Coil 3.0.0 R8 missing classes detected

[G00fY2]

Describe the bug
After switching to Coil 3.0.0 the R8 task fails with the following error:

12:07:37  ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/jenkins/agent/workspace/app_android-client_feature_coil3/app/build/outputs/mapping/release/missing_rules.txt.
12:07:37  ERROR: R8: Missing class coil3.PlatformContext (referenced from: coil3.network.ConnectivityChecker coil3.network.okhttp.OkHttpNetworkFetcher$OkHttpNetworkFetcherFactory$6.invoke(coil3.PlatformContext) and 1 other context)

The missing_rules.txt. contains -dontwarn coil3.PlatformContext. So maybe this should just be shipped as a consumer R8/ProGuard rule?

To Reproduce
Migrate to Coil 3.0, try to build minified Android app.

Version
Coil 3.0.0, AGP 8.7.2

[adhirajsinghchauhan]

+1. Additionally, I also get this:

Caused by: [CIRCULAR REFERENCE: com.android.tools.r8.internal.g: Missing class coil3.PlatformContext (referenced from: coil3.network.ConnectivityChecker coil3.network.okhttp.OkHttpNetworkFetcher$OkHttpNetworkFetcherFactory$6.invoke(coil3.PlatformContext) and 1 other context)]

So I don't think -dontwarn would help. Deps: coil-compose, coil-network-okhttp, and coil-network-cache-control, all at 3.0.0.

Per the docs, my application class is like so:

@HiltAndroidApp
MyApplication: Application(), Configuration.Provider, SingletonImageLoader.Factory {
    …
    @OptIn(ExperimentalCoilApi::class)
    override fun newImageLoader(context: PlatformContext) = ImageLoader.Builder(context)
        .components {
            add(OkHttpNetworkFetcherFactory(cacheStrategy = { CacheControlCacheStrategy() }))
        }.build()
}

[G00fY2]

@adhirajsinghchauhan You are right. After adding -dontwarn coil3.PlatformContext minified build task succeeded but images are not loaded at runtime. I see the following Coil error message printed by the logger (see below):

Failed - myimageurl.jpg - java.lang.NoClassDefFoundError: Failed resolution of: Lcoil3/PlatformContext;

Forgot to meantion that we also have this code in our Application class:

@HiltAndroidApp
class MyApp : Application(), SingletonImageLoader.Factory, Configuration.Provider {
    …
    @OptIn(ExperimentalCoilApi::class)
    override fun newImageLoader(context: PlatformContext): ImageLoader {
        return ImageLoader.Builder(this)
            .components {
                add(OkHttpNetworkFetcherFactory(cacheStrategy = { CacheControlCacheStrategy() }))
                add(SvgDecoder.Factory())
                add(VideoFrameDecoder.Factory())
            }
            .logger(
                object : Logger {
                    override var minLevel: Level = Level.Verbose

                    override fun log(
                        tag: String,
                        level: Level,
                        message: String?,
                        throwable: Throwable?
                    ) {
                        logVerbose("COIL") { message.toString() }
                    }
                }
            )
            .build()
    }

[colinrtwhite]

Hmm we had another report of R8 issues here, but I haven't been able to repro it locally. Missing coil3.PlatformContext is strange as it doesn't exist on Android - it's a typealias for android.content.Context.

Do you use any special R8 config or hardcoded R8 version? As a work-around you could try:

-keep class coil3.PlatformContext { *; }

[adhirajsinghchauhan]

I already tried the keep rule; doesn't help me. Build still fails.

(it does exist in the JAR though, and can be navigated to via Ctrl+N)

I'm using proguard-android-optimize.txt and a basic Crashlytics config:

-keepattributes SourceFile,LineNumberTable        # Keep file names and line numbers.
-keep public class * extends java.lang.Exception  # Optional: Keep custom exceptions.

Everything else is normal. AGP 8.7.2, compile & target SDK 35. If I turn off minification in a debug build, I get the same Coil error log message as above, and images don't load. Perplexing.

[colinrtwhite]

@adhirajsinghchauhan Inspecting the JAR indicates coil3.PlatformContextKt exists, but not coil3.PlatformContext. coil3.PlatformContextKt is the generated file for the PlatformContext source file and is empty (no methods/classes) in the Android JAR.

[JanMalch]

I'm also having issues with the coil3.PlatformContext. In fact, images aren't loading in a regular debug build. With the DebugLogger I see the following:

🚨 Failed - https://example.com/redacted.jpeg - java.lang.NoClassDefFoundError: Failed resolution of: Lcoil3/PlatformContext;

The throwable for the log call is null. The app is not a KMP app in any way.

[lmiskovic]

Same issue, images are not loading in debug build and debug logger saying

Failed - https://images.unsplash.com/photo-1665686377065.... - java.lang.NoClassDefFoundError: Failed resolution of: Lcoil3/PlatformContext;

Removing the custom fetcher factory resolves the issue, without following block it loads images properly

.fetcherFactory(OkHttpNetworkFetcherFactory(cacheStrategy = {
            CacheControlCacheStrategy()
        })

[adhirajsinghchauhan]

Removing the custom fetcher factory resolves the issue

Be wary though, as this is must be provided if your use-case requires respecting Cache-Control headers sent by your server.

I imagine anything that relies on PlatformContext under-the-hood will either not work at all, or have reduced functionality until this bug is fixed. I wonder if creating the coil3 package — with a copy of PlatformContext in our own codebases — would be a reasonable workaround? Haven't tested this idea yet.

[JanMalch]

I wonder if creating the coil3 package — with a copy of PlatformContext in our own codebases — would be a reasonable workaround? Haven't tested this idea yet.

I tried this, but it didn't work.

[lmiskovic]

Removing the custom fetcher factory resolves the issue

Be wary though, as this is must be provided if your use-case requires respecting Cache-Control headers sent by your server.

I imagine anything that relies on PlatformContext under-the-hood will either not work at all, or have reduced functionality until this bug is fixed. I wonder if creating the coil3 package — with a copy of PlatformContext in our own codebases — would be a reasonable workaround? Haven't tested this idea yet.

Ofcourse, postponing migration to 3.0.0 for now as I require Cache-Control header support

[colinrtwhite]

Does anyone have a way to reproduce this issue locally? Referencing PlatformContext in the view sample app which is Android-only, it builds fine. Cash App is also Android-only and builds without issue. Are you using the latest stable Kotlin version?

[JanMalch]

I've created a repository with detailed commits, for my issue with the debug build. Haven't tried a release build: https://github.com/JanMalch/coil3bug

As @lmiskovic mentioned, it only occurs after adding a cacheStrategy.
I found a fix by simply adding the connectivityChecker explicitly.

connectivityChecker = { ctx -> ConnectivityChecker(ctx) }

---

It seems that even an explicit connectivityChecker = ::ConnectivityChecker works.

[colinrtwhite]

@JanMalch Thanks for the repro project! I'm able to reproduce the error locally. It seems like there's some kind issue with the code generated for this function specifically:

fun OkHttpNetworkFetcherFactory(
    callFactory: () -> Call.Factory = ::OkHttpClient,
    cacheStrategy: () -> CacheStrategy = { CacheStrategy.DEFAULT },
    connectivityChecker: (PlatformContext) -> ConnectivityChecker = ::ConnectivityChecker,
)

Hopefully we can work around the generated code issue. For now folks can use your work around.

[G00fY2]

I found a fix by simply adding the connectivityChecker explicitly.

This is working. But we still get the R8 error for release builds:

09:59:42  ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/jenkins/agent/workspace/app_android-client_feature_coil3/app/build/outputs/mapping/release/missing_rules.txt.
09:59:42  ERROR: R8: Missing class coil3.PlatformContext (referenced from: coil3.network.ConnectivityChecker coil3.network.okhttp.OkHttpNetworkFetcher$OkHttpNetworkFetcherFactory$6.invoke(coil3.PlatformContext) and 1 other context)

When I build with -dontwarn coil3.PlatformContext the release build runs through and everything seems to work (images are loaded).

[colinrtwhite]

Hi folks, I merged a fix here. It fixes the issue in @JanMalch's project and didn't produce any R8 errors. @G00fY2 please test out the latest 3.1.0-SNAPSHOT snapshot and let me know if it resolves the R8 issue.

[G00fY2]

@colinrtwhite I switched to 3.1.0-SNAPSHOT and removed any custom proguard rules and the workaround from #2637 (comment). So we again only set

add(OkHttpNetworkFetcherFactory(cacheStrategy = { CacheControlCacheStrategy() }))

The release builds does not show any R8 errors anymore and images are loading (so no runtime errors). Looks like your changes fixed the issue! 🎊

[colinrtwhite]

Awesome, thanks for checking! Will ship this in 3.0.2 in the next day or two.