.NET 7 RC 1 how to show a warning from a linker step?

[jonathanpeppers]

We were originally doing this:

https://github.com/xamarin/xamarin-android/blob/4873dfafa6e72a5d898307df759c22da494fc692/src/Xamarin.Android.Build.Tasks/Linker/MonoDroid.Tuner/FixAbstractMethodsStep.cs#L59

And I believe this change made our warning disappear in projects by default: 82c6dc6

You can probably enable this warning with $(SuppressTrimAnalysisWarnings) set to false, but is there a way to make a warning always appear? Maybe we lost a way to do that?

[sbomer]

The assumption behind that change was that we could treat all warnings produced by the linker as belonging to the "trim analysis" category - but maybe we need a different concept to handle this if the Xamarin warnings should be shown even with SuppressTrimAnalysisWarnings. Do you think users would expect that warning to show up if they specified <SuppressTrimAnalysisWarnings>true</SuppressTrimAnalysisWarnings>?

In the meantime, if you need a workaround, you could try the following:

• when SuppressTrimAnalysisWarnings is true:
  • set ILLinkWarningLevel to 4
    this will still prevent the built-in warnings from showing since they all have a version 5
• where you produce the custom warnings, pass in (WarnVersion) 4