed.
        if (!(
            _super.visibility() == FunctionDefinition::Visibility::External &&
            _function.visibility() == FunctionDefinition::Visibility::Public
        ))
            overrideError(_function, _super, "Overriding function visibility differs.");
    }
    if (_function.stateMutability() != _super.stateMutability())
        overrideError(
            _function,
            _super,
            "Overriding function changes state mutability from \"" +
            stateMutabilityToString(_super.stateMutability()) +
            "\" to \"" +
            stateMutabilityToString(_function.stateMutability()) +
            "\"."
        );
}

void ContractLevelChecker::overrideError(FunctionDefinition const& function, FunctionDefinition const& super, string message)
{
    m_errorReporter.typeError(
        function.location(),
        SecondarySourceLocation().append("Overridden function is here:", super.location()),
        message
    );
}

void ContractLevelChecker::checkAbstractFunctions(ContractDefinition const& _contract)
{
    // Mapping from name to function definition (exactly one per argument type equality class) and
    // flag to indicate whether it is fully implemented.
    using FunTypeAndFlag = std::pair<FunctionTypePointer, bool>;
    map<string, vector<FunTypeAndFlag>> functions;

    auto registerFunction = [&](Declaration const& _declaration, FunctionTypePointer const& _type, bool _implemented)
    {
        auto& overloads = functions[_declaration.name()];
        auto it = find_if(overloads.begin(), overloads.end(), [&](FunTypeAndFlag const& _funAndFlag)
        {
            return _type->hasEqualParameterTypes(*_funAndFlag.first);
        });
        if (it == overloads.end())
            overloads.push_back(make_pair(_type, _implemented));
        else if (it->second)
        {
            if (!_implemented)
                m_errorReporter.typeError(_declaration.location(), "Redeclaring an already implemented function as abstract");
        }
        else if (_implemented)
            it->second = true;
    };

    // Search from base to derived, collect all functions and update
    // the 'implemented' flag.
    for (ContractDefinition const* contract: boost::adaptors::reverse(_contract.annotation().linearizedBaseContracts))
    {
        for (VariableDeclaration const* v: contract->stateVariables())
            if (v->isPartOfExternalInterface())
                registerFunction(*v, make_shared<FunctionType>(*v), true);

        for (FunctionDefinition const* function: contract->definedFunctions())
            if (!function->isConstructor())
                registerFunction(
                    *function,
                    make_shared<FunctionType>(*function)->asCallableFunction(false),
                    function->isImplemented()
                );
    }

    // Set to not fully implemented if at least one flag is false.
    for (auto const& it: functions)
        for (auto const& funAndFlag: it.second)
            if (!funAndFlag.second)
            {
                FunctionDefinition const* function = dynamic_cast<FunctionDefinition const*>(&funAndFlag.first->declaration());
                solAssert(function, "");
                _contract.annotation().unimplementedFunctions.push_back(function);
                break;
            }
}


void ContractLevelChecker::checkBaseConstructorArguments(ContractDefinition const& _contract)
{
    vector<ContractDefinition const*> const& bases = _contract.annotation().linearizedBaseContracts;

    // Determine the arguments that are used for the base constructors.
    for (ContractDefinition const* contract: bases)
    {
        if (FunctionDefinition const* constructor = contract->constructor())
            for (auto const& modifier: constructor->modifiers())
                if (auto baseContract = dynamic_cast<ContractDefinition const*>(
                    modifier->name()->annotation().referencedDeclaration
                ))
                {
                    if (modifier->arguments())
                    {
                        if (baseContract->constructor())
                            annotateBaseConstructorArguments(_contract, baseContract->constructor(), modifier.get());
                    }
                    else
                        m_errorReporter.declarationError(
                            modifier->location(),
                            "Modifier-style base constructor call without arguments."
                        );
                }

        for (ASTPointer<InheritanceSpecifier> const& base: contract->baseContracts())
        {
            ContractDefinition const* baseContract = dynamic_cast<ContractDefinition const*>(
                base->name().annotation().referencedDeclaration
            );
            solAssert(baseContract, "");

            if (baseContract->constructor() && base->arguments() && !base->arguments()->empty())
                annotateBaseConstructorArguments(_contract, baseContract->constructor(), base.get());
        }
    }

    // check that we get arguments for all base constructors that need it.
    // If not mark the contract as abstract (not fully implemented)
    for (ContractDefinition const* contract: bases)
        if (FunctionDefinition const* constructor = contract->constructor())
            if (contract != &_contract && !constructor->parameters().empty())
                if (!_contract.annotation().baseConstructorArguments.count(constructor))
                    _contract.annotation().unimplementedFunctions.push_back(constructor);
}

void ContractLevelChecker::annotateBaseConstructorArguments(
    ContractDefinition const& _currentContract,
    FunctionDefinition const* _baseConstructor,
    ASTNode const* _argumentNode
)
{
    solAssert(_baseConstructor, "");
    solAssert(_argumentNode, "");

    auto insertionResult = _currentContract.annotation().baseConstructorArguments.insert(
        std::make_pair(_baseConstructor, _argumentNode)
    );
    if (!insertionResult.second)
    {
        ASTNode const* previousNode = insertionResult.first->second;

        SourceLocation const* mainLocation = nullptr;
        SecondarySourceLocation ssl;

        if (
            _currentContract.location().contains(previousNode->location()) ||
            _currentContract.location().contains(_argumentNode->location())
        )
        {
            mainLocation = &previousNode->location();
            ssl.append("Second constructor call is here:", _argumentNode->location());
        }
        else
        {
            mainLocation = &_currentContract.location();
            ssl.append("First constructor call is here: ", _argumentNode->location());
            ssl.append("Second constructor call is here: ", previousNode->location());
        }

        m_errorReporter.declarationError(
            *mainLocation,
            ssl,
            "Base constructor arguments given twice."
        );
    }

}

void ContractLevelChecker::checkConstructor(ContractDefinition const& _contract)
{
    FunctionDefinition const* constructor = _contract.constructor();
    if (!constructor)
        return;

    if (!constructor->returnParameters().empty())
        m_errorReporter.typeError(constructor->returnParameterList()->location(), "Non-empty \"returns\" directive for constructor.");
    if (constructor->stateMutability() != StateMutability::NonPayable && constructor->stateMutability() != StateMutability::Payable)
        m_errorReporter.typeError(
            constructor->location(),
            "Constructor must be payable or non-payable, but is \"" +
            stateMutabilityToString(constructor->stateMutability()) +
            "\"."
        );
    if (constructor->visibility() != FunctionDefinition::Visibility::Public && constructor->visibility() != FunctionDefinition::Visibility::Internal)
        m_errorReporter.typeError(constructor->location(), "Constructor must be public or internal.");
}

void ContractLevelChecker::checkFallbackFunction(ContractDefinition const& _contract)
{
    FunctionDefinition const* fallback = _contract.fallbackFunction();
    if (!fallback)
        return;

    if (_contract.isLibrary())
        m_errorReporter.typeError(fallback->location(), "Libraries cannot have fallback functions.");
    if (fallback->stateMutability() != StateMutability::NonPayable && fallback->stateMutability() != StateMutability::Payable)
        m_errorReporter.typeError(
            fallback->location(),
            "Fallback function must be payable or non-payable, but is \"" +
            stateMutabilityToString(fallback->stateMutability()) +
            "\"."
    );
    if (!fallback->parameters().empty())
        m_errorReporter.typeError(fallback->parameterList().location(), "Fallback function cannot take parameters.");
    if (!fallback->returnParameters().empty())
        m_errorReporter.typeError(fallback->returnParameterList()->location(), "Fallback function cannot return values.");
    if (fallback->visibility() != FunctionDefinition::Visibility::External)
        m_errorReporter.typeError(fallback->location(), "Fallback function must be defined as \"external\".");
}

void ContractLevelChecker::checkExternalTypeClashes(ContractDefinition const& _contract)
{
    map<string, vector<pair<Declaration const*, FunctionTypePointer>>> externalDeclarations;
    for (ContractDefinition const* contract: _contract.annotation().linearizedBaseContracts)
    {
        for (FunctionDefinition const* f: contract->definedFunctions())
            if (f->isPartOfExternalInterface())
            {
                auto functionType = make_shared<FunctionType>(*f);
                // under non error circumstances this should be true
                if (functionType->interfaceFunctionType())
                    externalDeclarations[functionType->externalSignature()].push_back(
                        make_pair(f, functionType->asCallableFunction(false))
                    );
            }
        for (VariableDeclaration const* v: contract->stateVariables())
            if (v->isPartOfExternalInterface())
            {
                auto functionType = make_shared<FunctionType>(*v);
                // under non error circumstances this should be true
                if (functionType->interfaceFunctionType())
                    externalDeclarations[functionType->externalSignature()].push_back(
                        make_pair(v, functionType->asCallableFunction(false))
                    );
            }
    }
    for (auto const& it: externalDeclarations)
        for (size_t i = 0; i < it.second.size(); ++i)
            for (size_t j = i + 1; j < it.second.size(); ++j)
                if (!it.second[i].second->hasEqualParameterTypes(*it.second[j].second))
                    m_errorReporter.typeError(
                        it.second[j].first->location(),
                        "Function overload clash during conversion to external types for arguments."
                    );
}

void ContractLevelChecker::checkHashCollisions(ContractDefinition const& _contract)
{
    set<FixedHash<4>> hashes;
    for (auto const& it: _contract.interfaceFunctionList())
    {
        FixedHash<4> const& hash = it.first;
        if (hashes.count(hash))
            m_errorReporter.typeError(
                _contract.location(),
                string("Function signature hash collision for ") + it.second->externalSignature()
            );
        hashes.insert(hash);
    }
}

void ContractLevelChecker::checkLibraryRequirements(ContractDefinition const& _contract)
{
    if (!_contract.isLibrary())
        return;

    if (!_contract.baseContracts().empty())
        m_errorReporter.typeError(_contract.location(), "Library is not allowed to inherit.");

    for (auto const& var: _contract.stateVariables())
        if (!var->isConstant())
            m_errorReporter.typeError(var->location(), "Library cannot have non-constant state variables");
}