Add PWD to the Reedline state

[YizhePKU]

This PR adds the current working directory as part of the Reedline state, instead of using std::env::current_dir() to retrieve it from the environment. Applications should call Reedline::with_cwd() to update the current working directory when it changes.

This is necessary to support nushell/nushell#12922, which causes std::env::current_dir() to deviate from Nushell's $env.PWD.

[IanManske]

Currently, this sets cwd to an empty string in all cases, unless explicitly overwritten. Won't this break existing code that was relying on the std::env::current_dir behavior?

[devyn]

It would probably be best that it's either required or defaults to the actual current dir. Reedline is intended to be useful for more than just nushell

[devyn]

Just to make it clear - I don't think an empty string should be the default. I think making it an Option and then grabbing process working directory if it's None is probably the best way to go

[YizhePKU]

Just to make it clear - I don't think an empty string should be the default. I think making it an Option and then grabbing process working directory if it's None is probably the best way to go.

So you're saying that if cwd is set to None, we fallback to the old behavior (calling std::env::current_dir()), so that we don't break existing code that doesn't require special PWD logic?

That sounds good. I'll work on it.

[devyn]

Yeah, exactly. Thanks!

[fdncred]

@YizhePKU Do you have any more time to work on this in regards to @devyn's comments? I'd like to get this landed asap.

[YizhePKU]

I think this will do? I'll update the other PR if this gets merged.

[fdncred]

Thanks @YizhePKU! We appreciate you coming back around to this PR. @devyn, when you get a chance can you please look at this. I'd like to get it landed if possible.

[devyn]

Looks correct to me. Thanks!