Support multiple targets for checkOnSave (in conjunction with cargo 1.64.0+)

[poliorcetics]

This PR adds support for the ability to pass multiple --target flags when using
cargo 1.64.0+.

Questions

I needed to change the type of two configurations options, but I did not plurialize the names to
avoid too much churn, should I ?

Zulip thread

https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Issue.2013282.20.28supporting.20multiple.20targets.20with.201.2E64.2B.29

Example

To see it working, on a macOS machine:

$ cd /tmp
$ cargo new cargo-multiple-targets-support-ra-test
$ cd !$
$ mkdir .cargo
$ echo '
[build]
target = [
    "aarch64-apple-darwin",
    "x86_64-apple-darwin",
]
' > .cargo/config.toml
$ echo '
fn main() {
    #[cfg(all(target_arch = "aarch64", target_os = "macos"))]
    {
        let a = std::fs::read_to_string("/tmp/test-read");
    }

    #[cfg(all(target_arch = "x86_64", target_os = "macos"))]
    {
        let a = std::fs::read_to_string("/tmp/test-read");
    }

    #[cfg(all(target_arch = "x86_64", target_os = "windows"))]
    {
        let a = std::fs::read_to_string("/tmp/test-read");
    }
}
' > src/main.rs
# launch your favorite editor with the version of RA from this PR
#
# You should see warnings under the first two `let a = ...` but not the third

Screen

Helps with #13282

[poliorcetics]

I didn't make the change for the rust-project.json config because rustc does not accept multiple --target flags, contrarily to cargo

[flodiebold]

I don't think we can support this for cargo.target, at most for checkOnSave.

[poliorcetics]

I don't think we can support this for cargo.target, at most for checkOnSave.

cargo on 1.64.0+ accepts multiple targets, it's even supported in the .cargo/config.toml, why would cargo.target not support it ?

[flodiebold]

Because cargo.target controls our analysis, and that doesn't support multiple targets (without a lot more code).

[poliorcetics]

Because cargo.target controls our analysis, and that doesn't support multiple targets (without a lot more code).

Oh, I'll try to do it, either in this PR if it's not merged by then, or in another. For now, I removed it from the commit and changed back to an Option.

[poliorcetics]

Progress report

I made some progress on this today 🎉.

I have completions working for several targets at once:

But (because of course it's not perfectly working), completions for conflicting names fail, I don't which is chosen first (I suspect the first configured target):

[poliorcetics]

Go to definition and errors will point to the wrong item with the implementation I used, I removed that part and kept only the multiple targets when running cargo, not inside R-A

[bors]

☔ The latest upstream changes (presumably #13128) made this pull request unmergeable. Please resolve the merge conflicts.

[Veykril]

Thanks!
@bors r+

[bors]

📌 Commit 0d4737a has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit 0d4737a with merge 38fa47f...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing 38fa47f to master...