rust-guard

Prevents AI assistants from suggesting outdated Rust code patterns

cargo install rust-guard

use rust_guard_v2::Guard;

fn main() {
    let guard = Guard::new()
        .deny_pattern("try!")
        .deny_pattern("extern crate")
        .deny_pattern(".to_owned()")
        .suggest_instead(".to_owned()", ".to_string() or .clone()");
    
    let code = r#"
        let result = try!(some_operation());
    "#;
    
    match guard.check(code) {
        Ok(_) => println!("clean"),
        Err(violations) => {
            for v in violations {
                eprintln!("{}", v);
            }
        }
    }
}

notes

Catches common outdated patterns that LLMs trained on old Rust code still suggest. Add custom rules for your project's conventions.

Default rules include:

• try! macro (use ? operator)
• extern crate (2015 edition syntax)
• .to_owned() on &str (usually want .to_string())
• std::ascii::AsciiExt (deprecated)
• match ergonomics antipatterns

Run as pre-commit hook or in CI. Pairs well with clippy but focuses on patterns that evolved with editions rather than just correctness.

use rust_guard_v2::{Guard, Severity};

// custom project rules
let guard = Guard::new()
    .with_config("rust-guard.toml")
    .deny_pattern_with_context(
        r"\.unwrap\(\)",
        Severity::Warn,
        "prefer ? or expect() with context"
    )
    .deny_import("tokio::prelude", "import specific items instead")
    .require_feature_for_pattern(
        r"unsafe \{",
        "#![forbid(unsafe_code)] not set"
    );

// check entire project
guard.check_workspace(".")?;

// or integrate into build.rs
guard.check_src("src/")?;

MIT