Error recovery/resilience

Currently, all of the parse functions return Result<ast, ParseError>. This means that if the file has a syntax error, we get the error and nothing else. However, there are some use cases in which having access to parts which did parse successfully would be beneficial:

• Language servers usually want to keep functioning when the file is temporarily broken during editing.
• Linters might want to skip over broken parts and continue reporting lints, or maybe up to the syntax error.

On the other hand, interpreters usually don't have too much use for this AFAIK.

lalrpop seems to have some support for error recovery: https://lalrpop.github.io/lalrpop/tutorial/008_error_recovery.html
Alex Kladov has written about error recovery, most recently here: https://matklad.github.io/2023/05/21/resilient-ll-parsing-tutorial.html

Is RustPython/Parser interested in error recovery or is it out of scope?

まず、パーサーの parse 関数と、それらが現在どのように Result<ast, ParseError> を返しているかを読みます。リンクされている LALRPOP と resilient-LL parsing の資料を確認し、エラー回復のアプローチを比較します。エラー回復を対象範囲に含めるかどうかについてプロジェクトとして合意された判断があり、含める場合は、正常にパースされた部分を保持するための具体的な設計があることが完了の条件です。