it_always_has_the_normal_pointing_towards_the_first_body quickcheck failure

[arielb1]

As a part of the cargobomb project, we have been testing your crate against both nightly and experimental versions of rustc. cargobomb is a project that runs experimental and nightly versions of the compiler against a large body of public rust code, in order to detect regressions and perform measurements.

During one of these tests with an experimental compiler, a quickcheck test in your code had failed. That could have been caused by a bug in the experimental compiler, but it also might be caused by a problem in your code. The test report is available here.

The test failure is as follows:

Aug 20 23:32:30.000 INFO blam! failures:
Aug 20 23:32:30.000 INFO blam! 
Aug 20 23:32:30.000 INFO blam! ---- collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body stdout ----
Aug 20 23:32:30.001 INFO blam! 	thread 'collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body' panicked at 'Expected the projected relative distance in the direction of the normal to always be positive, but got -0.40838882', src/collisions/detection/gjkepa/../../../../tests/collisions/detection/gjkepa/gjk_epa_detection_test.rs:1:0
Aug 20 23:32:30.001 INFO blam! note: Run with `RUST_BACKTRACE=1` for a backtrace.
Aug 20 23:32:30.001 INFO blam! thread 'collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body' panicked at '[quickcheck] TEST FAILED (runtime error). Arguments: (UnitVec3D(Vec3D { x: -0.08164979, y: 0.41588578, z: -0.905744 }), UnitQuat(Quat { r: -0.9998616, i: 0.00013082517, j: -0.012743562, k: 0.010695696 }))
Aug 20 23:32:30.001 INFO blam! Error: "Expected the projected relative distance in the direction of the normal to always be positive, but got -0.40838882"', /cargo-home/registry/src/github.com-1ecc6299db9ec823/quickcheck-0.4.1/src/tester.rs:147:27

[yggie]

@arielb1 is this a consistent failure? if memory serves me right, this test has been known to cause failures from time to time. I have yet to find the time to address this problem, but if this test doesn’t fail consistently, it is unlikely to be related to the compiler but rather an unhandled edge case in my system.

[arielb1]

We did not attempt to run your program again.

This looks like a fuzzer failure - your program was run with the arguments UnitVec3D(Vec3D { x: -0.08164979, y: 0.41588578, z: -0.905744 }), UnitQuat(Quat { r: -0.9998616, i: 0.00013082517, j: -0.012743562, k: 0.010695696 }), and that caused the assertion failure. Can you try testing it?

[yggie]

I managed to reproduce the issue on the latest stable Rust compiler:

failures:

---- collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body stdout ----
        thread 'collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body' panicked at 'Expected the projected relative distance in the direction of the normal to always be positive, but got -0.40838885', src/collisions/detection/gjkepa/../../../../tests/collisions/detection/gjkepa/gjk_epa_detection_test.rs:1
note: Run with `RUST_BACKTRACE=1` for a backtrace.


failures:
    collisions::detection::gjkepa::gjk_epa_detection::tests::detection_behaviour::it_always_has_the_normal_pointing_towards_the_first_body

The output closely matches the output in the issue, the discrepancy is likely due to floating point inaccuracies. So I would say yes, this is likely just an issue of a flaky test, nothing wrong with the compiler!

[arielb1]

OK. Then it's up to you to fix it (and meanwhile, we'll mark it so we won't get confused by it on the cargobomb blacklist).