1| |#![allow(unused_assignments)] 2| |// expect-exit-status-101 3| | 4| 4|fn might_panic(should_panic: bool) { 5| 4| if should_panic { 6| 1| println!("panicking..."); 7| 1| panic!("panics"); 8| 3| } else { 9| 3| println!("Don't Panic"); 10| 3| } 11| 3|} 12| | 13| 1|fn main() -> Result<(), u8> { 14| 1| let mut countdown = 10; 15| 11| while countdown > 0 { 16| 11| if countdown == 1 { 17| 1| might_panic(true); 18| 10| } else if countdown < 5 { 19| 3| might_panic(false); 20| 6| } 21| 10| countdown -= 1; 22| | } 23| 0| Ok(()) 24| 0|} 25| | 26| |// Notes: 27| |// 1. Compare this program and its coverage results to those of the similar tests `abort.rs` and 28| |// `try_error_result.rs`. 29| |// 2. Since the `panic_unwind.rs` test is allowed to unwind, it is also allowed to execute the 30| |// normal program exit cleanup, including writing out the current values of the coverage 31| |// counters. 32| |// 3. The coverage results show (interestingly) that the `panic!()` call did execute, but it does 33| |// not show coverage of the `if countdown == 1` branch in `main()` that calls 34| |// `might_panic(true)` (causing the call to `panic!()`). 35| |// 4. The reason `main()`s `if countdown == 1` branch, calling `might_panic(true)`, appears 36| |// "uncovered" is, InstrumentCoverage (intentionally) treats `TerminatorKind::Call` terminators 37| |// as non-branching, because when a program executes normally, they always are. Errors handled 38| |// via the try `?` operator produce error handling branches that *are* treated as branches in 39| |// coverage results. By treating calls without try `?` operators as non-branching (assumed to 40| |// return normally and continue) the coverage graph can be simplified, producing smaller, 41| |// faster binaries, and cleaner coverage results. 42| |// 5. The reason the coverage results actually show `panic!()` was called is most likely because 43| |// `panic!()` is a macro, not a simple function call, and there are other `Statement`s and/or 44| |// `Terminator`s that execute with a coverage counter before the panic and unwind occur. 45| |// 6. Since the common practice is not to use `panic!()` for error handling, the coverage 46| |// implementation avoids incurring an additional cost (in program size and execution time) to 47| |// improve coverage results for an event that is generally not "supposed" to happen. 48| |// 7. FIXME(#78544): This issue describes a feature request for a proposed option to enable 49| |// more accurate coverage results for tests that intentionally panic.