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?

首先阅读解析器的 parse 函数，以及它们目前如何返回 Result<ast, ParseError>。查阅链接的 LALRPOP 和 resilient-LL parsing 材料，以比较错误恢复方案。完成的标准是：项目就错误恢复是否属于范围达成一致决定，并且在属于范围的情况下，制定出保留成功解析部分的具体设计。