C++ ExprResult::isInvalid方法代码示例

Parser::ExprResult Parser::ParseEquivOperand() {
  ExprResult E = ParseOrOperand();
  if (E.isInvalid()) return ExprResult();

  while (Tok.getKind() == tok::kw_OR) {
    llvm::SMLoc OpLoc = Tok.getLocation();
    Lex();
    ExprResult OrOp = ParseOrOperand();
    if (OrOp.isInvalid()) return ExprResult();
    E = BinaryExpr::Create(Context, OpLoc, BinaryExpr::Or, E, OrOp);
  }

  return E;
}

/// ParseAssignmentStmt
///   [R732]:
///     assignment-stmt :=
///         variable = expr
Parser::StmtResult Parser::ParseAssignmentStmt() {
  ExprResult LHS = ParsePrimaryExpr(true);
  if(LHS.isInvalid()) return StmtError();

  SourceLocation Loc = Tok.getLocation();
  if(!ConsumeIfPresent(tok::equal)) {
    Diag.Report(getExpectedLoc(),diag::err_expected_equal);
    return StmtError();
  }

  ExprResult RHS = ParseExpectedFollowupExpression("=");
  if(RHS.isInvalid()) return StmtError();
  return Actions.ActOnAssignmentStmt(Context, Loc, LHS, RHS, StmtLabel);
}

static bool actOnCoroutineBodyStart(Sema &S, Scope *SC, SourceLocation KWLoc,
                                    StringRef Keyword) {
  if (!checkCoroutineContext(S, KWLoc, Keyword))
    return false;
  auto *ScopeInfo = S.getCurFunction();
  assert(ScopeInfo->CoroutinePromise);

  // If we have existing coroutine statements then we have already built
  // the initial and final suspend points.
  if (!ScopeInfo->NeedsCoroutineSuspends)
    return true;

  ScopeInfo->setNeedsCoroutineSuspends(false);

  auto *Fn = cast<FunctionDecl>(S.CurContext);
  SourceLocation Loc = Fn->getLocation();
  // Build the initial suspend point
  auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
    ExprResult Suspend =
        buildPromiseCall(S, ScopeInfo->CoroutinePromise, Loc, Name, None);
    if (Suspend.isInvalid())
      return StmtError();
    Suspend = buildOperatorCoawaitCall(S, SC, Loc, Suspend.get());
    if (Suspend.isInvalid())
      return StmtError();
    Suspend = S.BuildResolvedCoawaitExpr(Loc, Suspend.get(),
                                         /*IsImplicit*/ true);
    Suspend = S.ActOnFinishFullExpr(Suspend.get());
    if (Suspend.isInvalid()) {
      S.Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
          << ((Name == "initial_suspend") ? 0 : 1);
      S.Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
      return StmtError();
    }
    return cast<Stmt>(Suspend.get());
  };

  StmtResult InitSuspend = buildSuspends("initial_suspend");
  if (InitSuspend.isInvalid())
    return true;

  StmtResult FinalSuspend = buildSuspends("final_suspend");
  if (FinalSuspend.isInvalid())
    return true;

  ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());

  return true;
}

// ParseExpression - Expressions are level-5 expressions optionally involving
// defined binary operators.
//
//   R722:
//     expr :=
//         [ expr defined-binary-op ] level-5-expr
//
//   R723:
//     defined-binary-op :=
//         . letter [ letter ] ... .
Parser::ExprResult Parser::ParseExpression() {
  ExprResult LHS = ParseLevel5Expr();
  if (LHS.isInvalid()) return LHS;

  if (!IsPresent(tok::defined_operator))
    return LHS;

  SourceLocation OpLoc = Tok.getLocation();
  IdentifierInfo *II = Tok.getIdentifierInfo();
  Lex();

  ExprResult RHS = ParseLevel5Expr();
  if (RHS.isInvalid()) return RHS;

  return DefinedBinaryOperatorExpr::Create(Context, OpLoc, LHS.take(), RHS.take(), II);
}

// Return true if a comma (or closing brace) is necessary after the
// __if_exists/if_not_exists statement.
bool Parser::ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
                                                    bool &InitExprsOk) {
  bool trailingComma = false;
  IfExistsCondition Result;
  if (ParseMicrosoftIfExistsCondition(Result))
    return false;
  
  BalancedDelimiterTracker Braces(*this, tok::l_brace);
  if (Braces.consumeOpen()) {
    Diag(Tok, diag::err_expected) << tok::l_brace;
    return false;
  }

  switch (Result.Behavior) {
  case IEB_Parse:
    // Parse the declarations below.
    break;
        
  case IEB_Dependent:
    Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
      << Result.IsIfExists;
    // Fall through to skip.
      
  case IEB_Skip:
    Braces.skipToEnd();
    return false;
  }

  while (!isEofOrEom()) {
    trailingComma = false;
    // If we know that this cannot be a designation, just parse the nested
    // initializer directly.
    ExprResult SubElt;
    if (MayBeDesignationStart())
      SubElt = ParseInitializerWithPotentialDesignator();
    else
      SubElt = ParseInitializer();

    if (Tok.is(tok::ellipsis))
      SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());
    
    // If we couldn't parse the subelement, bail out.
    if (!SubElt.isInvalid())
      InitExprs.push_back(SubElt.release());
    else
      InitExprsOk = false;

    if (Tok.is(tok::comma)) {
      ConsumeToken();
      trailingComma = true;
    }

    if (Tok.is(tok::r_brace))
      break;
  }

  Braces.consumeClose();

  return !trailingComma;
}

/// Look up the std::nothrow object.
static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
  NamespaceDecl *Std = S.getStdNamespace();
  assert(Std && "Should already be diagnosed");

  LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
                      Sema::LookupOrdinaryName);
  if (!S.LookupQualifiedName(Result, Std)) {
    // FIXME: <experimental/coroutine> should have been included already.
    // If we require it to include <new> then this diagnostic is no longer
    // needed.
    S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
    return nullptr;
  }

  // FIXME: Mark the variable as ODR used. This currently does not work
  // likely due to the scope at in which this function is called.
  auto *VD = Result.getAsSingle<VarDecl>();
  if (!VD) {
    Result.suppressDiagnostics();
    // We found something weird. Complain about the first thing we found.
    NamedDecl *Found = *Result.begin();
    S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
    return nullptr;
  }

  ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
  if (DR.isInvalid())
    return nullptr;

  return DR.get();
}

/// ParseUnaryExpression - Parse a unary-expression.
///        unary-expression:
///          inc-dec-expression
///          ++ unary-expression
///          -- unary-expression
///          unary-operator unary-expression
ExprResult Parser::ParseUnaryExpression() {
	ExprResult Res;
	tok::TokenKind SavedKind = Tok.getKind();

	switch (SavedKind) {
	case tok::DoubleAdd:
	case tok::DoubleSub:
		// unary operators
	case tok::Addition:
	case tok::Subtraction:
	case tok::Tilde:
	case tok::At: {
		SourceLocation SavedLoc = ConsumeToken();
		Res = ParsePostfixExpression();
		if (!Res.isInvalid()) {
			Res = Actions.ActOnUnaryOp(getCurScope(), SavedLoc, SavedKind,false,
					                       Res.get());
		}
		return move(Res);
	}
	default:
		break;
	}

	return ParsePostfixExpression();
}

static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
                                       SourceLocation Loc) {
  QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
  if (CoroHandleType.isNull())
    return ExprError();

  DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
  LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
                     Sema::LookupOrdinaryName);
  if (!S.LookupQualifiedName(Found, LookupCtx)) {
    S.Diag(Loc, diag::err_coroutine_handle_missing_member)
        << "from_address";
    return ExprError();
  }

  Expr *FramePtr =
      buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});

  CXXScopeSpec SS;
  ExprResult FromAddr =
      S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
  if (FromAddr.isInvalid())
    return ExprError();

  return S.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
}

// ParseExpression - Expressions are level-5 expresisons optionally involving
// defined binary operators.
//
//   R722:
//     expr :=
//         [ expr defined-binary-op ] level-5-expr
//
//   R723:
//     defined-binary-op :=
//         . letter [ letter ] ... .
Parser::ExprResult Parser::ParseExpression() {
  ExprResult LHS = ParseLevel5Expr();
  if (LHS.isInvalid()) return ExprResult();

  if (Tok.isNot(tok::defined_operator))
    return LHS;

  llvm::SMLoc OpLoc = Tok.getLocation();
  IdentifierInfo *II = Tok.getIdentifierInfo();
  Lex();

  ExprResult RHS = ParseLevel5Expr();
  if (RHS.isInvalid()) return ExprResult();

  return DefinedOperatorBinaryExpr::Create(Context, OpLoc, LHS, RHS, II);
}

ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
  if (!Coroutine)
    return ExprError();

  if (E->getType()->isPlaceholderType()) {
    ExprResult R = CheckPlaceholderExpr(E);
    if (R.isInvalid()) return ExprError();
    E = R.get();
  }

  if (E->getType()->isDependentType()) {
    Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
    return Res;
  }

  // If the expression is a temporary, materialize it as an lvalue so that we
  // can use it multiple times.
  if (E->getValueKind() == VK_RValue)
    E = CreateMaterializeTemporaryExpr(E->getType(), E, true);

  // Build the await_ready, await_suspend, await_resume calls.
  ReadySuspendResumeResult RSS =
      buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
  if (RSS.IsInvalid)
    return ExprError();

  Expr *Res = new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
                                        RSS.Results[2], RSS.OpaqueValue);

  return Res;
}

ExprResult Sema::ActOnCoyieldExpr(SourceLocation Loc, Expr *E) {
  auto *Context = checkCoroutineContext(*this, Loc, "co_yield");
  ExprResult Res = ExprError();

  if (Context && !Res.isInvalid())
    Context->CoroutineStmts.push_back(Res.get());
  return Res;
}

static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
                                           SourceLocation Loc, Expr *E) {
  ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
  if (R.isInvalid())
    return ExprError();
  return buildOperatorCoawaitCall(SemaRef, Loc, E,
                                  cast<UnresolvedLookupExpr>(R.get()));
}

ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
  if (!actOnCoroutineBodyStart(*this, S, Loc, "co_await")) {
    CorrectDelayedTyposInExpr(E);
    return ExprError();
  }

  if (E->getType()->isPlaceholderType()) {
    ExprResult R = CheckPlaceholderExpr(E);
    if (R.isInvalid()) return ExprError();
    E = R.get();
  }
  ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
  if (Lookup.isInvalid())
    return ExprError();
  return BuildUnresolvedCoawaitExpr(Loc, E,
                                   cast<UnresolvedLookupExpr>(Lookup.get()));
}

static ExprResult
BuildFieldReferenceExpr(Sema &S, Expr *BaseExpr, bool IsArrow,
                        const CXXScopeSpec &SS, FieldDecl *Field,
                        DeclAccessPair FoundDecl,
                        const DeclarationNameInfo &MemberNameInfo) {
  // x.a is an l-value if 'a' has a reference type. Otherwise:
  // x.a is an l-value/x-value/pr-value if the base is (and note
  //   that *x is always an l-value), except that if the base isn't
  //   an ordinary object then we must have an rvalue.
  ExprValueKind VK = VK_LValue;
  ExprObjectKind OK = OK_Ordinary;
  if (!IsArrow) {
    if (BaseExpr->getObjectKind() == OK_Ordinary)
      VK = BaseExpr->getValueKind();
    else
      VK = VK_RValue;
  }
  if (VK != VK_RValue && Field->isBitField())
    OK = OK_BitField;
  
  // Figure out the type of the member; see C99 6.5.2.3p3, C++ [expr.ref]
  QualType MemberType = Field->getType();
  if (const ReferenceType *Ref = MemberType->getAs<ReferenceType>()) {
    MemberType = Ref->getPointeeType();
    VK = VK_LValue;
  } else {
    QualType BaseType = BaseExpr->getType();
    if (IsArrow) BaseType = BaseType->getAs<PointerType>()->getPointeeType();

    Qualifiers BaseQuals = BaseType.getQualifiers();

    // CVR attributes from the base are picked up by members,
    // except that 'mutable' members don't pick up 'const'.
    if (Field->isMutable()) BaseQuals.removeConst();

    Qualifiers MemberQuals
    = S.Context.getCanonicalType(MemberType).getQualifiers();

    assert(!MemberQuals.hasAddressSpace());


    Qualifiers Combined = BaseQuals + MemberQuals;
    if (Combined != MemberQuals)
      MemberType = S.Context.getQualifiedType(MemberType, Combined);
  }

  S.UnusedPrivateFields.remove(Field);

  ExprResult Base =
  S.PerformObjectMemberConversion(BaseExpr, SS.getScopeRep(),
                                  FoundDecl, Field);
  if (Base.isInvalid())
    return ExprError();
  return S.Owned(BuildMemberExpr(S, S.Context, Base.take(), IsArrow,
                                 Field, FoundDecl, MemberNameInfo,
                                 MemberType, VK, OK));
}

ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
  if (!Coroutine)
    return ExprError();

  // Build yield_value call.
  ExprResult Awaitable =
      buildPromiseCall(*this, Coroutine, Loc, "yield_value", E);
  if (Awaitable.isInvalid())
    return ExprError();

  // Build 'operator co_await' call.
  Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
  if (Awaitable.isInvalid())
    return ExprError();

  return BuildCoyieldExpr(Loc, Awaitable.get());
}