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Diffstat (limited to 'tests/coverage/overflow.coverage')
| -rw-r--r-- | tests/coverage/overflow.coverage | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/tests/coverage/overflow.coverage b/tests/coverage/overflow.coverage new file mode 100644 index 000000000..4f8dffc0c --- /dev/null +++ b/tests/coverage/overflow.coverage @@ -0,0 +1,65 @@ + LL| |#![allow(unused_assignments)] + LL| |// compile-flags: -Coverflow-checks=yes + LL| |// failure-status: 101 + LL| | + LL| 4|fn might_overflow(to_add: u32) -> u32 { + LL| 4| if to_add > 5 { + LL| 1| println!("this will probably overflow"); + LL| 3| } + LL| 4| let add_to = u32::MAX - 5; + LL| 4| println!("does {} + {} overflow?", add_to, to_add); + LL| 4| let result = to_add + add_to; + LL| 4| println!("continuing after overflow check"); + LL| 4| result + LL| 4|} + LL| | + LL| 1|fn main() -> Result<(), u8> { + LL| 1| let mut countdown = 10; + LL| 11| while countdown > 0 { + LL| 11| if countdown == 1 { + LL| 1| let result = might_overflow(10); + LL| 1| println!("Result: {}", result); + LL| 10| } else if countdown < 5 { + LL| 3| let result = might_overflow(1); + LL| 3| println!("Result: {}", result); + LL| 6| } + LL| 10| countdown -= 1; + LL| | } + LL| 0| Ok(()) + LL| 0|} + LL| | + LL| |// Notes: + LL| |// 1. Compare this program and its coverage results to those of the very similar test `assert.rs`, + LL| |// and similar tests `panic_unwind.rs`, abort.rs` and `try_error_result.rs`. + LL| |// 2. This test confirms the coverage generated when a program passes or fails a + LL| |// compiler-generated `TerminatorKind::Assert` (based on an overflow check, in this case). + LL| |// 3. Similar to how the coverage instrumentation handles `TerminatorKind::Call`, + LL| |// compiler-generated assertion failures are assumed to be a symptom of a program bug, not + LL| |// expected behavior. To simplify the coverage graphs and keep instrumented programs as + LL| |// small and fast as possible, `Assert` terminators are assumed to always succeed, and + LL| |// therefore are considered "non-branching" terminators. So, an `Assert` terminator does not + LL| |// get its own coverage counter. + LL| |// 4. After an unhandled panic or failed Assert, coverage results may not always be intuitive. + LL| |// In this test, the final count for the statements after the `if` block in `might_overflow()` + LL| |// is 4, even though the lines after `to_add + add_to` were executed only 3 times. Depending + LL| |// on the MIR graph and the structure of the code, this count could have been 3 (which might + LL| |// have been valid for the overflowed add `+`, but should have been 4 for the lines before + LL| |// the overflow. The reason for this potential uncertainty is, a `CounterKind` is incremented + LL| |// via StatementKind::Counter at the end of the block, but (as in the case in this test), + LL| |// a CounterKind::Expression is always evaluated. In this case, the expression was based on + LL| |// a `Counter` incremented as part of the evaluation of the `if` expression, which was + LL| |// executed, and counted, 4 times, before reaching the overflow add. + LL| | + LL| |// If the program did not overflow, the coverage for `might_overflow()` would look like this: + LL| |// + LL| |// 4| |fn might_overflow(to_add: u32) -> u32 { + LL| |// 5| 4| if to_add > 5 { + LL| |// 6| 0| println!("this will probably overflow"); + LL| |// 7| 4| } + LL| |// 8| 4| let add_to = u32::MAX - 5; + LL| |// 9| 4| println!("does {} + {} overflow?", add_to, to_add); + LL| |// 10| 4| let result = to_add + add_to; + LL| |// 11| 4| println!("continuing after overflow check"); + LL| |// 12| 4| result + LL| |// 13| 4|} + |