diff options
| -rw-r--r-- | src/doc/guide-testing.md | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/src/doc/guide-testing.md b/src/doc/guide-testing.md index 60ce71dac84..8d113bb931a 100644 --- a/src/doc/guide-testing.md +++ b/src/doc/guide-testing.md @@ -556,8 +556,12 @@ extern crate test; # fn main() { # struct X; impl X { fn iter<T>(&self, _: || -> T) {} } let b = X; b.iter(|| { - test::black_box(range(0u, 1000).fold(0, |old, new| old ^ new)); -}); + let mut n = 1000_u32; + + test::black_box(&mut n); // pretend to modify `n` + + range(0, n).fold(0, |a, b| a ^ b) +}) # } ``` @@ -573,3 +577,6 @@ test bench_xor_1000_ints ... bench: 1 ns/iter (+/- 0) test result: ok. 0 passed; 0 failed; 0 ignored; 1 measured ``` + +However, the optimizer can still modify a testcase in an undesirable manner +even when using either of the above. |