Crate forward_goto

This crate provides a sound and safe way to jump from a goto forward in the control-flow to a label.

Rust has no goto mechanism with which it is possible to arbitrarily jump through the control-flow.

This crates provides a procedural macro that allows to write gotos that can jump forward in the control-flow to a specified label.

The jump is safe in terms of the borrow-checker, but several restrictions apply. See rewrite_forward_goto for more information.

use forward_goto::rewrite_forward_goto;
 
#[rewrite_forward_goto]
fn decode_msg(luck: impl Fn() -> bool, is_alan_turing: bool) {
    if is_alan_turing {
        forward_goto!('turing_complete);
    }
 
    println!("You'll need a lot of luck for this");
     
    if luck() {
        println!("Seems you were lucky");
 
        forward_label!('turing_complete);

        println!("Message decoded!");
    } else {
        println!("No luck today...");
    }
}

Attribute Macros

rewrite_forward_goto

This macro will rewrite the annotated function so that the control-flow will go from a goto forward_goto!('label) directly to a corresponding label forward_label!('label).