[cdac] Implement a JSON contract reader

[lambdageek]

Contributes to #99298

Implement a parser for the "compact" JSON contract descriptor format specified in data_contracts.md

The data model is a WIP - it's likely we will want something a bit more abstract (and less mutable).

This is not wired up to consume a real contract descriptor from target process memory at the moment. It's only exercised by unit tests for now.

TODO:

• hook up the unit tests to some testing infrastructure - either src/libraries or src/tests or to something else

[lambdageek]

By the way, the unit tests for cdacreader aren't hooked up to any CI infrastructure at the moment. I'm not sure if we should include them into src/tests or src/libraries or directly into some yaml pipeline. Open to suggestions.

[jkoritzinsky]

For hooking up the unit tests, I think hooking it up in the same way as the ILCompiler and ILLink unit tests will be the easiest way.

That way it won't take on additional dependencies or complexity introduced by the other test harnesses.

[lambdageek]

For hooking up the unit tests, I think hooking it up in the same way as the ILCompiler and ILLink unit tests will be the easiest way.

@jkoritzinsky just so I'm clear: I would need to add a new lane in the yaml file, right?

[jkoritzinsky]

You could add a subset and add that subset to the CLR Tools Tests job's build args (and update the path triggers). Then it will run as part of that job. No need for an additional job.

[lambdageek]

Added a tools.cdacreadertests subset - added it to the CLR_Tools_Tests test job

[elinor-fung]

Are there docs anywhere about tools tests (adding, running, etc) that we should update?

[lambdageek]

Are there docs anywhere about tools tests (adding, running, etc) that we should update?

Added a new PR with docs: #101186

[lambdageek]

.dotnet/sdk/9.0.100-preview.3.24204.13/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(266,5): error NETSDK1047: (NETCORE_ENGINEERING_TELEMETRY=Build) Assets file '/__w/1/s/artifacts/obj/cdacreader/project.assets.json' doesn't have a target for 'net9.0/linux-x64'. Ensure that restore has run and that you have included 'net9.0' in the TargetFrameworks for your project. You may also need to include 'linux-x64' in your project's RuntimeIdentifiers.

there's a relevant failure on the "CLR_Tools_Tests" lane that is similar to what we previously saw with the src/native/managed infrastructure - it's something about the right properties not flowing down to the Restore target, I think.

[elinor-fung]

Looks good to me - assuming whatever is going on with the CLR_Tools_Tests leg is straightforward to address.

[lambdageek]

Ah. The issue was that we now have two <ProjectReference Include="cdacreader.csproj"> items. One in compile-native.proj and the other in the unit test. But they had distinct AdditionalProperties metadata, and the one in compile-native.proj set Configuration and RuntimeIdentifier, whereas the test didn't. as a result the restore created a project.assets.json that was only correct for one reference and not the other. the fix is to set the same AdditionalProperties on both references.

We set RuntimeIdentifier=$(OutputRID) so that in the case of cross-arch build NativeAOT will target the target architecture. but I wonder if there's a better way to do that than by messing with ProjectReference - which is apparently kind of fragile.