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[NativeAOT] Low level API support for Objective-C scenarios #77472
Description
.NET 6 added some APIs to CoreCLR to support running the macOS version of Xamarin-macios. Reference:
High level questions about how to approach implementing this
- Is it desired to support this API in NativeAOT?
- Can the work to support the
ObjectiveCMarshalAPI be split over multiple PRs. If so, is there a recommended way to turn off the feature for release builds, but still have the CI system test the feature?
Outline of work
-
ObjectiveCMarshalAPI : - Testing: some of the tests for this API rely on Remote Executor, which is not currently supported by NativeAOT RemoteExecutor: support single file and NativeAOT arcade#11460
- [NativeAOT] support calling UnmanagedCallersOnly functions before managed main() #77957
- Xamarin-macios side work that is outside the scope of this issue. For a complete list see Enable support for NativeAOT targeting iOS via opt-in feature #80905
- Support for using the aforementioned NativeAOT hosting API.
- Changes to packaging to include the new NativeAOT-specific build of the native components.
- Change build system to account for NativeAOT when linking IL and enabling/disabling features like static registrar
- Changes to the build system to integrate with the final application linking that NativeAOT does.
- Support for retaining enough metadata and marshaling information to allow the runtime to work.
Unimplemented parts of the API
Since the Xamarin side does not use the lastMethod parameter of the UnhandledExceptionPropagationHandler delegate, implmenting that is tracked in a separate issue: #80985
Activity
jkotas commentedon Oct 26, 2022
Yes, we are happy to merge contributions that fill in missing functionality in NativeAOT.
These CoreCLR hosting APIs do not make a lot of sense in NativeAOT world. The basic NativeAOT hosting primitive is
UnmanagedCallersOnlymethod exported as C entrypoint. https://github.com/dotnet/samples/tree/main/core/nativeaot/NativeLibrary is a sample that shows how to it.jkotas commentedon Oct 26, 2022
Yes, that's fine. Smaller PRs are typically reviewed and merged faster that makes it easier to make progress.
lambdageek commentedon Oct 26, 2022
/cc @ivanpovazan
AustinWise commentedon Nov 6, 2022
I agree that the full set of CoreCLR hosting APIs does not make sense for NativeAOT. The only feature that Xamarin-macios needs from a "hosting" API is the ability to call
UnmanagedCallersOnlyfunctions and before the application's main method. I have filed #77957 for this feature.AaronRobinsonMSFT commentedon Nov 13, 2022
@AustinWise Marking this as future since there is no rush and no expectation all of it will be done in .NET 8. If you are able to make it happen hooray, just don't want to put undue pressure on you.
AustinWise commentedon Jan 27, 2023
@AaronRobinsonMSFT This API is now implemented to a sufficient degree to unblock #80905. The milestone can be updated to .NET 8.
One small piece of the API in unimplemented. Since Xamarin does not currently use it, I have separated it out to its own tracking ticket: #80985