Introduce non-nullable types in reactive integrations where appropriate #3393
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qwwdfsad
commented
Aug 5, 2022
qwwdfsad
commented
- For RxJava2, use them in internal implementations where appropriate
- For RxJava3, introduce & Any bound to generic argument in our extensions to avoid errors in Kotlin 1.8.0 due to non-nullability rx3 annotations being part of generics upper bound. This change went through commitee, and all the "unsound" declarations such as "RxSignature<Foo?>" were properly highlighted as warning that will become an error.
* For RxJava2, use them in internal implementations where appropriate * For RxJava3, introduce & Any bound to generic argument in our extensions to avoid errors in Kotlin 1.8.0 due to non-nullability rx3 annotations being part of generics upper bound. This change went through commitee, and all the "unsound" declarations such as "RxSignature<Foo?>" were properly highlighted as warning that will become an error.
| public suspend fun <T> MaybeSource<T>.awaitSingleOrNull(): T? = suspendCancellableCoroutine { cont -> | ||
| subscribe(object : MaybeObserver<T> { | ||
| public suspend fun <T> MaybeSource<T & Any>.awaitSingleOrNull(): T? = suspendCancellableCoroutine { cont -> | ||
| subscribe(object : MaybeObserver<T & Any> { | ||
| override fun onSubscribe(d: Disposable) { cont.disposeOnCancellation(d) } | ||
| override fun onComplete() { cont.resume(null) } | ||
| override fun onSuccess(t: T) { cont.resume(t) } |
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This bound seems to be properly propagated from the declaration site
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Since the object is implementing MaybeObserver<T & Any>, I think the method parameter needs to be T & Any to match.
Or you know what, actually, even if we were implementing plain MaybeObserver<T>, we'd probably still need the method parameter to be T & Any, since the interface declares its method as requiring a @NonNull T:
I think that's why, with the current parameter type of T, the build fails with the flags I posted in the build script.
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Thanks for pointing it out. T & Any is required since Kotlin 1.8.0, it was an omission on the language site
| @@ -176,8 +176,6 @@ configure(subprojects.findAll { !sourceless.contains(it.name) }) { | |||
| tasks.withType(AbstractKotlinCompile).all { | |||
| kotlinOptions.freeCompilerArgs += OptInPreset.optInAnnotations.collect { "-Xopt-in=" + it } | |||
| kotlinOptions.freeCompilerArgs += "-progressive" | |||
| // Disable KT-36770 for RxJava2 integration | |||
| kotlinOptions.freeCompilerArgs += "-XXLanguage:-ProhibitUsingNullableTypeParameterAgainstNotNullAnnotated" | |||
| // Remove null assertions to get smaller bytecode on Android | |||
| kotlinOptions.freeCompilerArgs += ["-Xno-param-assertions", "-Xno-receiver-assertions", "-Xno-call-assertions"] | |||
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I'm not sure exactly what -progressive enables, but I notice that I can get a few more errors (noted above) if I enable the flags from #3007. (Thanks for pointing me here from there!)
// Recognize rxjava3 nullness annotations even before that becomes the default (which may happen in 1.8): https://kotlinlang.org/docs/java-interop.html#nullability-annotations
kotlinOptions.freeCompilerArgs += "[email protected]:strict"
// Recognize nullness annotations on type arguments, etc.: https://kotlinlang.org/docs/java-interop.html#annotating-type-arguments-and-type-parameters
kotlinOptions.freeCompilerArgs += "-Xtype-enhancement-improvements-strict-mode"
