From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- src/test/run-make/coverage/overflow.rs | 63 ++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 src/test/run-make/coverage/overflow.rs (limited to 'src/test/run-make/coverage/overflow.rs') diff --git a/src/test/run-make/coverage/overflow.rs b/src/test/run-make/coverage/overflow.rs new file mode 100644 index 000000000..e537b0e95 --- /dev/null +++ b/src/test/run-make/coverage/overflow.rs @@ -0,0 +1,63 @@ +#![allow(unused_assignments)] +// expect-exit-status-101 + +fn might_overflow(to_add: u32) -> u32 { + if to_add > 5 { + println!("this will probably overflow"); + } + let add_to = u32::MAX - 5; + println!("does {} + {} overflow?", add_to, to_add); + let result = to_add + add_to; + println!("continuing after overflow check"); + result +} + +fn main() -> Result<(),u8> { + let mut countdown = 10; + while countdown > 0 { + if countdown == 1 { + let result = might_overflow(10); + println!("Result: {}", result); + } else if countdown < 5 { + let result = might_overflow(1); + println!("Result: {}", result); + } + countdown -= 1; + } + Ok(()) +} + +// Notes: +// 1. Compare this program and its coverage results to those of the very similar test `assert.rs`, +// and similar tests `panic_unwind.rs`, abort.rs` and `try_error_result.rs`. +// 2. This test confirms the coverage generated when a program passes or fails a +// compiler-generated `TerminatorKind::Assert` (based on an overflow check, in this case). +// 3. Similar to how the coverage instrumentation handles `TerminatorKind::Call`, +// compiler-generated assertion failures are assumed to be a symptom of a program bug, not +// expected behavior. To simplify the coverage graphs and keep instrumented programs as +// small and fast as possible, `Assert` terminators are assumed to always succeed, and +// therefore are considered "non-branching" terminators. So, an `Assert` terminator does not +// get its own coverage counter. +// 4. After an unhandled panic or failed Assert, coverage results may not always be intuitive. +// In this test, the final count for the statements after the `if` block in `might_overflow()` +// is 4, even though the lines after `to_add + add_to` were executed only 3 times. Depending +// on the MIR graph and the structure of the code, this count could have been 3 (which might +// have been valid for the overflowed add `+`, but should have been 4 for the lines before +// the overflow. The reason for this potential uncertainty is, a `CounterKind` is incremented +// via StatementKind::Counter at the end of the block, but (as in the case in this test), +// a CounterKind::Expression is always evaluated. In this case, the expression was based on +// a `Counter` incremented as part of the evaluation of the `if` expression, which was +// executed, and counted, 4 times, before reaching the overflow add. + +// If the program did not overflow, the coverage for `might_overflow()` would look like this: +// +// 4| |fn might_overflow(to_add: u32) -> u32 { +// 5| 4| if to_add > 5 { +// 6| 0| println!("this will probably overflow"); +// 7| 4| } +// 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|} -- cgit v1.2.3