Handle default methods in proxied interfaces #250
Draft
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Default methods on interfaces fed to java.lang.Proxy cannot be invoked without using method handles, which requires a Lookup with private access (acquired within the interface class). This commit adds a load path that propagates such a Lookup through to the eventual Proxy instance, allowing it to skip binding default methods to their (nonexistent) native function, instead calling the provided default method body. Fixes jnr#249.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
It turns out java.lang.Proxy works very poorly in the presence of interface default methods, leading to the issues described in #249. This PR is a prototype of logic to handle such methods using method handles, which works on Java 8-16.
This code is a little heinous, and requires the user (providing the interface) to also have a Lookup object acquired from within that interface, in order to dispatch to the "special" default method bodies.
Java 16 adds a standard way to redispatch to default methods, and the user-side Lookup requirement here is rather heinous, so this may be something we just make a hard error unless we are running on 16.
Fixes #249.