Code shared from the Rust Playground

playground.rs

#![allow(unexpected_cfgs)]
#![allow(deprecated)]

// --- SECTION 1: NIGHTLY (no_std + Allocator) ---
#[cfg(nightly)]
mod nightly_impl {
    #![feature(alloc_error_handler)]
    #![no_std]
    #![no_main]

    extern crate alloc;
    use core::panic::PanicInfo;
    
    // Versioned RNGs 
    use rand_0_8_5::{SeedableRng as SeedableRngL, Rng as RngL};
    use rand_0_8_5::rngs::SmallRng as SmallRngL;
    
    use rand_0_9_2::{SeedableRng as SeedableRngLatest, Rng as RngLatest};
    use rand_0_9_2::rngs::SmallRng as SmallRngLatest;

    #[no_mangle]
    pub extern "C" fn main(_argc: i32, _argv: *const *const u8) -> i32 {
        let seed = [0u8; 32];
        let mut rng8 = SmallRngL::from_seed(seed);
        let mut rng9 = SmallRngLatest::from_seed(seed);

        // r#gen escapes the 'gen' keyword reserved in Edition 2024
        let v8: u64 = rng8.r#gen();
        let v9: u64 = rng9.r#gen();

        if v8 == v9 { 0 } else { 1 }
    }

    #[panic_handler]
    fn panic(_info: &PanicInfo) -> ! { loop {} }

    #[alloc_error_handler]
    fn alloc_error_handler(_layout: core::alloc::Layout) -> ! { loop {} }
}

// --- SECTION 2: STABLE/BETA (Standard std) ---
#[cfg(not(nightly))]
mod stable_impl {
    use rand_0_8_5::{thread_rng as rng_v8, Rng as RngL};
    use rand_0_9_2::{thread_rng as rng_v9, Rng as RngLatest};

    pub fn main() {
        let mut v8 = rng_v8();
        let mut v9 = rng_v9();

        println!("--- Stable Channel Report ---");
        println!("Legacy (v0.8.5) u64: {}", v8.r#gen::<u64>());
        println!("Latest (v0.9.2) u64: {}", v9.r#gen::<u64>());
    }
}

// Entry point redirector
#[cfg(not(nightly))]
fn main() {
    stable_impl::main();
}