overrideCommand with a relative path (`./miri`/`./x.py`) does not work very well, and that is very hard to debug

[RalfJung]

I am using the following workspace settings for working on Miri with vscode:

// Place your settings in this file to overwrite default and user settings.
{
    "rust-analyzer.rustfmt.extraArgs": [
        "+nightly"
    ],
    "rust-analyzer.checkOnSave.overrideCommand": [
        "./miri",
        "check",
        "--message-format=json",
    ],
    "rust-analyzer.linkedProjects": [
        "./Cargo.toml",
        "./cargo-miri/Cargo.toml"
    ],
    //"rust-analyzer.rustcSource": "discover"
}

Whenever I save a file, an error pops up saying

cargo check failed: No such file or directory (os error 2)

That's all it says. I have no idea which file it is talking about, or what is even going wrong -- the cargo check seems to be working fine, I am getting the errors I am expected highlighted as they should. The only sign that anything going wrong is this error message, and the error is not giving any details that would be helpful in determining what is happening.

[Veykril]

This looks like a cargo problem to me(as in it doesn't emit the bad file's path), as we show the entire error message we receive from cargo here https://github.com/rust-analyzer/rust-analyzer/blob/cfa26c3ac3d85d502f75c2f6b760aadcc997a1a8/crates/rust-analyzer/src/main_loop.rs#L396-L401

[bjorn3]

The stderr of cargo is read but never presented to the user: https://github.com/rust-analyzer/rust-analyzer/blob/d1e756e05aab5410f6176fce26bf021453708b9b/crates/flycheck/src/lib.rs#L292

[RalfJung]

Also, running ./miri check --message-format=json does not show any such error. So if this error is coming from cargo, the question is what RA is doing that it invokes cargo in a way that causes that error.

This is also a regression, the same configuration used to work fine a few months ago.

[RalfJung]

This excerpt from the log might be interesting though it does not tell me much

[INFO rust_analyzer::main_loop] handle_event(FetchWorkspace(Report("metadata")))
[INFO rust_analyzer::reload] did fetch workspaces [Ok(Cargo { root: Some("miri"), n_packages: 57, sysroot: true, n_rustc_compiler_crates: 0, n_rustc_cfg: 67, n_cfg_overrides: 1 }), Ok(Cargo { root: Some("cargo-miri"), n_packages: 53, sysroot: true, n_rustc_compiler_crates: 0, n_rustc_cfg: 67, n_cfg_overrides: 1 })]
[INFO rust_analyzer::main_loop] handle_event(FetchWorkspace(End([Ok(Cargo { root: Some("miri"), n_packages: 57, sysroot: true, n_rustc_compiler_crates: 0, n_rustc_cfg: 67, n_cfg_overrides: 1 }), Ok(Cargo { root: Some("cargo-miri"), n_packages: 53, sysroot: true, n_rustc_compiler_crates: 0, n_rustc_cfg: 67, n_cfg_overrides: 1 })])))
[INFO rust_analyzer::reload] will switch workspaces
[INFO rust_analyzer::main_loop] handle_event(PrimeCaches(Begin))
[INFO rust_analyzer::main_loop] handle_event(Response(Response { id: RequestId(I32(12)), result: None, error: None }))
[INFO rust_analyzer::main_loop] handle_event(Response(Response { id: RequestId(I32(13)), result: None, error: None }))
[INFO rust_analyzer::main_loop] handle_event(Response(Response { id: RequestId(I32(14)), result: None, error: None }))
[INFO rust_analyzer::main_loop] handle_event(Request(Request { id: RequestId(I32(9)), method: "textDocument/semanticTokens/full", params: Object({"textDocument": Object({"uri": String("file:///home/r/src/rust/miri/tests/run-pass/portable-simd.rs")})}) }))
[INFO flycheck] restart flycheck "./miri" "check" "--message-format=json"
[INFO flycheck] restart flycheck "./miri" "check" "--message-format=json"
[INFO rust_analyzer::main_loop] handle_event(Progress { id: 1, progress: DidStart })
[ERROR flycheck] Flycheck failed to run the following command: "./miri" "check" "--message-format=json"
[INFO rust_analyzer::main_loop] handle_event(Progress { id: 1, progress: DidFinish(Err(Os { code: 2, kind: NotFound, message: "No such file or directory" })) })
[INFO rust_analyzer::main_loop] handle_event(Response(Response { id: RequestId(I32(15)), result: None, error: None }))
[INFO rust_analyzer::main_loop] handle_event(Response(Response { id: RequestId(I32(16)), result: None, error: None }))
[INFO rust_analyzer::main_loop] handle_event(Progress { id: 0, progress: DidFinish(Ok(())) })
[INFO rust_analyzer::main_loop] handle_event(Request(Request { id: RequestId(I32(10)), method: "textDocument/codeLens", params: Object({"textDocument": Object({"uri": String("file:///home/r/src/rust/miri/tests/run-pass/portable-simd.rs")})}) }))
[INFO rust_analyzer::main_loop] handle_event(Response { id: RequestId(I32(10)), error: None })
[INFO rust_analyzer::global_state] handled textDocument/codeLens - (10) in 104.40µs

Could it be the case that it starts ./miri ... twice, one of them works and gives me the in-editor warnings I expect, and the other fails with the error it shows?

[bjorn3]

It sees two workspaces: One for miri (at .) and one for cargo-miri (at ./cargo-miri) and then tries to run ./miri check --message-format=json within the directory of both workspaces. The first succeeds, but the second fails as it needs to be ../miri in that case.

[RalfJung]

That is new behavior though I think? We had two workspaces for a while. I don't remember exactly why but I do remember that making them one workspace did not work the way I wanted it to.

./miri check --message-format=json actually builds both of them.

[RalfJung]

I confirmed @bjorn3's theory by creating a dummy script cargo-miri/miri that does nothing -- then the error goes away.

Unfortunately, vscode still does not show errors or warnings for the cargo-miri crate -- it used to be enough to add it to linkedProjects to achieve this, but it seems that things changed over the last few weeks/months. So instead I made cargo-miri/miri a symlink to miri, and changed the script to adjust its working dir correctly even when being called through a symlink -- now things seem to work again.

But it looks like overrideCommand and linkedProjects currently do not behave well when used together.