保存时运行fmt

"[rust]": {
    "editor.defaultFormatter": "rust-lang.rust-analyzer",
    "editor.formatOnSave": true
}

Install rust-analyzer, if you have not already.
In Visual Studio Code's settings, enable Editor: Format On Save (editor.formatOnSave).

blog/A-IT/40-tools/编辑器/vscode/vscode-rust