Inspecting generated code

#[rtic::app] is a procedural macro that produces support code. If for some reason you need to inspect the code generated by this macro you have two options:

• You can inspect the file rtic-expansion.rs inside the target directory.
• Use the cargo-expand sub-command

Using generated rtic-expansion.rs

Locating this file depends on how building is performed.

Using e.g. cargo xtask build-example within the main RTIC repo will place the file based on "platform" used:

$ cargo xtask example-build --example smallest
$ cargo xtask example-build --example monotonic --platform esp32-c3

$ fd -u rtic-expansion.rs
examples/esp32c3/target/rtic-expansion.rs
examples/lm3s6965/target/rtic-expansion.rs

In the regular cargo project case it goes directly in the target folder.

This file contains the expansion of the #[rtic::app] item (not your whole program!) of the last built (via cargo build or cargo check) RTIC application. The expanded code is not pretty printed by default, so you'll want to run rustfmt on it before you read it.

$ cargo build --example smallest --target thumbv7m-none-eabi

$ rustfmt target/rtic-expansion.rs

$ tail target/rtic-expansion.rs

#[doc = r" Implementation details"]
mod app {
    #[doc = r" Always include the device crate which contains the vector table"]
    use lm3s6965 as _;
    #[no_mangle]
    unsafe extern "C" fn main() -> ! {
        rtic::export::interrupt::disable();
        let mut core: rtic::export::Peripherals = core::mem::transmute(());
        core.SCB.scr.modify(|r| r | 1 << 1);
        rtic::export::interrupt::enable();
        loop {
            rtic::export::wfi()
        }
    }
}

Using cargo-expand tool

If not available, install:

$ cargo install cargo-expand

This sub-command will expand all the macros, including the #[rtic::app] attribute, and modules in your crate and print the output to the console.

# produces the same output as before

cargo expand --example smallest | tail