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#![allow(unused_assignments)]
// expect-exit-status-101
fn might_panic(should_panic: bool) {
if should_panic {
println!("panicking...");
panic!("panics");
} else {
println!("Don't Panic");
}
}
fn main() -> Result<(), u8> {
let mut countdown = 10;
while countdown > 0 {
if countdown == 1 {
might_panic(true);
} else if countdown < 5 {
might_panic(false);
}
countdown -= 1;
}
Ok(())
}
// Notes:
// 1. Compare this program and its coverage results to those of the similar tests `abort.rs` and
// `try_error_result.rs`.
// 2. Since the `panic_unwind.rs` test is allowed to unwind, it is also allowed to execute the
// normal program exit cleanup, including writing out the current values of the coverage
// counters.
// 3. The coverage results show (interestingly) that the `panic!()` call did execute, but it does
// not show coverage of the `if countdown == 1` branch in `main()` that calls
// `might_panic(true)` (causing the call to `panic!()`).
// 4. The reason `main()`s `if countdown == 1` branch, calling `might_panic(true)`, appears
// "uncovered" is, InstrumentCoverage (intentionally) treats `TerminatorKind::Call` terminators
// as non-branching, because when a program executes normally, they always are. Errors handled
// via the try `?` operator produce error handling branches that *are* treated as branches in
// coverage results. By treating calls without try `?` operators as non-branching (assumed to
// return normally and continue) the coverage graph can be simplified, producing smaller,
// faster binaries, and cleaner coverage results.
// 5. The reason the coverage results actually show `panic!()` was called is most likely because
// `panic!()` is a macro, not a simple function call, and there are other `Statement`s and/or
// `Terminator`s that execute with a coverage counter before the panic and unwind occur.
// 6. Since the common practice is not to use `panic!()` for error handling, the coverage
// implementation avoids incurring an additional cost (in program size and execution time) to
// improve coverage results for an event that is generally not "supposed" to happen.
// 7. FIXME(#78544): This issue describes a feature request for a proposed option to enable
// more accurate coverage results for tests that intentionally panic.
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