Add API for providing classpath/library classes

[NebelNidas]

Describe your idea

Fernflower (code, usage) and CFR (code, usage) provide facilities for supplying classes that are not intended for decompilation themselves, but instead act as sources of additional metadata (e.g. for hierarchy completion). I'd like to see something similar implemented in JADX as well.

[skylot]

@NebelNidas well I plan to add this feature anyway.
Right ow jadx uses "core classpath" from Android (all needed data from android.jar in condensed storage) and Android apps storing all libraries inside apk, so we don't actually need such additional classpath data.
Such feature only needed for decompiling single/separate classes and only can improve type inference (generics restoration). If you know some other examples than generated code is not correct for such use case, please share 🙂

[NebelNidas]

well I plan to add this feature anyway.

Nice!

Right ow jadx uses "core classpath" from Android

What about Java classes loaded via the java-input plugin? My current use-case is decompiling Minecraft 😛

only can improve type inference (generics restoration)

From a quick question in the Vineflower Discord, these are some additional benefits that got mentioned:

• Switch on enums
• @Override annotations
• Local type verification
• Outer and inner class attributes