path: root/libsolidity/analysis/StaticAnalyzer.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 Federico Bond <federicobond@gmail.com>
 * @date 2016
 * Static analyzer and checker.
 */

#include <libsolidity/analysis/StaticAnalyzer.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/interface/ErrorReporter.h>
#include <memory>

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

bool StaticAnalyzer::analyze(SourceUnit const& _sourceUnit)
{
    _sourceUnit.accept(*this);
    return Error::containsOnlyWarnings(m_errorReporter.errors());
}

bool StaticAnalyzer::visit(ContractDefinition const& _contract)
{
    m_library = _contract.isLibrary();
    return true;
}

void StaticAnalyzer::endVisit(ContractDefinition const&)
{
    m_library = false;
}

bool StaticAnalyzer::visit(FunctionDefinition const& _function)
{
    if (_function.isImplemented())
        m_currentFunction = &_function;
    else
        solAssert(!m_currentFunction, "");
    solAssert(m_localVarUseCount.empty(), "");
    m_nonPayablePublic = _function.isPublic() && !_function.isPayable();
    return true;
}

void StaticAnalyzer::endVisit(FunctionDefinition const&)
{
    m_currentFunction = nullptr;
    m_nonPayablePublic = false;
    for (auto const& var: m_localVarUseCount)
        if (var.second == 0)
            m_errorReporter.warning(var.first->location(), "Unused local variable");
    m_localVarUseCount.clear();
}

bool StaticAnalyzer::visit(Identifier const& _identifier)
{
    if (m_currentFunction)
        if (auto var = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration))
        {
            solAssert(!var->name().empty(), "");
            if (var->isLocalVariable())
                m_localVarUseCount[var] += 1;
        }
    return true;
}

bool StaticAnalyzer::visit(VariableDeclaration const& _variable)
{
    if (m_currentFunction)
    {
        solAssert(_variable.isLocalVariable(), "");
        if (_variable.name() != "")
            // This is not a no-op, the entry might pre-exist.
            m_localVarUseCount[&_variable] += 0;
    }
    return true;
}

bool StaticAnalyzer::visit(Return const& _return)
{
    // If the return has an expression, it counts as
    // a "use" of the return parameters.
    if (m_currentFunction && _return.expression())
        for (auto const& var: m_currentFunction->returnParameters())
            if (!var->name().empty())
                m_localVarUseCount[var.get()] += 1;
    return true;
}

bool StaticAnalyzer::visit(ExpressionStatement const& _statement)
{
    if (_statement.expression().annotation().isPure)
        m_errorReporter.warning(
            _statement.location(),
            "Statement has no effect."
        );

    return true;
}

bool StaticAnalyzer::visit(MemberAccess const& _memberAccess)
{
    if (m_nonPayablePublic && !m_library)
        if (MagicType const* type = dynamic_cast<MagicType const*>(_memberAccess.expression().annotation().type.get()))
            if (type->kind() == MagicType::Kind::Message && _memberAccess.memberName() == "value")
                m_errorReporter.warning(
                    _memberAccess.location(),
                    "\"msg.value\" used in non-payable function. Do you want to add the \"payable\" modifier to this function?"
                );

    if (_memberAccess.memberName() == "callcode")
        if (auto const* type = dynamic_cast<FunctionType const*>(_memberAccess.annotation().type.get()))
            if (type->kind() == FunctionType::Kind::BareCallCode)
                m_errorReporter.warning(
                    _memberAccess.location(),
                    "\"callcode\" has been deprecated in favour of \"delegatecall\"."
                );

    return true;
}

bool StaticAnalyzer::visit(InlineAssembly const& _inlineAssembly)
{
    if (!m_currentFunction)
        return true;

    for (auto const& ref: _inlineAssembly.annotation().externalReferences)
    {
        if (auto var = dynamic_cast<VariableDeclaration const*>(ref.second.declaration))
        {
            solAssert(!var->name().empty(), "");
            if (var->isLocalVariable())
                m_localVarUseCount[var] += 1;
        }
    }

    return true;
}