3 [![Actions build status][actions-badge]][actions-url]
5 [actions-badge]: https://github.com/rust-lang/miri/workflows/CI/badge.svg?branch=master
6 [actions-url]: https://github.com/rust-lang/miri/actions
8 An experimental interpreter for [Rust][rust]'s
9 [mid-level intermediate representation][mir] (MIR). It can run binaries and
10 test suites of cargo projects and detect certain classes of
11 [undefined behavior](https://doc.rust-lang.org/reference/behavior-considered-undefined.html),
14 * Out-of-bounds memory accesses and use-after-free
15 * Invalid use of uninitialized data
16 * Violation of intrinsic preconditions (an [`unreachable_unchecked`] being
17 reached, calling [`copy_nonoverlapping`] with overlapping ranges, ...)
18 * Not sufficiently aligned memory accesses and references
19 * Violation of *some* basic type invariants (a `bool` that is not 0 or 1, for example,
20 or an invalid enum discriminant)
21 * **Experimental**: Violations of the [Stacked Borrows] rules governing aliasing
23 * **Experimental**: Data races (but no weak memory effects)
25 On top of that, Miri will also tell you about memory leaks: when there is memory
26 still allocated at the end of the execution, and that memory is not reachable
27 from a global `static`, Miri will raise an error.
29 You can use Miri to emulate programs on other targets, e.g. to ensure that
30 byte-level data manipulation works correctly both on little-endian and
31 big-endian systems. See
32 [cross-interpretation](#cross-interpretation-running-for-different-targets)
35 Miri has already discovered some [real-world bugs](#bugs-found-by-miri). If you
36 found a bug with Miri, we'd appreciate if you tell us and we'll add it to the
39 However, be aware that Miri will **not catch all cases of undefined behavior**
40 in your program, and cannot run all programs:
42 * There are still plenty of open questions around the basic invariants for some
43 types and when these invariants even have to hold. Miri tries to avoid false
44 positives here, so if your program runs fine in Miri right now that is by no
45 means a guarantee that it is UB-free when these questions get answered.
47 In particular, Miri does currently not check that integers/floats are
48 initialized or that references point to valid data.
49 * If the program relies on unspecified details of how data is laid out, it will
50 still run fine in Miri -- but might break (including causing UB) on different
51 compiler versions or different platforms.
52 * Program execution is non-deterministic when it depends, for example, on where
53 exactly in memory allocations end up, or on the exact interleaving of
54 concurrent threads. Miri tests one of many possible executions of your
55 program. You can alleviate this to some extent by running Miri with different
56 values for `-Zmiri-seed`, but that will still by far not explore all possible
58 * Miri runs the program as a platform-independent interpreter, so the program
59 has no access to most platform-specific APIs or FFI. A few APIs have been
60 implemented (such as printing to stdout) but most have not: for example, Miri
61 currently does not support SIMD or networking.
62 * Threading support is not finished yet. E.g., weak memory effects are not
63 emulated and spin loops (without syscalls) just loop forever. There is no
64 threading support on Windows.
66 [rust]: https://www.rust-lang.org/
67 [mir]: https://github.com/rust-lang/rfcs/blob/master/text/1211-mir.md
68 [`unreachable_unchecked`]: https://doc.rust-lang.org/stable/std/hint/fn.unreachable_unchecked.html
69 [`copy_nonoverlapping`]: https://doc.rust-lang.org/stable/std/ptr/fn.copy_nonoverlapping.html
70 [Stacked Borrows]: https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md
75 Install Miri on Rust nightly via `rustup`:
78 rustup +nightly component add miri
81 If `rustup` says the `miri` component is unavailable, that's because not all
82 nightly releases come with all tools. Check out
83 [this website](https://rust-lang.github.io/rustup-components-history) to
84 determine a nightly version that comes with Miri and install that using `rustup
85 toolchain install nightly-YYYY-MM-DD`. Either way, all of the following commands
86 assume the right toolchain is pinned via `rustup override set nightly` or
87 `rustup override set nightly-YYYY-MM-DD`. (Alternatively, use `cargo
88 +nightly`/`cargo +nightly-YYYY-MM-DD` for each of the following commands.)
90 Now you can run your project in Miri:
92 1. Run `cargo clean` to eliminate any cached dependencies. Miri needs your
93 dependencies to be compiled the right way, that would not happen if they have
94 previously already been compiled.
95 2. To run all tests in your project through Miri, use `cargo miri test`.
96 3. If you have a binary project, you can run it through Miri using `cargo miri run`.
98 The first time you run Miri, it will perform some extra setup and install some
99 dependencies. It will ask you for confirmation before installing anything.
101 `cargo miri run/test` supports the exact same flags as `cargo run/test`. For
102 example, `cargo miri test filter` only runs the tests containing `filter` in
105 You can pass arguments to Miri via `MIRIFLAGS`. For example,
106 `MIRIFLAGS="-Zmiri-disable-stacked-borrows" cargo miri run` runs the program
107 without checking the aliasing of references.
109 When compiling code via `cargo miri`, the `cfg(miri)` config flag is set for code
110 that will be interpret under Miri. You can use this to ignore test cases that fail
111 under Miri because they do things Miri does not support:
115 #[cfg_attr(miri, ignore)]
116 fn does_not_work_on_miri() {
117 tokio::run(futures::future::ok::<_, ()>(()));
121 There is no way to list all the infinite things Miri cannot do, but the
122 interpreter will explicitly tell you when it finds something unsupported:
125 error: unsupported operation: can't call foreign function: bind
127 = help: this is likely not a bug in the program; it indicates that the program \
128 performed an operation that the interpreter does not support
131 ### Cross-interpretation: running for different targets
133 Miri can not only run a binary or test suite for your host target, it can also
134 perform cross-interpretation for arbitrary foreign targets: `cargo miri run
135 --target x86_64-unknown-linux-gnu` will run your program as if it was a Linux
136 program, no matter your host OS. This is particularly useful if you are using
137 Windows, as the Linux target is much better supported than Windows targets.
139 You can also use this to test platforms with different properties than your host
140 platform. For example `cargo miri test --target mips64-unknown-linux-gnuabi64`
141 will run your test suite on a big-endian target, which is useful for testing
142 endian-sensitive code.
144 ### Running Miri on CI
146 To run Miri on CI, make sure that you handle the case where the latest nightly
147 does not ship the Miri component because it currently does not build. For
148 example, you can use the following snippet to always test with the latest
149 nightly that *does* come with Miri:
152 MIRI_NIGHTLY=nightly-$(curl -s https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-gnu/miri)
153 echo "Installing latest nightly with Miri: $MIRI_NIGHTLY"
154 rustup set profile minimal
155 rustup override set "$MIRI_NIGHTLY"
156 rustup component add miri
163 When using the above instructions, you may encounter a number of confusing compiler
166 ### "note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace"
168 You may see this when trying to get Miri to display a backtrace. By default, Miri
169 doesn't expose any environment to the program, so running
170 `RUST_BACKTRACE=1 cargo miri test` will not do what you expect.
172 To get a backtrace, you need to disable isolation
173 [using `-Zmiri-disable-isolation`][miri-flags]:
176 RUST_BACKTRACE=1 MIRIFLAGS="-Zmiri-disable-isolation" cargo miri test
179 #### "found possibly newer version of crate `std` which `<dependency>` depends on"
181 Your build directory may contain artifacts from an earlier build that have/have
182 not been built for Miri. Run `cargo clean` before switching from non-Miri to
183 Miri builds and vice-versa.
185 #### "found crate `std` compiled by an incompatible version of rustc"
187 You may be running `cargo miri` with a different compiler version than the one
188 used to build the custom libstd that Miri uses, and Miri failed to detect that.
189 Try deleting `~/.cache/miri`.
191 #### "no mir for `std::rt::lang_start_internal`"
193 This means the sysroot you are using was not compiled with Miri in mind. This
194 should never happen when you use `cargo miri` because that takes care of setting
195 up the sysroot. If you are using `miri` (the Miri driver) directly, see the
196 [contributors' guide](CONTRIBUTING.md) for how to use `./miri` to best do that.
199 ## Miri `-Z` flags and environment variables
200 [miri-flags]: #miri--z-flags-and-environment-variables
202 Miri adds its own set of `-Z` flags, which are usually set via the `MIRIFLAGS`
203 environment variable:
205 * `-Zmiri-check-number-validity` enables checking of integer and float validity
206 (e.g., they must be initialized and not carry pointer provenance) as part of
207 enforcing validity invariants. This has no effect when
208 `-Zmiri-disable-validation` is present.
209 * `-Zmiri-compare-exchange-weak-failure-rate=<rate>` changes the failure rate of
210 `compare_exchange_weak` operations. The default is `0.8` (so 4 out of 5 weak ops will fail).
211 You can change it to any value between `0.0` and `1.0`, where `1.0` means it
212 will always fail and `0.0` means it will never fail.
213 * `-Zmiri-disable-abi-check` disables checking [function ABI]. Using this flag
215 * `-Zmiri-disable-alignment-check` disables checking pointer alignment, so you
216 can focus on other failures, but it means Miri can miss bugs in your program.
217 Using this flag is **unsound**.
218 * `-Zmiri-disable-data-race-detector` disables checking for data races. Using
219 this flag is **unsound**.
220 * `-Zmiri-disable-stacked-borrows` disables checking the experimental
221 [Stacked Borrows] aliasing rules. This can make Miri run faster, but it also
222 means no aliasing violations will be detected. Using this flag is **unsound**
223 (but the affected soundness rules are experimental).
224 * `-Zmiri-disable-validation` disables enforcing validity invariants, which are
225 enforced by default. This is mostly useful to focus on other failures (such
226 as out-of-bounds accesses) first. Setting this flag means Miri can miss bugs
227 in your program. However, this can also help to make Miri run faster. Using
228 this flag is **unsound**.
229 * `-Zmiri-disable-isolation` disables host isolation. As a consequence,
230 the program has access to host resources such as environment variables, file
231 systems, and randomness.
232 * `-Zmiri-isolation-error=<action>` configures Miri's response to operations
233 requiring host access while isolation is enabled. `abort`, `hide`, `warn`,
234 and `warn-nobacktrace` are the supported actions. The default is to `abort`,
235 which halts the machine. Some (but not all) operations also support continuing
236 execution with a "permission denied" error being returned to the program.
237 `warn` prints a full backtrace when that happen; `warn-nobacktrace` is less
238 verbose. `hide` hides the warning entirely.
239 * `-Zmiri-env-exclude=<var>` keeps the `var` environment variable isolated from
240 the host so that it cannot be accessed by the program. Can be used multiple
241 times to exclude several variables. On Windows, the `TERM` environment
242 variable is excluded by default.
243 * `-Zmiri-ignore-leaks` disables the memory leak checker, and also allows some
244 remaining threads to exist when the main thread exits.
245 * `-Zmiri-measureme=<name>` enables `measureme` profiling for the interpreted program.
246 This can be used to find which parts of your program are executing slowly under Miri.
247 The profile is written out to a file with the prefix `<name>`, and can be processed
248 using the tools in the repository https://github.com/rust-lang/measureme.
249 * `-Zmiri-panic-on-unsupported` will makes some forms of unsupported functionality,
250 such as FFI and unsupported syscalls, panic within the context of the emulated
251 application instead of raising an error within the context of Miri (and halting
252 execution). Note that code might not expect these operations to ever panic, so
253 this flag can lead to strange (mis)behavior.
254 * `-Zmiri-seed=<hex>` configures the seed of the RNG that Miri uses to resolve
255 non-determinism. This RNG is used to pick base addresses for allocations.
256 When isolation is enabled (the default), this is also used to emulate system
257 entropy. The default seed is 0. **NOTE**: This entropy is not good enough
258 for cryptographic use! Do not generate secret keys in Miri or perform other
259 kinds of cryptographic operations that rely on proper random numbers.
260 * `-Zmiri-symbolic-alignment-check` makes the alignment check more strict. By
261 default, alignment is checked by casting the pointer to an integer, and making
262 sure that is a multiple of the alignment. This can lead to cases where a
263 program passes the alignment check by pure chance, because things "happened to
264 be" sufficiently aligned -- there is no UB in this execution but there would
265 be UB in others. To avoid such cases, the symbolic alignment check only takes
266 into account the requested alignment of the relevant allocation, and the
267 offset into that allocation. This avoids missing such bugs, but it also
268 incurs some false positives when the code does manual integer arithmetic to
269 ensure alignment. (The standard library `align_to` method works fine in both
270 modes; under symbolic alignment it only fills the middle slice when the
271 allocation guarantees sufficient alignment.)
272 * `-Zmiri-track-alloc-id=<id>` shows a backtrace when the given allocation is
273 being allocated or freed. This helps in debugging memory leaks and
275 * `-Zmiri-track-call-id=<id>` shows a backtrace when the given call id is
276 assigned to a stack frame. This helps in debugging UB related to Stacked
277 Borrows "protectors".
278 * `-Zmiri-track-pointer-tag=<tag>` shows a backtrace when the given pointer tag
279 is popped from a borrow stack (which is where the tag becomes invalid and any
280 future use of it will error). This helps you in finding out why UB is
281 happening and where in your code would be a good place to look for it.
282 * `-Zmiri-tag-raw-pointers` makes Stacked Borrows assign proper tags even for raw pointers. This can
283 make valid code using int-to-ptr casts fail to pass the checks, but also can help identify latent
284 aliasing issues in code that Miri accepts by default. You can recognize false positives by
285 `<untagged>` occurring in the message -- this indicates a pointer that was cast from an integer,
286 so Miri was unable to track this pointer. Note that it is not currently guaranteed that code that
287 works with `-Zmiri-tag-raw-pointers` also works without `-Zmiri-tag-raw-pointers`, but for the
288 vast majority of code, this will be the case.
290 [function ABI]: https://doc.rust-lang.org/reference/items/functions.html#extern-function-qualifier
292 Some native rustc `-Z` flags are also very relevant for Miri:
294 * `-Zmir-opt-level` controls how many MIR optimizations are performed. Miri
295 overrides the default to be `0`; be advised that using any higher level can
296 make Miri miss bugs in your program because they got optimized away.
297 * `-Zalways-encode-mir` makes rustc dump MIR even for completely monomorphic
298 functions. This is needed so that Miri can execute such functions, so Miri
299 sets this flag per default.
300 * `-Zmir-emit-retag` controls whether `Retag` statements are emitted. Miri
301 enables this per default because it is needed for [Stacked Borrows].
303 Moreover, Miri recognizes some environment variables:
305 * `MIRI_LOG`, `MIRI_BACKTRACE` control logging and backtrace printing during
306 Miri executions, also [see "Testing the Miri driver" in `CONTRIBUTING.md`][testing-miri].
307 * `MIRIFLAGS` (recognized by `cargo miri` and the test suite) defines extra
308 flags to be passed to Miri.
309 * `MIRI_LIB_SRC` defines the directory where Miri expects the sources of the
310 standard library that it will build and use for interpretation. This directory
311 must point to the `library` subdirectory of a `rust-lang/rust` repository
312 checkout. Note that changing files in that directory does not automatically
313 trigger a re-build of the standard library; you have to clear the Miri build
314 cache manually (on Linux, `rm -rf ~/.cache/miri`).
315 * `MIRI_SYSROOT` (recognized by `cargo miri` and the test suite)
316 indicates the sysroot to use. To do the same thing with `miri`
317 directly, use the `--sysroot` flag.
318 * `MIRI_TEST_TARGET` (recognized by the test suite) indicates which target
319 architecture to test against. `miri` and `cargo miri` accept the `--target`
320 flag for the same purpose.
322 The following environment variables are *internal* and must not be used by
323 anyone but Miri itself. They are used to communicate between different Miri
324 binaries, and as such worth documenting:
326 * `MIRI_BE_RUSTC` can be set to `host` or `target`. It tells the Miri driver to
327 actually not interpret the code but compile it like rustc would. With `target`, Miri sets
328 some compiler flags to prepare the code for interpretation; with `host`, this is not done.
329 This environment variable is useful to be sure that the compiled `rlib`s are compatible
331 * `MIRI_CALLED_FROM_XARGO` is set during the Miri-induced `xargo` sysroot build,
332 which will re-invoke `cargo-miri` as the `rustc` to use for this build.
333 * `MIRI_CALLED_FROM_RUSTDOC` when set to any value tells `cargo-miri` that it is
334 running as a child process of `rustdoc`, which invokes it twice for each doc-test
335 and requires special treatment, most notably a check-only build before interpretation.
336 This is set by `cargo-miri` itself when running as a `rustdoc`-wrapper.
337 * `MIRI_CWD` when set to any value tells the Miri driver to change to the given
338 directory after loading all the source files, but before commencing
339 interpretation. This is useful if the interpreted program wants a different
340 working directory at run-time than at build-time.
341 * `MIRI_VERBOSE` when set to any value tells the various `cargo-miri` phases to
342 perform verbose logging.
344 [testing-miri]: CONTRIBUTING.md#testing-the-miri-driver
346 ## Miri `extern` functions
348 Miri provides some `extern` functions that programs can import to access
349 Miri-specific functionality:
354 /// Miri-provided extern function to mark the block `ptr` points to as a "root"
355 /// for some static memory. This memory and everything reachable by it is not
356 /// considered leaking even if it still exists when the program terminates.
358 /// `ptr` has to point to the beginning of an allocated block.
359 fn miri_static_root(ptr: *const u8);
361 /// Miri-provided extern function to obtain a backtrace of the current call stack.
362 /// This returns a boxed slice of pointers - each pointer is an opaque value
363 /// that is only useful when passed to `miri_resolve_frame`
364 /// The `flags` argument must be `0`.
365 fn miri_get_backtrace(flags: u64) -> Box<[*mut ()]>;
367 /// Miri-provided extern function to resolve a frame pointer obtained
368 /// from `miri_get_backtrace`. The `flags` argument must be `0`,
369 /// and `MiriFrame` should be declared as follows:
373 /// struct MiriFrame {
374 /// // The name of the function being executed, encoded in UTF-8
376 /// // The filename of the function being executed, encoded in UTF-8
377 /// filename: Box<[u8]>,
378 /// // The line number currently being executed in `filename`, starting from '1'.
380 /// // The column number currently being executed in `filename`, starting from '1'.
382 /// // The function pointer to the function currently being executed.
383 /// // This can be compared against function pointers obtained by
384 /// // casting a function (e.g. `my_fn as *mut ()`)
389 /// The fields must be declared in exactly the same order as they appear in `MiriFrame` above.
390 /// This function can be called on any thread (not just the one which obtained `frame`).
391 fn miri_resolve_frame(frame: *mut (), flags: u64) -> MiriFrame;
393 /// Miri-provided extern function to begin unwinding with the given payload.
395 /// This is internal and unstable and should not be used; we give it here
396 /// just to be complete.
397 fn miri_start_panic(payload: *mut u8) -> !;
401 ## Contributing and getting help
403 If you want to contribute to Miri, great! Please check out our
404 [contribution guide](CONTRIBUTING.md).
406 For help with running Miri, you can open an issue here on
407 GitHub or use the [Miri stream on the Rust Zulip][zulip].
409 [zulip]: https://rust-lang.zulipchat.com/#narrow/stream/269128-miri
413 This project began as part of an undergraduate research course in 2015 by
414 @solson at the [University of Saskatchewan][usask]. There are [slides] and a
415 [report] available from that project. In 2016, @oli-obk joined to prepare miri
416 for eventually being used as const evaluator in the Rust compiler itself
417 (basically, for `const` and `static` stuff), replacing the old evaluator that
418 worked directly on the AST. In 2017, @RalfJung did an internship with Mozilla
419 and began developing miri towards a tool for detecting undefined behavior, and
420 also using miri as a way to explore the consequences of various possible
421 definitions for undefined behavior in Rust. @oli-obk's move of the miri engine
422 into the compiler finally came to completion in early 2018. Meanwhile, later
423 that year, @RalfJung did a second internship, developing miri further with
424 support for checking basic type invariants and verifying that references are
425 used according to their aliasing restrictions.
427 [usask]: https://www.usask.ca/
428 [slides]: https://solson.me/miri-slides.pdf
429 [report]: https://solson.me/miri-report.pdf
431 ## Bugs found by Miri
433 Miri has already found a number of bugs in the Rust standard library and beyond, which we collect here.
437 * [`Debug for vec_deque::Iter` accessing uninitialized memory](https://github.com/rust-lang/rust/issues/53566)
438 * [`Vec::into_iter` doing an unaligned ZST read](https://github.com/rust-lang/rust/pull/53804)
439 * [`From<&[T]> for Rc` creating a not sufficiently aligned reference](https://github.com/rust-lang/rust/issues/54908)
440 * [`BTreeMap` creating a shared reference pointing to a too small allocation](https://github.com/rust-lang/rust/issues/54957)
441 * [`Vec::append` creating a dangling reference](https://github.com/rust-lang/rust/pull/61082)
442 * [Futures turning a shared reference into a mutable one](https://github.com/rust-lang/rust/pull/56319)
443 * [`str` turning a shared reference into a mutable one](https://github.com/rust-lang/rust/pull/58200)
444 * [`rand` performing unaligned reads](https://github.com/rust-random/rand/issues/779)
445 * [The Unix allocator calling `posix_memalign` in an invalid way](https://github.com/rust-lang/rust/issues/62251)
446 * [`getrandom` calling the `getrandom` syscall in an invalid way](https://github.com/rust-random/getrandom/pull/73)
447 * [`Vec`](https://github.com/rust-lang/rust/issues/69770) and [`BTreeMap`](https://github.com/rust-lang/rust/issues/69769) leaking memory under some (panicky) conditions
448 * [`beef` leaking memory](https://github.com/maciejhirsz/beef/issues/12)
449 * [`EbrCell` using uninitialized memory incorrectly](https://github.com/Firstyear/concread/commit/b15be53b6ec076acb295a5c0483cdb4bf9be838f#diff-6282b2fc8e98bd089a1f0c86f648157cR229)
450 * [TiKV performing an unaligned pointer access](https://github.com/tikv/tikv/issues/7613)
451 * [`servo_arc` creating a dangling shared reference](https://github.com/servo/servo/issues/26357)
452 * [TiKV constructing out-of-bounds pointers (and overlapping mutable references)](https://github.com/tikv/tikv/pull/7751)
453 * [`encoding_rs` doing out-of-bounds pointer arithmetic](https://github.com/hsivonen/encoding_rs/pull/53)
454 * [TiKV using `Vec::from_raw_parts` incorrectly](https://github.com/tikv/agatedb/pull/24)
455 * Incorrect doctests for [`AtomicPtr`](https://github.com/rust-lang/rust/pull/84052) and [`Box::from_raw_in`](https://github.com/rust-lang/rust/pull/84053)
456 * [Insufficient alignment in `ThinVec`](https://github.com/Gankra/thin-vec/pull/27)
457 * [`crossbeam-epoch` calling `assume_init` on a partly-initialized `MaybeUninit`](https://github.com/crossbeam-rs/crossbeam/pull/779)
458 * [`integer-encoding` dereferencing a misaligned pointer](https://github.com/dermesser/integer-encoding-rs/pull/23)
460 Violations of [Stacked Borrows] found that are likely bugs (but Stacked Borrows is currently just an experiment):
462 * [`VecDeque::drain` creating overlapping mutable references](https://github.com/rust-lang/rust/pull/56161)
463 * Various `BTreeMap` problems
464 * [`BTreeMap` iterators creating mutable references that overlap with shared references](https://github.com/rust-lang/rust/pull/58431)
465 * [`BTreeMap::iter_mut` creating overlapping mutable references](https://github.com/rust-lang/rust/issues/73915)
466 * [`BTreeMap` node insertion using raw pointers outside their valid memory area](https://github.com/rust-lang/rust/issues/78477)
467 * [`LinkedList` cursor insertion creating overlapping mutable references](https://github.com/rust-lang/rust/pull/60072)
468 * [`Vec::push` invalidating existing references into the vector](https://github.com/rust-lang/rust/issues/60847)
469 * [`align_to_mut` violating uniqueness of mutable references](https://github.com/rust-lang/rust/issues/68549)
470 * [`sized-chunks` creating aliasing mutable references](https://github.com/bodil/sized-chunks/issues/8)
471 * [`String::push_str` invalidating existing references into the string](https://github.com/rust-lang/rust/issues/70301)
472 * [`ryu` using raw pointers outside their valid memory area](https://github.com/dtolnay/ryu/issues/24)
473 * [ink! creating overlapping mutable references](https://github.com/rust-lang/miri/issues/1364)
474 * [TiKV creating overlapping mutable reference and raw pointer](https://github.com/tikv/tikv/pull/7709)
475 * [Windows `Env` iterator using a raw pointer outside its valid memory area](https://github.com/rust-lang/rust/pull/70479)
476 * [`VecDeque::iter_mut` creating overlapping mutable references](https://github.com/rust-lang/rust/issues/74029)
477 * [Various standard library aliasing issues involving raw pointers](https://github.com/rust-lang/rust/pull/78602)
478 * [`<[T]>::copy_within` using a loan after invalidating it](https://github.com/rust-lang/rust/pull/85610)
482 Licensed under either of
484 * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
485 http://www.apache.org/licenses/LICENSE-2.0)
486 * MIT license ([LICENSE-MIT](LICENSE-MIT) or
487 http://opensource.org/licenses/MIT)
493 Unless you explicitly state otherwise, any contribution intentionally submitted
494 for inclusion in the work by you shall be dual licensed as above, without any
495 additional terms or conditions.