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[R8] Aapt2 rules are silently dropped from R8 input

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#12,942 3 comentarios 0 reacciones 0 asignados Ver en GitHub

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
48/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Activo
Stack tecnológico
android, csharp
Área
build-system, mobile-dev

Línea de trabajo

Start by tracing ProguardRuleOutput handling in src/Xamarin.Android.Build.Tasks/Tasks/Aapt2Link.cs around line 134, then inspect _UseAapt2ManifestProguardRules in src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Aapt2.targets around lines 247-250. Reproduce or instrument the multi-project R8 build and verify that generated aapt_rules.txt is consistently added to ProguardConfiguration and passed to R8.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Area: App+Library Build need-info
Android framework version

net10.0-android

Affected platform version

.NET 10.0.200

Description

Environment:

  • Android application with the multi-project solution;
  • AndroidLinkTool=r8
  • TrimMode=full

We are currently testing enabling full Android linking with tree-shaking. We noticed that sometimes builds compiled on CI are "broken" - crashing on startup with ClassNotFoundException. We ruled out environmental cause as there's no correlation between issue reproduction and build agents, all CI builds are "clean".
After analyzing the R8 outputs from broken builds (collected via --pg-conf-output extra argument) we found the root cause: broken builds (~4% of total) are all missing the section with generated Aapt2 rules (from aapt_rules.txt).

We managed to reproduce the issue with the additional binlog enabled, it shows the following picture:

  • _Aapt2ProguardRules is resolved into a relative path like obj/<Platform>/<Configuration>/net10.0-android36.0/aapt_rules.txt;
  • Aapt2Link task runs and competes successfully (JobWorked: True);
  • generated rules file is never added to the ProguardConfiguration - there's no Added Item(s): ProguardConfiguration=obj/.../aapt_rules.txt log;
  • aapt_rules.txt never passed to the R8, classes defined in manifest trimmed;

The issue might be caused by the Aapt2Link task operating on a relative path with incorrect captured WorkingDirectory:
https://github.com/dotnet/android/blob/7a170b185aa8e78fc18908834ada19b578668d39/src/Xamarin.Android.Build.Tasks/Tasks/Aapt2Link.cs#L134
Unlike other path variables, ProguardRuleOutput is never used with GetFullPath(), which may cause aapt_rules.txt being generated in the incorrect project. The Exists() guard then will skip adding this file to ProguardConfiguration not producing any errors
https://github.com/dotnet/android/blob/085b6f4e80f9812c3e9bb509c9b2a8a19de17d36/src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Aapt2.targets#L247-L250

Steps to Reproduce

There are no 100% reproduction steps, the issue seems to reproduce randomly with environment described above.

Did you find any workaround?

It seems that the issue is only with the merged aapt_rules.txt, individual manifest rules per ABI are using full paths - and thus should always land in the root project. It should be possible to include those files into ProguardConfiguration directly:

<Target Name="_UseAapt2ManifestProguardRules"
        Condition="'$(AndroidLinkTool)' != ''"
        BeforeTargets="_CalculateProguardConfigurationFiles">
  <ItemGroup>
    <_Aapt2ManifestProguardRules Include="$(MSBuildProjectDirectory)/$(IntermediateOutputPath)android/*/aapt_rules.txt" />
    <ProguardConfiguration Include="@(_Aapt2ManifestProguardRules)" />
  </ItemGroup>
</Target>

Another option might be using, but we didn't test it yet

<YieldDuringToolExecution>false</YieldDuringToolExecution>
Relevant log output
Lenguaje dominante
C#
Estrellas
2.1k
Forks
581
Merge medio
2 d 2 h
PR fusionados (30 d)
228

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