Rust Analyzer does not check project with custom build Rust correctly

help
1

Our wasi related project requires a custom built of Rust, so I build Rust with ./x.py build --stage 1 library and a custom config.toml, in a folder say MY_RUST_FOLDER, and use environments to override configures to make it compile with this custom version of Rust:

WASI_SDK=****
WASI_SDK_PATH=****
CC=****
RUST_WASI_TOOLCHAIN=****
RUSTC=****

and it worked for compiling from command lines.

To have type checking in VS Code, I have Rust Analyzer with project level settings:

{
  "editor.formatOnSave": true,
  "rust-analyzer.cargo.extraEnv": {
    "WASI_SDK": "{MY_KIT}//wasi-sdk-24.0-arm64-macos/",
    "WASI_SDK_PATH": "{MY_KIT}/wasi-sdk-24.0-arm64-macos/",
    "RUST_WASI_TOOLCHAIN": "{MY_RUST_FOLDER}",
    "CC": "{MY_KIT}/wasi-sdk-24.0-arm64-macos/bin/clang --sysroot={MY_KIT}/wasi-sdk-24.0-arm64-macos/share/wasi-sysroot",
    "CFLAGS": "--sysroot={MY_KIT}/wasi-sdk-24.0-arm64-macos/share/wasi-sysroot",
    "RUSTUP_TOOLCHAIN": "{MY_RUST_FOLDER}/build/aarch64-apple-darwin/stage1"
  },
  "rust-analyzer.server.extraEnv": {
    "CC": "{MY_KIT}//wasi-sdk-24.0-arm64-macos/bin/clang",
    "CFLAGS": "--sysroot={MY_KIT}//kit/wasi-sdk-24.0-arm64-macos/share/wasi-sysroot"
  },
  "rust-analyzer.rustc.path": "{MY_RUST_FOLDER}/build/host/stage1/bin/rustc",
  "rust-analyzer.rustc.source": "{MY_RUST_FOLDER}/build/host/stage1/lib/rustlib/src/rust/",
  "rust-analyzer.check.overrideCommand": [
    "cargo",
    "check",
    "--message-format=json"
  ],
  "rust-analyzer.check.targets": ["wasm32-wasip1"]
}

rustup show # latest info
Default host: aarch64-apple-darwin
rustup home:  {MY_HOME}/.rustup

installed toolchains
--------------------

nightly-aarch64-apple-darwin
1.81.0-aarch64-apple-darwin (default)
my-custom-toolchain

installed targets for active toolchain
--------------------------------------

aarch64-apple-darwin
wasm32-wasip1

active toolchain
----------------

1.81.0-aarch64-apple-darwin (default)
rustc 1.81.0 (eeb90cda1 2024-09-04) # installed 1.82 a while back, then removed...

rustup toolchain list # latest info
nightly-aarch64-apple-darwin
1.81.0-aarch64-apple-darwin (default)
my-custom-toolchain

it worked in first weeks, but recently(can't figure out why and after which change), it broke and got errors for all macros in VS code,

rquickjs::class: failed to build proc-macrorust-analyzermacro-error

also error message is noticed from LSP outputs:

2025-03-05T18:46:50.392243+08:00 ERROR FetchBuildDataError: error: "{MY_RUST_FOLDER}}/build/aarch64-apple-darwin/stage1/lib/rustlib/src/rust/library/Cargo.lock" does not exist, unable to build with the standard library, try:
        rustup component add rust-src --toolchain {MY_RUST_FOLDER}}/build/aarch64-apple-darwin/stage1

the message does not really fix my problem

error: error: invalid value '{MY_RUST_FOLDER}/build/aarch64-apple-darwin/stage1' for '--toolchain <toolchain>': invalid toolchain name: '/{MY_RUST_FOLDER}/build/aarch64-apple-darwin/stage1'

How to figure out what's the real problem here? Any other information I should check?

2

/Users/jon.chen/work/container/rust/build/aarch64-apple-darwin/stage1 is not a valid value for a toolchain name. You can however do rustup toolchain link stage1 /Users/jon.chen/work/container/rust/build/aarch64-apple-darwin/stage1 and then use stage1 as toolchain name instead.

3

not sure if I understand that correctly, but stage1 still appears an invalid name,

$ rustup toolchain list
nightly-aarch64-apple-darwin
1.81.0-aarch64-apple-darwin (default)
my-custom-toolchain
stage1

$ rustup component add rust-src --toolchain stage1
error: error: invalid value 'stage1' for '--toolchain <toolchain>': invalid toolchain name: 'stage1'

For more information, try '--help'.
: invalid toolchain name: 'stage1'
4

You should skip the rustup component add rust-src --toolchain stage1. The rust-src component is already installed for locally built toolchains. And rustup component add can't work for locally built toolchains as there is nowhere to download components from.

5

...which means the locally built toolchain is already installed and should already work?

6

If you set RUSTUP_TOOLCHAIN to stage1 it should work.

1 Like
7

only got to bypass failed to build proc-macrorust-analyzer macro-error with settings by now:

  "rust-analyzer.procMacro.attributes.enable": false,
  "rust-analyzer.procMacro.derive.enable": false,
  "rust-analyzer.procMacro.enable": false,

at least I got unneccesary warnings hidden.

8

another issue I noticed that my custom built Rust is 1.81 , and Rust analyzer auto updated and breaks for many 1.81 projects, so I have to switch back to some xxx.2308 version to get it compatible with my local Rust.

that error src/rust/library/Cargo.lock" does not exist, unable to build with the standard library still exists, but rust analyzer got to work in many std functions.

didn't try building 1.82+ locally for now.