simple features without cargo

i want to write a simple practice with quicksort in rust, it may be a small single file, and i dont want to make a dir and write a cargo.toml file for it, it's tedious, and may be i will write many files like this, i dont want to do so many things for such a small file, but i also want the functions with the plugin like autocomplete, diagnostic, format and so on, so are there any ways can let it work without cargo? I wrote c++ before, as far as i know, there are some plugins like clangd can provide these functions without any build tools for just one single file, and I want to migrate my habit to rust, are there any good ways?

No files, tests, or entry points are named. Start by reviewing rust-analyzer's existing handling of standalone Rust files and the discussion in this issue, then determine whether support without Cargo is in scope. Done would mean a decided approach and corresponding implementation or documentation for autocomplete, diagnostics, and formatting.