Amazon DynamoDBContext - NET 7 AOT Incompatibilities

[rac146]

Describe the bug

Was running some NET7 AOT experiments with DynamoDBContext and was receiving runtime errors after doing an AOT compilation:

System.NotSupportedException: 'System.Collections.Generic.HashSet`1[System.Boolean]' is missing native code or metadata. This can happen for code that is not compatible with trimming or AOT. Inspect and fix trimming and AOT related warnings that were generated when the app was published. For more information see https://aka.ms/nativeaot-compatibility
   at System.Reflection.Runtime.General.TypeUnifier.WithVerifiedTypeHandle(RuntimeConstructedGenericTypeInfo, RuntimeTypeInfo[]) + 0x88
   at Amazon.DynamoDBv2.CollectionConverter.<GetTargetTypes>d__1.MoveNext() + 0x1d4
   at Amazon.DynamoDBv2.ConverterCache.AddConverter(Converter converter, DynamoDBEntryConversion conversion) + 0x9b
   at Amazon.DynamoDBv2.DynamoDBEntryConversion.AddConverter(Type type) + 0x41
   at Amazon.DynamoDBv2.DynamoDBEntryConversion.AddConverters(String suffix) + 0x184
   at Amazon.DynamoDBv2.DynamoDBEntryConversion..ctor(ConversionSchema schema, Boolean isImmutable) + 0x6e
   at Amazon.DynamoDBv2.DynamoDBEntryConversion..cctor() + 0x25
   at System.Runtime.CompilerServices.ClassConstructorRunner.EnsureClassConstructorRun(StaticClassConstructionContext*) + 0xc6

Expected Behavior

For DynamoDB to be AOT NET 7 supported

Current Behavior

Errors out after dotnet publish in NET7 AOT mode

Reproduction Steps

Attempt to run any DynamoDB queries that use DynamoDBContext with latest version of AWS SDK

Possible Solution

Decided to hack into the SDK to find the culprit. Discovered .MakeGenericType is throwing the runtime errors.
Switched these 4 lines for experimentation purposes:

In DynamoDBEntryConversion.cs:
Line 651: var nullableType = typeof(Nullable<>).MakeGenericType(type)
Potential Fix?: yield return typeof(Nullable<>);

In SchemaV1.cs:

Line 379: yield return pt.MakeArrayType();
Fix?: yield return typeof(Array);
Line 382: yield return listType.MakeGenericType(pt);
Fix?: yield return typeof(List<>);
Line 384: yield return setType.MakeGenericType(pt);
Fix?: yield return typeof(HashSet<>);

This allowed my test application to run and work correctly. Is this is right long-term fix to the problem? I don't know, but just wanted to let you know!

Additional Information/Context

With AWS starting to push AOT further, it would be great to start working through the bugs that prevent an AOT build from working. I believe this fits as a bug opposed to a feature request, especially with the push towards AOT compatible lambdas!

AWS .NET SDK and/or Package version used

AWS SDK DynamoDBv2 3.7.101.44

Targeted .NET Platform

.NET 7

Operating System and version

Windows 10

[ashishdhingra]

Hi @rac146,

Good afternoon.

Thanks for opening the issue. Just wanted to check if you referred the blog post Building serverless .NET applications on AWS Lambda using .NET 7 for the Native AOT support. As mentioned, currently, the AWSSDK.Core library used by all the .NET AWS SDKs must also be excluded from trimming. I guess this is also the case with AWSSDK.* assemblies. Could you please try adding AWSSDK.DynamoDBv2 in rd.xml and see if it works. We have the internal backlog item to support trimming for AWS SDK for .NET assemblies, however, do not have the concrete timeline by which it would be supported.

Thanks,
Ashish

[rac146]

Hey Ashish,

Even excluding AWSSDK.DynamoDBv2 from trimming, the error still occurs. This error will present itself with or without trimming - this is flagged as an AOT analysis warning, not a trimming warning when running dotnet publish.

[rac146]

Here are the detailed errors when running dotnet publish with <TrimmerSingleWarn>false</TrimmerSingleWarn>

D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Services\DynamoDBv2\Custom\Conversion\DynamoDBEntryConversion.cs(652): AOT analysis warning IL3050: Amazon.DynamoDBv2.Converter`1.d__0.MoveNext(): Using member 'System.Type.MakeGenericType(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.

D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Services\DynamoDBv2\Custom\Conversion\SchemaV1.cs(379): AOT analysis warning IL3050: Amazon.DynamoDBv2.CollectionConverter.d__1.MoveNext(): Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.

D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Services\DynamoDBv2\Custom\Conversion\SchemaV1.cs(382): AOT analysis warning IL3050: Amazon.DynamoDBv2.CollectionConverter.d__1.MoveNext(): Using member 'System.Type.MakeGenericType(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.

D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Services\DynamoDBv2\Custom\Conversion\SchemaV1.cs(384): AOT analysis warning IL3050: Amazon.DynamoDBv2.CollectionConverter.d__1.MoveNext(): Using member 'System.Type.MakeGenericType(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.