Panicking

✅ Open the src/bin/panic.rs file and click the "Run" button.

This program attempts to index an array beyond its length and this results in a panic.

(HOST) INFO  flashing program (34.79 KiB)
(HOST) INFO  success!
────────────────────────────────────────────────────────────────────────────────
ERROR:panic_log -- panicked at 'index out of bounds: the len is 3 but the index is 3', src/bin/panic.rs:29:13
────────────────────────────────────────────────────────────────────────────────
stack backtrace:
   0: HardFaultTrampoline
      <exception entry>
[...]
   7: panic::bar
        at src/bin/panic.rs:29:13
   8: panic::foo
        at src/bin/panic.rs:22:5
   9: panic::__cortex_m_rt_main
        at src/bin/panic.rs:12:5
  10: main
        at src/bin/panic.rs:8:1
[...]
(HOST) ERROR the program panicked

In no_std programs the behavior of panic is defined using the #[panic_handler] attribute. In the example, the panic handler is defined in the panic_log crate but we can also implement it manually:

✅ Comment out the panic_log import and add the following function to the example:

#[panic_handler]
fn panic(info: &core::panic::PanicInfo) -> ! {
    log::error!("{}", info);
    loop {
        asm::bkpt()
    }
}

Now run the program again. Try changing the format string of the error! macro.

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Panicking

1.6 KiB

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