Stream: t-compiler/wg-rls-2.0

Topic: OUT_DIR from cargo check


Emil Lauridsen (Mar 12 2020 at 13:19, on Zulip):

So I'm currently working on making the cargo check code provide OUT_DIR for packages that run a build script, and the actual interfacing with cargo is easy. I'm not sure about how to hook it up to the rest of rust-analyzer however.

I currently have a cargo package id (e.g. gl 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)) and an OUT_DIR path, but I'm not quite sure how to access and update the corresponding crate from on_check_task in main_loop.rs. If anybody with more experience in how the crate graph is stored inside a WorldState could point me in the right direction it would be appreciated.

Secondly I'd also love some input on how/when to schedule getting the OUT_DIR values. As we all know by know, cargo check isn't always that fast, so running it asynchronously is a must. I'm not quite sure when to launch it to get the OUT_DIR values however. Ideally we'd have a way to ask cargo for just the OUT_DIRs without having to check the entire world, but that's not the situation currently.

std::Veetaha (Mar 12 2020 at 13:33, on Zulip):

@Emil Lauridsen , this may not be very related, but I noticed a suspicions thing in rls code. They depend on cargo as a package. I am not sure how this works, maybe this could mean they can access out-dir api in their code (though I don't see any code doing exactly that)?

Florian Diebold (Mar 12 2020 at 14:23, on Zulip):

the WorldState contains an AnalysisHost. I think you should be able to create an AnalysisChange, set_crate_graph on that and then apply_change on the analysis host.

Edwin Cheng (Mar 13 2020 at 05:45, on Zulip):

@Christopher Durham have some idea what the steps of the general cache process should be,you may be interested.

https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/How.20to.20get.20.60Out-Dir.60/near/190024836

Christopher Durham (Mar 13 2020 at 05:49, on Zulip):

Keep in mind when I wrote that I was under the impression that a new cargo check wouldn't re-emit the build-script-executed message. I may be wrong there, and that should simplify the process.

Edwin Cheng (Mar 13 2020 at 05:57, on Zulip):

And there is a vscode api ExtensionContext which provide some cache related directory api , which might be usefull too.

Emil Lauridsen (Mar 13 2020 at 12:47, on Zulip):

Check seems to always replay the build-script-executed events, so we luckily shouldn't need to worry about that

Emil Lauridsen (Mar 13 2020 at 13:35, on Zulip):

@matklad It looks to me like we have no way to identify a crate in the CrateGraph by the id/name we get from cargo, is that right? If so, how would you prefer going about storing such a mapping so that we can actually set OUT_DIR without blocking on the first cargo check?

matklad (Mar 13 2020 at 13:36, on Zulip):

When we lower cargo metadata to crate graph, we can remmeber a mapping from package name/target name to CrateId

Emil Lauridsen (Mar 13 2020 at 14:47, on Zulip):

Okay I've almost got it working, just gotta figure out how the get/create a ExternSourceId for a path on the fly. This would all be a lot easier if OUT_DIR was available form cargo metadata, it's turning out a bit more dirty than I'd like, so looking forward to some feedback once I get the last bit going.

Jeremy Kolb (Mar 13 2020 at 14:52, on Zulip):

The cargo issue for that is not very encouraging

Edwin Cheng (Mar 13 2020 at 15:11, on Zulip):

@Emil Lauridsen Currently ExternSourceId is just a re-wrapper of SourceRooId, such that :

let extern_source_id =  ExternSoruceId(source_root_id.0);
Emil Lauridsen (Mar 13 2020 at 15:25, on Zulip):

Form the code in world.rs ~L130 it seems to be a wrapped VfsRoot id, but that appears to use the same ids so I think I got it figured out

Emil Lauridsen (Mar 13 2020 at 15:49, on Zulip):

I created a draft PR with my current work: https://github.com/rust-analyzer/rust-analyzer/pull/3582

Laurențiu Nicola (Mar 19 2020 at 10:44, on Zulip):

Why is rust-analyzer.cargoFeatures.loadOutDirsFromCheck disabled by default? Can we enable it in the future?

matklad (Mar 19 2020 at 10:47, on Zulip):

It slows down initial load a lot

Laurențiu Nicola (Mar 19 2020 at 10:49, on Zulip):

Oh, right. Maybe we can turn it on when we support changing workspace contents dynamically?

Laurențiu Nicola (Mar 19 2020 at 10:49, on Zulip):

And I assume that's only on the first load

Emil Lauridsen (Mar 19 2020 at 18:58, on Zulip):

Would could do it lazily, the main blocker is how annoying (if even possible) adding a new VFS root and source roots on the fly. With that in place at some point, we could just run the initial cargo check in a thread like we run cargo check on save, and update the OUT_DIRs on the fly.

Last update: May 29 2020 at 17:15UTC