Stop using undocumented attribute trimming about xamarin-android

[jonathanpeppers]

I guess this was added in 60e983c, so it's been here since .NET 6.

This means we shouldn't use any _-prefixed switch listed here?

• https://github.com/dotnet/runtime/blob/e5d9a3d81c830952bcf244e8e95b3afe4b8702c5/docs/workflow/trimming/feature-switches.md

[jonathanpeppers]

The only other undocumented one is $(_SystemDiagnosticsMetricsMeterIsSupported). We did enable that on purpose as it contributed to a startup time regression in .NET 8.

[jonathanpeppers]

It looks like a medium-sized app is about 77kb bigger and hello world android 20kb bigger.

That seems reasonable if there is concern of something breaking from the setting.

[MichalStrehovsky]

The only other undocumented one is $(_SystemDiagnosticsMetricsMeterIsSupported). We did enable that on purpose as it contributed to a startup time regression in .NET 8.

This looks to be implemented by Microsoft.Android.Sdk.RuntimeConfig.targets, so it's not a "private" of the SDK, it's a private of Xamarin.

I would suggest switching to the MetricsSupport property and deleting all of _SystemDiagnosticsMetricsMeterIsSupported. The other one is public and documented and it looks like these two properties do the exact same thing:

https://github.com/search?q=org%3Adotnet+System.Diagnostics.Metrics.Meter.IsSupported&type=code

[jonathanpeppers]

I opened:

• #9068