Error when Mono-specific AOT settings are enabled with CoreCLR

[Copilot]

RunAOTCompilation=true was still enabling MonoAOT for CoreCLR builds, causing mono-aot-cross to fail later with a runtime-critical type error. CoreCLR builds should reject Mono-specific AOT settings early with an actionable MSBuild error.

• Runtime property validation

  • Detect RunAOTCompilation=true when the selected Android runtime is not MonoVM.
  • Detect EnableLLVM=true when the selected Android runtime is not MonoVM.

• MSBuild error

  • Reuse the existing XA1044 code for incompatible Mono-specific properties used with non-Mono runtimes.
  • Change the existing XA1044 diagnostics from warnings to errors.

• Test coverage

  • Update the CoreCLR AOT tests to expect build failures with XA1044 instead of successful builds with XA1044 warnings.

[simonrozsival]

@copilot let's keep the existing codes, but only change the warnings to errors.

[Copilot]

@copilot let's keep the existing codes, but only change the warnings to errors.

Addressed in 4b1c20a by removing the new XA1045 path and changing the existing XA1044 warning checks to AndroidError.

[Copilot]

Pull request overview

This PR improves runtime-property validation in the Android MSBuild targets so Mono-specific AOT settings don’t silently apply to CoreCLR builds and fail later in the pipeline, by emitting an early XA1044 build error and updating tests accordingly.

Changes:

• Convert XA1044 diagnostics for RunAOTCompilation/EnableLLVM incompatibility into build-stopping errors.
• Keep rejecting Mono-specific AOT properties when $(_AndroidRuntime) != MonoVM (and reset them), but now fail the build immediately.
• Update CoreCLR-focused AOT tests to expect XA1044 errors and build failure.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets	Switch XA1044 from AndroidWarning to AndroidError in _CheckNonIdealAppConfigurations to fail builds early.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/AotTests.cs	Update CoreCLR AOT-related tests to assert build failures and check for error XA1044.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.DefaultProperties.targets	Update comment to reflect error behavior while continuing to set XA1044 flags and reset incompatible properties.

[simonrozsival]

@copilot the BuildAMassiveApp unit test is now broken:

...
"C:\a\_work\1\a\TestRelease\04-29_14.53.13\temp\BuildAMassiveApp\BuildAMassiveApp.sln" (Build target) (1:2) ->
"C:\a\_work\1\a\TestRelease\04-29_14.53.13\temp\BuildAMassiveApp\App1\App1.csproj" (default target) (2:6) ->
(_CheckNonIdealAppConfigurations target) -> C:\a\_work\1\s\bin\Release\dotnet\packs\Microsoft.Android.Sdk.Windows\36.99.0-ci.pr.gh11246.152\tools\Xamarin.Android.Common.targets(556,3): error XA1044: The MSBuild property 'RunAOTCompilation' is not compatible with the CoreCLR runtime and will be ignored. Either remove the property or guard it with a condition: Condition="'$(UseMonoRuntime)' == 'true'" [C:\a\_work\1\a\TestRelease\04-29_14.53.13\temp\BuildAMassiveApp\App1\App1.csproj]
0 Warning(s)
1 Error(s)

I believe we should parametrize the test to build both with Mono and with CoreCLR and to set AotAssemblies = true only for Mono.

[Copilot]

@copilot the BuildAMassiveApp unit test is now broken:

...

...

Fixed in 6974b72 by parameterizing BuildAMassiveApp for MonoVM and CoreCLR and setting AotAssemblies=true only for the MonoVM case.