rootvector2 opened a new pull request, #746: URL: https://github.com/apache/commons-collections/pull/746
`ListIteratorWrapper.remove()` gates on a `removeState` flag that `next()` sets only in the branch that pulls a fresh element from the wrapped iterator, and `previous()` recomputes it from the cursor position alone, so walking back into the element cache with `previous()` and then forward again until the cursor is level with the wrapped iterator leaves the flag false and `remove()` throws `IllegalStateException` for a removal `java.util.ListIterator` requires to succeed, while `reset()` rewinds the cursor without clearing the flag so `next()`, `reset()`, `remove()` deletes an element the `remove()` javadoc says it must reject; the flag is now derived from whether the element last returned by the wrapped iterator can still be removed from it. Found with a randomized differential test of the library's list iterators against `java.util.ArrayList.listIterator()`, which also confirmed `ListIteratorWrapper` is the only one that caches a plain `Iterator` this way (the siblings either del egate to a real `ListIterator` or reject `remove()` outright). - [x] Read the [contribution guidelines](CONTRIBUTING.md) for this project. - [x] Read the [ASF Generative Tooling Guidance](https://www.apache.org/legal/generative-tooling.html) if you use Artificial Intelligence (AI). - [x] I used AI to create any part of, or all of, this pull request. Which AI tool was used to create this pull request, and to what extent did it contribute? Claude Code, used to run the differential test that located the defect and to draft this patch and the two regression tests. - [x] Run a successful build using the default [Maven](https://maven.apache.org/) goal with `mvn`; that's `mvn` on the command line by itself. - [x] Write unit tests that match behavioral changes, where the tests fail if the changes to the runtime are not applied. This may not always be possible, but it is a best practice. - [x] Write a pull request description that is detailed enough to understand what the pull request does, how, and why. - [x] Each commit in the pull request should have a meaningful subject line and body. Note that a maintainer may squash commits during the merge process. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
