error: extern blocks must be unsafe

[paulclem1]

Describe the Bug

compiler reports "error: extern blocks must be unsafe" on compiling the following extern "C" {

     fn c_function_name(x: i32) -> i32; 
     //fn c_function_name();
 } 

Even when wrapped in an unsafe loop, the code won't compile. The compiler responds with "error: expected item, found keyword unsafe" if I wrap the extern C with "unsafe" as directed by the compiler

A clear and concise description of what you expected to happen:

Code should compile with no unsafe wrapping, and, as Ive stated above, compiler responds with a contradictory error if i do exactly what it asks.

I need to implement the extern C to overcome a cc error reported by the compiler. I'm in the process of writing code using the egui_macroquad crate to generate an oscilloscope trace. I'm using example code generated by AI. When I used egui_plot I had no cc error. Here is the full AI generated example code use macroquad::prelude::*; use egui_macroquad; use std::env; use std::path::PathBuf; use std::ffi::CString; //use cc; //use macroquad::ui::widgets::Window; use egui::{Context, RichText, Window}; unsafe { extern "C" {

     fn c_function_name(x: i32) -> i32; // Replace with your C function
     //fn c_function_name();
 }  }

#[macroquad::main("egui with macroquad")] async fn main() { unsafe { let result = c_function_name(5); // Call your C function // Use the result in your Macroquad code } let mut ctx = Context::default(); loop { clear_background(WHITE);

    // Process keys, mouse, etc. (your normal game logic)

    // Call egui_macroquad::ui to create and interact with the egui UI
    egui_macroquad::ui(|egui_ctx| {
       // egui_macroquad::Window::new("My UI").show(egui_ctx, |ui| {
       egui::Window::new("My UI").open(&mut true).show(&ctx, |ui| {         
        //Window::new("My UI").show(egui_ctx, |ui| {        
            ui.label("This is an egui window!");
        });
    });

    // Draw things before egui (your normal Macroquad drawing)

    // Call egui_macroquad::draw to render the egui UI
    egui_macroquad::draw();
    /*unsafe {
         let result = c_function_name(10);
         println!("Result from C: {}", result);
     }  */

[shniubobo]

Have you read this guide and this rust book chapter? You can find examples there on how to use unsafe.

Even when wrapped in an unsafe loop, the code won't compile. The compiler responds with "error: expected item, found keyword unsafe"

What do you mean by wrapping a function declaration in a loop? That compiler error means you have written something syntactically wrong. Your problem should be solved just by turning extern "C" into unsafe extern "C".

Code should compile with no unsafe wrapping

Not in Rust 2024. See the linked guide above.