// SmartPtrModeling.cpp - Model behavior of C++ smart pointers - C++ ------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines a checker that models various aspects of

// C++ smart pointer behavior.

//

//===----------------------------------------------------------------------===//

#include "Move.h"

#include "clang/AST/ExprCXX.h"

#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"

#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"

#include "clang/StaticAnalyzer/Core/Checker.h"

#include "clang/StaticAnalyzer/Core/CheckerManager.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"

using namespace clang;

using namespace ento;

namespace {

class SmartPtrModeling : public Checker<eval::Call> {

  bool isNullAfterMoveMethod(const CallEvent &Call) const;

public:

  bool evalCall(const CallEvent &Call, CheckerContext &C) const;

};

} // end of anonymous namespace

bool SmartPtrModeling::isNullAfterMoveMethod(const CallEvent &Call) const {

  // TODO: Update CallDescription to support anonymous calls?

  // TODO: Handle other methods, such as .get() or .release().

  // But once we do, we'd need a visitor to explain null dereferences

  // that are found via such modeling.

  const auto *CD = dyn_cast_or_null<CXXConversionDecl>(Call.getDecl());

  return CD && 
CD->getConversionType()->isBooleanType()90
;

}

bool SmartPtrModeling::evalCall(const CallEvent &Call,

                                CheckerContext &C) const {

  if (!isNullAfterMoveMethod(Call))

    return false;

  ProgramStateRef State = C.getState();

  const MemRegion *ThisR =

      cast<CXXInstanceCall>(&Call)->getCXXThisVal().getAsRegion();

  if (!move::isMovedFrom(State, ThisR)) {

    // TODO: Model this case as well. At least, avoid invalidation of globals.

    return false;

  }

  // TODO: Add a note to bug reports describing this decision.

  C.addTransition(

      State->BindExpr(Call.getOriginExpr(), C.getLocationContext(),

                      C.getSValBuilder().makeZeroVal(Call.getResultType())));

  return true;

}

void ento::registerSmartPtrModeling(CheckerManager &Mgr) {

  Mgr.registerChecker<SmartPtrModeling>();

}

bool ento::shouldRegisterSmartPtrModeling(const LangOptions &LO) {

  return LO.CPlusPlus;

}