C# CType.AsAggregateType方法代码示例

 private AggregateType GetUserDefinedBinopArgumentType(CType type)
 {
     for (; ;)
     {
         switch (type.GetTypeKind())
         {
             case TypeKind.TK_NullableType:
                 type = type.StripNubs();
                 break;
             case TypeKind.TK_TypeParameterType:
                 type = type.AsTypeParameterType().GetEffectiveBaseClass();
                 break;
             case TypeKind.TK_AggregateType:
                 if ((type.isClassType() || type.isStructType()) && !type.AsAggregateType().getAggregate().IsSkipUDOps())
                 {
                     return type.AsAggregateType();
                 }
                 return null;
             default:
                 return null;
         }
     }
 }

        ////////////////////////////////////////////////////////////////////////////////

        private bool UpperBoundInterfaceInference(AggregateType pSource, CType pDest)
        {
            if (!pSource.isInterfaceType())
            {
                return false;
            }

            // SPEC:  Otherwise, if U is an interface CType C<U1...Uk> and V is a class CType
            // SPEC:   or struct CType and there is a unique set V1...Vk such that V directly 
            // SPEC:   or indirectly implements C<V1...Vk> then an exact ...
            // SPEC:  ... and U is an interface CType ...

            if (!pDest.isStructType() && !pDest.isClassType() &&
                !pDest.isInterfaceType())
            {
                return false;
            }

            var interfaces = pDest.AllPossibleInterfaces();
            AggregateType pInterface = null;
            foreach (AggregateType pCurrent in interfaces)
            {
                if (pCurrent.GetOwningAggregate() == pSource.GetOwningAggregate())
                {
                    if (pInterface == null)
                    {
                        pInterface = pCurrent;
                    }
                    else if (pInterface != pCurrent)
                    {
                        // Not unique. Bail out.
                        return false;
                    }
                }
            }
            if (pInterface == null)
            {
                return false;
            }
            UpperBoundTypeArgumentInference(pInterface, pDest.AsAggregateType());
            return true;
        }

        ////////////////////////////////////////////////////////////////////////////////
        //
        // Output types
        //
        private bool DoesOutputTypeContain(EXPR pSource, CType pDest,
            TypeParameterType pParam)
        {
            // SPEC: If E is a method group or an anonymous function and T is a delegate
            // SPEC: CType or expression tree CType then the return CType of T is an output CType
            // SPEC: of E with CType T.

            pDest = pDest.GetDelegateTypeOfPossibleExpression();
            if (!pDest.isDelegateType())
            {
                return false;
            }

            if (!pSource.isUNBOUNDLAMBDA() && !pSource.isMEMGRP())
            {
                return false;
            }

            CType pDelegateReturn = pDest.AsAggregateType().GetDelegateReturnType(GetSymbolLoader());
            if (pDelegateReturn == null)
            {
                return false;
            }
            return TypeManager.TypeContainsType(pDelegateReturn, pParam);
        }

        ////////////////////////////////////////////////////////////////////////////////

        private bool LowerBoundClassInference(CType pSource, AggregateType pDest)
        {
            if (!pDest.isClassType())
            {
                return false;
            }

            // SPEC:  Otherwise, if V is a class CType C<V1...Vk> and U is a class CType which
            // SPEC:   inherits directly or indirectly from C<U1...Uk> 
            // SPEC:   then an exact inference is made from each Ui to the corresponding Vi.
            // SPEC:  Otherwise, if V is a class CType C<V1...Vk> and U is a CType parameter
            // SPEC:   with effective base class C<U1...Uk> 
            // SPEC:   then an exact inference is made from each Ui to the corresponding Vi.
            // SPEC:  Otherwise, if V is a class CType C<V1...Vk> and U is a CType parameter
            // SPEC:   with an effective base class which inherits directly or indirectly from
            // SPEC:   C<U1...Uk> then an exact inference is made
            // SPEC:   from each Ui to the corresponding Vi.

            AggregateType pSourceBase = null;

            if (pSource.isClassType())
            {
                pSourceBase = pSource.AsAggregateType().GetBaseClass();
            }
            else if (pSource.IsTypeParameterType())
            {
                pSourceBase = pSource.AsTypeParameterType().GetEffectiveBaseClass();
            }

            while (pSourceBase != null)
            {
                if (pSourceBase.GetOwningAggregate() == pDest.GetOwningAggregate())
                {
                    ExactTypeArgumentInference(pSourceBase, pDest);
                    return true;
                }
                pSourceBase = pSourceBase.GetBaseClass();
            }
            return false;
        }

        ////////////////////////////////////////////////////////////////////////////////

        private bool UpperBoundConstructedInference(CType pSource, CType pDest)
        {
            if (!pSource.IsAggregateType())
            {
                return false;
            }

            AggregateType pConstructedSource = pSource.AsAggregateType();
            TypeArray pSourceArgs = pConstructedSource.GetTypeArgsAll();
            if (pSourceArgs.size == 0)
            {
                return false;
            }

            // SPEC:  Otherwise, if V is a constructed CType C<V1...Vk> and U is
            // SPEC:   C<U1...Uk> then an exact inference,
            // SPEC:   lower bound inference or upper bound inference
            // SPEC:   is made from each Ui to the corresponding Vi.

            if (pDest.IsAggregateType() &&
                pConstructedSource.GetOwningAggregate() == pDest.AsAggregateType().GetOwningAggregate())
            {
                if (pDest.isInterfaceType() || pDest.isDelegateType())
                {
                    UpperBoundTypeArgumentInference(pConstructedSource, pDest.AsAggregateType());
                }
                else
                {
                    ExactTypeArgumentInference(pConstructedSource, pDest.AsAggregateType());
                }
                return true;
            }

            // SPEC:  Otherwise, if U is a class CType C<U1...Uk> and V is a class CType which
            // SPEC:   inherits directly or indirectly from C<V1...Vk> then an exact ...

            if (UpperBoundClassInference(pConstructedSource, pDest))
            {
                return true;
            }

            // SPEC:  Otherwise, if U is an interface CType C<U1...Uk> and V is a class CType
            // SPEC:   or struct CType and there is a unique set V1...Vk such that V directly 
            // SPEC:   or indirectly implements C<V1...Vk> then an exact ...
            // SPEC:  ... and U is an interface CType ...

            if (UpperBoundInterfaceInference(pConstructedSource, pDest))
            {
                return true;
            }

            return false;
        }

        ////////////////////////////////////////////////////////////////////////////////

        private bool MethodGroupReturnTypeInference(EXPR pSource, CType pType)
        {
            // SPEC:  Otherwise, if E is a method group and T is a delegate CType or
            // SPEC:   expression tree CType with parameter types T1...Tk and return
            // SPEC:   CType Tb and overload resolution of E with the types T1...Tk
            // SPEC:   yields a single method with return CType U then a lower-bound
            // SPEC:   inference is made from U to Tb.

            if (!pSource.isMEMGRP())
            {
                return false;
            }
            pType = pType.GetDelegateTypeOfPossibleExpression();
            if (!pType.isDelegateType())
            {
                return false;
            }
            AggregateType pDelegateType = pType.AsAggregateType();
            CType pDelegateReturnType = pDelegateType.GetDelegateReturnType(GetSymbolLoader());
            if (pDelegateReturnType == null)
            {
                return false;
            }
            if (pDelegateReturnType.IsVoidType())
            {
                return false;
            }

            // At this point we are in the second phase; we know that all the input types are fixed.

            TypeArray pDelegateParameters = GetFixedDelegateParameters(pDelegateType);
            if (pDelegateParameters == null)
            {
                return false;
            }

            ArgInfos argInfo = new ArgInfos() { carg = pDelegateParameters.size, types = pDelegateParameters, fHasExprs = false, prgexpr = null };

            var argsBinder = new ExpressionBinder.GroupToArgsBinder(_binder, 0/* flags */, pSource.asMEMGRP(), argInfo, null, false, pDelegateType);

            bool success = argsBinder.Bind(false);
            if (!success)
            {
                return false;
            }

            MethPropWithInst mwi = argsBinder.GetResultsOfBind().GetBestResult();
            CType pMethodReturnType = GetTypeManager().SubstType(mwi.Meth().RetType,
                mwi.GetType(), mwi.TypeArgs);
            if (pMethodReturnType.IsVoidType())
            {
                return false;
            }

            LowerBoundInference(pMethodReturnType, pDelegateReturnType);
            return true;
        }

        ////////////////////////////////////////////////////////////////////////////////

        private bool LowerBoundArrayInference(CType pSource, CType pDest)
        {
            // SPEC:  Otherwise, if U is an array CType Ue[...] and V is either an array
            // SPEC:   CType Ve[...] of the same rank, or if U is a one-dimensional array
            // SPEC:   CType Ue[] and V is one of IEnumerable<Ve>, ICollection<Ve>, 
            // SPEC:   IList<Ve>, IReadOnlyCollection<Ve> or IReadOnlyList<Ve> then
            // SPEC:    if Ue is known to be a reference CType then a lower-bound inference
            // SPEC:     from Ue to Ve is made.
            // SPEC:    otherwise an exact inference from Ue to Ve is made.

            // Consider the following:
            //
            // abstract class B<T> { public abstract M<U>(U u) : where U : T; }
            // class D : B<int[]> {
            //   static void M<X>(X[] x) { }
            //   public override M<U>(U u) { M(u); } // should infer M<int>
            // }

            if (pSource.IsTypeParameterType())
            {
                pSource = pSource.AsTypeParameterType().GetEffectiveBaseClass();
            }

            if (!pSource.IsArrayType())
            {
                return false;
            }
            ArrayType pArraySource = pSource.AsArrayType();
            CType pElementSource = pArraySource.GetElementType();
            CType pElementDest = null;

            if (pDest.IsArrayType())
            {
                ArrayType pArrayDest = pDest.AsArrayType();
                if (pArrayDest.rank != pArraySource.rank)
                {
                    return false;
                }
                pElementDest = pArrayDest.GetElementType();
            }
            else if (pDest.isPredefType(PredefinedType.PT_G_IENUMERABLE) ||
                pDest.isPredefType(PredefinedType.PT_G_ICOLLECTION) ||
                pDest.isPredefType(PredefinedType.PT_G_ILIST) ||
                pDest.isPredefType(PredefinedType.PT_G_IREADONLYCOLLECTION) ||
                pDest.isPredefType(PredefinedType.PT_G_IREADONLYLIST))
            {
                if (pArraySource.rank != 1)
                {
                    return false;
                }
                AggregateType pAggregateDest = pDest.AsAggregateType();
                pElementDest = pAggregateDest.GetTypeArgsThis().Item(0);
            }
            else
            {
                return false;
            }

            if (pElementSource.IsRefType())
            {
                LowerBoundInference(pElementSource, pElementDest);
            }
            else
            {
                ExactInference(pElementSource, pElementDest);
            }
            return true;
        }

            /////////////////////////////////////////////////////////////////////////////////

            public static MethodOrPropertySymbol FindMostDerivedMethod(
                    SymbolLoader symbolLoader,
                    MethodOrPropertySymbol pMethProp,
                    CType pType)
            {
                MethodSymbol method;
                bool bIsIndexer = false;

                if (pMethProp.IsMethodSymbol())
                {
                    method = pMethProp.AsMethodSymbol();
                }
                else
                {
                    PropertySymbol prop = pMethProp.AsPropertySymbol();
                    method = prop.methGet != null ? prop.methGet : prop.methSet;
                    if (method == null)
                    {
                        return null;
                    }
                    bIsIndexer = prop.isIndexer();
                }

                if (!method.isVirtual)
                {
                    return method;
                }

                if (pType == null)
                {
                    // This must be a static call.
                    return method;
                }

                // Now get the slot method.
                if (method.swtSlot != null && method.swtSlot.Meth() != null)
                {
                    method = method.swtSlot.Meth();
                }

                if (!pType.IsAggregateType())
                {
                    // Not something that can have overrides anyway.
                    return method;
                }

                for (AggregateSymbol pAggregate = pType.AsAggregateType().GetOwningAggregate();
                        pAggregate != null && pAggregate.GetBaseAgg() != null;
                        pAggregate = pAggregate.GetBaseAgg())
                {
                    for (MethodOrPropertySymbol meth = symbolLoader.LookupAggMember(method.name, pAggregate, symbmask_t.MASK_MethodSymbol | symbmask_t.MASK_PropertySymbol).AsMethodOrPropertySymbol();
                            meth != null;
                            meth = symbolLoader.LookupNextSym(meth, pAggregate, symbmask_t.MASK_MethodSymbol | symbmask_t.MASK_PropertySymbol).AsMethodOrPropertySymbol())
                    {
                        if (!meth.isOverride)
                        {
                            continue;
                        }
                        if (meth.swtSlot.Sym != null && meth.swtSlot.Sym == method)
                        {
                            if (bIsIndexer)
                            {
                                Debug.Assert(meth.IsMethodSymbol());
                                return meth.AsMethodSymbol().getProperty();
                            }
                            else
                            {
                                return meth;
                            }
                        }
                    }
                }

                // If we get here, it means we can have two cases: one is that we have 
                // a delegate. This is because the delegate invoke method is virtual and is 
                // an override, but we wont have the slots set up correctly, and will 
                // not find the base type in the inheritance hierarchy. The second is that
                // we're calling off of the base itself.
                Debug.Assert(method.parent.IsAggregateSymbol());
                return method;
            }

        /***************************************************************************************************

         There exists an explicit conversion ...
         * From a generic delegate type S to generic delegate type T, provided all of the follow are true:
            o Both types are constructed generic types of the same generic delegate type, D<X1,... Xk>.That is,
              S is D<S1,... Sk> and T is D<T1,... Tk>.
            o S is not compatible with or identical to T.
            o If type parameter Xi is declared to be invariant then Si must be identical to Ti.
            o If type parameter Xi is declared to be covariant ("out") then Si must be convertible 
              to Ti via an identify conversion,  implicit reference conversion, or explicit reference conversion.
            o If type parameter Xi is declared to be contravariant ("in") then either Si must be identical to Ti, 
              or Si and Ti must both be reference types.
        ***************************************************************************************************/
        public static bool HasGenericDelegateExplicitReferenceConversion(SymbolLoader loader, CType pSource, CType pTarget)
        {
            if (!pSource.isDelegateType() ||
                !pTarget.isDelegateType() ||
                pSource.getAggregate() != pTarget.getAggregate() ||
                loader.HasIdentityOrImplicitReferenceConversion(pSource, pTarget))
            {
                return false;
            }

            TypeArray pTypeParams = pSource.getAggregate().GetTypeVarsAll();
            TypeArray pSourceArgs = pSource.AsAggregateType().GetTypeArgsAll();
            TypeArray pTargetArgs = pTarget.AsAggregateType().GetTypeArgsAll();

            Debug.Assert(pTypeParams.size == pSourceArgs.size);
            Debug.Assert(pTypeParams.size == pTargetArgs.size);

            for (int iParam = 0; iParam < pTypeParams.size; ++iParam)
            {
                CType pSourceArg = pSourceArgs.Item(iParam);
                CType pTargetArg = pTargetArgs.Item(iParam);

                // If they're identical then this one is automatically good, so skip it.
                // If we have an error type, then we're in some fault tolerance. Let it through.
                if (pSourceArg == pTargetArg || pTargetArg.IsErrorType() || pSourceArg.IsErrorType())
                {
                    continue;
                }
                TypeParameterType pParam = pTypeParams.Item(iParam).AsTypeParameterType();
                if (pParam.Invariant)
                {
                    return false;
                }

                if (pParam.Covariant)
                {
                    if (!FExpRefConv(loader, pSourceArg, pTargetArg))
                    {
                        return false;
                    }
                }
                else if (pParam.Contravariant)
                {
                    if (!pSourceArg.IsRefType() || !pTargetArg.IsRefType())
                    {
                        return false;
                    }
                }
            }
            return true;
        }

        // Check the constraints of any type arguments in the given Type.
        public static bool CheckConstraints(CSemanticChecker checker, ErrorHandling errHandling, CType type, CheckConstraintsFlags flags)
        {
            type = type.GetNakedType(false);

            if (type.IsNullableType())
            {
                CType typeT = type.AsNullableType().GetAts(checker.GetErrorContext());
                if (typeT != null)
                    type = typeT;
                else
                    type = type.GetNakedType(true);
            }

            if (!type.IsAggregateType())
                return true;

            AggregateType ats = type.AsAggregateType();

            if (ats.GetTypeArgsAll().size == 0)
            {
                // Common case: there are no type vars, so there are no constraints.
                ats.fConstraintsChecked = true;
                ats.fConstraintError = false;
                return true;
            }

            if (ats.fConstraintsChecked)
            {
                // Already checked.
                if (!ats.fConstraintError || (flags & CheckConstraintsFlags.NoDupErrors) != 0)
                {
                    // No errors or no need to report errors again.
                    return !ats.fConstraintError;
                }
            }

            TypeArray typeVars = ats.getAggregate().GetTypeVars();
            TypeArray typeArgsThis = ats.GetTypeArgsThis();
            TypeArray typeArgsAll = ats.GetTypeArgsAll();

            Debug.Assert(typeVars.size == typeArgsThis.size);

            if (!ats.fConstraintsChecked)
            {
                ats.fConstraintsChecked = true;
                ats.fConstraintError = false;
            }

            // Check the outer type first. If CheckConstraintsFlags.Outer is not specified and the
            // outer type has already been checked then don't bother checking it.
            if (ats.outerType != null && ((flags & CheckConstraintsFlags.Outer) != 0 || !ats.outerType.fConstraintsChecked))
            {
                CheckConstraints(checker, errHandling, ats.outerType, flags);
                ats.fConstraintError |= ats.outerType.fConstraintError;
            }

            if (typeVars.size > 0)
                ats.fConstraintError |= !CheckConstraintsCore(checker, errHandling, ats.getAggregate(), typeVars, typeArgsThis, typeArgsAll, null, (flags & CheckConstraintsFlags.NoErrors));

            // Now check type args themselves.
            for (int i = 0; i < typeArgsThis.size; i++)
            {
                CType arg = typeArgsThis.Item(i).GetNakedType(true);
                if (arg.IsAggregateType() && !arg.AsAggregateType().fConstraintsChecked)
                {
                    CheckConstraints(checker, errHandling, arg.AsAggregateType(), flags | CheckConstraintsFlags.Outer);
                    if (arg.AsAggregateType().fConstraintError)
                        ats.fConstraintError = true;
                }
            }
            return !ats.fConstraintError;
        }

            private bool DoesTypeArgumentsContainErrorSym(CType var)
            {
                if (!var.IsAggregateType())
                {
                    return false;
                }

                TypeArray typeVars = var.AsAggregateType().GetTypeArgsAll();
                for (int i = 0; i < typeVars.size; i++)
                {
                    CType type = typeVars.Item(i);
                    if (type.IsErrorType())
                    {
                        return true;
                    }
                    else if (type.IsAggregateType())
                    {
                        // If we have an agg type sym, check if its type args have errors.
                        if (DoesTypeArgumentsContainErrorSym(type))
                        {
                            return true;
                        }
                    }
                }
                return false;
            }

//.........这里部分代码省略.........

            for (int j = itypeMin; j < bnds.size; j++)
            {
                CType typeBnd = bnds.Item(j);
                if (!SatisfiesBound(checker, arg, typeBnd))
                {
                    if (fReportErrors)
                    {
                        // The bound isn't satisfied because of a constaint type. Explain to the user why not.
                        // There are 4 main cases, based on the type of the supplied type argument:
                        //  - reference type, or type parameter known to be a reference type
                        //  - nullable type, from which there is a boxing conversion to the constraint type(see below for details)
                        //  - type varaiable
                        //  - value type
                        // These cases are broken out because: a) The sets of conversions which can be used 
                        // for constraint satisfaction is different based on the type argument supplied, 
                        // and b) Nullable is one funky type, and user's can use all the help they can get
                        // when using it.
                        ErrorCode error;
                        if (arg.IsRefType())
                        {
                            // A reference type can only satisfy bounds to types 
                            // to which they have an implicit reference conversion
                            error = ErrorCode.ERR_GenericConstraintNotSatisfiedRefType;
                        }
                        else if (arg.IsNullableType() && checker.GetSymbolLoader().HasBaseConversion(arg.AsNullableType().GetUnderlyingType(), typeBnd))    // This is inlining FBoxingConv
                        {
                            // nullable types do not satisfy bounds to every type that they are boxable to
                            // They only satisfy bounds of object and ValueType
                            if (typeBnd.isPredefType(PredefinedType.PT_ENUM) || arg.AsNullableType().GetUnderlyingType() == typeBnd)
                            {
                                // Nullable types don't satisfy bounds of EnumType, or the underlying type of the enum
                                // even though the conversion from Nullable to these types is a boxing conversion
                                // This is a rare case, because these bounds can never be directly stated ...
                                // These bounds can only occur when one type paramter is constrained to a second type parameter
                                // and the second type parameter is instantiated with Enum or the underlying type of the first type
                                // parameter
                                error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableEnum;
                            }
                            else
                            {
                                // Nullable types don't satisfy the bounds of any interface type
                                // even when there is a boxing conversion from the Nullable type to 
                                // the interface type. This will be a relatively common scenario
                                // so we cal it out separately from the previous case.
                                Debug.Assert(typeBnd.isInterfaceType());
                                error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableInterface;
                            }
                        }
                        else if (arg.IsTypeParameterType())
                        {
                            // Type variables can satisfy bounds through boxing and type variable conversions
                            Debug.Assert(!arg.IsRefType());
                            error = ErrorCode.ERR_GenericConstraintNotSatisfiedTyVar;
                        }
                        else
                        {
                            // Value types can only satisfy bounds through boxing conversions.
                            // Note that the exceptional case of Nullable types and boxing is handled above.
                            error = ErrorCode.ERR_GenericConstraintNotSatisfiedValType;
                        }
                        errHandling.Error(error, new ErrArgRef(symErr), new ErrArg(typeBnd, ErrArgFlags.Unique), var, new ErrArgRef(arg, ErrArgFlags.Unique));
                    }
                    fError = true;
                }
            }

            // Check the newable constraint.
            if (!var.HasNewConstraint() || arg.IsValType())
            {
                return !fError;
            }

            if (arg.isClassType())
            {
                AggregateSymbol agg = arg.AsAggregateType().getAggregate();

                // Due to late binding nature of IDE created symbols, the AggregateSymbol might not
                // have all the information necessary yet, if it is not fully bound.
                // by calling LookupAggMember, it will ensure that we will update all the
                // information necessary at least for the given method.
                checker.GetSymbolLoader().LookupAggMember(checker.GetNameManager().GetPredefName(PredefinedName.PN_CTOR), agg, symbmask_t.MASK_ALL);

                if (agg.HasPubNoArgCtor() && !agg.IsAbstract())
                {
                    return !fError;
                }
            }
            else if (arg.IsTypeParameterType() && arg.AsTypeParameterType().HasNewConstraint())
            {
                return !fError;
            }

            if (fReportErrors)
            {
                errHandling.ErrorRef(ErrorCode.ERR_NewConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
            }

            return false;
        }

        ////////////////////////////////////////////////////////////////////////////////
        // For a base call we need to remap from the virtual to the specific override 
        // to invoke.  This is also used to map a virtual on pObject (like ToString) to 
        // the specific override when the pObject is a simple type (int, bool, char, 
        // etc). In these cases it is safe to assume that any override won't later be 
        // removed.... We start searching from "typeObj" up the superclass hierarchy 
        // until we find a method with an exact signature match.

        public static void RemapToOverride(SymbolLoader symbolLoader, SymWithType pswt, CType typeObj)
        {
            // For a property/indexer we remap the accessors, not the property/indexer.
            // Since every event has both accessors we remap the event instead of the accessors.
            Debug.Assert(pswt && (pswt.Sym.IsMethodSymbol() || pswt.Sym.IsEventSymbol() || pswt.Sym.IsMethodOrPropertySymbol()));
            Debug.Assert(typeObj != null);

            // Don't remap static or interface methods.
            if (typeObj.IsNullableType())
            {
                typeObj = typeObj.AsNullableType().GetAts(symbolLoader.GetErrorContext());
                if (typeObj == null)
                {
                    VSFAIL("Why did GetAts return null?");
                    return;
                }
            }

            // Don't remap non-virtual members
            if (!typeObj.IsAggregateType() || typeObj.isInterfaceType() || !pswt.Sym.IsVirtual())
            {
                return;
            }

            symbmask_t mask = pswt.Sym.mask();

            AggregateType atsObj = typeObj.AsAggregateType();

            // Search for an override version of the method.
            while (atsObj != null && atsObj.getAggregate() != pswt.Sym.parent)
            {
                for (Symbol symT = symbolLoader.LookupAggMember(pswt.Sym.name, atsObj.getAggregate(), mask);
                     symT != null;
                     symT = symbolLoader.LookupNextSym(symT, atsObj.getAggregate(), mask))
                {
                    if (symT.IsOverride() && (symT.SymBaseVirtual() == pswt.Sym || symT.SymBaseVirtual() == pswt.Sym.SymBaseVirtual()))
                    {
                        pswt.Set(symT, atsObj);
                        return;
                    }
                }
                atsObj = atsObj.GetBaseClass();
            }
        }

        private AggregateType GetEnumBinOpType(ExpressionKind ek, CType argType1, CType argType2, out AggregateType ppEnumType)
        {
            Debug.Assert(argType1.isEnumType() || argType2.isEnumType());

            AggregateType type1 = argType1.AsAggregateType();
            AggregateType type2 = argType2.AsAggregateType();

            AggregateType typeEnum = type1.isEnumType() ? type1 : type2;

            Debug.Assert(type1 == typeEnum || type1 == typeEnum.underlyingEnumType());
            Debug.Assert(type2 == typeEnum || type2 == typeEnum.underlyingEnumType());

            AggregateType typeDst = typeEnum;

            switch (ek)
            {
                case ExpressionKind.EK_BITAND:
                case ExpressionKind.EK_BITOR:
                case ExpressionKind.EK_BITXOR:
                    Debug.Assert(type1 == type2);
                    break;

                case ExpressionKind.EK_ADD:
                    Debug.Assert(type1 != type2);
                    break;

                case ExpressionKind.EK_SUB:
                    if (type1 == type2)
                        typeDst = typeEnum.underlyingEnumType();
                    break;

                default:
                    Debug.Assert(ek.isRelational());
                    typeDst = GetReqPDT(PredefinedType.PT_BOOL);
                    break;
            }

            ppEnumType = typeEnum;
            return typeDst;
        }

        public static bool TypeContainsTyVars(CType type, TypeArray typeVars)
        {
        LRecurse:  // Label used for "tail" recursion.
            switch (type.GetTypeKind())
            {
                default:
                    Debug.Assert(false, "Bad Symbol kind in TypeContainsTyVars");
                    return false;

                case TypeKind.TK_UnboundLambdaType:
                case TypeKind.TK_BoundLambdaType:
                case TypeKind.TK_NullType:
                case TypeKind.TK_VoidType:
                case TypeKind.TK_OpenTypePlaceholderType:
                case TypeKind.TK_MethodGroupType:
                    return false;

                case TypeKind.TK_ArrayType:
                case TypeKind.TK_NullableType:
                case TypeKind.TK_ParameterModifierType:
                case TypeKind.TK_PointerType:
                    type = type.GetBaseOrParameterOrElementType();
                    goto LRecurse;

                case TypeKind.TK_AggregateType:
                    { // BLOCK
                        AggregateType ats = type.AsAggregateType();

                        for (int i = 0; i < ats.GetTypeArgsAll().Size; i++)
                        {
                            if (TypeContainsTyVars(ats.GetTypeArgsAll().Item(i), typeVars))
                            {
                                return true;
                            }
                        }
                    }
                    return false;

                case TypeKind.TK_ErrorType:
                    if (type.AsErrorType().HasParent())
                    {
                        ErrorType err = type.AsErrorType();
                        Debug.Assert(err.nameText != null && err.typeArgs != null);

                        for (int i = 0; i < err.typeArgs.Size; i++)
                        {
                            if (TypeContainsTyVars(err.typeArgs.Item(i), typeVars))
                            {
                                return true;
                            }
                        }
                        if (err.HasTypeParent())
                        {
                            type = err.GetTypeParent();
                            goto LRecurse;
                        }
                    }
                    return false;

                case TypeKind.TK_TypeParameterType:
                    if (typeVars != null && typeVars.Size > 0)
                    {
                        int ivar = type.AsTypeParameterType().GetIndexInTotalParameters();
                        return ivar < typeVars.Size && type == typeVars.Item(ivar);
                    }
                    return true;
            }
        }