Cannot use Java 17 records due to Android

[andreabergia]

I spent a bit of time understanding why the CI of #2386 was failing on the Android steps, and Claude helped me figure out that, basically, we can't really use Java 17's record unless the minSDK is set to 35. It currently is set to 26.

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Here's some detail from Claude's analysis:

The chain of cause:

1. java.lang.Record is a Java 16 feature; on Android it's only available natively from API 35 (Android 15).
2. it-android has minSdk = 26, so D8 must desugar the records — replacing the java.lang.Record superclass with a synthetic stand-in.
3. That synthetic class is a "global synthetic" (shared across the dex output), and D8 needs a "global-synthetics consumer" wired up to receive it.
4. The transform AGP picks here is DexingNoClasspathTransform — note the attribute string in the error includes enableGlobalSynthetics=false. That transform variant has no consumer, so D8 refuses to emit the synthetic and the build aborts.

Fix options (in order of how invasive they are):

1. Convert the two records back to regular final classes with the same source(), scope(), etc. accessor names — preserves
   the public API, no build-system changes, works on every AGP/JDK combination. Most defensible for a library that supports
   old Android targets.
2. Force AGP onto a transform that has a global-synthetics consumer — e.g. set
   android.enableGlobalSyntheticsGeneration=true in gradle.properties, or enable core library desugaring on it-android.
   Lighter touch on the source code, but couples Rhino's release artifact compatibility to AGP behavior across plugin
   versions.
3. Bump it-android minSdk to 35 — not realistic given the workflow tests API 26/28/30/34.

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I think the only sensible option is to go with option 1 and forbid the usage of record anywhere in Rhino, sadly.

[anonyein]

R8 desugaring helps bridge the gap between modern Java language features (like record) and older Android runtimes that lack native support for java.lang.Record.

ScriptCompileSpec and FunctionCompileSpec, these two record classes are safe and unlikely to trigger any R8 desugaring compatibility problems when used on lower API levels (pre‑Android 14).

Is the ‘Build and test for Android’ part processed with desugaring?

Failed to transform main (project :rhino) to match attributes {artifactType=android-dex, dexing-component-attributes=ComponentSpecificParameters(minSdkVersion=26, debuggable=true, enableCoreLibraryDesugaring=false, enableGlobalSynthetics=false, enableApiModeling=false, dependenciesClassesAreInstrumented=false, asmTransformComponent=null, useJacocoTransformInstrumentation=false, enableDesugaring=true, needsClasspath=false, useFullClasspath=false, componentIfUsingFullClasspath=null), org.gradle.category=library, org.gradle.dependency.bundling=external, org.gradle.jvm.version=17, org.gradle.libraryelements=classes, org.gradle.usage=java-runtime}.

why “enableCoreLibraryDesugaring=false, enableGlobalSynthetics=false”

When enableGlobalSynthetics=false, no global synthetic consumer is available. D8 cannot create or consume the required synthetic classes for record, and throws the Invalid build configuration error.

Add a flag in gradle.properties
android.useFullClasspathForDexingTransform=true

[andreabergia]

Add a flag in gradle.properties android.useFullClasspathForDexingTransform=true

That didn't work: see #2395 and https://github.com/mozilla/rhino/actions/runs/25437339971/job/74618770060?pr=2395

[andreabergia]

Another attempt also failed: #2396

[anonyein]

Another attempt also failed: #2396

Check it on a real APK, and decompile to see if it's correct. I tested it with other modules and it worked.
swc4j also use “record”, and it function well

from the log
> Failed to transform main (project :rhino) to match attributes {artifactType=android-dex, dexing-component-attributes=ComponentSpecificParameters(minSdkVersion=26, debuggable=true, enableCoreLibraryDesugaring=true, enableGlobalSynthetics=false, enableApiModeling=false, dependenciesClassesAreInstrumented=false, asmTransformComponent=null, useJacocoTransformInstrumentation=false, enableDesugaring=true, needsClasspath=false, useFullClasspath=false, componentIfUsingFullClasspath=null), org.gradle.category=library, org.gradle.dependency.bundling=external, org.gradle.jvm.version=17, org.gradle.libraryelements=classes, org.gradle.usage=java-runtime}.
still enableGlobalSynthetics=false, "it-android" or "rhino" project has not been set successfully
edit the gradle.properties of "it-android" or "rhino" project

### Despite multiple attempts, the build still fails in the emulator.
Testing should adopt a different approach, test after packaging the APK