ClassName.bestGuess() fails for classes starting with a lowercase character

[vRallev]

package abc

class MyClass @Inject constructor(a: asg) {
  class asg @Inject constructor()
}

Calling ClassName.bestGuess("abc.MyClass.asg") fails:

e: java.lang.IllegalArgumentException: couldn't make a guess for abc.MyClass.asg
        at com.squareup.kotlinpoet.ClassName$Companion.bestGuess(TypeName.kt:465)

One could argue that classes should start with an uppercase letter, but Kotlin allows it and it's the input of another program that internally uses Kotlin Poet.

[JakeWharton]

Java also allows this and JavaPoet will fail in the same way. If you're inside a Kotlin compiler plugin you shouldn't need to use bestGuess and can instead get the package and list of simple names to create the ClassName "normally".

[vRallev]

What exactly do you mean with "normally"? Do you mean the constructor? The compiler often works with full qualified names and then it's very convenient to rely on bestGuess() rather than breaking down the string manually. I see how Kotlin Poet has less context and might not be able to make the decision. So the exception is by design?

[JakeWharton]

Yes, because MyClass could also be a package segment that just happened to be capitalized as well. So we have no idea if it's a nested class named MyClass.asg in the abc package or a class named adg in the abc.MyClass package. The only way we can guess is if you follow the standard naming rules of package segments starting with lowercase and type names starting with uppercase. It could even be a class named adc in the default package with MyClass and asg nested types. There's just no context, like you said.

The compiler API should give you a way to break apart a qualified reference into component parts. Otherwise I don't see how it would know how to emit bytecode where these cases are all defined differently since / splits packages whereas $ splits nested types.

[vRallev]

Sounds reasonable. Thanks for clarifying.