Don't panic!()

Ensure that code can't panic at compile time.

Example

This code will compile and (not) run just fine:

let should_panic = false;
if should_panic {
    dont_panic!("This will never execute.");
}

However, this code will cause linking error:

let should_panic = true;
if should_panic {
    dont_panic!("This will never execute.");
}

Caveats

• This works only when appropriate opt_level is specified - it may require release build.
• The error message is weird link error. You don't get line number, etc.
• There may be situations in which you know that the code is unreachable but compiler can't prove it.