nested java class resolves to error with kotlin compile testing 1.3.5

[yigit]

I couldn't yet reproduce this in KSP so might not be a KSP issue but after updating room to use kotlin compile testing 1.3.5 (where there was a bug fix to pass down java files as root files), a room test started failing:

Test input:

            import java.util.List;
            class Baz {
                int intField;
                List<Integer> listOfInts;
                List incompleteGeneric;
                Nested nested;
                static class Nested {
                }
            }

Resolving the nested field's type returns error.

override fun resolve(): KSType {
        val resolvedType = ResolverImpl.instance.resolveUserType(this)
        return if ((resolvedType.declaration as? KSClassDeclarationDescriptorImpl)?.descriptor is NotFoundClasses.MockClassDescriptor) {
            KSErrorType
        } else resolvedType
    }

Another change was to update kotlin to 1.4.21-2, that might also be related.
Will investigate further.

[yigit]

can reproduce w/ kotlin compile testing w/o room.
still investigating.
yigit/kotlin-compile-testing@2e35c09

[yigit]

and it works fine if i don't add it as a java source roots:

https://github.com/google/ksp/blob/master/compiler-plugin/src/main/kotlin/com/google/devtools/ksp/KotlinSymbolProcessingPlugin.kt#L200

maybe our testing infra does not do that?

[yigit]

in kotlin compile testing, resolvedType.declaration is KSClassDeclarationDescriptorImpl while in KSP test infra, it is KSClassDeclarationJavaImpl.

[yigit]

moved to kotlin compile testing as i cannot reproduce this in a sample project.
tschuchortdev/kotlin-compile-testing#105

[yigit]

i can reproduce this little bit easier by finding the nested class directly and calling asStarType because it fails with NPE in:

private val descriptor: ClassDescriptor? by lazy {
        ResolverImpl.moduleClassResolver.resolveClass(JavaClassImpl(psi))
    }

but again, works fine in ksp testing infra, fails in kotlin compile testing.

[yigit]

i have some level of repro for this:
yigit@8b15edb

still trying to isolate and not sure why i couldn't repro in my test. similarly it happens in a java source class but it is actually a root class, not a nested one.

[yigit]

to keep the bug updated, it happens in KSP test infra when the file path does not match the class's package name.

This is something IDE complains about in a regular project but nevertheless, javac compiles it w/o any issues (and kotlin compiler is fine w/ that too).

I'm still not sure how/why we create the PSI file triggers this, not i'm not sure how to find the correct source root for kotlin compile testing.

[yigit]

so tl;dr;
I created a sample project where i have:

package foo.bar;
class JavaSrc {
}

package foo.baz;
class KotlinSrc {
}

This code compiles fine.
But if I change KotlinSrc class to reference JavaSrc, compilation fails.

Seems like the tl;dr; is that this is OK for java but not ok from kotlin.
Moreover, if I move that JavaSrc to a dependent module, it again works fine from kotlin (because it is a class file).

[ting-yuan]

Per offline discussion, the behavior is aligned to kotlinc when used through kotlin-gradle-plugin. Investigations are needed when calling directly.