no-std Build

The feature no_std automatically converts the scripting engine into a no-std build.

Usually, a no-std build goes hand-in-hand with minimal builds because typical embedded hardware (the primary target for no-std) has limited storage.

Nightly required

Currently, no_std requires the nightly compiler due to the crates that it uses.

Implementation

Rhai allocates, so the first thing that must be included in any no-std project is an allocator crate, such as wee_alloc.

Then there is the need to set up proper error/panic handlers. The following example uses panic = "abort" and wee_alloc as the allocator.

// Set up for no-std. #![no_std] // The following no-std features are usually needed. #![feature(alloc_error_handler, start, core_intrinsics, lang_items, link_cfg)] // Set up the global allocator. extern crate alloc; extern crate wee_alloc; #[global_allocator] static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT; // Rust needs a CRT runtime on Windows when compiled with MSVC. #[cfg(all(windows, target_env = "msvc"))] #[link(name = "msvcrt")] #[link(name = "libcmt")] extern "C" {} // Set up panic and error handlers #[alloc_error_handler] fn err_handler(_: core::alloc::Layout) -> ! { core::intrinsics::abort(); } #[panic_handler] #[lang = "panic_impl"] extern "C" fn rust_begin_panic(_: &core::panic::PanicInfo) -> ! { core::intrinsics::abort(); } #[lang = "eh_personality"] extern "C" fn eh_personality() {} #[no_mangle] extern "C" fn rust_eh_register_frames() {} #[no_mangle] extern "C" fn rust_eh_unregister_frames() {} #[no_mangle] extern "C" fn _Unwind_Resume() {} #[start] fn main(_argc: isize, _argv: *const *const u8) -> isize { // ... main program ... }

Samples

Check out the no-std sample applications for different operating environments.