C++ ObjCMethodCall::getResultType方法代码示例

void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
                                               const ObjCMethodCall &msg,
                                               ExplodedNode *N) const {

  if (!BT_msg_ret)
    BT_msg_ret.reset(
        new BuiltinBug(this, "Receiver in message expression is 'nil'"));

  const ObjCMessageExpr *ME = msg.getOriginExpr();

  QualType ResTy = msg.getResultType();

  SmallString<200> buf;
  llvm::raw_svector_ostream os(buf);
  os << "The receiver of message '";
  ME->getSelector().print(os);
  os << "' is nil";
  if (ResTy->isReferenceType()) {
    os << ", which results in forming a null reference";
  } else {
    os << " and returns a value of type '";
    msg.getResultType().print(os, C.getLangOpts());
    os << "' that will be garbage";
  }

  auto report = llvm::make_unique<BugReport>(*BT_msg_ret, os.str(), N);
  report->addRange(ME->getReceiverRange());
  // FIXME: This won't track "self" in messages to super.
  if (const Expr *receiver = ME->getInstanceReceiver()) {
    bugreporter::trackNullOrUndefValue(N, receiver, *report);
  }
  C.emitReport(std::move(report));
}

void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
                                               const ObjCMethodCall &msg,
                                               ExplodedNode *N) const {

  if (!BT_msg_ret)
    BT_msg_ret.reset(
      new BuiltinBug("Receiver in message expression is "
                     "'nil' and returns a garbage value"));

  const ObjCMessageExpr *ME = msg.getOriginExpr();

  SmallString<200> buf;
  llvm::raw_svector_ostream os(buf);
  os << "The receiver of message '" << ME->getSelector().getAsString()
     << "' is nil and returns a value of type '";
  msg.getResultType().print(os, C.getLangOpts());
  os << "' that will be garbage";

  BugReport *report = new BugReport(*BT_msg_ret, os.str(), N);
  report->addRange(ME->getReceiverRange());
  // FIXME: This won't track "self" in messages to super.
  if (const Expr *receiver = ME->getInstanceReceiver()) {
    report->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
                                                                    receiver,
                                                                    report));
  }
  C.EmitReport(report);
}

void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
                                              ProgramStateRef state,
                                              const ObjCMethodCall &Msg) const {
  ASTContext &Ctx = C.getASTContext();
  static CheckerProgramPointTag Tag(this, "NilReceiver");

  // Check the return type of the message expression.  A message to nil will
  // return different values depending on the return type and the architecture.
  QualType RetTy = Msg.getResultType();
  CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
  const LocationContext *LCtx = C.getLocationContext();

  if (CanRetTy->isStructureOrClassType()) {
    // Structure returns are safe since the compiler zeroes them out.
    SVal V = C.getSValBuilder().makeZeroVal(RetTy);
    C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
    return;
  }

  // Other cases: check if sizeof(return type) > sizeof(void*)
  if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
                                  .isConsumedExpr(Msg.getOriginExpr())) {
    // Compute: sizeof(void *) and sizeof(return type)
    const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
    const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);

    if (CanRetTy.getTypePtr()->isReferenceType()||
        (voidPtrSize < returnTypeSize &&
         !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
           (Ctx.FloatTy == CanRetTy ||
            Ctx.DoubleTy == CanRetTy ||
            Ctx.LongDoubleTy == CanRetTy ||
            Ctx.LongLongTy == CanRetTy ||
            Ctx.UnsignedLongLongTy == CanRetTy)))) {
      if (ExplodedNode *N = C.generateSink(state, nullptr, &Tag))
        emitNilReceiverBug(C, Msg, N);
      return;
    }

    // Handle the safe cases where the return value is 0 if the
    // receiver is nil.
    //
    // FIXME: For now take the conservative approach that we only
    // return null values if we *know* that the receiver is nil.
    // This is because we can have surprises like:
    //
    //   ... = [[NSScreens screens] objectAtIndex:0];
    //
    // What can happen is that [... screens] could return nil, but
    // it most likely isn't nil.  We should assume the semantics
    // of this case unless we have *a lot* more knowledge.
    //
    SVal V = C.getSValBuilder().makeZeroVal(RetTy);
    C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
    return;
  }

  C.addTransition(state);
}