Support warning/error messages about mpapt

[Foso]

Hi, i haven't documented it yet. But i wrote an extension method MessageCollector.printMessage(diagnosticKind: DiagnosticKind, message: String)
(in https://github.com/Foso/MpApt/blob/master/mpapt-runtime/src/main/java/de/jensklingenberg/mpapt/utils/KaptUtils.kt)
to try to provide a similar api to the java annotation processor.

You can get the MessageCollector from the configuration like this:

val messager = configuration.get(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY,MessageCollector.NONE)
messager.printMessage(DiagnosticKind.ERROR,"My error message")

I will add it to the documentation

[evant]

👍 any plan to add an argument to pass the element the warning/error happened on?

[Foso]

I hadn't considered this before, but i took a quick look how can be done with compiler api. I changed the printMessage() and added the CompilerMessageLocation as a parameter.

Inside your processor, you can use it like that:

configuration.messager().printMessage(DiagnosticKind.ERROR,"My error message", CompilerMessageLocation.Companion.create("/home/jens/Code/2019/MpApt/kotlin-plugin-shared/src/main/java/de/jensklingenberg/MpAptTestProcessor.kt",42,106))

This will print the message to the log and stop the compiler:

e: /home/jens/Code/2019/MpApt/kotlin-plugin-shared/src/main/java/de/jensklingenberg/MpAptTestProcessor.kt: (42, 106): My error message

I can't add an element parameter yet, because my element type doesn't have the (line,column)-Information. But i think it could be possible to get information out of a "descriptor"