opt_level::OPT_LEVEL

Get the value of rustc's -Copt-level= flag at runtime.

Useful for sizing tests to run fewer iterations in slow build modes.

According to https://doc.rust-lang.org/cargo/reference/profiles.html#opt-level the possible values are:

• 0: no optimizations
• 1: basic optimizations
• 2: some optimizations
• 3: all optimizations
• s: optimize for binary size
• z: optimize for binary size, but also turn off loop vectorization

Example

use rand::rngs::SmallRng;
use rand::{RngCore as _, SeedableRng as _};

const N: usize = if cfg!(miri) {
    500
} else if let b"0" = opt_level::OPT_LEVEL.as_bytes() {
    10_000
} else {
    100_000_000
};

#[test]
fn random_test() {
    let mut rng = SmallRng::from_os_rng();

    for _ in 0..N {
        let bits = rng.next_u64();
        ...
        assert_eq!(..., ...);
    }
}

License