Rust Analyzer writes target/rust-analyzer/flycheck in wrong directory

[lvaroqui-gpfw]

Hello,

Since a couple of days (probably the merge of #20806), rust-analyzer creates a target folder in the root of my git repository with the following tree:

target
└── rust-analyzer
    └── rust-analyzer
        └── flycheck0
            ├── stderr
            └── stdout

The root of my repo is not a Cargo project/workspace, I only have a rust project in a sub folder (which contains the expected target/rust-analyzer folder). I'd expect the flychecks to be placed in the existing path/to/cargo_project/target folder.

This will be annoying for users as if not ignored by .gitignore, this will produce a new folder automatically that may be committed by mistake.

Relevant options

• rust-analyzer.cargo.targetDir: true
• rust-analyzer.linkedProjects: [ "path/to/cargo_project/Cargo.toml" ]

Env

• VSCode Extension nightly
• Ubuntu 22.04

[ShoyuVanilla]

Maybe this is a good place to use the build-dir #20150

[xcenweb]

Window srust version 1.90.0 (1159e78c4 2025-09-14) nightly! I also encountered this problem.

[Vlad-Shcherbina]

Another manifestation of what looks like the same issue: rust-analyzer doesn't respect custom target dir setting.

To reproduce, create a trivial project (e.g. cargo init --bin) and add .cargo/config.toml with the following content:

[build]
target-dir = "my_custom_target_dir"

Immediately after opening the project in VSCode, the plugin will create these two files:

target/rust-analyzer/flycheck0/stderr
target/rust-analyzer/flycheck0/stdout

They should be in my_custom_target_dir/ instead.

[ShoyuVanilla]

Another manifestation of what looks like the same issue: rust-analyzer doesn't respect custom target dir setting.

I guess that happens when you have rust-analyzer.cargo.targetDir: true with target-dir in your cargo config file, right? I'll fix it as well.

[Vlad-Shcherbina]

The behavior I described was with "rust-analyzer.cargo.targetDir": null (the default) in VSCode's settings.json.
If it's set to true, I'm getting this:

target/rust-analyzer/debug/...
target/rust-analyzer/rust-analyzer/flycheck0/{stdout,stderr}

Custom target dir is still not respected (I would say the expected behavior is for rust-analyzer to nest its own target dir inside custom target dir).

[ShoyuVanilla]

Yes, target/rust-analyzer/rust-analyzer/flycheck being written regardless of cargo's target-dir configuration is the issue in the OP and target/rust-analyzer/debug being written when "rust-analyzer.cargo.targetDir": true" is another one (I guess the later has been existing before the former)