Rust-analyzer uses lowercase letters for Windows drives

[jyn514]

When I run x check in the rust-lang/rust repo, it unconditionally recompiles rustc_llvm on Windows only. CARGO_LOG=info shows the following:

[2023-04-29T10:37:19Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for rustc_llvm v0.0.0 (C:\Users\jyn\src\rust2\compiler\rustc_llvm)/RunCustomBuild/TargetInner { ..: custom_build_target("build-script-build", "C:\\Users\\jyn\\src\\rust2\\compiler\\rustc_llvm\\build.rs", Edition2021) }      
[2023-04-29T10:37:19Z INFO  cargo::core::compiler::fingerprint]     dirty: EnvVarChanged { name: "LLVM_CONFIG", old_value: Some("c:\\Users\\jyn\\src\\rust2\\build\\x86_64-pc-windows-msvc\\ci-llvm\\bin\\llvm-config.exe"), new_value: Some("C:\\Users\\jyn\\src\\rust2\\build\\x86_64-pc-windows-msvc\\ci-llvm\\bin\\llvm-config.exe") }

I think c:\ must be coming from rust-analyzer; running x check twice in a row doesn't recompile, only if I've saved in between. Disabling checkOnSave makes the problem go away.

---

some more detailed tracing:

LLVM_CONFIG is set here: https://github.com/rust-lang/rust/blob/8ce92daa854e329f4fb7ac75c28dbeea3f5bb125/src/bootstrap/compile.rs#L890
llvm_config comes from https://github.com/rust-lang/rust/blob/8ce92daa854e329f4fb7ac75c28dbeea3f5bb125/src/bootstrap/llvm.rs#L83
which in turn comes from https://github.com/rust-lang/rust/blob/214894275722249e434d24507771b6fef789df55/src/bootstrap/config.rs#L1319;
ci_llvm_root is just forwarding self.out https://github.com/rust-lang/rust/blob/214894275722249e434d24507771b6fef789df55/src/bootstrap/config.rs#L1516
which defaults to build and is set to an absolute path here: https://github.com/rust-lang/rust/blob/214894275722249e434d24507771b6fef789df55/src/bootstrap/util.rs#L469-L475

I don't know why GetFullPathName would return a different value between the bootstrap launched from powershell and the one launched by rust-analyzer.

---

rust-analyzer version: rust-analyzer version: 0.4.1494-standalone (370b72c 2023-04-28)

rustc version: HEAD is branched from rust-lang/rust@572c0d5; the beta compiler version is beta-2023-04-20.

relevant settings: various; bootstrap sets lots of things. .vscode/settings.json is as follows:

{
    "rust-analyzer.check.invocationLocation": "root",
    "rust-analyzer.check.invocationStrategy": "once",
    "rust-analyzer.check.overrideCommand": [
        "python",
        "x.py",
        "check",
        "--json-output"
    ],
    "rust-analyzer.linkedProjects": ["src/bootstrap/Cargo.toml", "Cargo.toml"],
    "rust-analyzer.rustfmt.overrideCommand": [
        "./build/host/rustfmt/bin/rustfmt",
        "--edition=2021"
    ],
    "rust-analyzer.procMacro.server": "./build/host/stage0/libexec/rust-analyzer-proc-macro-srv",
    "rust-analyzer.procMacro.enable": true,
    "rust-analyzer.cargo.buildScripts.enable": true,
    "rust-analyzer.cargo.buildScripts.invocationLocation": "root",
    "rust-analyzer.cargo.buildScripts.invocationStrategy": "once",
    "rust-analyzer.cargo.buildScripts.overrideCommand": [
        "python",
        "x.py",
        "check",
        "--json-output"
    ],
    "rust-analyzer.cargo.sysrootSrc": "./library",
    "rust-analyzer.rustc.source": "./Cargo.toml"
}

[Veykril]

A simple guess from my side would be that we set the current dir explicitly for most (if not all) commands and we only deal with paths in absolute forms, meaning we canonicalize paths where possible. It might be that canonicalizing returns lower case drive letters for some reason? One thing to check would be putting absolute paths instead of relative ones in the linkedProjects config

[Veykril]

It's vscode sending us lowercase driver letters for the workspace roots

"InitializeParams":{
   "processId":15652,
   "clientInfo":{
      "name":"Visual Studio Code",
      "version":"1.76.2"
   },
   "locale":"en-us",
   "rootPath":"c:\\workspace\\rust\\rust-analyzer",
   "rootUri":"file:///c%3A/workspace/rust/rust-analyzer",
   "initializationOptions":{
      "..."
   },
   "trace":"off",
   "workspaceFolders":[
      {
         "uri":"file:///c%3A/workspace/rust/rust-analyzer",
         "name":"rust-analyzer"
      }
   ],
   "..."
}

[Veykril]

So I'm fairly certain this is a wont fix on the VSCode side (judging from past discussions regarding their broken path caching in regards to letter casing) which means we probably want to fix this on the r-a side somehow.

Actually, can drive letters even be lowercase on windows? I assume we can just force them to be uppercase

[jyn514]

One thing to check would be putting absolute paths instead of relative ones in the linkedProjects config

That did not help :(

Actually, can drive letters even be lowercase on windows? I assume we can just force them to be uppercase

👍 that seems like a good solution. We could also try doing that in bootstrap, but I imagine other people on windows have this problem too and just haven't complained.

[jyn514]

"can be lowercase" is not really the right way to think about it though - NTFS is case-insensitive on Windows.

[Veykril]

"can be lowercase" is not really the right way to think about it though - NTFS is case-insensitive on Windows.

Well it is case-insensitive in that the casing doesn't matter for checking paths etc. Casing is still very much a thing for displaying/fetching, so assuming the drive letter of a drive could be assigned in lowercase, fixing it by just uppercasing it wouldn't really fix the problem in theory (since we could end up with the reverse if VSCode always reported it as uppercase).
But that's nitpicking and not something to worry about.
I'd say we fix it in r-a since in theory there can be general built scripts observing this and causing a similar invalidation (build probing comes to mind).