What’s on the classpath used by the proxies return...

# ksp

[philglass]

What’s on the classpath used by the proxies returned from getAnnotationsByType? Is it expected that KClass annotation parameters that reference user-defined classes won’t work?

Both of these examples fail with a KSTypesNotPresentException ultimately caused by a ClassNotFoundException if I try to access the includes property on the proxy:

@Module class First
@Module(includes = [First::class]) Second

@Module(includes = [FromUpstreamModule::class]) Third

This works (it’s invalid for unrelated reasons, but the class lookup works):

@Module(includes = [Unit::class]) Fourth

This fails with the same exception but for a slightly different reason - it’s trying to look up kotlin.String at runtime (presumably it should be translated to java.lang.String at some point for JVM projects):

@Module(includes = [String::class]) Fifth

[Jiaxiang]

If you are trying to access a class from the source code in reflection, then it is kinda expected it will fail, since the class is not yet to be compiled to class files. But it seems in your case it is not the exact same issue, what do you mean by “access the includes property on the proxy”?

[philglass]

Something like this:

annotated.getAnnotationsByType(Module::class).single().includes

[Jiaxiang]

I see, I will expect at least first case to fail since the class is not yet compiled.

[philglass]

Where @Module is defined like this (my actual use case is slightly different but fundamentally the same):

@Target(AnnotationTarget.CLASS)
@Retention(AnnotationRetention.BINARY)
annotation class Module(val includes: Array<KClass<*>> = [])

[Jiaxiang]

is Module defined in another compile module as well?

[philglass]

Yeah

[Jiaxiang]

I will be interested in the failure of Third and Fifth, I will take a note.

[philglass]

It’s not really a problem - using KSAnnotation.arguments works fine, I get a List<KSType> as the argument value. I guess I was wondering what the use case for getAnnotationsByType is if things like this are expected to blow up - is it more of a convenience for annotations with primitive/`String` etc. parameters?

[Jiaxiang]

I can’t recall the initial motivation add it, but I think it is related to be compatible to some common Java annotation processor utility functions that some processors are using, it is located in the api util module meaning it can be implemented by processor users themselves, and added there just for some convenience

[glureau]

Just spend a couple of hours before finding this discussion. Could be good to have a warning or warn when allowing retrieval of annotation using KClass 😅

[glureau]

Just found that it's also an issue with Annotation that has another Annotation as parameter : if the default value is used, calling the member from getAnnotationsByType() generate a NullPointerException. ⚠️