linux-bionic-arm64 built from feature/net8.0: MarshalDirectiveException

[rene-descartes2021]

Error is in log, from running ./OmniSharp:
https://gist.github.com/rene-descartes2021/67209d2df3b22e17578a75c625f33ebb

Subset of the above log:

System.Runtime.InteropServices.MarshalDirectiveException: Array size control parameter must be an integral type.
[...]
at OmniSharp.MSBuild.Discovery.Providers.SdkInstanceProvider.GetInstances() in /data/data/com.termux/files/home/dev/omnisharp-roslyn/src/OmniSharp.Host/MSBuild/Discovery/Providers/SdkInstanceProvider.cs:line 33

I built OmniSharp on Termux, had to adjust scripts/platform.cake a bit to get it to detect the platform and emit the linux-bionic-arm64 rid for use by the Install target (not publishing for all platforms). Otherwise it emits linux-arm64 which won't work, that uses wrong libc. Here is link to a commit with most everything relevant.

Built by:

./build.sh --target Install --archive --test-configuration Release --configuration Release --verbosity diagnostic --use-global-dotnet-sdk --install-path "$HOME/.local/share/omnisharp"

Does anyone gets the same problem when running the linux-bionic-arm64 product of #2653 (which publishes for all platforms)?

[rene-descartes2021]

Looking at the call stack, I think it's due to the callback function MarshallAs SizeParamIndex=0 pointing at, for the array length, an enum not an integer.
Array size control parameter must be an integral type.
https://github.com/microsoft/MSBuildLocator/blob/main/src/MSBuildLocator/DotNetSdkLocationHelper.cs#L122
https://github.com/microsoft/MSBuildLocator/blob/main/src/MSBuildLocator/NativeMethods.cs#L43

So... Maybe a bug to file at Microsoft/MSBuildLocator, or? Enum implicit type should be integral though?

EDIT: Maybe using mono runtime the marshalling is a bit different, and it is not accepting the enum?:
https://github.com/dotnet/runtime/blob/1713d65316467e3eaf23514b6642eba5869f1b70/src/mono/mono/component/marshal-ilgen.c#L487

Looking in their issues, Microsoft/MSBuildLocator does not appear to support mono, I assume the context they said that in also includes dotnet using the mono runtime (dotnet compiled with --use-mono-runtime). So, maybe one of their env variables may work around the problem, or see how OmniSharp can be adjusted to not use MSBuildLocator.

[rene-descartes2021]

Here is proposal to workaround above Microsoft/MSBuildLocator issue when sdk.path in OmniSharp.json is set. I tested and now OmniSharp works, no errors, startup seems fine.

Patch:
https://gist.github.com/rene-descartes2021/58bd4307cb5cd869c71a3797de9b8b51

Example OmniSharp.json that works on Termux:
https://gist.github.com/rene-descartes2021/2f9cd3599147f6ab571a331006eda120

Maybe a different condition than sdk.path could be used, like a test to see if mono runtime is in use?