IL Link warning failures in System.Private.DataContractSerialization breaking the build #42926

I'm seeing a variety of trim analysis warnings causing build failures in master and locally due to #42824

Here's some of the warnings I've seen:

D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\ClassDataContract.cs(390,17): Trim analysis error IL2070: System.Runtime.Serialization.ClassDataContract.IsNonAttributedTypeValidForSerialization(Type): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the parameter 'type' of method 'System.Runtime.Serialization.ClassDataContract.IsNonAttributedTypeValidForSerialization(Type)' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\ClassDataContract.cs(1428,17): Trim analysis error IL2075: System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper.GetNonAttributedTypeConstructor(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.DataContractCriticalHelper.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\DataContract.cs(1981,29): Trim analysis error IL2070: System.Runtime.Serialization.DataContract.ImportKnownTypeAttributes(Type,Dictionary<Type,Type>,Dictionary2&): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the parameter 'type' of method 'System.Runtime.Serialization.DataContract.ImportKnownTypeAttributes(Type,Dictionary<Type,Type>,Dictionary2&)' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlDataContract.cs(288,25): Trim analysis error IL2075: System.Runtime.Serialization.XmlDataContract.GenerateCreateXmlSerializableDelegate(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Reflection.Assembly.GetType(String)' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlDataContract.cs(295,25): Trim analysis error IL2075: System.Runtime.Serialization.XmlDataContract.GenerateCreateXmlSerializableDelegate(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(576,29): Trim analysis error IL2075: System.Runtime.Serialization.Json.JsonFormatReaderGenerator.CriticalHelper.ReadCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\Json\JsonFormatReaderGenerator.cs(580,29): Trim analysis error IL2075: System.Runtime.Serialization.Json.JsonFormatReaderGenerator.CriticalHelper.ReadCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlDataContract.cs(244,13): Trim analysis error IL2075: System.Runtime.Serialization.XmlDataContract.GetConstructor(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\CollectionDataContract.cs(886,17): Trim analysis error IL2075: System.Runtime.Serialization.CollectionDataContract.CollectionDataContractCriticalHelper.GetCollectionElementType(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.Globals.get_TypeOfGenericDictionaryEnumerator()' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlFormatReaderGenerator.cs(599,29): Trim analysis error IL2075: System.Runtime.Serialization.XmlFormatReaderGenerator.CriticalHelper.ReadCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlFormatWriterGenerator.cs(412,21): Trim analysis error IL2075: System.Runtime.Serialization.XmlFormatWriterGenerator.CriticalHelper.WriteCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.Globals.get_TypeOfGenericDictionaryEnumerator()' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlFormatWriterGenerator.cs(413,21): Trim analysis error IL2075: System.Runtime.Serialization.XmlFormatWriterGenerator.CriticalHelper.WriteCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.Globals.get_TypeOfGenericDictionaryEnumerator()' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlFormatWriterGenerator.cs(460,25): Trim analysis error IL2075: System.Runtime.Serialization.XmlFormatWriterGenerator.CriticalHelper.WriteCollection(CollectionDataContract): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.Globals.get_TypeOfGenericDictionaryEnumerator()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\XmlFormatGeneratorStatics.cs(211,21): Trim analysis error IL2075: System.Runtime.Serialization.XmlFormatGeneratorStatics.get_HashtableCtor(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.Globals.get_TypeOfHashtable()' don't match those on the implicit 'this' parameter of method 'System.Type.GetConstructor(BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj] D:\source\runtime\src\libraries\System.Private.DataContractSerialization\src\System\Runtime\Serialization\DataContract.cs(1128,25): Trim analysis error IL2075: System.Runtime.Serialization.DataContract.DataContractCriticalHelper.get_ParseMethod(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Runtime.Serialization.DataContract.DataContractCriticalHelper.get_UnderlyingType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String,BindingFlags,Binder,Type[],ParameterModifier[])'. The source value must declare at least the same requirements as those declared on the target location it's assigned to [D:\source\runtime\src\libraries\src.proj]

cc: @eerhardt