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[Mono.Android] Compile RuntimeFeature into a single assembly to avoid conflict warnings#11669

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[Mono.Android] Compile RuntimeFeature into a single assembly to avoid conflict warnings#11669
simonrozsival wants to merge 3 commits into
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dev/simonrozsival/runtimefeature-single-assembly

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@simonrozsival simonrozsival commented Jun 16, 2026

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Summary

Microsoft.Android.Runtime.RuntimeFeature was compiled into two assemblies:

  • Mono.Android.Runtime.dll (src/Mono.Android.Runtime/Mono.Android.Runtime.csproj)
  • Mono.Android.dll (src/Mono.Android/Mono.Android.csproj)

Because Mono.Android references Mono.Android.Runtime (which exposes its internals via InternalsVisibleTo), compiling Mono.Android.dll emitted 58 CS0436 warnings:

warning CS0436: The type 'RuntimeFeature' in
'src/Mono.Android/Microsoft.Android.Runtime/RuntimeFeature.cs' conflicts with the
imported type 'RuntimeFeature' in 'Mono.Android.Runtime'.

This PR makes RuntimeFeature live in exactly one assembly.

Changes

  • Mono.Android.csproj — remove the duplicate <Compile> of RuntimeFeature.cs, so it is compiled only into Mono.Android.Runtime.dll (the lower-level assembly that already owns it).
  • Mono.Android.Runtime/Properties/AssemblyInfo.cs.in — grant internals to Microsoft.Android.Runtime.NativeAOT (JreRuntime.cs) and Mono.Android.NET-Tests (test sources), which previously reached RuntimeFeature through Mono.Android.dll.
  • AndroidRuntime.cs, JNIEnv.cs, TypeManager.cs — add using RuntimeFeature = Microsoft.Android.Runtime.RuntimeFeature;. Once RuntimeFeature is only imported, the unqualified name becomes ambiguous with System.Runtime.CompilerServices.RuntimeFeature (CS0104). The alias disambiguates it, matching the alias already used in JNIEnvInit.cs.

Relationship to #11625

This is a focused subset of #11625, addressing only the RuntimeFeature duplication. It intentionally drops that PR's class rename (RuntimeFeature → AndroidRuntimeFeature) and the unrelated warning cleanups. (The CS0104 ambiguity above is exactly why #11625 renamed the type; here it is resolved with the using alias instead.)

Verification

Building Mono.Android + Microsoft.Android.Runtime.NativeAOT:

CS0436 CS0104 Build
Before 58 0 ✅
After 0 0 ✅

Metadata check (monodis --typedef) — Microsoft.Android.Runtime.RuntimeFeature is now defined in only one assembly:

Assembly Defines RuntimeFeature
Mono.Android.dll 0
Mono.Android.Runtime.dll 1
Microsoft.Android.Runtime.NativeAOT.dll 0

@simonrozsival
[Mono.Android] Compile RuntimeFeature into a single assembly
6e3bdb5 
`Microsoft.Android.Runtime.RuntimeFeature` was compiled into both
`Mono.Android.Runtime.dll` and `Mono.Android.dll`. Because `Mono.Android`
references `Mono.Android.Runtime` (which exposes its internals to
`Mono.Android` via `InternalsVisibleTo`), building `Mono.Android.dll`
emitted 58 `CS0436` warnings:

    warning CS0436: The type 'RuntimeFeature' in
    'src/Mono.Android/Microsoft.Android.Runtime/RuntimeFeature.cs' conflicts
    with the imported type 'RuntimeFeature' in 'Mono.Android.Runtime'.

Compile `RuntimeFeature.cs` only into `Mono.Android.Runtime.dll` (the
lower-level assembly that already owns it) and let the other assemblies use
it through `InternalsVisibleTo`:

  * Remove the duplicate `<Compile Include="...RuntimeFeature.cs" />` from
    `Mono.Android.csproj`.
  * Grant `Mono.Android.Runtime` internals to
    `Microsoft.Android.Runtime.NativeAOT` and `Mono.Android.NET-Tests`, which
    previously accessed `RuntimeFeature` through `Mono.Android.dll`.
  * Once `RuntimeFeature` is only imported (no longer source-compiled) into
    `Mono.Android`, the unqualified name `RuntimeFeature` becomes ambiguous
    with `System.Runtime.CompilerServices.RuntimeFeature`. Add
    `using RuntimeFeature = Microsoft.Android.Runtime.RuntimeFeature;` to the
    three affected files, matching the alias already used in `JNIEnvInit.cs`.

`Microsoft.Android.Runtime.RuntimeFeature` is now defined in exactly one
assembly (`Mono.Android.Runtime.dll`), and the 58 `CS0436` warnings are gone.

This is a focused subset of #11625 that addresses only the `RuntimeFeature`
duplication, without that PR's class rename or unrelated warning cleanups.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot AI review requested due to automatic review settings June 16, 2026 15:34
@simonrozsival simonrozsival changed the title [Mono.Android] Compile RuntimeFeature into a single assembly [Mono.Android] Compile RuntimeFeature into a single assembly to avoid conflict warnings Jun 16, 2026
Copilot AI reviewed Jun 16, 2026
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Pull request overview

This PR removes the duplicate compilation of Microsoft.Android.Runtime.RuntimeFeature into Mono.Android.dll, ensuring it is defined only in Mono.Android.Runtime.dll to eliminate CS0436 type-conflict warnings and avoid CS0104 ambiguity with System.Runtime.CompilerServices.RuntimeFeature.

Changes:

  • Stop compiling Microsoft.Android.Runtime/RuntimeFeature.cs into Mono.Android.dll (leaving it only in Mono.Android.Runtime.dll).
  • Add InternalsVisibleTo entries in Mono.Android.Runtime for Microsoft.Android.Runtime.NativeAOT and Mono.Android.NET-Tests.
  • Disambiguate RuntimeFeature usage via using RuntimeFeature = Microsoft.Android.Runtime.RuntimeFeature; in the affected source files.
Show a summary per file
File Description
src/Mono.Android/Mono.Android.csproj Removes duplicate Compile entry for RuntimeFeature.cs to prevent cross-assembly type conflicts.
src/Mono.Android/Java.Interop/TypeManager.cs Adds RuntimeFeature type alias to avoid CS0104 ambiguity.
src/Mono.Android/Android.Runtime/JNIEnv.cs Adds RuntimeFeature type alias to avoid CS0104 ambiguity (while still using BCL RuntimeFeature fully-qualified).
src/Mono.Android/Android.Runtime/AndroidRuntime.cs Adds RuntimeFeature type alias to avoid CS0104 ambiguity.
src/Mono.Android.Runtime/Properties/AssemblyInfo.cs.in Grants internals access to NativeAOT and test assemblies now that RuntimeFeature is owned by Mono.Android.Runtime.

Copilot's findings

  • Files reviewed: 5/5 changed files
  • Comments generated: 0

@simonrozsival

simonrozsival commented Jun 17, 2026

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@copilot we definitely changed something that affects the numbers of warnings and how our tests filter them. For example, this test is now failing:

[TESTLOG] Test BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2 Starting
/Users/cloudtest/vss/_work/1/s/bin/Release/dotnet/dotnet build /Users/cloudtest/vss/_work/1/a/TestRelease/06-16_16.35.29/temp/BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2/UnnamedProject.csproj /t:Build,SignAndroidPackage /noconsolelogger "/flp1:LogFile=/Users/cloudtest/vss/_work/1/a/TestRelease/06-16_16.35.29/temp/BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2/build.log;Encoding=UTF-8;Verbosity=normal" -nodeReuse:false @"/Users/cloudtest/vss/_work/1/a/TestRelease/06-16_16.35.29/temp/BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2/project.rsp"
Found Time Elapsed 00:00:32.9100000
[TESTLOG] Test BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2 Complete
[TESTLOG] Test BuildHasTrimmerWarningsMonoVMSuppressTrimAnalysisWarningsfalse[IL2055]True2 Outcome=Failed

  Failed BuildHasTrimmerWarnings(MonoVM,"SuppressTrimAnalysisWarnings=false",["IL2055"],True,2) [33 s]
  Error Message:
     Should receive 2 warnings
  Expected: True
  But was:  False

  Stack Trace:
     at Xamarin.Android.Build.Tests.BuildTest2.BuildHasTrimmerWarnings(AndroidRuntime runtime, String properties, String[] codes, Boolean isRelease, Nullable`1 totalWarnings) in /Users/cloudtest/vss/_work/1/s/android/src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest2.cs:line 573

1)    at Xamarin.Android.Build.Tests.BuildTest2.BuildHasTrimmerWarnings(AndroidRuntime runtime, String properties, String[] codes, Boolean isRelease, Nullable`1 totalWarnings) in /Users/cloudtest/vss/_work/1/s/android/src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest2.cs:line 573

I want to
a) improve our build tests so that they have better assertions (not just "Expected: True But was: False" - not helpful)
b) make sure all tests still pass - read the full CI build logs and analyze them. make sure the assertions are updated after we reduced the number of warnings.

Copilot AI and others added 2 commits June 17, 2026 12:14
@simonrozsival
[Xamarin.Android.Build.Tests] Improve trimmer warning assertions and …
7824101 
…adjust warning totals

Co-authored-by: simonrozsival <374616+simonrozsival@users.noreply.github.com>
@simonrozsival
[Xamarin.Android.Build.Tests] Refine warning summary parsing in Build…
f54cbc8 
…HasTrimmerWarnings

Co-authored-by: simonrozsival <374616+simonrozsival@users.noreply.github.com>

Copilot AI commented Jun 17, 2026

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@copilot we definitely changed something that affects the numbers of warnings and how our tests filter them. For example, this test is now failing:

[TESTLOG] Test BuildHasTrimmerWarningsMonoVMSu...

Addressed in commits 7824101 and f54cbc8.

Changes made:

  • Improved BuildHasTrimmerWarnings assertions so failures now include the parsed warning summary line, build log path, and the warning lines that were found (instead of only Expected: True / But was: False).
  • Updated warning-count expectations for MonoVM/CoreCLR release cases where the total warning count dropped after RuntimeFeature deduplication.
  • Kept NativeAOT expected totals unchanged for the existing NativeAOT-specific warning behavior.

Validation:

  • Rebuilt Xamarin.Android.Build.Tests successfully with ./dotnet-local.sh build src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Xamarin.Android.Build.Tests.csproj.
  • Ran security scan + final review checks on the updated test changes.

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@jonathanpeppers jonathanpeppers Awaiting requested review from jonathanpeppers jonathanpeppers is a code owner

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