rust analyzer handle multi target_arch incorrectly, and should provide reload config command

rust analyzer handle multi target_arch incorrectly

rust-analyzer version: (eg. output of "rust-analyzer: Show RA Version" command, accessible in VSCode via Ctrl/⌘+Shift+P)

rust-analyzer version: 1.86.0-nightly (b3b368a 2025-01-05) [/home/vscode/.rustup/toolchains/nightly-2025-01-06-x86_64-unknown-linux-gnu/bin/rust-analyzer]

rustc version: (eg. output of rustc -V)

rustc 1.86.0-nightly (b3b368a18 2025-01-05)

editor or extension: (eg. VSCode, Vim, Emacs, etc. For VSCode users, specify your extension version; for users of other editors, provide the distribution if applicable)

VSCode

relevant settings: (eg. client settings, or environment variables like CARGO, RUSTC, RUSTUP_HOME or CARGO_HOME)

See below

repository link (if public, optional): (eg. rust-analyzer)

code snippet to reproduce:

Given code

core::arch::wasm32::unreachable();

Given layout and vscode config

        "rust-analyzer.linkedProjects": [
            "Cargo.toml",
            "path/to/wasm/crate/Cargo.toml"
        ],

---

When path/to/wasm/crate/.cargo/config.toml

target = [
    "wasm32-unknown-unknown",

Given code works fine.

core::arch::wasm32::unreachable();

---

When path/to/wasm/crate/.cargo/config.toml changed to

target = [
    "wasm32-unknown-unknown",
    "x86_64-unknown-linux-gnu",

After painfully slow full RA server restart, RA complain.

error[E0433]: failed to resolve: could not find `wasm32` in `arch`
  --> src/lib.rs:39:17
   |
39 |     core::arch::wasm32::unreachable();
   |                 ^^^^^^ could not find `wasm32` in `arch`

---

Change back to

target = [
    "wasm32-unknown-unknown",
    # "x86_64-unknown-linux-gnu"

After painfully slow full RA server restart, RA does not complain.

Given code works fine.

core::arch::wasm32::unreachable();

---

Conclusion

• RA should handle multi target_arch correctly

• RA should also provide reload config command, because fully restart server is painfully slow

Start with the provided linkedProjects setup and the wasm32/x86_64 target list in path/to/wasm/crate/.cargo/config.toml, reproducing the incorrect resolution after changing targets. Read the rust-analyzer configuration handling around project reloads; done means multi-target code resolves correctly and configuration changes no longer require a full server restart.