mirror of https://github.com/rust-lang/rust
68 lines
2.6 KiB
Rust
68 lines
2.6 KiB
Rust
#![feature(c_unwind)]
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#![allow(unused_assignments)]
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extern "C" fn might_abort(should_abort: bool) {
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if should_abort {
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println!("aborting...");
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panic!("panics and aborts");
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} else {
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println!("Don't Panic");
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}
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}
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#[rustfmt::skip]
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fn main() -> Result<(), u8> {
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let mut countdown = 10;
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while countdown > 0 {
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if countdown < 5 {
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might_abort(false);
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}
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// See discussion (below the `Notes` section) on coverage results for the closing brace.
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if countdown < 5 { might_abort(false); } // Counts for different regions on one line.
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// For the following example, the closing brace is the last character on the line.
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// This shows the character after the closing brace is highlighted, even if that next
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// character is a newline.
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if countdown < 5 { might_abort(false); }
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countdown -= 1;
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}
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Ok(())
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}
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// Notes:
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// 1. Compare this program and its coverage results to those of the similar tests
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// `panic_unwind.rs` and `try_error_result.rs`.
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// 2. This test confirms the coverage generated when a program includes `UnwindAction::Terminate`.
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// 3. The test does not invoke the abort. By executing to a successful completion, the coverage
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// results show where the program did and did not execute.
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// 4. If the program actually aborted, the coverage counters would not be saved (which "works as
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// intended"). Coverage results would show no executed coverage regions.
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// 6. If `should_abort` is `true` and the program aborts, the program exits with a `132` status
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// (on Linux at least).
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/*
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Expect the following coverage results:
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```text
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16| 11| while countdown > 0 {
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17| 10| if countdown < 5 {
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18| 4| might_abort(false);
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19| 6| }
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```
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This is actually correct.
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The condition `countdown < 5` executed 10 times (10 loop iterations).
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It evaluated to `true` 4 times, and executed the `might_abort()` call.
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It skipped the body of the `might_abort()` call 6 times. If an `if` does not include an explicit
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`else`, the coverage implementation injects a counter, at the character immediately after the `if`s
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closing brace, to count the "implicit" `else`. This is the only way to capture the coverage of the
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non-true condition.
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As another example of why this is important, say the condition was `countdown < 50`, which is always
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`true`. In that case, we wouldn't have a test for what happens if `might_abort()` is not called.
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The closing brace would have a count of `0`, highlighting the missed coverage.
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*/
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