nah

nah is a proc-macro crate for flagging clean-code and code-style violations at compile time.

What it does

The crate provides a set of attribute macros that can be attached to functions, structs, enums, traits, and impl blocks.

• In normal mode, the macro does not break the build; it emits a Cargo warning instead.
• If the DEPLOY=1 environment variable is set, the macro turns the violation into a hard compile error.
• If PROFILE=release, the check is skipped and the annotated item is returned unchanged.

Supported attributes

Complexity & metrics

• #[high_complexity]
• #[arrow_anti_pattern]
• #[too_many_arguments]
• #[huge_item]

Duplication

• #[duplicate]
• #[have_duplicate_code]
• #[copy_paste_programming]

Code smells & architecture

• #[spaghetti_code]
• #[god_object]
• #[dead_code_candidate]
• #[no_needing_function]
• #[premature_optimization]
• #[magic_numbers]
• #[temporary_field]
• #[kiss_violation]

Side effects & clean functions

• #[side_effects]
• #[output_arguments]
• #[flag_argument]

SOLID violations

• #[srp_violation]
• #[ocp_violation]
• #[lsp_violation]
• #[isp_violation]
• #[dip_violation]

Psychological technical debt

• #[crutch]
• #[broken_window]
• #[boy_scout_fail]

Installation

Add the dependency to your Cargo.toml:

[dependencies]
nah = "0.1"

Usage example

use nah::too_many_arguments;

#[too_many_arguments("Consider grouping parameters into a config struct")]
pub fn render(
    a: i32,
    b: i32,
    c: i32,
    d: i32,
) {
    println!("{} {} {} {}", a, b, c, d);
}

You can also use an attribute without a message:

use nah::spaghetti_code;

#[spaghetti_code]
fn legacy_parser() {}

Build behavior

Development mode

If DEPLOY is not set to 1, compilation continues, but Cargo prints a warning like this:

cargo:warning=[nah] Clean Code violation on `render`: `#[too_many_arguments]` -> Reason: Consider grouping parameters into a config struct.

Deployment mode

If DEPLOY=1, compilation stops with an error and the build fails.

DEPLOY=1 cargo build

Release mode

If PROFILE=release, the macro returns the original item without warnings or errors.

Notes

• The macro accepts an optional string message, for example: #[kiss_violation("Too clever, simplify this code")].
• The message is only used for diagnostics and does not affect code generation.
• Supported items include fn, struct, enum, trait, and impl.

Tests

This repository includes integration tests powered by trybuild.

Run them with:

cargo test

License

MIT