private bool IsWideningPromotion(IType targeType, IType sourceType) { var externalTargetType = targeType as ExternalType; if (null == externalTargetType) { return(false); } var externalSourceType = sourceType as ExternalType; if (null == externalSourceType) { return(false); } return(NumericTypes.IsWideningPromotion(externalTargetType.ActualType, externalSourceType.ActualType)); }