Crate flexpect

flexpect

#[flexpect::e(...)] compiles to #[expect(...)] for newer versions of Rust and to #[allow(...)] when not supported.

Purpose

This crate enables getting the benefits of #[expect(...)] while maintaining a minimum supported Rust version that’s earlier than 1.81.

Usage

Add flexpect to your Cargo.toml:

[dependencies]
flexpect = "0.1.0"

Then use the #[flexpect::e(...)] or #[flexpect::flexpect(...)] attributes instead of #[expect(...)]:

#[flexpect::e(unused_variables)] // instead of #[expect(unused_variables)]
fn example() {
    let x = 1;
}

use flexpect::flexpect;

#[flexpect(clippy::clone_on_copy)]  // instead of #[expect(clippy::clone_on_copy)]
fn clippy_example() {
    let _ = 32.clone();
}

How it works

• On Rust versions before 1.43.0, the attribute is ignored due to compiler bugs.
• From Rust 1.43.0 to 1.80, it translates to #[allow(...)].
• From Rust 1.81 onwards, it translates to #[expect(...)].

The minimum supported Rust version is 1.38.

Limitations

flexpect does not work as inner attributes (#![flexpect::e(...)]) nor on statements, expressions or blocks due to compiler limitations.

Attribute Macros

e

#[flexpect::e(...)] compiles to #[expect(...)] for newer versions of Rust and to #[allow(...)] when not supported.

flexpect

#[flexpect(...)] compiles to #[expect(...)] for newer versions of Rust and to #[allow(...)] when not supported.