This class mixes in a few standard traits, so that it is easier to extend from Java.

This class implements a Reporter that displays messages on a text console

Unique IDs identifying the messages

A re-usable Reporter used in Contexts#test

This trait implements isHidden so that we avoid reporting non-sensical messages.

A Message contains all semantic information necessary to easily comprehend what caused the message to be logged. Each message can be turned into a Diagnostic which contains the log level and can later be consumed by a subclass of Reporter. However, the error position is only part of Diagnostic, not Message.

NOTE: you should not persist a message directly, because most messages take an implicit Context and these contexts weigh in at about 4mb per instance. Therefore, persisting these will result in a memory leak.

Instead use the persist method to create an instance that does not keep a reference to these contexts.

The fallback Message containing no explanation and having no kind

The extractor for NoExplanation can be used to check whether any error lacks an explanation

A simple not found message (either for idents, or member selection. Messages of this class are sometimes dropped in favor of other, more specific messages.

This interface provides methods to issue information, warning and error messages.

This class implements a Reporter that stores all messages

Beware that this reporter can leak memory, and force messages in two scenarios:

• During debugging config.Printers.typr is set from noPrinter to new Printer, which forces the message
• The reporter is not flushed and the message containers capture a Context (about 4MB)

Messages

The role of messages is to provide the necessary details for a simple to understand diagnostic event. Each message can be turned into a message container (one of the above) by calling the appropriate method on them. For instance:

EmptyCatchBlock(tree).error(pos)   // res: Error
EmptyCatchBlock(tree).warning(pos) // res: Warning

A re-usable Reporter used in Contexts#test

This class implements a Reporter that throws all errors and sends warnings and other info to the underlying reporter.

This module is carefully optimized to give zero overhead if Config.tracingEnabled is false. The trace operation is called in various hotspots, so every tiny bit of overhead is unacceptable: boxing, closures, additional method calls are all out.

This trait implements isHidden so that multiple messages per position are suppressed, unless they are of increasing severity.