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+ 1| |#![allow(unused_assignments)]
+ 2| |// failure-status: 101
+ 3| |
+ 4| 4|fn might_overflow(to_add: u32) -> u32 {
+ 5| 4| if to_add > 5 {
+ 6| 1| println!("this will probably overflow");
+ 7| 3| }
+ 8| 4| let add_to = u32::MAX - 5;
+ 9| 4| println!("does {} + {} overflow?", add_to, to_add);
+ 10| 4| let result = to_add + add_to;
+ 11| 4| println!("continuing after overflow check");
+ 12| 4| result
+ 13| 4|}
+ 14| |
+ 15| 1|fn main() -> Result<(),u8> {
+ 16| 1| let mut countdown = 10;
+ 17| 11| while countdown > 0 {
+ 18| 11| if countdown == 1 {
+ 19| 1| let result = might_overflow(10);
+ 20| 1| println!("Result: {}", result);
+ 21| 10| } else if countdown < 5 {
+ 22| 3| let result = might_overflow(1);
+ 23| 3| println!("Result: {}", result);
+ 24| 6| }
+ 25| 10| countdown -= 1;
+ 26| | }
+ 27| 0| Ok(())
+ 28| 0|}
+ 29| |
+ 30| |// Notes:
+ 31| |// 1. Compare this program and its coverage results to those of the very similar test `assert.rs`,
+ 32| |// and similar tests `panic_unwind.rs`, abort.rs` and `try_error_result.rs`.
+ 33| |// 2. This test confirms the coverage generated when a program passes or fails a
+ 34| |// compiler-generated `TerminatorKind::Assert` (based on an overflow check, in this case).
+ 35| |// 3. Similar to how the coverage instrumentation handles `TerminatorKind::Call`,
+ 36| |// compiler-generated assertion failures are assumed to be a symptom of a program bug, not
+ 37| |// expected behavior. To simplify the coverage graphs and keep instrumented programs as
+ 38| |// small and fast as possible, `Assert` terminators are assumed to always succeed, and
+ 39| |// therefore are considered "non-branching" terminators. So, an `Assert` terminator does not
+ 40| |// get its own coverage counter.
+ 41| |// 4. After an unhandled panic or failed Assert, coverage results may not always be intuitive.
+ 42| |// In this test, the final count for the statements after the `if` block in `might_overflow()`
+ 43| |// is 4, even though the lines after `to_add + add_to` were executed only 3 times. Depending
+ 44| |// on the MIR graph and the structure of the code, this count could have been 3 (which might
+ 45| |// have been valid for the overflowed add `+`, but should have been 4 for the lines before
+ 46| |// the overflow. The reason for this potential uncertainty is, a `CounterKind` is incremented
+ 47| |// via StatementKind::Counter at the end of the block, but (as in the case in this test),
+ 48| |// a CounterKind::Expression is always evaluated. In this case, the expression was based on
+ 49| |// a `Counter` incremented as part of the evaluation of the `if` expression, which was
+ 50| |// executed, and counted, 4 times, before reaching the overflow add.
+ 51| |
+ 52| |// If the program did not overflow, the coverage for `might_overflow()` would look like this:
+ 53| |//
+ 54| |// 4| |fn might_overflow(to_add: u32) -> u32 {
+ 55| |// 5| 4| if to_add > 5 {
+ 56| |// 6| 0| println!("this will probably overflow");
+ 57| |// 7| 4| }
+ 58| |// 8| 4| let add_to = u32::MAX - 5;
+ 59| |// 9| 4| println!("does {} + {} overflow?", add_to, to_add);
+ 60| |// 10| 4| let result = to_add + add_to;
+ 61| |// 11| 4| println!("continuing after overflow check");
+ 62| |// 12| 4| result
+ 63| |// 13| 4|}
+