/src/solidity/libsolidity/analysis/OverrideChecker.cpp

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/*
  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/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
 * Component that verifies overloads, abstract contracts, function clashes and others
 * checks at contract or function level.
 */

#include <libsolidity/analysis/OverrideChecker.h>

#include <libsolidity/ast/AST.h>
#include <libsolidity/ast/TypeProvider.h>
#include <libsolidity/analysis/TypeChecker.h>
#include <liblangutil/ErrorReporter.h>
#include <libsolutil/Visitor.h>

#include <boost/algorithm/string/predicate.hpp>


using namespace solidity;
using namespace solidity::frontend;
using namespace solidity::langutil;

using solidity::util::GenericVisitor;
using solidity::util::contains_if;
using solidity::util::joinHumanReadable;

namespace
{

// Helper struct to do a search by name
struct MatchByName
{
  std::string const& m_name;
  bool operator()(OverrideProxy const& _item)
  {
    return _item.name() == m_name;
  }
};

/**
 * Construct the override graph for this signature.
 * Reserve node 0 for the current contract and node
 * 1 for an artificial top node to which all override paths
 * connect at the end.
 */
struct OverrideGraph
{
  OverrideGraph(std::set<OverrideProxy> const& _baseCallables)
  {
    for (auto const& baseFunction: _baseCallables)
      addEdge(0, visit(baseFunction));
  }
  std::map<OverrideProxy, int> nodes;
  std::map<int, OverrideProxy> nodeInv;
  std::map<int, std::set<int>> edges;
  size_t numNodes = 2;
  void addEdge(int _a, int _b)
  {
    edges[_a].insert(_b);
    edges[_b].insert(_a);
  }
private:
  /// Completes the graph starting from @a _function and
  /// @returns the node ID.
  int visit(OverrideProxy const& _function)
  {
    auto it = nodes.find(_function);
    if (it != nodes.end())
      return it->second;
    int currentNode = static_cast<int>(numNodes++);
    nodes[_function] = currentNode;
    nodeInv[currentNode] = _function;

    if (!_function.baseFunctions().empty())
      for (auto const& baseFunction: _function.baseFunctions())
        addEdge(currentNode, visit(baseFunction));
    else
      addEdge(currentNode, 1);

    return currentNode;
  }
};

/**
 * Detect cut vertices following https://en.wikipedia.org/wiki/Biconnected_component#Pseudocode
 * Can ignore the root node, since it is never a cut vertex in our case.
 */
struct CutVertexFinder
{
  CutVertexFinder(OverrideGraph const& _graph): m_graph(_graph)
  {
    run();
  }
  std::set<OverrideProxy> const& cutVertices() const { return m_cutVertices; }

private:
  OverrideGraph const& m_graph;

  std::vector<bool> m_visited = std::vector<bool>(m_graph.numNodes, false);
  std::vector<int> m_depths = std::vector<int>(m_graph.numNodes, -1);
  std::vector<int> m_low = std::vector<int>(m_graph.numNodes, -1);
  std::vector<int> m_parent = std::vector<int>(m_graph.numNodes, -1);
  std::set<OverrideProxy> m_cutVertices{};

  void run(size_t _u = 0, size_t _depth = 0)
  {
    m_visited.at(_u) = true;
    m_depths.at(_u) = m_low.at(_u) = static_cast<int>(_depth);
    for (int const v: m_graph.edges.at(static_cast<int>(_u)))
    {
      auto const vInd = static_cast<size_t>(v);
      if (!m_visited.at(vInd))
      {
        m_parent[vInd] = static_cast<int>(_u);
        run(vInd, _depth + 1);
        if (m_low[vInd] >= m_depths[_u] && m_parent[_u] != -1)
          m_cutVertices.insert(m_graph.nodeInv.at(static_cast<int>(_u)));
        m_low[_u] = std::min(m_low[_u], m_low[vInd]);
      }
      else if (v != m_parent[_u])
        m_low[_u] = std::min(m_low[_u], m_depths[vInd]);
    }
  }
};

std::vector<ContractDefinition const*> resolveDirectBaseContracts(ContractDefinition const& _contract)
{
  std::vector<ContractDefinition const*> resolvedContracts;

  for (ASTPointer<InheritanceSpecifier> const& specifier: _contract.baseContracts())
  {
    Declaration const* baseDecl =
      specifier->name().annotation().referencedDeclaration;
    auto contract = dynamic_cast<ContractDefinition const*>(baseDecl);
    if (contract)
      resolvedContracts.emplace_back(contract);
  }

  return resolvedContracts;
}

std::vector<ASTPointer<IdentifierPath>> sortByContract(std::vector<ASTPointer<IdentifierPath>> const& _list)
{
  auto sorted = _list;

  stable_sort(sorted.begin(), sorted.end(),
    [] (ASTPointer<IdentifierPath> _a, ASTPointer<IdentifierPath> _b) {
      if (!_a || !_b)
        return _a < _b;

      Declaration const* aDecl = _a->annotation().referencedDeclaration;
      Declaration const* bDecl = _b->annotation().referencedDeclaration;

      if (!aDecl || !bDecl)
        return aDecl < bDecl;

      return aDecl->id() < bDecl->id();
    }
  );

  return sorted;
}

OverrideProxy makeOverrideProxy(CallableDeclaration const& _callable)
{
  if (auto const* fun = dynamic_cast<FunctionDefinition const*>(&_callable))
    return OverrideProxy{fun};
  else if (auto const* mod = dynamic_cast<ModifierDefinition const*>(&_callable))
    return OverrideProxy{mod};
  else
    solAssert(false, "Invalid call to makeOverrideProxy.");
  return {};
}

}

bool OverrideProxy::operator<(OverrideProxy const& _other) const
{
  return id() < _other.id();
}

bool OverrideProxy::isVariable() const
{
  return std::holds_alternative<VariableDeclaration const*>(m_item);
}

bool OverrideProxy::isFunction() const
{
  return std::holds_alternative<FunctionDefinition const*>(m_item);
}

bool OverrideProxy::isModifier() const
{
  return std::holds_alternative<ModifierDefinition const*>(m_item);
}

bool OverrideProxy::CompareBySignature::operator()(OverrideProxy const& _a, OverrideProxy const& _b) const
{
  return _a.overrideComparator() < _b.overrideComparator();
}

size_t OverrideProxy::id() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) -> size_t { return static_cast<size_t>(_item->id()); }
  }, m_item);
}

std::shared_ptr<OverrideSpecifier> OverrideProxy::overrides() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) { return _item->overrides(); }
  }, m_item);
}

std::set<OverrideProxy> OverrideProxy::baseFunctions() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) -> std::set<OverrideProxy> {
      std::set<OverrideProxy> ret;
      for (auto const* f: _item->annotation().baseFunctions)
        ret.insert(makeOverrideProxy(*f));
      return ret;
    }
  }, m_item);
}

void OverrideProxy::storeBaseFunction(OverrideProxy const& _base) const
{
  std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) {
      _item->annotation().baseFunctions.emplace(std::get<FunctionDefinition const*>(_base.m_item));
    },
    [&](ModifierDefinition const* _item) {
      _item->annotation().baseFunctions.emplace(std::get<ModifierDefinition const*>(_base.m_item));
    },
    [&](VariableDeclaration const* _item) {
      _item->annotation().baseFunctions.emplace(std::get<FunctionDefinition const*>(_base.m_item));
    }
  }, m_item);
}

std::string const& OverrideProxy::name() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) -> std::string const& { return _item->name(); }
  }, m_item);
}

ContractDefinition const& OverrideProxy::contract() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) -> ContractDefinition const& {
      return dynamic_cast<ContractDefinition const&>(*_item->scope());
    }
  }, m_item);
}

std::string const& OverrideProxy::contractName() const
{
  return contract().name();
}

Visibility OverrideProxy::visibility() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return _item->visibility(); },
    [&](ModifierDefinition const* _item) { return _item->visibility(); },
    [&](VariableDeclaration const*) { return Visibility::External; }
  }, m_item);
}

StateMutability OverrideProxy::stateMutability() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return _item->stateMutability(); },
    [&](ModifierDefinition const*) { solAssert(false, "Requested state mutability from modifier."); return StateMutability{}; },
    [&](VariableDeclaration const* _var) { return _var->isConstant() ? StateMutability::Pure : StateMutability::View; }
  }, m_item);
}

bool OverrideProxy::virtualSemantics() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return _item->virtualSemantics(); },
    [&](ModifierDefinition const* _item) { return _item->virtualSemantics(); },
    [&](VariableDeclaration const*) { return false; }
  }, m_item);
}

Token OverrideProxy::functionKind() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return _item->kind(); },
    [&](ModifierDefinition const*) { return Token::Function; },
    [&](VariableDeclaration const*) { return Token::Function; }
  }, m_item);
}

FunctionType const* OverrideProxy::externalFunctionType() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return FunctionType(*_item).asExternallyCallableFunction(false); },
    [&](VariableDeclaration const* _item) { return FunctionType(*_item).asExternallyCallableFunction(false); },
    [&](ModifierDefinition const*) -> FunctionType const* { solAssert(false, "Requested function type of modifier."); return nullptr; }
  }, m_item);
}

FunctionType const* OverrideProxy::originalFunctionType() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return TypeProvider::function(*_item); },
    [&](VariableDeclaration const*) -> FunctionType const* { solAssert(false, "Requested specific function type of variable."); return nullptr; },
    [&](ModifierDefinition const*) -> FunctionType const* { solAssert(false, "Requested specific function type of modifier."); return nullptr; }
  }, m_item);
}

ModifierType const* OverrideProxy::modifierType() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const*) -> ModifierType const* { solAssert(false, "Requested modifier type of function."); return nullptr; },
    [&](VariableDeclaration const*) -> ModifierType const* { solAssert(false, "Requested modifier type of variable."); return nullptr; },
    [&](ModifierDefinition const* _modifier) -> ModifierType const* { return TypeProvider::modifier(*_modifier); }
  }, m_item);
}


Declaration const* OverrideProxy::declaration() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _function) -> Declaration const* { return _function; },
    [&](VariableDeclaration const* _variable) -> Declaration const* { return _variable; },
    [&](ModifierDefinition const* _modifier) -> Declaration const* { return _modifier; }
  }, m_item);
}

SourceLocation const& OverrideProxy::location() const
{
  return std::visit(GenericVisitor{
    [&](auto const* _item) -> SourceLocation const& { return _item->location(); }
  }, m_item);
}

std::string OverrideProxy::astNodeName() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const*) { return "function"; },
    [&](ModifierDefinition const*) { return "modifier"; },
    [&](VariableDeclaration const*) { return "public state variable"; },
  }, m_item);
}

std::string OverrideProxy::astNodeNameCapitalized() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const*) { return "Function"; },
    [&](ModifierDefinition const*) { return "Modifier"; },
    [&](VariableDeclaration const*) { return "Public state variable"; },
  }, m_item);
}

std::string OverrideProxy::distinguishingProperty() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const*) { return "name and parameter types"; },
    [&](ModifierDefinition const*) { return "name"; },
    [&](VariableDeclaration const*) { return "name and parameter types"; },
  }, m_item);
}

bool OverrideProxy::unimplemented() const
{
  return std::visit(GenericVisitor{
    [&](FunctionDefinition const* _item) { return !_item->isImplemented(); },
    [&](ModifierDefinition const* _item) { return !_item->isImplemented(); },
    [&](VariableDeclaration const*) { return false; }
  }, m_item);
}

bool OverrideProxy::OverrideComparator::operator<(OverrideComparator const& _other) const
{
  if (name != _other.name)
    return name < _other.name;

  if (!functionKind || !_other.functionKind)
    return false;

  if (functionKind != _other.functionKind)
    return *functionKind < *_other.functionKind;

  // Parameters do not matter for non-regular functions.
  if (functionKind != Token::Function)
    return false;

  if (!parameterTypes || !_other.parameterTypes)
    return false;

  return boost::lexicographical_compare(*parameterTypes, *_other.parameterTypes);
}

OverrideProxy::OverrideComparator const& OverrideProxy::overrideComparator() const
{
  if (!m_comparator)
  {
    m_comparator = std::make_shared<OverrideComparator>(std::visit(GenericVisitor{
      [&](FunctionDefinition const* _function)
      {
        std::vector<std::string> paramTypes;
        for (Type const* t: externalFunctionType()->parameterTypes())
          paramTypes.emplace_back(t->richIdentifier());
        return OverrideComparator{
          _function->name(),
          _function->kind(),
          std::move(paramTypes)
        };
      },
      [&](VariableDeclaration const* _var)
      {
        std::vector<std::string> paramTypes;
        for (Type const* t: externalFunctionType()->parameterTypes())
          paramTypes.emplace_back(t->richIdentifier());
        return OverrideComparator{
          _var->name(),
          Token::Function,
          std::move(paramTypes)
        };
      },
      [&](ModifierDefinition const* _mod)
      {
        return OverrideComparator{
          _mod->name(),
          {},
          {}
        };
      }
    }, m_item));
  }

  return *m_comparator;
}

bool OverrideChecker::CompareByID::operator()(ContractDefinition const* _a, ContractDefinition const* _b) const
{
  if (!_a || !_b)
    return _a < _b;

  return _a->id() < _b->id();
}

void OverrideChecker::check(ContractDefinition const& _contract)
{
  checkIllegalOverrides(_contract);
  checkAmbiguousOverrides(_contract);
}

void OverrideChecker::checkIllegalOverrides(ContractDefinition const& _contract)
{
  OverrideProxyBySignatureMultiSet const& inheritedFuncs = inheritedFunctions(_contract);
  OverrideProxyBySignatureMultiSet const& inheritedMods = inheritedModifiers(_contract);

  for (ModifierDefinition const* modifier: _contract.functionModifiers())
  {
    if (contains_if(inheritedFuncs, MatchByName{modifier->name()}))
      m_errorReporter.typeError(
        5631_error,
        modifier->location(),
        "Override changes function or public state variable to modifier."
      );

    checkOverrideList(OverrideProxy{modifier}, inheritedMods);
  }

  for (FunctionDefinition const* function: _contract.definedFunctions())
  {
    if (function->isConstructor())
      continue;

    if (contains_if(inheritedMods, MatchByName{function->name()}))
      m_errorReporter.typeError(1469_error, function->location(), "Override changes modifier to function.");

    checkOverrideList(OverrideProxy{function}, inheritedFuncs);
  }
  for (auto const* stateVar: _contract.stateVariables())
  {
    if (!stateVar->isPublic())
    {
      if (stateVar->overrides())
        m_errorReporter.typeError(8022_error, stateVar->location(), "Override can only be used with public state variables.");

      continue;
    }

    if (contains_if(inheritedMods, MatchByName{stateVar->name()}))
      m_errorReporter.typeError(1456_error, stateVar->location(), "Override changes modifier to public state variable.");

    checkOverrideList(OverrideProxy{stateVar}, inheritedFuncs);
  }

}

void OverrideChecker::checkOverride(OverrideProxy const& _overriding, OverrideProxy const& _super)
{
  solAssert(_super.isModifier() == _overriding.isModifier(), "");

  if (_super.isFunction() || _super.isModifier())
    _overriding.storeBaseFunction(_super);

  if (_overriding.isModifier() && *_overriding.modifierType() != *_super.modifierType())
    m_errorReporter.typeError(
      1078_error,
      _overriding.location(),
      "Override changes modifier signature."
    );

  if (!_overriding.overrides() && !(_super.isFunction() && _super.contract().isInterface()))
    overrideError(
      _overriding,
      _super,
      9456_error,
      "Overriding " + _overriding.astNodeName() + " is missing \"override\" specifier.",
      "Overridden " + _overriding.astNodeName() + " is here:"
    );

  if (_super.isVariable())
    overrideError(
      _super,
      _overriding,
      1452_error,
      "Cannot override public state variable.",
      "Overriding " + _overriding.astNodeName() + " is here:"
    );
  else if (!_super.virtualSemantics())
    overrideError(
      _super,
      _overriding,
      4334_error,
      "Trying to override non-virtual " + _super.astNodeName() + ". Did you forget to add \"virtual\"?",
      "Overriding " + _overriding.astNodeName() + " is here:"
    );

  if (_overriding.isVariable())
  {
    if (_super.visibility() != Visibility::External)
      overrideError(
        _overriding,
        _super,
        5225_error,
        "Public state variables can only override functions with external visibility.",
        "Overridden function is here:"
      );
    solAssert(_overriding.visibility() == Visibility::External, "");
  }
  else if (_overriding.visibility() != _super.visibility())
  {
    // Visibility change from external to public is fine.
    // Any other change is disallowed.
    if (!(
      _super.visibility() == Visibility::External &&
      _overriding.visibility() == Visibility::Public
    ))
      overrideError(
        _overriding,
        _super,
        9098_error,
        "Overriding " + _overriding.astNodeName() + " visibility differs.",
        "Overridden " + _overriding.astNodeName() + " is here:"
      );
  }

  if (_overriding.unimplemented() && !_super.unimplemented())
  {
    solAssert(!_overriding.isVariable() || !_overriding.unimplemented(), "");
    overrideError(
      _overriding,
      _super,
      4593_error,
      "Overriding an implemented " + _super.astNodeName() +
      " with an unimplemented " + _overriding.astNodeName() +
      " is not allowed."
    );
  }

  if (_super.isFunction())
  {
    FunctionType const* functionType = _overriding.externalFunctionType();
    FunctionType const* superType = _super.externalFunctionType();

    bool returnTypesDifferAlready = false;
    if (_overriding.functionKind() != Token::Fallback)
    {
      solAssert(functionType->hasEqualParameterTypes(*superType), "Override doesn't have equal parameters!");

      if (!functionType->hasEqualReturnTypes(*superType))
      {
        returnTypesDifferAlready = true;
        overrideError(
          _overriding,
          _super,
          4822_error,
          "Overriding " + _overriding.astNodeName() + " return types differ.",
          "Overridden " + _overriding.astNodeName() + " is here:"
        );
      }
    }

    // The override proxy considers calldata and memory the same data location.
    // Here we do a more specific check:
    // Data locations of parameters and return variables have to match
    // unless we have a public function overriding an external one.
    if (
      _overriding.isFunction() &&
      !returnTypesDifferAlready &&
      _super.visibility() != Visibility::External &&
      _overriding.functionKind() != Token::Fallback
    )
    {
      if (!_overriding.originalFunctionType()->hasEqualParameterTypes(*_super.originalFunctionType()))
        overrideError(
          _overriding,
          _super,
          7723_error,
          "Data locations of parameters have to be the same when overriding non-external functions, but they differ.",
          "Overridden " + _overriding.astNodeName() + " is here:"
        );
      if (!_overriding.originalFunctionType()->hasEqualReturnTypes(*_super.originalFunctionType()))
        overrideError(
          _overriding,
          _super,
          1443_error,
          "Data locations of return variables have to be the same when overriding non-external functions, but they differ.",
          "Overridden " + _overriding.astNodeName() + " is here:"
        );
    }

    // Stricter mutability is always okay except when super is Payable
    if (
      (_overriding.isFunction() || _overriding.isVariable()) &&
      (
        _overriding.stateMutability() > _super.stateMutability() ||
        _super.stateMutability() == StateMutability::Payable
      ) &&
      _overriding.stateMutability() != _super.stateMutability()
    )
      overrideError(
        _overriding,
        _super,
        6959_error,
        "Overriding " +
        _overriding.astNodeName() +
        " changes state mutability from \"" +
        stateMutabilityToString(_super.stateMutability()) +
        "\" to \"" +
        stateMutabilityToString(_overriding.stateMutability()) +
        "\"."
      );
  }
}

void OverrideChecker::overrideListError(
  OverrideProxy const& _item,
  std::set<ContractDefinition const*, CompareByID> _secondary,
  ErrorId _error,
  std::string const& _message1,
  std::string const& _message2
)
{
  // Using a set rather than a vector so the order is always the same
  std::set<std::string> names;
  SecondarySourceLocation ssl;
  for (Declaration const* c: _secondary)
  {
    ssl.append("This contract: ", c->location());
    names.insert("\"" + c->name() + "\"");
  }
  std::string contractSingularPlural = "contract ";
  if (_secondary.size() > 1)
    contractSingularPlural = "contracts ";

  m_errorReporter.typeError(
    _error,
    _item.overrides() ? _item.overrides()->location() : _item.location(),
    ssl,
    _message1 +
    contractSingularPlural +
    _message2 +
    joinHumanReadable(names, ", ", " and ") +
    "."
  );
}

void OverrideChecker::overrideError(
  OverrideProxy const& _overriding,
  OverrideProxy const& _super,
  ErrorId _error,
  std::string const& _message,
  std::optional<std::string> const& _secondaryMsg
)
{
  m_errorReporter.typeError(
    _error,
    _overriding.location(),
    SecondarySourceLocation().append(
      _secondaryMsg.value_or("Overridden " + _super.astNodeName() + " is here:"),
      _super.location()
    ),
    _message
  );
}

void OverrideChecker::checkAmbiguousOverrides(ContractDefinition const& _contract) const
{
  {
    // Fetch inherited functions and sort them by signature.
    // We get at least one function per signature and direct base contract, which is
    // enough because we re-construct the inheritance graph later.
    OverrideProxyBySignatureMultiSet nonOverriddenFunctions = inheritedFunctions(_contract);

    // Remove all functions that match the signature of a function in the current contract.
    for (FunctionDefinition const* f: _contract.definedFunctions())
      nonOverriddenFunctions.erase(OverrideProxy{f});
    for (VariableDeclaration const* v: _contract.stateVariables())
      if (v->isPublic())
        nonOverriddenFunctions.erase(OverrideProxy{v});

    // Walk through the set of functions signature by signature.
    for (auto it = nonOverriddenFunctions.cbegin(); it != nonOverriddenFunctions.cend();)
    {
      std::set<OverrideProxy> baseFunctions;
      for (auto nextSignature = nonOverriddenFunctions.upper_bound(*it); it != nextSignature; ++it)
        baseFunctions.insert(*it);

      checkAmbiguousOverridesInternal(std::move(baseFunctions), _contract.location());
    }
  }

  {
    OverrideProxyBySignatureMultiSet modifiers = inheritedModifiers(_contract);
    for (ModifierDefinition const* mod: _contract.functionModifiers())
      modifiers.erase(OverrideProxy{mod});

    for (auto it = modifiers.cbegin(); it != modifiers.cend();)
    {
      std::set<OverrideProxy> baseModifiers;
      for (auto next = modifiers.upper_bound(*it); it != next; ++it)
        baseModifiers.insert(*it);

      checkAmbiguousOverridesInternal(std::move(baseModifiers), _contract.location());
    }

  }
}

void OverrideChecker::checkAmbiguousOverridesInternal(std::set<OverrideProxy> _baseCallables, SourceLocation const& _location) const
{
  if (_baseCallables.size() <= 1)
    return;

  OverrideGraph overrideGraph(_baseCallables);
  CutVertexFinder cutVertexFinder{overrideGraph};

  // Remove all base functions overridden by cut vertices (they don't need to be overridden).
  for (OverrideProxy const& function: cutVertexFinder.cutVertices())
  {
    std::set<OverrideProxy> toTraverse = function.baseFunctions();
    while (!toTraverse.empty())
    {
      OverrideProxy base = *toTraverse.begin();
      toTraverse.erase(toTraverse.begin());
      _baseCallables.erase(base);
      for (OverrideProxy const& f: base.baseFunctions())
        toTraverse.insert(f);
    }
    // Remove unimplemented base functions at the cut vertices itself as well.
    if (function.unimplemented())
      _baseCallables.erase(function);
  }

  // If more than one function is left, they have to be overridden.
  if (_baseCallables.size() <= 1)
    return;

  SecondarySourceLocation ssl;
  for (OverrideProxy const& baseFunction: _baseCallables)
    ssl.append("Definition in \"" + baseFunction.contractName() + "\": ", baseFunction.location());

  std::string callableName = _baseCallables.begin()->astNodeName();
  if (_baseCallables.begin()->isVariable())
    callableName = "function";
  std::string distinguishingProperty = _baseCallables.begin()->distinguishingProperty();

  bool foundVariable = false;
  for (auto const& base: _baseCallables)
    if (base.isVariable())
      foundVariable = true;

  std::string message =
    "Derived contract must override " + callableName + " \"" +
    _baseCallables.begin()->name() +
    "\". Two or more base classes define " + callableName + " with same " + distinguishingProperty + ".";

  if (foundVariable)
    message +=
      " Since one of the bases defines a public state variable which cannot be overridden, "
      "you have to change the inheritance layout or the names of the functions.";

  m_errorReporter.typeError(6480_error, _location, ssl, message);
}

std::set<ContractDefinition const*, OverrideChecker::CompareByID> OverrideChecker::resolveOverrideList(OverrideSpecifier const& _overrides) const
{
  std::set<ContractDefinition const*, CompareByID> resolved;

  for (ASTPointer<IdentifierPath> const& override: _overrides.overrides())
  {
    Declaration const* decl  = override->annotation().referencedDeclaration;
    solAssert(decl, "Expected declaration to be resolved.");

    // If it's not a contract it will be caught
    // in the reference resolver
    if (ContractDefinition const* contract = dynamic_cast<decltype(contract)>(decl))
      resolved.insert(contract);
  }

  return resolved;
}

void OverrideChecker::checkOverrideList(OverrideProxy _item, OverrideProxyBySignatureMultiSet const& _inherited)
{
  std::set<ContractDefinition const*, CompareByID> specifiedContracts =
    _item.overrides() ?
    resolveOverrideList(*_item.overrides()) :
    decltype(specifiedContracts){};

  // Check for duplicates in override list
  if (_item.overrides() && specifiedContracts.size() != _item.overrides()->overrides().size())
  {
    // Sort by contract id to find duplicate for error reporting
    std::vector<ASTPointer<IdentifierPath>> list =
      sortByContract(_item.overrides()->overrides());

    // Find duplicates and output error
    for (size_t i = 1; i < list.size(); i++)
    {
      Declaration const* aDecl = list[i]->annotation().referencedDeclaration;
      Declaration const* bDecl = list[i-1]->annotation().referencedDeclaration;
      if (!aDecl || !bDecl)
        continue;

      if (aDecl->id() == bDecl->id())
      {
        SecondarySourceLocation ssl;
        ssl.append("First occurrence here: ", list[i-1]->location());
        m_errorReporter.typeError(
          4520_error,
          list[i]->location(),
          ssl,
          "Duplicate contract \"" +
          joinHumanReadable(list[i]->path(), ".") +
          "\" found in override list of \"" +
          _item.name() +
          "\"."
        );
      }
    }
  }

  std::set<ContractDefinition const*, CompareByID> expectedContracts;

  // Build list of expected contracts
  for (auto [begin, end] = _inherited.equal_range(_item); begin != end; begin++)
  {
    // Validate the override
    checkOverride(_item, *begin);

    expectedContracts.insert(&begin->contract());
  }

  if (_item.overrides() && expectedContracts.empty())
    m_errorReporter.typeError(
      7792_error,
      _item.overrides()->location(),
      _item.astNodeNameCapitalized() + " has override specified but does not override anything."
    );

  std::set<ContractDefinition const*, CompareByID> missingContracts;
  // If we expect only one contract, no contract needs to be specified
  if (expectedContracts.size() > 1)
    missingContracts = expectedContracts - specifiedContracts;

  if (!missingContracts.empty())
    overrideListError(
      _item,
      missingContracts,
      4327_error,
      _item.astNodeNameCapitalized() + " needs to specify overridden ",
      ""
    );

  auto surplusContracts = specifiedContracts - expectedContracts;
  if (!surplusContracts.empty())
    overrideListError(
      _item,
      surplusContracts,
      2353_error,
      "Invalid ",
      "specified in override list: "
    );
}

OverrideChecker::OverrideProxyBySignatureMultiSet const& OverrideChecker::inheritedFunctions(ContractDefinition const& _contract) const
{
  if (!m_inheritedFunctions.count(&_contract))
  {
    OverrideProxyBySignatureMultiSet result;

    for (auto const* base: resolveDirectBaseContracts(_contract))
    {
      std::set<OverrideProxy, OverrideProxy::CompareBySignature> functionsInBase;
      for (FunctionDefinition const* fun: base->definedFunctions())
        if (!fun->isConstructor())
          functionsInBase.emplace(OverrideProxy{fun});
      for (VariableDeclaration const* var: base->stateVariables())
        if (var->isPublic())
          functionsInBase.emplace(OverrideProxy{var});

      result += functionsInBase;

      for (OverrideProxy const& func: inheritedFunctions(*base))
        if (!functionsInBase.count(func))
          result.insert(func);
    }

    m_inheritedFunctions[&_contract] = result;
  }

  return m_inheritedFunctions[&_contract];
}

OverrideChecker::OverrideProxyBySignatureMultiSet const& OverrideChecker::inheritedModifiers(ContractDefinition const& _contract) const
{
  if (!m_inheritedModifiers.count(&_contract))
  {
    OverrideProxyBySignatureMultiSet result;

    for (auto const* base: resolveDirectBaseContracts(_contract))
    {
      std::set<OverrideProxy, OverrideProxy::CompareBySignature> modifiersInBase;
      for (ModifierDefinition const* mod: base->functionModifiers())
        modifiersInBase.emplace(OverrideProxy{mod});

      for (OverrideProxy const& mod: inheritedModifiers(*base))
        modifiersInBase.insert(mod);

      result += modifiersInBase;
    }

    m_inheritedModifiers[&_contract] = result;
  }

  return m_inheritedModifiers[&_contract];
}

Coverage Report

Created: 2025-06-24 07:59