Macro std::panic

macro_rules! panic {
    () => { ... };
    ($msg:expr) => { ... };
    ($msg:expr,) => { ... };
    ($fmt:expr, $($arg:tt)+) => { ... };
}

Panics the current thread.

This allows a program to terminate immediately and provide feedback to the caller of the program. panic! should be used when a program reaches an unrecoverable state.

This macro is the perfect way to assert conditions in example code and in tests. panic! is closely tied with the unwrap method of both Option and Result enums. Both implementations call panic! when they are set to None or Err variants.

This macro is used to inject panic into a Rust thread, causing the thread to panic entirely. Each thread's panic can be reaped as the Box<Any> type, and the single-argument form of the panic! macro will be the value which is transmitted.

Result enum is often a better solution for recovering from errors than using the panic! macro. This macro should be used to avoid proceeding using incorrect values, such as from external sources. Detailed information about error handling is found in the book.

The multi-argument form of this macro panics with a string and has the format! syntax for building a string.

See also the macro compile_error!, for raising errors during compilation.

Current implementation

If the main thread panics it will terminate all your threads and end your program with code 101.

Examples

panic!();
panic!("this is a terrible mistake!");
panic!(4); // panic with the value of 4 to be collected elsewhere
panic!("this is a {} {message}", "fancy", message = "message");