IsRefType() public method

public IsRefType ( ) : bool
return bool
Esempio n. 1
0
        private bool TryArrayVarianceAdjustmentToGetAccessibleType(CSemanticChecker semanticChecker, BindingContext bindingContext, ArrayType typeSrc, out CType typeDst)
        {
            Debug.Assert(typeSrc != null);

            typeDst = null;

            // We are here because we have an array type with an inaccessible element type. If possible,
            // we should create a new array type that has an accessible element type for which a
            // conversion exists.

            CType elementType = typeSrc.GetElementType();

            if (!elementType.IsRefType())
            {
                // Covariant array conversions exist for reference types only.
                return(false);
            }

            CType intermediateType;

            if (GetBestAccessibleType(semanticChecker, bindingContext, elementType, out intermediateType))
            {
                typeDst = this.GetArray(intermediateType, typeSrc.rank, typeSrc.IsSZArray);

                Debug.Assert(semanticChecker.CheckTypeAccess(typeDst, bindingContext.ContextForMemberLookup));
                return(true);
            }

            return(false);
        }
Esempio n. 2
0
        /***************************************************************************************************
        *
        *  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 = ((AggregateType)pSource).GetTypeArgsAll();
            TypeArray pTargetArgs = ((AggregateType)pTarget).GetTypeArgsAll();

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

            for (int iParam = 0; iParam < pTypeParams.Count; ++iParam)
            {
                CType pSourceArg = pSourceArgs[iParam];
                CType pTargetArg = pTargetArgs[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)
                {
                    continue;
                }

                TypeParameterType pParam = (TypeParameterType)pTypeParams[iParam];
                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);
        }
Esempio n. 3
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        public bool HasImplicitBoxingConversion(CType pSource, CType pDest)
        {
            Debug.Assert(pSource != null);
            Debug.Assert(pDest != null);

            // Certain type parameter conversions are classified as boxing conversions.

            if (pSource.IsTypeParameterType() &&
                HasImplicitBoxingTypeParameterConversion(pSource.AsTypeParameterType(), pDest))
            {
                return(true);
            }

            // The rest of the boxing conversions only operate when going from a value type
            // to a reference type.

            if (!pSource.IsValType() || !pDest.IsRefType())
            {
                return(false);
            }

            // A boxing conversion exists from a nullable type to a reference type
            // if and only if a boxing conversion exists from the underlying type.

            if (pSource.IsNullableType())
            {
                return(HasImplicitBoxingConversion(pSource.AsNullableType().GetUnderlyingType(), pDest));
            }

            // A boxing conversion exists from any non-nullable value type to object,
            // to System.ValueType, and to any interface type implemented by the
            // non-nullable value type.  Furthermore, an enum type can be converted
            // to the type System.Enum.

            // We set the base class of the structs to System.ValueType, System.Enum, etc,
            // so we can just check here.

            if (IsBaseClass(pSource, pDest))
            {
                return(true);
            }
            if (HasAnyBaseInterfaceConversion(pSource, pDest))
            {
                return(true);
            }
            return(false);
        }
Esempio n. 4
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        private bool HasImplicitBoxingConversion(CType pSource, CType pDest)
        {
            Debug.Assert(pSource != null);
            Debug.Assert(pDest != null);
            Debug.Assert(!(pSource is TypeParameterType));

            // The rest of the boxing conversions only operate when going from a value type
            // to a reference type.

            if (!pDest.IsRefType())
            {
                return(false);
            }

            // A boxing conversion exists from a nullable type to a reference type
            // if and only if a boxing conversion exists from the underlying type.
            if (pSource is NullableType nubSource)
            {
                pSource = nubSource.UnderlyingType; // pSource.IsValType() known to be true.
            }
            else if (!pSource.IsValType())
            {
                return(false);
            }


            // A boxing conversion exists from any non-nullable value type to object,
            // to System.ValueType, and to any interface type implemented by the
            // non-nullable value type.  Furthermore, an enum type can be converted
            // to the type System.Enum.

            // We set the base class of the structs to System.ValueType, System.Enum, etc,
            // so we can just check here.

            return(IsBaseClass(pSource, pDest) || HasAnyBaseInterfaceConversion(pSource, pDest));
        }
Esempio n. 5
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        private static bool CheckSingleConstraint(CSemanticChecker checker, ErrorHandling errHandling, Symbol symErr, TypeParameterType var, CType arg, TypeArray typeArgsCls, TypeArray typeArgsMeth, CheckConstraintsFlags flags)
        {
            bool fReportErrors = 0 == (flags & CheckConstraintsFlags.NoErrors);

            if (arg is OpenTypePlaceholderType)
            {
                return(true);
            }

            if (arg is ErrorType)
            {
                // Error should have been reported previously.
                return(false);
            }

            if (checker.CheckBogus(arg))
            {
                if (fReportErrors)
                {
                    errHandling.ErrorRef(ErrorCode.ERR_BogusType, arg);
                }

                return(false);
            }

            if (arg is PointerType)
            {
                if (fReportErrors)
                {
                    errHandling.Error(ErrorCode.ERR_BadTypeArgument, arg);
                }

                return(false);
            }

            if (arg.isStaticClass())
            {
                if (fReportErrors)
                {
                    checker.ReportStaticClassError(null, arg, ErrorCode.ERR_GenericArgIsStaticClass);
                }

                return(false);
            }

            bool fError = false;

            if (var.HasRefConstraint() && !arg.IsRefType())
            {
                if (fReportErrors)
                {
                    errHandling.ErrorRef(ErrorCode.ERR_RefConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
                }

                fError = true;
            }

            TypeArray bnds     = checker.GetSymbolLoader().GetTypeManager().SubstTypeArray(var.GetBounds(), typeArgsCls, typeArgsMeth);
            int       itypeMin = 0;

            if (var.HasValConstraint())
            {
                // If we have a type variable that is constrained to a value type, then we
                // want to check if its a nullable type, so that we can report the
                // constraint error below. In order to do this however, we need to check
                // that either the type arg is not a value type, or it is a nullable type.
                //
                // To check whether or not its a nullable type, we need to get the resolved
                // bound from the type argument and check against that.

                bool bIsValueType = arg.IsValType();
                bool bIsNullable  = arg is NullableType;
                if (bIsValueType && arg is TypeParameterType typeArg)
                {
                    TypeArray pArgBnds = typeArg.GetBounds();
                    if (pArgBnds.Count > 0)
                    {
                        bIsNullable = pArgBnds[0] is NullableType;
                    }
                }

                if (!bIsValueType || bIsNullable)
                {
                    if (fReportErrors)
                    {
                        errHandling.ErrorRef(ErrorCode.ERR_ValConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
                    }

                    fError = true;
                }

                // Since FValCon() is set it is redundant to check System.ValueType as well.
                if (bnds.Count != 0 && bnds[0].isPredefType(PredefinedType.PT_VALUE))
                {
                    itypeMin = 1;
                }
            }

            for (int j = itypeMin; j < bnds.Count; j++)
            {
                CType typeBnd = bnds[j];
                if (!SatisfiesBound(checker, arg, typeBnd))
                {
                    if (fReportErrors)
                    {
                        // The bound isn't satisfied because of a constraint 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 variable
                        //  - 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 is NullableType nubArg && checker.GetSymbolLoader().HasBaseConversion(nubArg.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) || nubArg.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 is TypeParameterType)
                        {
                            // 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;
                }
            }
Esempio n. 6
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        /***************************************************************************************************
            Determine whether there is an explicit or implicit reference conversion (or identity conversion)
            from typeSrc to typeDst. This is when:
         
         13.2.3 Explicit reference conversions
        
        The explicit reference conversions are:
        *   From object to any reference-type.
        *   From any class-type S to any class-type T, provided S is a base class of T.
        *   From any class-type S to any interface-type T, provided S is not sealed and provided S does not implement T.
        *   From any interface-type S to any class-type T, provided T is not sealed or provided T implements S.
        *   From any interface-type S to any interface-type T, provided S is not derived from T.
        *   From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
            o   S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
            o   An explicit reference conversion exists from SE to TE.
        *   From System.Array and the interfaces it implements, to any array-type.
        *   From System.Delegate and the interfaces it implements, to any delegate-type.
        *   From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces, provided there is an explicit reference conversion from S to T.
        *   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.
        *   From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T are the same type or there is an implicit or explicit reference conversion from S to T.
        
        For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
        *   From the effective base class C of T to T and from any base class of C to T.
        *   From any interface-type to T.
        *   From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
        *   From a type-parameter U to T provided that T depends on U (§25.7). [Note: Since T is known to be a reference type, within the scope of T, the run-time type of U will always be a reference type, even if U is not known to be a reference type at compile-time. end note]
        
            * Both src and dst are reference types and there is a builtin explicit conversion from
              src to dst.
            * Or src is a reference type and dst is a base type of src (in which case the conversion is
              implicit as well).
            * Or dst is a reference type and src is a base type of dst.
         
            The latter two cases can happen with type variables even though the other type variable is not
            a reference type.
        ***************************************************************************************************/
        public static bool FExpRefConv(SymbolLoader loader, CType typeSrc, CType typeDst)
        {
            Debug.Assert(typeSrc != null);
            Debug.Assert(typeDst != null);
            if (typeSrc.IsRefType() && typeDst.IsRefType())
            {
                // is there an implicit reference conversion in either direction?
                // this handles the bulk of the cases ...
                if (loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst) ||
                    loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc))
                {
                    return true;
                }

                // For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
                // •    From any interface-type to T.
                // •    From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
                if (typeSrc.isInterfaceType() && typeDst.IsTypeParameterType())
                {
                    return true;
                }
                if (typeSrc.IsTypeParameterType() && typeDst.isInterfaceType())
                {
                    return true;
                }

                // * From any class-type S to any interface-type T, provided S is not sealed
                // * From any interface-type S to any class-type T, provided T is not sealed
                // * From any interface-type S to any interface-type T, provided S is not derived from T.
                if (typeSrc.IsAggregateType() && typeDst.IsAggregateType())
                {
                    AggregateSymbol aggSrc = typeSrc.AsAggregateType().getAggregate();
                    AggregateSymbol aggDest = typeDst.AsAggregateType().getAggregate();

                    if ((aggSrc.IsClass() && !aggSrc.IsSealed() && aggDest.IsInterface()) ||
                        (aggSrc.IsInterface() && aggDest.IsClass() && !aggDest.IsSealed()) ||
                        (aggSrc.IsInterface() && aggDest.IsInterface()))
                    {
                        return true;
                    }
                }

                // *    From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
                //     o    S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
                //     o    An explicit reference conversion exists from SE to TE.
                if (typeSrc.IsArrayType() && typeDst.IsArrayType())
                {
                    return typeSrc.AsArrayType().rank == typeDst.AsArrayType().rank && FExpRefConv(loader, typeSrc.AsArrayType().GetElementType(), typeDst.AsArrayType().GetElementType());
                }

                // *    From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> 
                //      and their base interfaces, provided there is an explicit reference conversion from S to T.
                if (typeSrc.IsArrayType())
                {
                    if (typeSrc.AsArrayType().rank != 1 ||
                        !typeDst.isInterfaceType() || typeDst.AsAggregateType().GetTypeArgsAll().Size != 1)
                    {
                        return false;
                    }

                    AggregateSymbol aggIList = loader.GetOptPredefAgg(PredefinedType.PT_G_ILIST);
                    AggregateSymbol aggIReadOnlyList = loader.GetOptPredefAgg(PredefinedType.PT_G_IREADONLYLIST);

                    if ((aggIList == null ||
                        !loader.IsBaseAggregate(aggIList, typeDst.AsAggregateType().getAggregate())) &&
                        (aggIReadOnlyList == null ||
                        !loader.IsBaseAggregate(aggIReadOnlyList, typeDst.AsAggregateType().getAggregate())))
                    {
                        return false;
                    }

                    return FExpRefConv(loader, typeSrc.AsArrayType().GetElementType(), typeDst.AsAggregateType().GetTypeArgsAll().Item(0));
                }

                if (typeDst.IsArrayType() && typeSrc.IsAggregateType())
                {
                    // * From System.Array and the interfaces it implements, to any array-type.
                    if (loader.HasIdentityOrImplicitReferenceConversion(loader.GetReqPredefType(PredefinedType.PT_ARRAY), typeSrc))
                    {
                        return true;
                    }

                    // *    From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a 
                    //      one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to 
                    //      System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T
                    //      are the same type or there is an implicit or explicit reference conversion from S to T.
                    ArrayType arrayDest = typeDst.AsArrayType();
                    AggregateType aggtypeSrc = typeSrc.AsAggregateType();
                    if (arrayDest.rank != 1 || !typeSrc.isInterfaceType() ||
                        aggtypeSrc.GetTypeArgsAll().Size != 1)
                    {
                        return false;
                    }

                    AggregateSymbol aggIList = loader.GetOptPredefAgg(PredefinedType.PT_G_ILIST);
                    AggregateSymbol aggIReadOnlyList = loader.GetOptPredefAgg(PredefinedType.PT_G_IREADONLYLIST);

                    if ((aggIList == null ||
                        !loader.IsBaseAggregate(aggIList, aggtypeSrc.getAggregate())) &&
                        (aggIReadOnlyList == null ||
                        !loader.IsBaseAggregate(aggIReadOnlyList, aggtypeSrc.getAggregate())))
                    {
                        return false;
                    }

                    CType typeArr = arrayDest.GetElementType();
                    CType typeLst = aggtypeSrc.GetTypeArgsAll().Item(0);

                    Debug.Assert(!typeArr.IsNeverSameType());
                    return typeArr == typeLst || FExpRefConv(loader, typeArr, typeLst);
                }
                if (HasGenericDelegateExplicitReferenceConversion(loader, typeSrc, typeDst))
                {
                    return true;
                }
            }
            else if (typeSrc.IsRefType())
            {
                // conversion of T . U, where T : class, U
                // .. these constraints implies where U : class
                return loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst);
            }
            else if (typeDst.IsRefType())
            {
                // conversion of T . U, where U : class, T 
                // .. these constraints implies where T : class
                return loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc);
            }
            return false;
        }
Esempio n. 7
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        // WARNING: These methods do not precisely match the spec.
        // WARNING: For example most also return true for identiy conversions,
        // WARNING: FExpRefConv includes all Implict and Explicit reference conversions.

        /***************************************************************************************************
            Determine whether there is an implicit reference conversion from typeSrc to typeDst. This is
            when the source is a reference type and the destination is a base type of the source. Note
            that typeDst.IsRefType() may still return false (when both are type parameters).
        ***************************************************************************************************/
        public static bool FImpRefConv(SymbolLoader loader, CType typeSrc, CType typeDst)
        {
            return typeSrc.IsRefType() && loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst);
        }
Esempio n. 8
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        private static bool CheckSingleConstraint(CSemanticChecker checker, ErrorHandling errHandling, Symbol symErr, TypeParameterType var, CType arg, TypeArray typeArgsCls, TypeArray typeArgsMeth, CheckConstraintsFlags flags)
        {
            bool fReportErrors = 0 == (flags & CheckConstraintsFlags.NoErrors);

            if (arg.IsOpenTypePlaceholderType())
            {
                return true;
            }

            if (arg.IsErrorType())
            {
                // Error should have been reported previously.
                return false;
            }

            if (checker.CheckBogus(arg))
            {
                if (fReportErrors)
                {
                    errHandling.ErrorRef(ErrorCode.ERR_BogusType, arg);
                }

                return false;
            }

            if (arg.IsPointerType() || arg.isSpecialByRefType())
            {
                if (fReportErrors)
                {
                    errHandling.Error(ErrorCode.ERR_BadTypeArgument, arg);
                }

                return false;
            }

            if (arg.isStaticClass())
            {
                if (fReportErrors)
                {
                    checker.ReportStaticClassError(null, arg, ErrorCode.ERR_GenericArgIsStaticClass);
                }

                return false;
            }

            bool fError = false;
            if (var.HasRefConstraint() && !arg.IsRefType())
            {
                if (fReportErrors)
                {
                    errHandling.ErrorRef(ErrorCode.ERR_RefConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
                }

                fError = true;
            }

            TypeArray bnds = checker.GetSymbolLoader().GetTypeManager().SubstTypeArray(var.GetBounds(), typeArgsCls, typeArgsMeth);
            int itypeMin = 0;

            if (var.HasValConstraint())
            {
                // If we have a type variable that is constrained to a value type, then we
                // want to check if its a nullable type, so that we can report the 
                // constraint error below. In order to do this however, we need to check 
                // that either the type arg is not a value type, or it is a nullable type.
                //
                // To check whether or not its a nullable type, we need to get the resolved
                // bound from the type argument and check against that.

                bool bIsValueType = arg.IsValType();
                bool bIsNullable = arg.IsNullableType();
                if (bIsValueType && arg.IsTypeParameterType())
                {
                    TypeArray pArgBnds = arg.AsTypeParameterType().GetBounds();
                    if (pArgBnds.size > 0)
                    {
                        bIsNullable = pArgBnds.Item(0).IsNullableType();
                    }
                }

                if (!bIsValueType || bIsNullable)
                {
                    if (fReportErrors)
                    {
                        errHandling.ErrorRef(ErrorCode.ERR_ValConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
                    }

                    fError = true;
                }

                // Since FValCon() is set it is redundant to check System.ValueType as well.
                if (bnds.size != 0 && bnds.Item(0).isPredefType(PredefinedType.PT_VALUE))
                {
                    itypeMin = 1;
                }
            }

            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;
        }
Esempio n. 9
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        private bool HasImplicitReferenceConversion(CType pSource, CType pDest)
        {
            Debug.Assert(pSource != null);
            Debug.Assert(pDest != null);
            Debug.Assert(!(pSource is TypeParameterType));

            // The implicit reference conversions are:
            // * From any reference type to Object.
            if (pSource.IsRefType() && pDest.isPredefType(PredefinedType.PT_OBJECT))
            {
                return(true);
            }

            if (pSource is AggregateType aggSource)
            {
                if (pDest is AggregateType aggDest)
                {
                    switch (aggSource.GetOwningAggregate().AggKind())
                    {
                    case AggKindEnum.Class:
                        switch (aggDest.GetOwningAggregate().AggKind())
                        {
                        case AggKindEnum.Class:
                            // * From any class type S to any class type T provided S is derived from T.
                            return(IsBaseClass(aggSource, aggDest));

                        case AggKindEnum.Interface:
                            // ORIGINAL RULES:
                            //    // * From any class type S to any interface type T provided S implements T.
                            //    if (pSource.isClassType() && pDest.isInterfaceType() && IsBaseInterface(pSource, pDest))
                            //    {
                            //        return true;
                            //    }
                            //    // * from any interface type S to any interface type T, provided S is derived from T.
                            //    if (pSource.isInterfaceType() && pDest.isInterfaceType() && IsBaseInterface(pSource, pDest))
                            //    {
                            //        return true;
                            //    }

                            // VARIANCE EXTENSIONS:
                            // * From any class type S to any interface type T provided S implements an interface
                            //   convertible to T.
                            // * From any interface type S to any interface type T provided S implements an interface
                            //   convertible to T.
                            // * From any interface type S to any interface type T provided S is not T and S is
                            //   an interface convertible to T.

                            return(HasAnyBaseInterfaceConversion(aggSource, aggDest));
                        }

                        break;

                    case AggKindEnum.Interface:
                        if (aggDest.isInterfaceType())
                        {
                            return(HasAnyBaseInterfaceConversion(aggSource, aggDest) ||
                                   HasInterfaceConversion(aggSource, aggDest));
                        }

                        break;

                    case AggKindEnum.Delegate:
                        // * From any delegate type to System.Delegate
                        //
                        // SPEC OMISSION:
                        //
                        // The spec should actually say
                        //
                        // * From any delegate type to System.Delegate
                        // * From any delegate type to System.MulticastDelegate
                        // * From any delegate type to any interface implemented by System.MulticastDelegate
                        if (aggDest.isPredefType(PredefinedType.PT_MULTIDEL) ||
                            aggDest.isPredefType(PredefinedType.PT_DELEGATE) || IsBaseInterface(
                                GetPredefindType(PredefinedType.PT_MULTIDEL), aggDest))
                        {
                            return(true);
                        }

                        // VARIANCE EXTENSION:
                        // * From any delegate type S to a delegate type T provided S is not T and
                        //   S is a delegate convertible to T
                        return(pDest.isDelegateType() && HasDelegateConversion(aggSource, aggDest));
                    }
                }
            }
            else if (pSource is ArrayType arrSource)
            {
                // * From an array type S with an element type SE to an array type T with element type TE
                //   provided that all of the following are true:
                //   * S and T differ only in element type. In other words, S and T have the same number of dimensions.
                //   * Both SE and TE are reference types.
                //   * An implicit reference conversion exists from SE to TE.
                if (pDest is ArrayType arrDest)
                {
                    return(HasCovariantArrayConversion(arrSource, arrDest));
                }

                if (pDest is AggregateType aggDest)
                {
                    // * From any array type to System.Array or any interface implemented by System.Array.
                    if (aggDest.isPredefType(PredefinedType.PT_ARRAY) ||
                        IsBaseInterface(GetPredefindType(PredefinedType.PT_ARRAY), aggDest))
                    {
                        return(true);
                    }

                    // * From a single-dimensional array type S[] to IList<T> and its base
                    //   interfaces, provided that there is an implicit identity or reference
                    //   conversion from S to T.
                    return(HasArrayConversionToInterface(arrSource, pDest));
                }
            }
            else if (pSource is NullType)
            {
                // * From the null literal to any reference type
                // NOTE: We extend the specification here. The C# 3.0 spec does not describe
                // a "null type". Rather, it says that the null literal is typeless, and is
                // convertible to any reference or nullable type. However, the C# 2.0 and 3.0
                // implementations have a "null type" which some expressions other than the
                // null literal may have. (For example, (null??null), which is also an
                // extension to the specification.)
                return(pDest.IsRefType() || pDest is NullableType);
            }

            return(false);
        }
Esempio n. 10
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        /***************************************************************************************************
        *   Determine whether there is an explicit or implicit reference conversion (or identity conversion)
        *   from typeSrc to typeDst. This is when:
        *
        *  13.2.3 Explicit reference conversions
        *
        *  The explicit reference conversions are:
        *   From object to any reference-type.
        *   From any class-type S to any class-type T, provided S is a base class of T.
        *   From any class-type S to any interface-type T, provided S is not sealed and provided S does not implement T.
        *   From any interface-type S to any class-type T, provided T is not sealed or provided T implements S.
        *   From any interface-type S to any interface-type T, provided S is not derived from T.
        *   From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
        *   o   S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
        *   o   An explicit reference conversion exists from SE to TE.
        *   From System.Array and the interfaces it implements, to any array-type.
        *   From System.Delegate and the interfaces it implements, to any delegate-type.
        *   From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces, provided there is an explicit reference conversion from S to T.
        *   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.
        *   From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T are the same type or there is an implicit or explicit reference conversion from S to T.
        *
        *  For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
        *   From the effective base class C of T to T and from any base class of C to T.
        *   From any interface-type to T.
        *   From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
        *   From a type-parameter U to T provided that T depends on U (§25.7). [Note: Since T is known to be a reference type, within the scope of T, the run-time type of U will always be a reference type, even if U is not known to be a reference type at compile-time. end note]
        *
        * Both src and dst are reference types and there is a builtin explicit conversion from
        *     src to dst.
        * Or src is a reference type and dst is a base type of src (in which case the conversion is
        *     implicit as well).
        * Or dst is a reference type and src is a base type of dst.
        *
        *   The latter two cases can happen with type variables even though the other type variable is not
        *   a reference type.
        ***************************************************************************************************/
        public static bool FExpRefConv(SymbolLoader loader, CType typeSrc, CType typeDst)
        {
            Debug.Assert(typeSrc != null);
            Debug.Assert(typeDst != null);
            if (typeSrc.IsRefType() && typeDst.IsRefType())
            {
                // is there an implicit reference conversion in either direction?
                // this handles the bulk of the cases ...
                if (loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst) ||
                    loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc))
                {
                    return(true);
                }

                // For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
                // •    From any interface-type to T.
                // •    From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
                if (typeSrc.isInterfaceType() && typeDst is TypeParameterType)
                {
                    return(true);
                }
                if (typeSrc is TypeParameterType && typeDst.isInterfaceType())
                {
                    return(true);
                }

                // * From any class-type S to any interface-type T, provided S is not sealed
                // * From any interface-type S to any class-type T, provided T is not sealed
                // * From any interface-type S to any interface-type T, provided S is not derived from T.
                if (typeSrc is AggregateType atSrc && typeDst is AggregateType atDst)
                {
                    AggregateSymbol aggSrc  = atSrc.getAggregate();
                    AggregateSymbol aggDest = atDst.getAggregate();

                    if ((aggSrc.IsClass() && !aggSrc.IsSealed() && aggDest.IsInterface()) ||
                        (aggSrc.IsInterface() && aggDest.IsClass() && !aggDest.IsSealed()) ||
                        (aggSrc.IsInterface() && aggDest.IsInterface()))
                    {
                        return(true);
                    }
                }

                if (typeSrc is ArrayType arrSrc)
                {
                    // *    From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
                    //     o    S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
                    //     o    An explicit reference conversion exists from SE to TE.
                    if (typeDst is ArrayType arrDst)
                    {
                        return(arrSrc.rank == arrDst.rank &&
                               arrSrc.IsSZArray == arrDst.IsSZArray &&
                               FExpRefConv(loader, arrSrc.GetElementType(), arrDst.GetElementType()));
                    }

                    // *    From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T>
                    //      and their base interfaces, provided there is an explicit reference conversion from S to T.
                    if (!arrSrc.IsSZArray ||
                        !typeDst.isInterfaceType())
                    {
                        return(false);
                    }

                    AggregateType aggDst      = (AggregateType)typeDst;
                    TypeArray     typeArgsAll = aggDst.GetTypeArgsAll();

                    if (typeArgsAll.Count != 1)
                    {
                        return(false);
                    }

                    AggregateSymbol aggIList         = loader.GetPredefAgg(PredefinedType.PT_G_ILIST);
                    AggregateSymbol aggIReadOnlyList = loader.GetPredefAgg(PredefinedType.PT_G_IREADONLYLIST);

                    if ((aggIList == null ||
                         !SymbolLoader.IsBaseAggregate(aggIList, aggDst.getAggregate())) &&
                        (aggIReadOnlyList == null ||
                         !SymbolLoader.IsBaseAggregate(aggIReadOnlyList, aggDst.getAggregate())))
                    {
                        return(false);
                    }

                    return(FExpRefConv(loader, arrSrc.GetElementType(), typeArgsAll[0]));
                }

                if (typeDst is ArrayType arrayDest && typeSrc is AggregateType aggtypeSrc)
                {
                    // * From System.Array and the interfaces it implements, to any array-type.
                    if (loader.HasIdentityOrImplicitReferenceConversion(loader.GetPredefindType(PredefinedType.PT_ARRAY), typeSrc))
                    {
                        return(true);
                    }

                    // *    From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a
                    //      one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to
                    //      System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T
                    //      are the same type or there is an implicit or explicit reference conversion from S to T.
                    if (!arrayDest.IsSZArray || !typeSrc.isInterfaceType() ||
                        aggtypeSrc.GetTypeArgsAll().Count != 1)
                    {
                        return(false);
                    }

                    AggregateSymbol aggIList         = loader.GetPredefAgg(PredefinedType.PT_G_ILIST);
                    AggregateSymbol aggIReadOnlyList = loader.GetPredefAgg(PredefinedType.PT_G_IREADONLYLIST);

                    if ((aggIList == null ||
                         !SymbolLoader.IsBaseAggregate(aggIList, aggtypeSrc.getAggregate())) &&
                        (aggIReadOnlyList == null ||
                         !SymbolLoader.IsBaseAggregate(aggIReadOnlyList, aggtypeSrc.getAggregate())))
                    {
                        return(false);
                    }

                    CType typeArr = arrayDest.GetElementType();
                    CType typeLst = aggtypeSrc.GetTypeArgsAll()[0];

                    Debug.Assert(!(typeArr is MethodGroupType));
                    return(typeArr == typeLst || FExpRefConv(loader, typeArr, typeLst));
                }
                if (HasGenericDelegateExplicitReferenceConversion(loader, typeSrc, typeDst))
                {
                    return(true);
                }
            }
            else if (typeSrc.IsRefType())
            {
                // conversion of T . U, where T : class, U
                // .. these constraints implies where U : class
                return(loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst));
            }
            else if (typeDst.IsRefType())
            {
                // conversion of T . U, where U : class, T
                // .. these constraints implies where T : class
                return(loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc));
            }
            return(false);
        }
Esempio n. 11
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        // WARNING: These methods do not precisely match the spec.
        // WARNING: For example most also return true for identity conversions,
        // WARNING: FExpRefConv includes all Implicit and Explicit reference conversions.

        /***************************************************************************************************
        *   Determine whether there is an implicit reference conversion from typeSrc to typeDst. This is
        *   when the source is a reference type and the destination is a base type of the source. Note
        *   that typeDst.IsRefType() may still return false (when both are type parameters).
        ***************************************************************************************************/
        public static bool FImpRefConv(SymbolLoader loader, CType typeSrc, CType typeDst)
        {
            return(typeSrc.IsRefType() && loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst));
        }
Esempio n. 12
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        public bool HasImplicitBoxingConversion(CType pSource, CType pDest)
        {
            Debug.Assert(pSource != null);
            Debug.Assert(pDest != null);

            // Certain type parameter conversions are classified as boxing conversions.

            if (pSource.IsTypeParameterType() &&
                HasImplicitBoxingTypeParameterConversion(pSource.AsTypeParameterType(), pDest))
            {
                return true;
            }

            // The rest of the boxing conversions only operate when going from a value type
            // to a reference type.

            if (!pSource.IsValType() || !pDest.IsRefType())
            {
                return false;
            }

            // A boxing conversion exists from a nullable type to a reference type
            // if and only if a boxing conversion exists from the underlying type.

            if (pSource.IsNullableType())
            {
                return HasImplicitBoxingConversion(pSource.AsNullableType().GetUnderlyingType(), pDest);
            }

            // A boxing conversion exists from any non-nullable value type to object,
            // to System.ValueType, and to any interface type implemented by the
            // non-nullable value type.  Furthermore, an enum type can be converted
            // to the type System.Enum.

            // We set the base class of the structs to System.ValueType, System.Enum, etc,
            // so we can just check here.

            if (IsBaseClass(pSource, pDest))
            {
                return true;
            }
            if (HasAnyBaseInterfaceConversion(pSource, pDest))
            {
                return true;
            }
            return false;
        }
Esempio n. 13
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        public bool HasImplicitReferenceConversion(CType pSource, CType pDest)
        {
            Debug.Assert(pSource != null);
            Debug.Assert(pDest != null);

            // The implicit reference conversions are:
            // * From any reference type to Object.
            if (pSource.IsRefType() && pDest.isPredefType(PredefinedType.PT_OBJECT))
            {
                return true;
            }
            // * From any class type S to any class type T provided S is derived from T.
            if (pSource.isClassType() && pDest.isClassType() && IsBaseClass(pSource, pDest))
            {
                return true;
            }

            // ORIGINAL RULES:
            //    // * From any class type S to any interface type T provided S implements T.
            //    if (pSource.isClassType() && pDest.isInterfaceType() && IsBaseInterface(pSource, pDest))
            //    {
            //        return true;
            //    }
            //    // * from any interface type S to any interface type T, provided S is derived from T.
            //    if (pSource.isInterfaceType() && pDest.isInterfaceType() && IsBaseInterface(pSource, pDest))
            //    {
            //        return true;
            //    }

            // VARIANCE EXTENSIONS:
            // * From any class type S to any interface type T provided S implements an interface
            //   convertible to T.
            // * From any interface type S to any interface type T provided S implements an interface
            //   convertible to T.
            // * From any interface type S to any interface type T provided S is not T and S is 
            //   an interface convertible to T.

            if (pSource.isClassType() && pDest.isInterfaceType() && HasAnyBaseInterfaceConversion(pSource, pDest))
            {
                return true;
            }
            if (pSource.isInterfaceType() && pDest.isInterfaceType() && HasAnyBaseInterfaceConversion(pSource, pDest))
            {
                return true;
            }
            if (pSource.isInterfaceType() && pDest.isInterfaceType() && pSource != pDest &&
                HasInterfaceConversion(pSource.AsAggregateType(), pDest.AsAggregateType()))
            {
                return true;
            }

            // * From an array type S with an element type SE to an array type T with element type TE
            //   provided that all of the following are true:
            //   * S and T differ only in element type. In other words, S and T have the same number of dimensions.
            //   * Both SE and TE are reference types.
            //   * An implicit reference conversion exists from SE to TE.
            if (pSource.IsArrayType() && pDest.IsArrayType() &&
                HasCovariantArrayConversion(pSource.AsArrayType(), pDest.AsArrayType()))
            {
                return true;
            }
            // * From any array type to System.Array or any interface implemented by System.Array.
            if (pSource.IsArrayType() && (pDest.isPredefType(PredefinedType.PT_ARRAY) ||
                IsBaseInterface(GetReqPredefType(PredefinedType.PT_ARRAY, false), pDest)))
            {
                return true;
            }
            // * From a single-dimensional array type S[] to IList<T> and its base
            //   interfaces, provided that there is an implicit identity or reference
            //   conversion from S to T.
            if (pSource.IsArrayType() && HasArrayConversionToInterface(pSource.AsArrayType(), pDest))
            {
                return true;
            }

            // * From any delegate type to System.Delegate
            // 
            // SPEC OMISSION:
            // 
            // The spec should actually say
            //
            // * From any delegate type to System.Delegate 
            // * From any delegate type to System.MulticastDelegate
            // * From any delegate type to any interface implemented by System.MulticastDelegate
            if (pSource.isDelegateType() &&
                (pDest.isPredefType(PredefinedType.PT_MULTIDEL) ||
                pDest.isPredefType(PredefinedType.PT_DELEGATE) ||
                IsBaseInterface(GetReqPredefType(PredefinedType.PT_MULTIDEL, false), pDest)))
            {
                return true;
            }

            // VARIANCE EXTENSION:
            // * From any delegate type S to a delegate type T provided S is not T and
            //   S is a delegate convertible to T

            if (pSource.isDelegateType() && pDest.isDelegateType() &&
                HasDelegateConversion(pSource.AsAggregateType(), pDest.AsAggregateType()))
            {
                return true;
            }

            // * From the null literal to any reference type
            // NOTE: We extend the specification here. The C# 3.0 spec does not describe
            // a "null type". Rather, it says that the null literal is typeless, and is
            // convertible to any reference or nullable type. However, the C# 2.0 and 3.0
            // implementations have a "null type" which some expressions other than the
            // null literal may have. (For example, (null??null), which is also an
            // extension to the specification.)
            if (pSource.IsNullType() && pDest.IsRefType())
            {
                return true;
            }
            if (pSource.IsNullType() && pDest.IsNullableType())
            {
                return true;
            }

            // * Implicit conversions involving type parameters that are known to be reference types.
            if (pSource.IsTypeParameterType() &&
                HasImplicitReferenceTypeParameterConversion(pSource.AsTypeParameterType(), pDest))
            {
                return true;
            }

            return false;
        }