Pass miri checks.

[rcgoodfellow]

Right now miri is not pleased with us.

WARNING: Do not attempt to just run cargo +nightly miri test as this will run the base_xfer which shleps 1M frames through a ring. This takes less than a second, even with debug compiled code, but it takes an undetermined amount of time and CPU under miri. I gave up after 5 minutes and a toasty, battery drained laptop.

MIRIFLAGS=-Zmiri-disable-isolation cargo +nightly miri test ring_rollover

    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running unittests (target/miri/aarch64-apple-darwin/debug/deps/xfr-dce907680d28ade4)

running 1 test
test tests::ring_rollover ... warning: thread support is experimental and incomplete: weak memory effects are not emulated.

error: Undefined Behavior: Data race detected between Read on Thread(id = 2) and Write on Thread(id = 1) at alloc364431 (current vector clock = VClock([30, 0, 20]), conflicting timestamp = VClock([0, 8]))
   --> src/lib.rs:499:18
    |
499 |             Some(elements[i])
    |                  ^^^^^^^^^^^ Data race detected between Read on Thread(id = 2) and Write on Thread(id = 1) at alloc364431 (current vector clock = VClock([30, 0, 20]), conflicting timestamp = VClock([0, 8]))
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

    = note: inside `<RingIterator<8_usize, 8_usize, 64_usize> as std::iter::Iterator>::next` at src/lib.rs:499:18
note: inside closure at src/lib.rs:868:23
   --> src/lib.rs:868:23
    |
868 |             for fp in c.consumable() {
    |                       ^^^^^^^^^^^^^^
    = note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<[closure@src/lib.rs:861:24: 886:10], ()>` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:122:18
    = note: inside closure at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/thread/mod.rs:498:17
    = note: inside `<std::panic::AssertUnwindSafe<[closure@std::thread::Builder::spawn_unchecked_<[closure@src/lib.rs:861:24: 886:10], ()>::{closure#1}::{closure#0}]> as std::ops::FnOnce<()>>::call_once` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:271:9
    = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<[closure@std::thread::Builder::spawn_unchecked_<[closure@src/lib.rs:861:24: 886:10], ()>::{closure#1}::{closure#0}]>, ()>` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/panicking.rs:492:40
    = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<[closure@std::thread::Builder::spawn_unchecked_<[closure@src/lib.rs:861:24: 886:10], ()>::{closure#1}::{closure#0}]>>` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/panicking.rs:456:19
    = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<[closure@std::thread::Builder::spawn_unchecked_<[closure@src/lib.rs:861:24: 886:10], ()>::{closure#1}::{closure#0}]>, ()>` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/panic.rs:137:14
    = note: inside closure at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/thread/mod.rs:497:30
    = note: inside `<[closure@std::thread::Builder::spawn_unchecked_<[closure@src/lib.rs:861:24: 886:10], ()>::{closure#1}] as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5
    = note: inside `<std::boxed::Box<dyn std::ops::FnOnce()> as std::ops::FnOnce<()>>::call_once` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1854:9
    = note: inside `<std::boxed::Box<std::boxed::Box<dyn std::ops::FnOnce()>> as std::ops::FnOnce<()>>::call_once` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1854:9
    = note: inside `std::sys::unix::thread::Thread::new::thread_start` at /Users/ry/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/sys/unix/thread.rs:108:17

error: aborting due to previous error; 1 warning emitted

error: test failed, to rerun pass '--lib'