Adding upstream version 115.7.0esr.upstream/115.7.0esr upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
author: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-07 19:33:14 +0000
committer: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-07 19:33:14 +0000
commit: 36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree: 105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/arbitrary
parent: Initial commit. (diff)
download: firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
15 files changed, 3825 insertions, 0 deletions
diff --git a/third_party/rust/arbitrary/.cargo-checksum.json b/third_party/rust/arbitrary/.cargo-checksum.json
new file mode 100644
index 0000000000..b53838bcf0
--- /dev/null
+++ b/third_party/rust/arbitrary/.cargo-checksum.json
@@ -0,0 +1 @@
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+\ No newline at end of file
diff --git a/third_party/rust/arbitrary/CHANGELOG.md b/third_party/rust/arbitrary/CHANGELOG.md
new file mode 100644
index 0000000000..2d4bb7205a
--- /dev/null
+++ b/third_party/rust/arbitrary/CHANGELOG.md
@@ -0,0 +1,460 @@
+## Unreleased
+
+Released YYYY-MM-DD.
+
+### Added
+
+* TODO (or remove section if none)
+
+### Changed
+
+* TODO (or remove section if none)
+
+### Deprecated
+
+* TODO (or remove section if none)
+
+### Removed
+
+* TODO (or remove section if none)
+
+### Fixed
+
+* (Included in `arbitrary_derive`  1.2.1) Fixed bug in Derive macro around `no_std` path uses [#131](https://github.com/rust-fuzz/arbitrary/pull/131)
+
+### Security
+
+* TODO (or remove section if none)
+
+--------------------------------------------------------------------------------
+
+## 1.2.3
+
+Released 2023-01-20.
+
+### Fixed
+
+* The `derive(Arbitrary)` will now annotate the generated `impl`s with a `#[automatically_derived]`
+  attribute to indicate to e.g. clippy that lints should not fire for the code within the derived
+  implementation.
+
+## 1.2.2
+
+Released 2023-01-03.
+
+### Fixed
+
+* Ensured that `arbitrary` and `derive_arbitrary` versions are synced up so that
+  they don't, e.g., emit generated code that depends on newer versions of
+  `arbitrary` than the one currently in
+  use. [#134](https://github.com/rust-fuzz/arbitrary/issues/134)
+
+## 1.2.1
+
+### Fixed
+
+* Fixed an issue where `std::thread_local!` macro invocations in derive code
+  were not fully prefixed, causing confusing build errors in certain situations.
+
+## 1.2.0
+
+Released 2022-10-20.
+
+### Added
+
+* Support custom arbitrary implementation for fields on
+  derive. [#129](https://github.com/rust-fuzz/arbitrary/pull/129)
+
+--------------------------------------------------------------------------------
+
+## 1.1.6
+
+Released 2022-09-08.
+
+### Fixed
+
+* Fixed a potential panic due to an off-by-one error in the `Arbitrary`
+  implementation for `std::ops::Bound<T>`.
+
+--------------------------------------------------------------------------------
+
+## 1.1.5
+
+Released 2022-09-20.
+
+### Added
+
+* Implemented `Arbitrary` for `std::ops::Bound<T>`.
+
+### Fixed
+
+* Fixed a bug where `Unstructured::int_in_range` could return out-of-range
+  integers when generating arbitrary signed integers.
+
+--------------------------------------------------------------------------------
+
+## 1.1.4
+
+Released 2022-08-29.
+
+### Added
+
+* Implemented `Arbitrary` for `Rc<str>` and `Arc<str>`
+
+### Changed
+
+* Allow overriding the error type in `arbitrary::Result`
+* The `Unstructured::arbitrary_loop` method will consume fewer bytes of input
+  now.
+
+### Fixed
+
+* Fixed a bug where `Unstructured::int_in_range` could return out-of-range
+  integers.
+
+--------------------------------------------------------------------------------
+
+## 1.1.3
+
+Released 2022-06-23.
+
+### Fixed
+
+* Fixed some potential (but highly unlikely) name-clashes inside
+  `derive(Arbitrary)`'s generated
+  code. [#111](https://github.com/rust-fuzz/arbitrary/pull/111)
+* Fixed an edge case where `derive(Arbitrary)` for recursive types that detected
+  an overflow would not reset the overflow
+  detection. [#111](https://github.com/rust-fuzz/arbitrary/pull/111)
+
+--------------------------------------------------------------------------------
+
+## 1.1.2
+
+Released 2022-06-16.
+
+### Fixed
+
+* Fixed a warning inside `derive(Arbitrary)`-generated
+  code. [#110](https://github.com/rust-fuzz/arbitrary/pull/110)
+
+--------------------------------------------------------------------------------
+
+## 1.1.1
+
+Released 2022-06-14.
+
+### Fixed
+
+* Fixed a stack overflow when using `derive(Arbitrary)` with recursive types and
+  empty inputs. [#109](https://github.com/rust-fuzz/arbitrary/pull/109)
+
+--------------------------------------------------------------------------------
+
+## 1.1.0
+
+Released 2022-02-09.
+
+### Added
+
+* Added the `Unstructured::ratio` method to generate a boolean that is `true` at
+  the given rate.
+
+* Added the `Unstructured::arbitrary_loop` method to call a function an
+  arbitrary number of times.
+
+--------------------------------------------------------------------------------
+
+## 1.0.3
+
+Released 2021-11-20.
+
+### Fixed
+
+* Fixed documentation for `Unstructured::fill_bytes`. We forgot to update this
+  way back in [#53](https://github.com/rust-fuzz/arbitrary/pull/53) when the
+  behavior changed.
+
+--------------------------------------------------------------------------------
+
+## 1.0.2
+
+Released 2021-08-25.
+
+### Added
+
+* `Arbitrary` impls for `HashMap`s and `HashSet`s with custom `Hasher`s
+  [#87](https://github.com/rust-fuzz/arbitrary/pull/87)
+
+--------------------------------------------------------------------------------
+
+## 1.0.1
+
+Released 2021-05-20.
+
+### Added
+
+* `Arbitrary` impls for `NonZeroX` types [#79](https://github.com/rust-fuzz/arbitrary/pull/79)
+* `Arbitrary` impls for all arrays using const generics [#55](https://github.com/rust-fuzz/arbitrary/pull/55)
+* `Arbitrary` impls for `Ipv4Addr` and `Ipv6Addr` [#84](https://github.com/rust-fuzz/arbitrary/pull/84)
+
+### Fixed
+
+* Use fewer bytes for `Unstructured::int_in_range()` [#80](https://github.com/rust-fuzz/arbitrary/pull/80)
+* Use correct range for `char` generation [#83](https://github.com/rust-fuzz/arbitrary/pull/83)
+
+--------------------------------------------------------------------------------
+
+## 1.0.0
+
+Released 2020-02-24.
+
+See 1.0.0-rc1 and 1.0.0-rc2 for changes since 0.4.7, which was the last main
+line release.
+
+--------------------------------------------------------------------------------
+
+## 1.0.0-rc2
+
+Released 2021-02-09.
+
+### Added
+
+* The `Arbitrary` trait is now implemented for `&[u8]`. [#67](https://github.com/rust-fuzz/arbitrary/pull/67)
+
+### Changed
+
+* Rename `Unstructured#get_bytes` to `Unstructured#bytes`. [#70](https://github.com/rust-fuzz/arbitrary/pull/70)
+* Passing an empty slice of choices to `Unstructured#choose` returns an error. Previously it would panic. [71](https://github.com/rust-fuzz/arbitrary/pull/71)
+
+--------------------------------------------------------------------------------
+
+## 1.0.0-rc1
+
+Released 2020-11-25.
+
+### Added
+
+* The `Arbitrary` trait is now implemented for `&str`. [#63](https://github.com/rust-fuzz/arbitrary/pull/63)
+
+### Changed
+
+* The `Arbitrary` trait now has a lifetime parameter, allowing `Arbitrary` implementations that borrow from the raw input (e.g. the new `&str` implementaton). The `derive(Arbitrary)` macro also supports deriving `Arbitrary` on types with lifetimes now. [#63](https://github.com/rust-fuzz/arbitrary/pull/63)
+
+### Removed
+
+* The `shrink` method on the `Arbitrary` trait has been removed.
+
+  We have found that, in practice, using [internal reduction](https://drmaciver.github.io/papers/reduction-via-generation-preview.pdf) via approaches like `cargo fuzz tmin`, where the raw input bytes are reduced rather than the `T: Arbitrary` type constructed from those raw bytes, has the best efficiency-to-maintenance ratio. To the best of our knowledge, no one is relying on or using the `Arbitrary::shrink` method. If you *are* using and relying on the `Arbitrary::shrink` method, please reach out by [dropping a comment here](https://github.com/rust-fuzz/arbitrary/issues/62) and explaining how you're using it and what your use case is. We'll figure out what the best solution is, including potentially adding shrinking functionality back to the `arbitrary` crate.
+
+--------------------------------------------------------------------------------
+
+## 0.4.7
+
+Released 2020-10-14.
+
+### Added
+
+* Added an optimization to avoid unnecessarily consuming bytes from the
+  underlying data when there is only one possible choice in
+  `Unstructured::{int_in_range, choose, etc..}`.
+
+* Added license files to the derive crate.
+
+### Changed
+
+* The `Arbitrary` implementation for `std::time::Duration` should now be faster
+  and produce durations with a more-uniform distribution of nanoseconds.
+
+--------------------------------------------------------------------------------
+
+## 0.4.6
+
+Released 2020-08-22.
+
+### Added
+
+* Added the `Unstructured::peek_bytes` method.
+
+### Changed
+
+* Test case reduction via `cargo fuzz tmin` should be much more effective at
+  reducing the sizes of collections now. (See
+  [#53](https://github.com/rust-fuzz/arbitrary/pull/53) and the commit messages
+  for details.)
+
+* Fuzzing with mutation-based fuzzers (like libFuzzer) should be more efficient
+  now. (See [#53](https://github.com/rust-fuzz/arbitrary/pull/53) and the commit
+  messages for details)
+
+--------------------------------------------------------------------------------
+
+## 0.4.5
+
+Released 2020-06-18.
+
+### Added
+
+* Implement `Arbitrary` for zero length arrays.
+* Implement `Arbitrary` for `Range` and `RangeInclusive`.
+
+--------------------------------------------------------------------------------
+
+## 0.4.4
+
+Released 2020-04-29.
+
+### Fixed
+
+* Fixed the custom derive for enums when used via its full path (like
+  `#[derive(arbitrary::Arbitrary)]` rather than like `#[derive(Arbitrary)]`).
+
+
+## 0.4.3
+
+Released 2020-04-28.
+
+### Fixed
+
+* Fixed the custom derive when used via its full path (like
+  `#[derive(arbitrary::Arbitrary)]` rather than like `#[derive(Arbitrary)]`).
+
+--------------------------------------------------------------------------------
+
+## 0.4.2
+
+Released 2020-04-17.
+
+### Changed
+
+* We forgot to release a new version of the `derive_arbitrary` crate last
+  release. This release fixes that and so the `synstructure` dependency is
+  finally actually removed in the cargo releases.
+
+--------------------------------------------------------------------------------
+
+## 0.4.1
+
+Released 2020-03-18.
+
+### Removed
+
+* Removed an internal dependency on the `synstructure` crate when the `derive`
+  feature is enabled. This should not have any visible downstream effects other
+  than faster build times!
+
+--------------------------------------------------------------------------------
+
+## 0.4.0
+
+Released 2020-01-22.
+
+This is technically a breaking change, but we expect that nearly everyone should
+be able to upgrade without any compilation errors. The only exception is if you
+were implementing the `Arbitrary::size_hint` method by hand. If so, see the
+"changed" section below and the [API docs for
+`Arbitrary::shrink`](https://docs.rs/arbitrary/0.4.0/arbitrary/trait.Arbitrary.html#method.size_hint)
+for details.
+
+### Added
+
+* Added [the `arbitary::size_hint::recursion_guard` helper
+  function][recursion_guard] for guarding against infinite recursion in
+  `size_hint` implementations for recursive types.
+
+### Changed
+
+* The `Arbitrary::size_hint` signature now takes a `depth: usize`
+  parameter. This should be passed along unmodified to any nested calls of other
+  `size_hint` methods. If you're implementing `size_hint` for a recursive type
+  (like a linked list or tree) or a generic type with type parameters, you
+  should use [the new `arbitrary::size_hint::recursion_guard` helper
+  function][recursion_guard].
+
+### Fixed
+
+* Fixed infinite recursion in generated `size_hint` implementations
+  from `#[derive(Arbitrary)]` for recursive types.
+
+[recursion_guard]: https://docs.rs/arbitrary/0.4.0/arbitrary/size_hint/fn.recursion_guard.html
+
+--------------------------------------------------------------------------------
+
+## 0.3.2
+
+Released 2020-01-16.
+
+### Changed
+
+* Updated the custom derive's dependencies.
+
+--------------------------------------------------------------------------------
+
+## 0.3.2
+
+Released 2020-01-15.
+
+### Fixed
+
+* Fixed an over-eager assertion condition in `Unstructured::int_in_range` that
+  would incorrectly trigger when given valid ranges of length one.
+
+--------------------------------------------------------------------------------
+
+## 0.3.1
+
+Released 2020-01-14.
+
+### Fixed
+
+* Fixed some links and version numbers in README.
+
+--------------------------------------------------------------------------------
+
+## 0.3.0
+
+Released 2020-01-14.
+
+### Added
+
+* Added the `"derive"` cargo feature, to enable `#[derive(Arbitrary)]` for
+  custom types. Enabling this feature re-exports functionality from the
+  `derive_arbitrary` crate.
+* The custom derive for `Arbitrary` implements the shrink method for you now.
+* All implementations of `Arbitrary` for `std` types implement shrinking now.
+* Added the `Arbitrary::arbitrary_take_rest` method allows an `Arbitrary`
+  implementation to consume all of the rest of the remaining raw input. It has a
+  default implementation that forwards to `Arbitrary::arbitrary` and the custom
+  derive creates a smart implementation for your custom types.
+* Added the `Arbitrary::size_hint` method for hinting how many raw bytes an
+  implementation needs to construct itself. This has a default implementation,
+  but the custom derive creates a smart implementation for your custom types.
+* Added the `Unstructured::choose` method to choose one thing among a set of
+  choices.
+* Added the `Unstructured::arbitrary_len` method to get an arbitrary length for
+  a collection of some arbitrary type.
+* Added the `Unstructured::arbitrary_iter` method to create an iterator of
+  arbitrary instance of some type.
+
+### Changed
+
+* The `Arbitrary` trait was simplified a bit.
+* `Unstructured` is a concrete type now, not a trait.
+* Switched to Rust 2018 edition.
+
+### Removed
+
+* `RingBuffer` and `FiniteBuffer` are removed. Use `Unstructured` instead.
+
+### Fixed
+
+* Better `Arbitrary` implementation for `char`.
+* Better `Arbitrary` implementation for `String`.
+
+--------------------------------------------------------------------------------
+
+## 0.2.0
+
+--------------------------------------------------------------------------------
+
+## 0.1.0
diff --git a/third_party/rust/arbitrary/Cargo.lock b/third_party/rust/arbitrary/Cargo.lock
new file mode 100644
index 0000000000..26d8335110
--- /dev/null
+++ b/third_party/rust/arbitrary/Cargo.lock
@@ -0,0 +1,56 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "arbitrary"
+version = "1.2.3"
+dependencies = [
+ "derive_arbitrary",
+]
+
+[[package]]
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+version = "1.2.3"
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+checksum = "8beee4701e2e229e8098bbdecdca12449bc3e322f137d269182fa1291e20bd00"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
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+ "unicode-ident",
+]
+
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+checksum = "8856d8364d252a14d474036ea1358d63c9e6965c8e5c1885c18f73d70bff9c7b"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f4064b5b16e03ae50984a5a8ed5d4f8803e6bc1fd170a3cda91a1be4b18e3f5"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
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diff --git a/third_party/rust/arbitrary/Cargo.toml b/third_party/rust/arbitrary/Cargo.toml
new file mode 100644
index 0000000000..9b116114df
--- /dev/null
+++ b/third_party/rust/arbitrary/Cargo.toml
@@ -0,0 +1,50 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.63.0"
+name = "arbitrary"
+version = "1.2.3"
+authors = [
+    "The Rust-Fuzz Project Developers",
+    "Nick Fitzgerald <fitzgen@gmail.com>",
+    "Manish Goregaokar <manishsmail@gmail.com>",
+    "Simonas Kazlauskas <arbitrary@kazlauskas.me>",
+    "Brian L. Troutwine <brian@troutwine.us>",
+    "Corey Farwell <coreyf@rwell.org>",
+]
+description = "The trait for generating structured data from unstructured data"
+documentation = "https://docs.rs/arbitrary/"
+readme = "README.md"
+keywords = [
+    "arbitrary",
+    "testing",
+]
+categories = ["development-tools::testing"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/rust-fuzz/arbitrary/"
+
+[[example]]
+name = "derive_enum"
+required-features = ["derive"]
+
+[[test]]
+name = "derive"
+path = "./tests/derive.rs"
+required-features = ["derive"]
+
+[dependencies.derive_arbitrary]
+version = "1.2.3"
+optional = true
+
+[features]
+derive = ["derive_arbitrary"]
diff --git a/third_party/rust/arbitrary/LICENSE-APACHE b/third_party/rust/arbitrary/LICENSE-APACHE
new file mode 100644
index 0000000000..16fe87b06e
--- /dev/null
+++ b/third_party/rust/arbitrary/LICENSE-APACHE
@@ -0,0 +1,201 @@
+                              Apache License
+                        Version 2.0, January 2004
+                     http://www.apache.org/licenses/
+
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diff --git a/third_party/rust/arbitrary/LICENSE-MIT b/third_party/rust/arbitrary/LICENSE-MIT
new file mode 100644
index 0000000000..d74f9e93d4
--- /dev/null
+++ b/third_party/rust/arbitrary/LICENSE-MIT
@@ -0,0 +1,27 @@
+MIT License
+
+Copyright (c) 2019 Manish Goregaokar
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
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+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
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+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/third_party/rust/arbitrary/README.md b/third_party/rust/arbitrary/README.md
new file mode 100644
index 0000000000..3f5619b687
--- /dev/null
+++ b/third_party/rust/arbitrary/README.md
@@ -0,0 +1,129 @@
+<div align="center">
+
+  <h1><code>Arbitrary</code></h1>
+
+  <p><strong>The trait for generating structured data from arbitrary, unstructured input.</strong></p>
+
+  <img alt="GitHub Actions Status" src="https://github.com/rust-fuzz/rust_arbitrary/workflows/Rust/badge.svg"/>
+
+</div>
+
+## About
+
+The `Arbitrary` crate lets you construct arbitrary instances of a type.
+
+This crate is primarily intended to be combined with a fuzzer like [libFuzzer
+and `cargo-fuzz`](https://github.com/rust-fuzz/cargo-fuzz) or
+[AFL](https://github.com/rust-fuzz/afl.rs), and to help you turn the raw,
+untyped byte buffers that they produce into well-typed, valid, structured
+values. This allows you to combine structure-aware test case generation with
+coverage-guided, mutation-based fuzzers.
+
+## Documentation
+
+[**Read the API documentation on `docs.rs`!**](https://docs.rs/arbitrary)
+
+## Example
+
+Say you're writing a color conversion library, and you have an `Rgb` struct to
+represent RGB colors. You might want to implement `Arbitrary` for `Rgb` so that
+you could take arbitrary `Rgb` instances in a test function that asserts some
+property (for example, asserting that RGB converted to HSL and converted back to
+RGB always ends up exactly where we started).
+
+### Automatically Deriving `Arbitrary`
+
+Automatically deriving the `Arbitrary` trait is the recommended way to implement
+`Arbitrary` for your types.
+
+Automatically deriving `Arbitrary` requires you to enable the `"derive"` cargo
+feature:
+
+```toml
+# Cargo.toml
+
+[dependencies]
+arbitrary = { version = "1", features = ["derive"] }
+```
+
+And then you can simply add `#[derive(Arbitrary)]` annotations to your types:
+
+```rust
+// rgb.rs
+
+use arbitrary::Arbitrary;
+
+#[derive(Arbitrary)]
+pub struct Rgb {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+```
+
+#### Customizing single fields
+
+This can be particular handy if your structure uses a type that does not implement `Arbitrary` or you want to have more customization for particular fields.
+
+```rust
+#[derive(Arbitrary)]
+pub struct Rgba {
+    // set `r` to Default::default()
+    #[arbitrary(default)]
+    pub r: u8,
+
+    // set `g` to 255
+    #[arbitrary(value = 255)]
+    pub g: u8,
+
+    // Generate `b` with a custom function of type
+    //
+    //    fn(&mut Unstructured) -> arbitrary::Result<T>
+    //
+    // where `T` is the field's type.
+    #[arbitrary(with = arbitrary_b)]
+    pub b: u8,
+
+    // Generate `a` with a custom closure (shortuct to avoid a custom funciton)
+    #[arbitrary(with = |u: &mut Unstructured| u.int_in_range(0..=64))]
+    pub a: u8,
+}
+
+fn arbitrary_b(u: &mut Unstructured) -> arbitrary::Result<u8> {
+    u.int_in_range(64..=128)
+}
+```
+
+### Implementing `Arbitrary` By Hand
+
+Alternatively, you can write an `Arbitrary` implementation by hand:
+
+```rust
+// rgb.rs
+
+use arbitrary::{Arbitrary, Result, Unstructured};
+
+#[derive(Copy, Clone, Debug)]
+pub struct Rgb {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+
+impl<'a> Arbitrary<'a> for Rgb {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        let r = u8::arbitrary(u)?;
+        let g = u8::arbitrary(u)?;
+        let b = u8::arbitrary(u)?;
+        Ok(Rgb { r, g, b })
+    }
+}
+```
+
+## License
+
+Licensed under dual MIT or Apache-2.0 at your choice.
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in this project by you, as defined in the Apache-2.0 license,
+shall be dual licensed as above, without any additional terms or conditions.
diff --git a/third_party/rust/arbitrary/examples/derive_enum.rs b/third_party/rust/arbitrary/examples/derive_enum.rs
new file mode 100644
index 0000000000..c4fc9c9588
--- /dev/null
+++ b/third_party/rust/arbitrary/examples/derive_enum.rs
@@ -0,0 +1,27 @@
+//! A simple example of deriving the `Arbitrary` trait for an `enum`.
+//!
+//! Note that this requires enabling the "derive" cargo feature.
+
+// Various enums/fields that we are deriving `Arbitrary` for aren't actually
+// used except to show off the derive.
+#![allow(dead_code)]
+
+use arbitrary::{Arbitrary, Unstructured};
+
+#[derive(Arbitrary, Debug)]
+enum MyEnum {
+    UnitVariant,
+    TupleVariant(bool, u32),
+    StructVariant { x: i8, y: (u8, i32) },
+}
+
+fn main() {
+    let raw = b"This is some raw, unstructured data!";
+
+    let mut unstructured = Unstructured::new(raw);
+
+    let instance = MyEnum::arbitrary(&mut unstructured)
+        .expect("`unstructured` has enough underlying data to create all variants of `MyEnum`");
+
+    println!("Here is an arbitrary enum: {:?}", instance);
+}
diff --git a/third_party/rust/arbitrary/publish.sh b/third_party/rust/arbitrary/publish.sh
new file mode 100755
index 0000000000..24db2bd779
--- /dev/null
+++ b/third_party/rust/arbitrary/publish.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+set -eux
+
+cd $(dirname $0)/derive
+
+cargo publish
+
+cd ..
+
+# Let the crates.io index figure out we've published `derive_arbitrary` already.
+sleep 5
+
+cargo publish
diff --git a/third_party/rust/arbitrary/src/error.rs b/third_party/rust/arbitrary/src/error.rs
new file mode 100644
index 0000000000..1d3df2a22e
--- /dev/null
+++ b/third_party/rust/arbitrary/src/error.rs
@@ -0,0 +1,53 @@
+use std::{error, fmt};
+
+/// An enumeration of buffer creation errors
+#[derive(Debug, Clone, Copy)]
+#[non_exhaustive]
+pub enum Error {
+    /// No choices were provided to the Unstructured::choose call
+    EmptyChoose,
+    /// There was not enough underlying data to fulfill some request for raw
+    /// bytes.
+    NotEnoughData,
+    /// The input bytes were not of the right format
+    IncorrectFormat,
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::EmptyChoose => write!(
+                f,
+                "`arbitrary::Unstructured::choose` must be given a non-empty set of choices"
+            ),
+            Error::NotEnoughData => write!(
+                f,
+                "There is not enough underlying raw data to construct an `Arbitrary` instance"
+            ),
+            Error::IncorrectFormat => write!(
+                f,
+                "The raw data is not of the correct format to construct this type"
+            ),
+        }
+    }
+}
+
+impl error::Error for Error {}
+
+/// A `Result` with the error type fixed as `arbitrary::Error`.
+///
+/// Either an `Ok(T)` or `Err(arbitrary::Error)`.
+pub type Result<T, E = Error> = std::result::Result<T, E>;
+
+#[cfg(test)]
+mod tests {
+    // Often people will import our custom `Result` type because 99.9% of
+    // results in a file will be `arbitrary::Result` but then have that one last
+    // 0.1% that want to have a custom error type. Don't make them prefix that
+    // 0.1% as `std::result::Result`; instead, let `arbitrary::Result` have an
+    // overridable error type.
+    #[test]
+    fn can_use_custom_error_types_with_result() -> super::Result<(), String> {
+        Ok(())
+    }
+}
diff --git a/third_party/rust/arbitrary/src/lib.rs b/third_party/rust/arbitrary/src/lib.rs
new file mode 100644
index 0000000000..a3fa48ba39
--- /dev/null
+++ b/third_party/rust/arbitrary/src/lib.rs
@@ -0,0 +1,1342 @@
+// Copyright © 2019 The Rust Fuzz Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! The `Arbitrary` trait crate.
+//!
+//! This trait provides an [`Arbitrary`](./trait.Arbitrary.html) trait to
+//! produce well-typed, structured values, from raw, byte buffers. It is
+//! generally intended to be used with fuzzers like AFL or libFuzzer. See the
+//! [`Arbitrary`](./trait.Arbitrary.html) trait's documentation for details on
+//! automatically deriving, implementing, and/or using the trait.
+
+#![deny(bad_style)]
+#![deny(missing_docs)]
+#![deny(future_incompatible)]
+#![deny(nonstandard_style)]
+#![deny(rust_2018_compatibility)]
+#![deny(rust_2018_idioms)]
+#![deny(unused)]
+
+#[cfg(feature = "derive_arbitrary")]
+pub use derive_arbitrary::*;
+
+mod error;
+pub use error::*;
+
+pub mod unstructured;
+#[doc(inline)]
+pub use unstructured::Unstructured;
+
+pub mod size_hint;
+
+use core::array;
+use core::cell::{Cell, RefCell, UnsafeCell};
+use core::iter;
+use core::mem;
+use core::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
+use core::num::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};
+use core::ops::{Range, RangeBounds, RangeFrom, RangeInclusive, RangeTo, RangeToInclusive};
+use core::str;
+use core::time::Duration;
+use std::borrow::{Cow, ToOwned};
+use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque};
+use std::ffi::{CString, OsString};
+use std::hash::BuildHasher;
+use std::net::{Ipv4Addr, Ipv6Addr};
+use std::ops::Bound;
+use std::path::PathBuf;
+use std::rc::Rc;
+use std::sync::atomic::{AtomicBool, AtomicIsize, AtomicUsize};
+use std::sync::{Arc, Mutex};
+
+/// Generate arbitrary structured values from raw, unstructured data.
+///
+/// The `Arbitrary` trait allows you to generate valid structured values, like
+/// `HashMap`s, or ASTs, or `MyTomlConfig`, or any other data structure from
+/// raw, unstructured bytes provided by a fuzzer.
+///
+/// # Deriving `Arbitrary`
+///
+/// Automatically deriving the `Arbitrary` trait is the recommended way to
+/// implement `Arbitrary` for your types.
+///
+/// Using the custom derive requires that you enable the `"derive"` cargo
+/// feature in your `Cargo.toml`:
+///
+/// ```toml
+/// [dependencies]
+/// arbitrary = { version = "1", features = ["derive"] }
+/// ```
+///
+/// Then, you add the `#[derive(Arbitrary)]` annotation to your `struct` or
+/// `enum` type definition:
+///
+/// ```
+/// # #[cfg(feature = "derive")] mod foo {
+/// use arbitrary::Arbitrary;
+/// use std::collections::HashSet;
+///
+/// #[derive(Arbitrary)]
+/// pub struct AddressBook {
+///     friends: HashSet<Friend>,
+/// }
+///
+/// #[derive(Arbitrary, Hash, Eq, PartialEq)]
+/// pub enum Friend {
+///     Buddy { name: String },
+///     Pal { age: usize },
+/// }
+/// # }
+/// ```
+///
+/// Every member of the `struct` or `enum` must also implement `Arbitrary`.
+///
+/// # Implementing `Arbitrary` By Hand
+///
+/// Implementing `Arbitrary` mostly involves nested calls to other `Arbitrary`
+/// arbitrary implementations for each of your `struct` or `enum`'s members. But
+/// sometimes you need some amount of raw data, or you need to generate a
+/// variably-sized collection type, or something of that sort. The
+/// [`Unstructured`][crate::Unstructured] type helps you with these tasks.
+///
+/// ```
+/// # #[cfg(feature = "derive")] mod foo {
+/// # pub struct MyCollection<T> { _t: std::marker::PhantomData<T> }
+/// # impl<T> MyCollection<T> {
+/// #     pub fn new() -> Self { MyCollection { _t: std::marker::PhantomData } }
+/// #     pub fn insert(&mut self, element: T) {}
+/// # }
+/// use arbitrary::{Arbitrary, Result, Unstructured};
+///
+/// impl<'a, T> Arbitrary<'a> for MyCollection<T>
+/// where
+///     T: Arbitrary<'a>,
+/// {
+///     fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+///         // Get an iterator of arbitrary `T`s.
+///         let iter = u.arbitrary_iter::<T>()?;
+///
+///         // And then create a collection!
+///         let mut my_collection = MyCollection::new();
+///         for elem_result in iter {
+///             let elem = elem_result?;
+///             my_collection.insert(elem);
+///         }
+///
+///         Ok(my_collection)
+///     }
+/// }
+/// # }
+/// ```
+pub trait Arbitrary<'a>: Sized {
+    /// Generate an arbitrary value of `Self` from the given unstructured data.
+    ///
+    /// Calling `Arbitrary::arbitrary` requires that you have some raw data,
+    /// perhaps given to you by a fuzzer like AFL or libFuzzer. You wrap this
+    /// raw data in an `Unstructured`, and then you can call `<MyType as
+    /// Arbitrary>::arbitrary` to construct an arbitrary instance of `MyType`
+    /// from that unstructured data.
+    ///
+    /// Implementations may return an error if there is not enough data to
+    /// construct a full instance of `Self`, or they may fill out the rest of
+    /// `Self` with dummy values. Using dummy values when the underlying data is
+    /// exhausted can help avoid accidentally "defeating" some of the fuzzer's
+    /// mutations to the underlying byte stream that might otherwise lead to
+    /// interesting runtime behavior or new code coverage if only we had just a
+    /// few more bytes. However, it also requires that implementations for
+    /// recursive types (e.g. `struct Foo(Option<Box<Foo>>)`) avoid infinite
+    /// recursion when the underlying data is exhausted.
+    ///
+    /// ```
+    /// # #[cfg(feature = "derive")] fn foo() {
+    /// use arbitrary::{Arbitrary, Unstructured};
+    ///
+    /// #[derive(Arbitrary)]
+    /// pub struct MyType {
+    ///     // ...
+    /// }
+    ///
+    /// // Get the raw data from the fuzzer or wherever else.
+    /// # let get_raw_data_from_fuzzer = || &[];
+    /// let raw_data: &[u8] = get_raw_data_from_fuzzer();
+    ///
+    /// // Wrap that raw data in an `Unstructured`.
+    /// let mut unstructured = Unstructured::new(raw_data);
+    ///
+    /// // Generate an arbitrary instance of `MyType` and do stuff with it.
+    /// if let Ok(value) = MyType::arbitrary(&mut unstructured) {
+    /// #   let do_stuff = |_| {};
+    ///     do_stuff(value);
+    /// }
+    /// # }
+    /// ```
+    ///
+    /// See also the documentation for [`Unstructured`][crate::Unstructured].
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self>;
+
+    /// Generate an arbitrary value of `Self` from the entirety of the given
+    /// unstructured data.
+    ///
+    /// This is similar to Arbitrary::arbitrary, however it assumes that it is
+    /// the last consumer of the given data, and is thus able to consume it all
+    /// if it needs.  See also the documentation for
+    /// [`Unstructured`][crate::Unstructured].
+    fn arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<Self> {
+        Self::arbitrary(&mut u)
+    }
+
+    /// Get a size hint for how many bytes out of an `Unstructured` this type
+    /// needs to construct itself.
+    ///
+    /// This is useful for determining how many elements we should insert when
+    /// creating an arbitrary collection.
+    ///
+    /// The return value is similar to
+    /// [`Iterator::size_hint`][iterator-size-hint]: it returns a tuple where
+    /// the first element is a lower bound on the number of bytes required, and
+    /// the second element is an optional upper bound.
+    ///
+    /// The default implementation return `(0, None)` which is correct for any
+    /// type, but not ultimately that useful. Using `#[derive(Arbitrary)]` will
+    /// create a better implementation. If you are writing an `Arbitrary`
+    /// implementation by hand, and your type can be part of a dynamically sized
+    /// collection (such as `Vec`), you are strongly encouraged to override this
+    /// default with a better implementation. The
+    /// [`size_hint`][crate::size_hint] module will help with this task.
+    ///
+    /// ## Invariant
+    ///
+    /// It must be possible to construct every possible output using only inputs
+    /// of lengths bounded by these parameters. This applies to both
+    /// [`Arbitrary::arbitrary`] and [`Arbitrary::arbitrary_take_rest`].
+    ///
+    /// This is trivially true for `(0, None)`. To restrict this further, it
+    /// must be proven that all inputs that are now excluded produced redundant
+    /// outputs which are still possible to produce using the reduced input
+    /// space.
+    ///
+    /// ## The `depth` Parameter
+    ///
+    /// If you 100% know that the type you are implementing `Arbitrary` for is
+    /// not a recursive type, or your implementation is not transitively calling
+    /// any other `size_hint` methods, you can ignore the `depth` parameter.
+    /// Note that if you are implementing `Arbitrary` for a generic type, you
+    /// cannot guarantee the lack of type recursion!
+    ///
+    /// Otherwise, you need to use
+    /// [`arbitrary::size_hint::recursion_guard(depth)`][crate::size_hint::recursion_guard]
+    /// to prevent potential infinite recursion when calculating size hints for
+    /// potentially recursive types:
+    ///
+    /// ```
+    /// use arbitrary::{Arbitrary, Unstructured, size_hint};
+    ///
+    /// // This can potentially be a recursive type if `L` or `R` contain
+    /// // something like `Box<Option<MyEither<L, R>>>`!
+    /// enum MyEither<L, R> {
+    ///     Left(L),
+    ///     Right(R),
+    /// }
+    ///
+    /// impl<'a, L, R> Arbitrary<'a> for MyEither<L, R>
+    /// where
+    ///     L: Arbitrary<'a>,
+    ///     R: Arbitrary<'a>,
+    /// {
+    ///     fn arbitrary(u: &mut Unstructured) -> arbitrary::Result<Self> {
+    ///         // ...
+    /// #       unimplemented!()
+    ///     }
+    ///
+    ///     fn size_hint(depth: usize) -> (usize, Option<usize>) {
+    ///         // Protect against potential infinite recursion with
+    ///         // `recursion_guard`.
+    ///         size_hint::recursion_guard(depth, |depth| {
+    ///             // If we aren't too deep, then `recursion_guard` calls
+    ///             // this closure, which implements the natural size hint.
+    ///             // Don't forget to use the new `depth` in all nested
+    ///             // `size_hint` calls! We recommend shadowing the
+    ///             // parameter, like what is done here, so that you can't
+    ///             // accidentally use the wrong depth.
+    ///             size_hint::or(
+    ///                 <L as Arbitrary>::size_hint(depth),
+    ///                 <R as Arbitrary>::size_hint(depth),
+    ///             )
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// [iterator-size-hint]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.size_hint
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        let _ = depth;
+        (0, None)
+    }
+}
+
+impl<'a> Arbitrary<'a> for () {
+    fn arbitrary(_: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(())
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, Some(0))
+    }
+}
+
+impl<'a> Arbitrary<'a> for bool {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(<u8 as Arbitrary<'a>>::arbitrary(u)? & 1 == 1)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <u8 as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+macro_rules! impl_arbitrary_for_integers {
+    ( $( $ty:ty: $unsigned:ty; )* ) => {
+        $(
+            impl<'a> Arbitrary<'a> for $ty {
+                fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+                    let mut buf = [0; mem::size_of::<$ty>()];
+                    u.fill_buffer(&mut buf)?;
+                    let mut x: $unsigned = 0;
+                    for i in 0..mem::size_of::<$ty>() {
+                        x |= buf[i] as $unsigned << (i * 8);
+                    }
+                    Ok(x as $ty)
+                }
+
+                #[inline]
+                fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+                    let n = mem::size_of::<$ty>();
+                    (n, Some(n))
+                }
+
+            }
+        )*
+    }
+}
+
+impl_arbitrary_for_integers! {
+    u8: u8;
+    u16: u16;
+    u32: u32;
+    u64: u64;
+    u128: u128;
+    usize: usize;
+    i8: u8;
+    i16: u16;
+    i32: u32;
+    i64: u64;
+    i128: u128;
+    isize: usize;
+}
+
+macro_rules! impl_arbitrary_for_floats {
+    ( $( $ty:ident : $unsigned:ty; )* ) => {
+        $(
+            impl<'a> Arbitrary<'a> for $ty {
+                fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+                    Ok(Self::from_bits(<$unsigned as Arbitrary<'a>>::arbitrary(u)?))
+                }
+
+                #[inline]
+                fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                    <$unsigned as Arbitrary<'a>>::size_hint(depth)
+                }
+            }
+        )*
+    }
+}
+
+impl_arbitrary_for_floats! {
+    f32: u32;
+    f64: u64;
+}
+
+impl<'a> Arbitrary<'a> for char {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        use std::char;
+        // The highest unicode code point is 0x11_FFFF
+        const CHAR_END: u32 = 0x11_0000;
+        // The size of the surrogate blocks
+        const SURROGATES_START: u32 = 0xD800;
+        let mut c = <u32 as Arbitrary<'a>>::arbitrary(u)? % CHAR_END;
+        if let Some(c) = char::from_u32(c) {
+            Ok(c)
+        } else {
+            // We found a surrogate, wrap and try again
+            c -= SURROGATES_START;
+            Ok(char::from_u32(c)
+                .expect("Generated character should be valid! This is a bug in arbitrary-rs"))
+        }
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <u32 as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for AtomicBool {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <bool as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for AtomicIsize {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <isize as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for AtomicUsize {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <usize as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+macro_rules! impl_range {
+    (
+        $range:ty,
+        $value_closure:expr,
+        $value_ty:ty,
+        $fun:ident($fun_closure:expr),
+        $size_hint_closure:expr
+    ) => {
+        impl<'a, A> Arbitrary<'a> for $range
+        where
+            A: Arbitrary<'a> + Clone + PartialOrd,
+        {
+            fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+                let value: $value_ty = Arbitrary::arbitrary(u)?;
+                Ok($fun(value, $fun_closure))
+            }
+
+            #[inline]
+            fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                $size_hint_closure(depth)
+            }
+        }
+    };
+}
+
+impl_range!(
+    Range<A>,
+    |r: &Range<A>| (r.start.clone(), r.end.clone()),
+    (A, A),
+    bounded_range(|(a, b)| a..b),
+    |depth| crate::size_hint::and(
+        <A as Arbitrary>::size_hint(depth),
+        <A as Arbitrary>::size_hint(depth)
+    )
+);
+impl_range!(
+    RangeFrom<A>,
+    |r: &RangeFrom<A>| r.start.clone(),
+    A,
+    unbounded_range(|a| a..),
+    |depth| <A as Arbitrary>::size_hint(depth)
+);
+impl_range!(
+    RangeInclusive<A>,
+    |r: &RangeInclusive<A>| (r.start().clone(), r.end().clone()),
+    (A, A),
+    bounded_range(|(a, b)| a..=b),
+    |depth| crate::size_hint::and(
+        <A as Arbitrary>::size_hint(depth),
+        <A as Arbitrary>::size_hint(depth)
+    )
+);
+impl_range!(
+    RangeTo<A>,
+    |r: &RangeTo<A>| r.end.clone(),
+    A,
+    unbounded_range(|b| ..b),
+    |depth| <A as Arbitrary>::size_hint(depth)
+);
+impl_range!(
+    RangeToInclusive<A>,
+    |r: &RangeToInclusive<A>| r.end.clone(),
+    A,
+    unbounded_range(|b| ..=b),
+    |depth| <A as Arbitrary>::size_hint(depth)
+);
+
+pub(crate) fn bounded_range<CB, I, R>(bounds: (I, I), cb: CB) -> R
+where
+    CB: Fn((I, I)) -> R,
+    I: PartialOrd,
+    R: RangeBounds<I>,
+{
+    let (mut start, mut end) = bounds;
+    if start > end {
+        mem::swap(&mut start, &mut end);
+    }
+    cb((start, end))
+}
+
+pub(crate) fn unbounded_range<CB, I, R>(bound: I, cb: CB) -> R
+where
+    CB: Fn(I) -> R,
+    R: RangeBounds<I>,
+{
+    cb(bound)
+}
+
+impl<'a> Arbitrary<'a> for Duration {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(Self::new(
+            <u64 as Arbitrary>::arbitrary(u)?,
+            u.int_in_range(0..=999_999_999)?,
+        ))
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::and(
+            <u64 as Arbitrary>::size_hint(depth),
+            <u32 as Arbitrary>::size_hint(depth),
+        )
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Option<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(if <bool as Arbitrary<'a>>::arbitrary(u)? {
+            Some(Arbitrary::arbitrary(u)?)
+        } else {
+            None
+        })
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::and(
+            <bool as Arbitrary>::size_hint(depth),
+            crate::size_hint::or((0, Some(0)), <A as Arbitrary>::size_hint(depth)),
+        )
+    }
+}
+
+impl<'a, A: Arbitrary<'a>, B: Arbitrary<'a>> Arbitrary<'a> for std::result::Result<A, B> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(if <bool as Arbitrary<'a>>::arbitrary(u)? {
+            Ok(<A as Arbitrary>::arbitrary(u)?)
+        } else {
+            Err(<B as Arbitrary>::arbitrary(u)?)
+        })
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::and(
+            <bool as Arbitrary>::size_hint(depth),
+            crate::size_hint::or(
+                <A as Arbitrary>::size_hint(depth),
+                <B as Arbitrary>::size_hint(depth),
+            ),
+        )
+    }
+}
+
+macro_rules! arbitrary_tuple {
+    () => {};
+    ($last: ident $($xs: ident)*) => {
+        arbitrary_tuple!($($xs)*);
+
+        impl<'a, $($xs: Arbitrary<'a>,)* $last: Arbitrary<'a>> Arbitrary<'a> for ($($xs,)* $last,) {
+            fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+                Ok(($($xs::arbitrary(u)?,)* Arbitrary::arbitrary(u)?,))
+            }
+
+            #[allow(unused_mut, non_snake_case)]
+            fn arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<Self> {
+                $(let $xs = $xs::arbitrary(&mut u)?;)*
+                let $last = $last::arbitrary_take_rest(u)?;
+                Ok(($($xs,)* $last,))
+            }
+
+            #[inline]
+            fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                crate::size_hint::and_all(&[
+                    <$last as Arbitrary>::size_hint(depth),
+                    $( <$xs as Arbitrary>::size_hint(depth) ),*
+                ])
+            }
+        }
+    };
+}
+arbitrary_tuple!(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z);
+
+// Helper to safely create arrays since the standard library doesn't
+// provide one yet. Shouldn't be necessary in the future.
+struct ArrayGuard<T, const N: usize> {
+    dst: *mut T,
+    initialized: usize,
+}
+
+impl<T, const N: usize> Drop for ArrayGuard<T, N> {
+    fn drop(&mut self) {
+        debug_assert!(self.initialized <= N);
+        let initialized_part = core::ptr::slice_from_raw_parts_mut(self.dst, self.initialized);
+        unsafe {
+            core::ptr::drop_in_place(initialized_part);
+        }
+    }
+}
+
+fn try_create_array<F, T, const N: usize>(mut cb: F) -> Result<[T; N]>
+where
+    F: FnMut(usize) -> Result<T>,
+{
+    let mut array: mem::MaybeUninit<[T; N]> = mem::MaybeUninit::uninit();
+    let array_ptr = array.as_mut_ptr();
+    let dst = array_ptr as _;
+    let mut guard: ArrayGuard<T, N> = ArrayGuard {
+        dst,
+        initialized: 0,
+    };
+    unsafe {
+        for (idx, value_ptr) in (*array.as_mut_ptr()).iter_mut().enumerate() {
+            core::ptr::write(value_ptr, cb(idx)?);
+            guard.initialized += 1;
+        }
+        mem::forget(guard);
+        Ok(array.assume_init())
+    }
+}
+
+impl<'a, T, const N: usize> Arbitrary<'a> for [T; N]
+where
+    T: Arbitrary<'a>,
+{
+    #[inline]
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        try_create_array(|_| <T as Arbitrary<'a>>::arbitrary(u))
+    }
+
+    #[inline]
+    fn arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<Self> {
+        let mut array = Self::arbitrary(&mut u)?;
+        if let Some(last) = array.last_mut() {
+            *last = Arbitrary::arbitrary_take_rest(u)?;
+        }
+        Ok(array)
+    }
+
+    #[inline]
+    fn size_hint(d: usize) -> (usize, Option<usize>) {
+        crate::size_hint::and_all(&array::from_fn::<_, N, _>(|_| {
+            <T as Arbitrary>::size_hint(d)
+        }))
+    }
+}
+
+impl<'a> Arbitrary<'a> for &'a [u8] {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        let len = u.arbitrary_len::<u8>()?;
+        u.bytes(len)
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        Ok(u.take_rest())
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Vec<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, K: Arbitrary<'a> + Ord, V: Arbitrary<'a>> Arbitrary<'a> for BTreeMap<K, V> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a> + Ord> Arbitrary<'a> for BTreeSet<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Bound<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        match u.int_in_range::<u8>(0..=2)? {
+            0 => Ok(Bound::Included(A::arbitrary(u)?)),
+            1 => Ok(Bound::Excluded(A::arbitrary(u)?)),
+            2 => Ok(Bound::Unbounded),
+            _ => unreachable!(),
+        }
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        size_hint::or(
+            size_hint::and((1, Some(1)), A::size_hint(depth)),
+            (1, Some(1)),
+        )
+    }
+}
+
+impl<'a, A: Arbitrary<'a> + Ord> Arbitrary<'a> for BinaryHeap<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, K: Arbitrary<'a> + Eq + ::std::hash::Hash, V: Arbitrary<'a>, S: BuildHasher + Default>
+    Arbitrary<'a> for HashMap<K, V, S>
+{
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a> + Eq + ::std::hash::Hash, S: BuildHasher + Default> Arbitrary<'a>
+    for HashSet<A, S>
+{
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for LinkedList<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for VecDeque<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_iter()?.collect()
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        u.arbitrary_take_rest_iter()?.collect()
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a, A> Arbitrary<'a> for Cow<'a, A>
+where
+    A: ToOwned + ?Sized,
+    <A as ToOwned>::Owned: Arbitrary<'a>,
+{
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Cow::Owned)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::recursion_guard(depth, |depth| {
+            <<A as ToOwned>::Owned as Arbitrary>::size_hint(depth)
+        })
+    }
+}
+
+impl<'a> Arbitrary<'a> for &'a str {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        let size = u.arbitrary_len::<u8>()?;
+        match str::from_utf8(u.peek_bytes(size).unwrap()) {
+            Ok(s) => {
+                u.bytes(size).unwrap();
+                Ok(s)
+            }
+            Err(e) => {
+                let i = e.valid_up_to();
+                let valid = u.bytes(i).unwrap();
+                let s = unsafe {
+                    debug_assert!(str::from_utf8(valid).is_ok());
+                    str::from_utf8_unchecked(valid)
+                };
+                Ok(s)
+            }
+        }
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        let bytes = u.take_rest();
+        str::from_utf8(bytes).map_err(|_| Error::IncorrectFormat)
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+impl<'a> Arbitrary<'a> for String {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <&str as Arbitrary>::arbitrary(u).map(Into::into)
+    }
+
+    fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self> {
+        <&str as Arbitrary>::arbitrary_take_rest(u).map(Into::into)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <&str as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for CString {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <Vec<u8> as Arbitrary>::arbitrary(u).map(|mut x| {
+            x.retain(|&c| c != 0);
+            Self::new(x).unwrap()
+        })
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <Vec<u8> as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for OsString {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <String as Arbitrary>::arbitrary(u).map(From::from)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <String as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for PathBuf {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <OsString as Arbitrary>::arbitrary(u).map(From::from)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <OsString as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Box<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::recursion_guard(depth, <A as Arbitrary>::size_hint)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Box<[A]> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <Vec<A> as Arbitrary>::arbitrary(u).map(|x| x.into_boxed_slice())
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <Vec<A> as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a> Arbitrary<'a> for Box<str> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <String as Arbitrary>::arbitrary(u).map(|x| x.into_boxed_str())
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <String as Arbitrary>::size_hint(depth)
+    }
+}
+
+// impl Arbitrary for Box<CStr> {
+//     fn arbitrary(u: &mut Unstructured<'_>) -> Result<Self> {
+//         <CString as Arbitrary>::arbitrary(u).map(|x| x.into_boxed_c_str())
+//     }
+// }
+
+// impl Arbitrary for Box<OsStr> {
+//     fn arbitrary(u: &mut Unstructured<'_>) -> Result<Self> {
+//         <OsString as Arbitrary>::arbitrary(u).map(|x| x.into_boxed_osstr())
+//
+//     }
+// }
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Arc<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::recursion_guard(depth, <A as Arbitrary>::size_hint)
+    }
+}
+
+impl<'a> Arbitrary<'a> for Arc<str> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <&str as Arbitrary>::arbitrary(u).map(Into::into)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <&str as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Rc<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        crate::size_hint::recursion_guard(depth, <A as Arbitrary>::size_hint)
+    }
+}
+
+impl<'a> Arbitrary<'a> for Rc<str> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        <&str as Arbitrary>::arbitrary(u).map(Into::into)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <&str as Arbitrary>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Cell<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <A as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for RefCell<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <A as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for UnsafeCell<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <A as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for Mutex<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(Self::new)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <A as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for iter::Empty<A> {
+    fn arbitrary(_: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(iter::empty())
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, Some(0))
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for ::std::marker::PhantomData<A> {
+    fn arbitrary(_: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(::std::marker::PhantomData)
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, Some(0))
+    }
+}
+
+impl<'a, A: Arbitrary<'a>> Arbitrary<'a> for ::std::num::Wrapping<A> {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Arbitrary::arbitrary(u).map(::std::num::Wrapping)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        <A as Arbitrary<'a>>::size_hint(depth)
+    }
+}
+
+macro_rules! implement_nonzero_int {
+    ($nonzero:ty, $int:ty) => {
+        impl<'a> Arbitrary<'a> for $nonzero {
+            fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+                match Self::new(<$int as Arbitrary<'a>>::arbitrary(u)?) {
+                    Some(n) => Ok(n),
+                    None => Err(Error::IncorrectFormat),
+                }
+            }
+
+            #[inline]
+            fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                <$int as Arbitrary<'a>>::size_hint(depth)
+            }
+        }
+    };
+}
+
+implement_nonzero_int! { NonZeroI8, i8 }
+implement_nonzero_int! { NonZeroI16, i16 }
+implement_nonzero_int! { NonZeroI32, i32 }
+implement_nonzero_int! { NonZeroI64, i64 }
+implement_nonzero_int! { NonZeroI128, i128 }
+implement_nonzero_int! { NonZeroIsize, isize }
+implement_nonzero_int! { NonZeroU8, u8 }
+implement_nonzero_int! { NonZeroU16, u16 }
+implement_nonzero_int! { NonZeroU32, u32 }
+implement_nonzero_int! { NonZeroU64, u64 }
+implement_nonzero_int! { NonZeroU128, u128 }
+implement_nonzero_int! { NonZeroUsize, usize }
+
+impl<'a> Arbitrary<'a> for Ipv4Addr {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(Ipv4Addr::from(u32::arbitrary(u)?))
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (4, Some(4))
+    }
+}
+
+impl<'a> Arbitrary<'a> for Ipv6Addr {
+    fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+        Ok(Ipv6Addr::from(u128::arbitrary(u)?))
+    }
+
+    #[inline]
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (16, Some(16))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    /// Generates an arbitrary `T`, and checks that the result is consistent with the
+    /// `size_hint()` reported by `T`.
+    fn checked_arbitrary<'a, T: Arbitrary<'a>>(u: &mut Unstructured<'a>) -> Result<T> {
+        let (min, max) = T::size_hint(0);
+
+        let len_before = u.len();
+        let result = T::arbitrary(u);
+
+        let consumed = len_before - u.len();
+
+        if let Some(max) = max {
+            assert!(
+                consumed <= max,
+                "incorrect maximum size: indicated {}, actually consumed {}",
+                max,
+                consumed
+            );
+        }
+
+        if result.is_ok() {
+            assert!(
+                consumed >= min,
+                "incorrect minimum size: indicated {}, actually consumed {}",
+                min,
+                consumed
+            );
+        }
+
+        result
+    }
+
+    /// Like `checked_arbitrary()`, but calls `arbitrary_take_rest()` instead of `arbitrary()`.
+    fn checked_arbitrary_take_rest<'a, T: Arbitrary<'a>>(u: Unstructured<'a>) -> Result<T> {
+        let (min, _) = T::size_hint(0);
+
+        let len_before = u.len();
+        let result = T::arbitrary_take_rest(u);
+
+        if result.is_ok() {
+            assert!(
+                len_before >= min,
+                "incorrect minimum size: indicated {}, worked with {}",
+                min,
+                len_before
+            );
+        }
+
+        result
+    }
+
+    #[test]
+    fn finite_buffer_fill_buffer() {
+        let x = [1, 2, 3, 4];
+        let mut rb = Unstructured::new(&x);
+        let mut z = [0; 2];
+        rb.fill_buffer(&mut z).unwrap();
+        assert_eq!(z, [1, 2]);
+        rb.fill_buffer(&mut z).unwrap();
+        assert_eq!(z, [3, 4]);
+        rb.fill_buffer(&mut z).unwrap();
+        assert_eq!(z, [0, 0]);
+    }
+
+    #[test]
+    fn arbitrary_for_integers() {
+        let x = [1, 2, 3, 4];
+        let mut buf = Unstructured::new(&x);
+        let expected = 1 | (2 << 8) | (3 << 16) | (4 << 24);
+        let actual = checked_arbitrary::<i32>(&mut buf).unwrap();
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn arbitrary_for_bytes() {
+        let x = [1, 2, 3, 4, 4];
+        let mut buf = Unstructured::new(&x);
+        let expected = &[1, 2, 3, 4];
+        let actual = checked_arbitrary::<&[u8]>(&mut buf).unwrap();
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn arbitrary_take_rest_for_bytes() {
+        let x = [1, 2, 3, 4];
+        let buf = Unstructured::new(&x);
+        let expected = &[1, 2, 3, 4];
+        let actual = checked_arbitrary_take_rest::<&[u8]>(buf).unwrap();
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn arbitrary_collection() {
+        let x = [
+            1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 12,
+        ];
+        assert_eq!(
+            checked_arbitrary::<&[u8]>(&mut Unstructured::new(&x)).unwrap(),
+            &[1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3]
+        );
+        assert_eq!(
+            checked_arbitrary::<Vec<u8>>(&mut Unstructured::new(&x)).unwrap(),
+            &[2, 4, 6, 8, 1]
+        );
+        assert_eq!(
+            checked_arbitrary::<Vec<u32>>(&mut Unstructured::new(&x)).unwrap(),
+            &[84148994]
+        );
+        assert_eq!(
+            checked_arbitrary::<String>(&mut Unstructured::new(&x)).unwrap(),
+            "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x01\x02\x03"
+        );
+    }
+
+    #[test]
+    fn arbitrary_take_rest() {
+        let x = [1, 2, 3, 4];
+        assert_eq!(
+            checked_arbitrary_take_rest::<&[u8]>(Unstructured::new(&x)).unwrap(),
+            &[1, 2, 3, 4]
+        );
+        assert_eq!(
+            checked_arbitrary_take_rest::<Vec<u8>>(Unstructured::new(&x)).unwrap(),
+            &[1, 2, 3, 4]
+        );
+        assert_eq!(
+            checked_arbitrary_take_rest::<Vec<u32>>(Unstructured::new(&x)).unwrap(),
+            &[0x4030201]
+        );
+        assert_eq!(
+            checked_arbitrary_take_rest::<String>(Unstructured::new(&x)).unwrap(),
+            "\x01\x02\x03\x04"
+        );
+
+        assert_eq!(
+            checked_arbitrary_take_rest::<&[u8]>(Unstructured::new(&[])).unwrap(),
+            &[]
+        );
+        assert_eq!(
+            checked_arbitrary_take_rest::<Vec<u8>>(Unstructured::new(&[])).unwrap(),
+            &[]
+        );
+    }
+
+    #[test]
+    fn size_hint_for_tuples() {
+        assert_eq!(
+            (7, Some(7)),
+            <(bool, u16, i32) as Arbitrary<'_>>::size_hint(0)
+        );
+        assert_eq!((1, None), <(u8, Vec<u8>) as Arbitrary>::size_hint(0));
+    }
+}
+
+/// Multiple conflicting arbitrary attributes are used on the same field:
+/// ```compile_fail
+/// #[derive(::arbitrary::Arbitrary)]
+/// struct Point {
+///     #[arbitrary(value = 2)]
+///     #[arbitrary(value = 2)]
+///     x: i32,
+/// }
+/// ```
+///
+/// An unknown attribute:
+/// ```compile_fail
+/// #[derive(::arbitrary::Arbitrary)]
+/// struct Point {
+///     #[arbitrary(unknown_attr)]
+///     x: i32,
+/// }
+/// ```
+///
+/// An unknown attribute with a value:
+/// ```compile_fail
+/// #[derive(::arbitrary::Arbitrary)]
+/// struct Point {
+///     #[arbitrary(unknown_attr = 13)]
+///     x: i32,
+/// }
+/// ```
+///
+/// `value` without RHS:
+/// ```compile_fail
+/// #[derive(::arbitrary::Arbitrary)]
+/// struct Point {
+///     #[arbitrary(value)]
+///     x: i32,
+/// }
+/// ```
+///
+/// `with` without RHS:
+/// ```compile_fail
+/// #[derive(::arbitrary::Arbitrary)]
+/// struct Point {
+///     #[arbitrary(with)]
+///     x: i32,
+/// }
+/// ```
+#[cfg(all(doctest, feature = "derive"))]
+pub struct CompileFailTests;
diff --git a/third_party/rust/arbitrary/src/size_hint.rs b/third_party/rust/arbitrary/src/size_hint.rs
new file mode 100644
index 0000000000..045c148a29
--- /dev/null
+++ b/third_party/rust/arbitrary/src/size_hint.rs
@@ -0,0 +1,124 @@
+//! Utilities for working with and combining the results of
+//! [`Arbitrary::size_hint`][crate::Arbitrary::size_hint].
+
+/// Protects against potential infinite recursion when calculating size hints
+/// due to indirect type recursion.
+///
+/// When the depth is not too deep, calls `f` with `depth + 1` to calculate the
+/// size hint.
+///
+/// Otherwise, returns the default size hint: `(0, None)`.
+#[inline]
+pub fn recursion_guard(
+    depth: usize,
+    f: impl FnOnce(usize) -> (usize, Option<usize>),
+) -> (usize, Option<usize>) {
+    const MAX_DEPTH: usize = 20;
+    if depth > MAX_DEPTH {
+        (0, None)
+    } else {
+        f(depth + 1)
+    }
+}
+
+/// Take the sum of the `lhs` and `rhs` size hints.
+#[inline]
+pub fn and(lhs: (usize, Option<usize>), rhs: (usize, Option<usize>)) -> (usize, Option<usize>) {
+    let lower = lhs.0 + rhs.0;
+    let upper = lhs.1.and_then(|lhs| rhs.1.map(|rhs| lhs + rhs));
+    (lower, upper)
+}
+
+/// Take the sum of all of the given size hints.
+///
+/// If `hints` is empty, returns `(0, Some(0))`, aka the size of consuming
+/// nothing.
+#[inline]
+pub fn and_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
+    hints.iter().copied().fold((0, Some(0)), and)
+}
+
+/// Take the minimum of the lower bounds and maximum of the upper bounds in the
+/// `lhs` and `rhs` size hints.
+#[inline]
+pub fn or(lhs: (usize, Option<usize>), rhs: (usize, Option<usize>)) -> (usize, Option<usize>) {
+    let lower = std::cmp::min(lhs.0, rhs.0);
+    let upper = lhs
+        .1
+        .and_then(|lhs| rhs.1.map(|rhs| std::cmp::max(lhs, rhs)));
+    (lower, upper)
+}
+
+/// Take the maximum of the `lhs` and `rhs` size hints.
+///
+/// If `hints` is empty, returns `(0, Some(0))`, aka the size of consuming
+/// nothing.
+#[inline]
+pub fn or_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
+    if let Some(head) = hints.first().copied() {
+        hints[1..].iter().copied().fold(head, or)
+    } else {
+        (0, Some(0))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn and() {
+        assert_eq!((5, Some(5)), super::and((2, Some(2)), (3, Some(3))));
+        assert_eq!((5, None), super::and((2, Some(2)), (3, None)));
+        assert_eq!((5, None), super::and((2, None), (3, Some(3))));
+        assert_eq!((5, None), super::and((2, None), (3, None)));
+    }
+
+    #[test]
+    fn or() {
+        assert_eq!((2, Some(3)), super::or((2, Some(2)), (3, Some(3))));
+        assert_eq!((2, None), super::or((2, Some(2)), (3, None)));
+        assert_eq!((2, None), super::or((2, None), (3, Some(3))));
+        assert_eq!((2, None), super::or((2, None), (3, None)));
+    }
+
+    #[test]
+    fn and_all() {
+        assert_eq!((0, Some(0)), super::and_all(&[]));
+        assert_eq!(
+            (7, Some(7)),
+            super::and_all(&[(1, Some(1)), (2, Some(2)), (4, Some(4))])
+        );
+        assert_eq!(
+            (7, None),
+            super::and_all(&[(1, Some(1)), (2, Some(2)), (4, None)])
+        );
+        assert_eq!(
+            (7, None),
+            super::and_all(&[(1, Some(1)), (2, None), (4, Some(4))])
+        );
+        assert_eq!(
+            (7, None),
+            super::and_all(&[(1, None), (2, Some(2)), (4, Some(4))])
+        );
+    }
+
+    #[test]
+    fn or_all() {
+        assert_eq!((0, Some(0)), super::or_all(&[]));
+        assert_eq!(
+            (1, Some(4)),
+            super::or_all(&[(1, Some(1)), (2, Some(2)), (4, Some(4))])
+        );
+        assert_eq!(
+            (1, None),
+            super::or_all(&[(1, Some(1)), (2, Some(2)), (4, None)])
+        );
+        assert_eq!(
+            (1, None),
+            super::or_all(&[(1, Some(1)), (2, None), (4, Some(4))])
+        );
+        assert_eq!(
+            (1, None),
+            super::or_all(&[(1, None), (2, Some(2)), (4, Some(4))])
+        );
+    }
+}
diff --git a/third_party/rust/arbitrary/src/unstructured.rs b/third_party/rust/arbitrary/src/unstructured.rs
new file mode 100644
index 0000000000..0bfdff2881
--- /dev/null
+++ b/third_party/rust/arbitrary/src/unstructured.rs
@@ -0,0 +1,1031 @@
+// Copyright © 2019 The Rust Fuzz Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Wrappers around raw, unstructured bytes.
+
+use crate::{Arbitrary, Error, Result};
+use std::marker::PhantomData;
+use std::ops::ControlFlow;
+use std::{mem, ops};
+
+/// A source of unstructured data.
+///
+/// An `Unstructured` helps `Arbitrary` implementations interpret raw data
+/// (typically provided by a fuzzer) as a "DNA string" that describes how to
+/// construct the `Arbitrary` type. The goal is that a small change to the "DNA
+/// string" (the raw data wrapped by an `Unstructured`) results in a small
+/// change to the generated `Arbitrary` instance. This helps a fuzzer
+/// efficiently explore the `Arbitrary`'s input space.
+///
+/// `Unstructured` is deterministic: given the same raw data, the same series of
+/// API calls will return the same results (modulo system resource constraints,
+/// like running out of memory). However, `Unstructured` does not guarantee
+/// anything beyond that: it makes not guarantee that it will yield bytes from
+/// the underlying data in any particular order.
+///
+/// You shouldn't generally need to use an `Unstructured` unless you are writing
+/// a custom `Arbitrary` implementation by hand, instead of deriving it. Mostly,
+/// you should just be passing it through to nested `Arbitrary::arbitrary`
+/// calls.
+///
+/// # Example
+///
+/// Imagine you were writing a color conversion crate. You might want to write
+/// fuzz tests that take a random RGB color and assert various properties, run
+/// functions and make sure nothing panics, etc.
+///
+/// Below is what translating the fuzzer's raw input into an `Unstructured` and
+/// using that to generate an arbitrary RGB color might look like:
+///
+/// ```
+/// # #[cfg(feature = "derive")] fn foo() {
+/// use arbitrary::{Arbitrary, Unstructured};
+///
+/// /// An RGB color.
+/// #[derive(Arbitrary)]
+/// pub struct Rgb {
+///     r: u8,
+///     g: u8,
+///     b: u8,
+/// }
+///
+/// // Get the raw bytes from the fuzzer.
+/// #   let get_input_from_fuzzer = || &[];
+/// let raw_data: &[u8] = get_input_from_fuzzer();
+///
+/// // Wrap it in an `Unstructured`.
+/// let mut unstructured = Unstructured::new(raw_data);
+///
+/// // Generate an `Rgb` color and run our checks.
+/// if let Ok(rgb) = Rgb::arbitrary(&mut unstructured) {
+/// #   let run_my_color_conversion_checks = |_| {};
+///     run_my_color_conversion_checks(rgb);
+/// }
+/// # }
+/// ```
+pub struct Unstructured<'a> {
+    data: &'a [u8],
+}
+
+impl<'a> Unstructured<'a> {
+    /// Create a new `Unstructured` from the given raw data.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let u = Unstructured::new(&[1, 2, 3, 4]);
+    /// ```
+    pub fn new(data: &'a [u8]) -> Self {
+        Unstructured { data }
+    }
+
+    /// Get the number of remaining bytes of underlying data that are still
+    /// available.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::{Arbitrary, Unstructured};
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3]);
+    ///
+    /// // Initially have three bytes of data.
+    /// assert_eq!(u.len(), 3);
+    ///
+    /// // Generating a `bool` consumes one byte from the underlying data, so
+    /// // we are left with two bytes afterwards.
+    /// let _ = bool::arbitrary(&mut u);
+    /// assert_eq!(u.len(), 2);
+    /// ```
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.data.len()
+    }
+
+    /// Is the underlying unstructured data exhausted?
+    ///
+    /// `unstructured.is_empty()` is the same as `unstructured.len() == 0`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::{Arbitrary, Unstructured};
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4]);
+    ///
+    /// // Initially, we are not empty.
+    /// assert!(!u.is_empty());
+    ///
+    /// // Generating a `u32` consumes all four bytes of the underlying data, so
+    /// // we become empty afterwards.
+    /// let _ = u32::arbitrary(&mut u);
+    /// assert!(u.is_empty());
+    /// ```
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Generate an arbitrary instance of `A`.
+    ///
+    /// This is simply a helper method that is equivalent to `<A as
+    /// Arbitrary>::arbitrary(self)`. This helper is a little bit more concise,
+    /// and can be used in situations where Rust's type inference will figure
+    /// out what `A` should be.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[cfg(feature="derive")] fn foo() -> arbitrary::Result<()> {
+    /// use arbitrary::{Arbitrary, Unstructured};
+    ///
+    /// #[derive(Arbitrary)]
+    /// struct MyType {
+    ///     // ...
+    /// }
+    ///
+    /// fn do_stuff(value: MyType) {
+    /// #   let _ = value;
+    ///     // ...
+    /// }
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4]);
+    ///
+    /// // Rust's type inference can figure out that `value` should be of type
+    /// // `MyType` here:
+    /// let value = u.arbitrary()?;
+    /// do_stuff(value);
+    /// # Ok(()) }
+    /// ```
+    pub fn arbitrary<A>(&mut self) -> Result<A>
+    where
+        A: Arbitrary<'a>,
+    {
+        <A as Arbitrary<'a>>::arbitrary(self)
+    }
+
+    /// Get the number of elements to insert when building up a collection of
+    /// arbitrary `ElementType`s.
+    ///
+    /// This uses the [`<ElementType as
+    /// Arbitrary>::size_hint`][crate::Arbitrary::size_hint] method to smartly
+    /// choose a length such that we most likely have enough underlying bytes to
+    /// construct that many arbitrary `ElementType`s.
+    ///
+    /// This should only be called within an `Arbitrary` implementation.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::{Arbitrary, Result, Unstructured};
+    /// # pub struct MyCollection<T> { _t: std::marker::PhantomData<T> }
+    /// # impl<T> MyCollection<T> {
+    /// #     pub fn with_capacity(capacity: usize) -> Self { MyCollection { _t: std::marker::PhantomData } }
+    /// #     pub fn insert(&mut self, element: T) {}
+    /// # }
+    ///
+    /// impl<'a, T> Arbitrary<'a> for MyCollection<T>
+    /// where
+    ///     T: Arbitrary<'a>,
+    /// {
+    ///     fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
+    ///         // Get the number of `T`s we should insert into our collection.
+    ///         let len = u.arbitrary_len::<T>()?;
+    ///
+    ///         // And then create a collection of that length!
+    ///         let mut my_collection = MyCollection::with_capacity(len);
+    ///         for _ in 0..len {
+    ///             let element = T::arbitrary(u)?;
+    ///             my_collection.insert(element);
+    ///         }
+    ///
+    ///         Ok(my_collection)
+    ///     }
+    /// }
+    /// ```
+    pub fn arbitrary_len<ElementType>(&mut self) -> Result<usize>
+    where
+        ElementType: Arbitrary<'a>,
+    {
+        let byte_size = self.arbitrary_byte_size()?;
+        let (lower, upper) = <ElementType as Arbitrary>::size_hint(0);
+        let elem_size = upper.unwrap_or(lower * 2);
+        let elem_size = std::cmp::max(1, elem_size);
+        Ok(byte_size / elem_size)
+    }
+
+    fn arbitrary_byte_size(&mut self) -> Result<usize> {
+        if self.data.is_empty() {
+            Ok(0)
+        } else if self.data.len() == 1 {
+            self.data = &[];
+            Ok(0)
+        } else {
+            // Take lengths from the end of the data, since the `libFuzzer` folks
+            // found that this lets fuzzers more efficiently explore the input
+            // space.
+            //
+            // https://github.com/rust-fuzz/libfuzzer-sys/blob/0c450753/libfuzzer/utils/FuzzedDataProvider.h#L92-L97
+
+            // We only consume as many bytes as necessary to cover the entire
+            // range of the byte string.
+            // Note: We cast to u64 so we don't overflow when checking std::u32::MAX + 4 on 32-bit archs
+            let len = if self.data.len() as u64 <= std::u8::MAX as u64 + 1 {
+                let bytes = 1;
+                let max_size = self.data.len() - bytes;
+                let (rest, for_size) = self.data.split_at(max_size);
+                self.data = rest;
+                Self::int_in_range_impl(0..=max_size as u8, for_size.iter().copied())?.0 as usize
+            } else if self.data.len() as u64 <= std::u16::MAX as u64 + 2 {
+                let bytes = 2;
+                let max_size = self.data.len() - bytes;
+                let (rest, for_size) = self.data.split_at(max_size);
+                self.data = rest;
+                Self::int_in_range_impl(0..=max_size as u16, for_size.iter().copied())?.0 as usize
+            } else if self.data.len() as u64 <= std::u32::MAX as u64 + 4 {
+                let bytes = 4;
+                let max_size = self.data.len() - bytes;
+                let (rest, for_size) = self.data.split_at(max_size);
+                self.data = rest;
+                Self::int_in_range_impl(0..=max_size as u32, for_size.iter().copied())?.0 as usize
+            } else {
+                let bytes = 8;
+                let max_size = self.data.len() - bytes;
+                let (rest, for_size) = self.data.split_at(max_size);
+                self.data = rest;
+                Self::int_in_range_impl(0..=max_size as u64, for_size.iter().copied())?.0 as usize
+            };
+
+            Ok(len)
+        }
+    }
+
+    /// Generate an integer within the given range.
+    ///
+    /// Do not use this to generate the size of a collection. Use
+    /// `arbitrary_len` instead.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `range.start > range.end`. That is, the given range must be
+    /// non-empty.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::{Arbitrary, Unstructured};
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4]);
+    ///
+    /// let x: i32 = u.int_in_range(-5_000..=-1_000)
+    ///     .expect("constructed `u` with enough bytes to generate an `i32`");
+    ///
+    /// assert!(-5_000 <= x);
+    /// assert!(x <= -1_000);
+    /// ```
+    pub fn int_in_range<T>(&mut self, range: ops::RangeInclusive<T>) -> Result<T>
+    where
+        T: Int,
+    {
+        let (result, bytes_consumed) = Self::int_in_range_impl(range, self.data.iter().cloned())?;
+        self.data = &self.data[bytes_consumed..];
+        Ok(result)
+    }
+
+    fn int_in_range_impl<T>(
+        range: ops::RangeInclusive<T>,
+        mut bytes: impl Iterator<Item = u8>,
+    ) -> Result<(T, usize)>
+    where
+        T: Int,
+    {
+        let start = *range.start();
+        let end = *range.end();
+        assert!(
+            start <= end,
+            "`arbitrary::Unstructured::int_in_range` requires a non-empty range"
+        );
+
+        // When there is only one possible choice, don't waste any entropy from
+        // the underlying data.
+        if start == end {
+            return Ok((start, 0));
+        }
+
+        // From here on out we work with the unsigned representation. All of the
+        // operations performed below work out just as well whether or not `T`
+        // is a signed or unsigned integer.
+        let start = start.to_unsigned();
+        let end = end.to_unsigned();
+
+        let delta = end.wrapping_sub(start);
+        debug_assert_ne!(delta, T::Unsigned::ZERO);
+
+        // Compute an arbitrary integer offset from the start of the range. We
+        // do this by consuming `size_of(T)` bytes from the input to create an
+        // arbitrary integer and then clamping that int into our range bounds
+        // with a modulo operation.
+        let mut arbitrary_int = T::Unsigned::ZERO;
+        let mut bytes_consumed: usize = 0;
+
+        while (bytes_consumed < mem::size_of::<T>())
+            && (delta >> T::Unsigned::from_usize(bytes_consumed * 8)) > T::Unsigned::ZERO
+        {
+            let byte = match bytes.next() {
+                None => break,
+                Some(b) => b,
+            };
+            bytes_consumed += 1;
+
+            // Combine this byte into our arbitrary integer, but avoid
+            // overflowing the shift for `u8` and `i8`.
+            arbitrary_int = if mem::size_of::<T>() == 1 {
+                T::Unsigned::from_u8(byte)
+            } else {
+                (arbitrary_int << 8) | T::Unsigned::from_u8(byte)
+            };
+        }
+
+        let offset = if delta == T::Unsigned::MAX {
+            arbitrary_int
+        } else {
+            arbitrary_int % (delta.checked_add(T::Unsigned::ONE).unwrap())
+        };
+
+        // Finally, we add `start` to our offset from `start` to get the result
+        // actual value within the range.
+        let result = start.wrapping_add(offset);
+
+        // And convert back to our maybe-signed representation.
+        let result = T::from_unsigned(result);
+        debug_assert!(*range.start() <= result);
+        debug_assert!(result <= *range.end());
+
+        Ok((result, bytes_consumed))
+    }
+
+    /// Choose one of the given choices.
+    ///
+    /// This should only be used inside of `Arbitrary` implementations.
+    ///
+    /// Returns an error if there is not enough underlying data to make a
+    /// choice or if no choices are provided.
+    ///
+    /// # Examples
+    ///
+    /// Selecting from an array of choices:
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]);
+    /// let choices = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];
+    ///
+    /// let choice = u.choose(&choices).unwrap();
+    ///
+    /// println!("chose {}", choice);
+    /// ```
+    ///
+    /// An error is returned if no choices are provided:
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]);
+    /// let choices: [char; 0] = [];
+    ///
+    /// let result = u.choose(&choices);
+    ///
+    /// assert!(result.is_err());
+    /// ```
+    pub fn choose<'b, T>(&mut self, choices: &'b [T]) -> Result<&'b T> {
+        let idx = self.choose_index(choices.len())?;
+        Ok(&choices[idx])
+    }
+
+    /// Choose a value in `0..len`.
+    ///
+    /// Returns an error if the `len` is zero.
+    ///
+    /// # Examples
+    ///
+    /// Using Fisher–Yates shuffle shuffle to gerate an arbitrary permutation.
+    ///
+    /// [Fisher–Yates shuffle]: https://en.wikipedia.org/wiki/Fisher–Yates_shuffle
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]);
+    /// let mut permutation = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];
+    /// let mut to_permute = &mut permutation[..];
+    /// while to_permute.len() > 1 {
+    ///     let idx = u.choose_index(to_permute.len()).unwrap();
+    ///     to_permute.swap(0, idx);
+    ///     to_permute = &mut to_permute[1..];
+    /// }
+    ///
+    /// println!("permutation: {:?}", permutation);
+    /// ```
+    ///
+    /// An error is returned if the length is zero:
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]);
+    /// let array: [i32; 0] = [];
+    ///
+    /// let result = u.choose_index(array.len());
+    ///
+    /// assert!(result.is_err());
+    /// ```
+    pub fn choose_index(&mut self, len: usize) -> Result<usize> {
+        if len == 0 {
+            return Err(Error::EmptyChoose);
+        }
+        let idx = self.int_in_range(0..=len - 1)?;
+        Ok(idx)
+    }
+
+    /// Generate a boolean according to the given ratio.
+    ///
+    /// # Panics
+    ///
+    /// Panics when the numerator and denominator do not meet these constraints:
+    ///
+    /// * `0 < numerator <= denominator`
+    ///
+    /// # Example
+    ///
+    /// Generate a boolean that is `true` five sevenths of the time:
+    ///
+    /// ```
+    /// # fn foo() -> arbitrary::Result<()> {
+    /// use arbitrary::Unstructured;
+    ///
+    /// # let my_data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
+    /// let mut u = Unstructured::new(&my_data);
+    ///
+    /// if u.ratio(5, 7)? {
+    ///     // Take this branch 5/7 of the time.
+    /// }
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn ratio<T>(&mut self, numerator: T, denominator: T) -> Result<bool>
+    where
+        T: Int,
+    {
+        assert!(T::ZERO < numerator);
+        assert!(numerator <= denominator);
+        let x = self.int_in_range(T::ONE..=denominator)?;
+        Ok(x <= numerator)
+    }
+
+    /// Fill a `buffer` with bytes from the underlying raw data.
+    ///
+    /// This should only be called within an `Arbitrary` implementation. This is
+    /// a very low-level operation. You should generally prefer calling nested
+    /// `Arbitrary` implementations like `<Vec<u8>>::arbitrary` and
+    /// `String::arbitrary` over using this method directly.
+    ///
+    /// If this `Unstructured` does not have enough underlying data to fill the
+    /// whole `buffer`, it pads the buffer out with zeros.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4]);
+    ///
+    /// let mut buf = [0; 2];
+    ///
+    /// assert!(u.fill_buffer(&mut buf).is_ok());
+    /// assert_eq!(buf, [1, 2]);
+    ///
+    /// assert!(u.fill_buffer(&mut buf).is_ok());
+    /// assert_eq!(buf, [3, 4]);
+    ///
+    /// assert!(u.fill_buffer(&mut buf).is_ok());
+    /// assert_eq!(buf, [0, 0]);
+    /// ```
+    pub fn fill_buffer(&mut self, buffer: &mut [u8]) -> Result<()> {
+        let n = std::cmp::min(buffer.len(), self.data.len());
+        buffer[..n].copy_from_slice(&self.data[..n]);
+        for byte in buffer[n..].iter_mut() {
+            *byte = 0;
+        }
+        self.data = &self.data[n..];
+        Ok(())
+    }
+
+    /// Provide `size` bytes from the underlying raw data.
+    ///
+    /// This should only be called within an `Arbitrary` implementation. This is
+    /// a very low-level operation. You should generally prefer calling nested
+    /// `Arbitrary` implementations like `<Vec<u8>>::arbitrary` and
+    /// `String::arbitrary` over using this method directly.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3, 4]);
+    ///
+    /// assert!(u.bytes(2).unwrap() == &[1, 2]);
+    /// assert!(u.bytes(2).unwrap() == &[3, 4]);
+    /// ```
+    pub fn bytes(&mut self, size: usize) -> Result<&'a [u8]> {
+        if self.data.len() < size {
+            return Err(Error::NotEnoughData);
+        }
+
+        let (for_buf, rest) = self.data.split_at(size);
+        self.data = rest;
+        Ok(for_buf)
+    }
+
+    /// Peek at `size` number of bytes of the underlying raw input.
+    ///
+    /// Does not consume the bytes, only peeks at them.
+    ///
+    /// Returns `None` if there are not `size` bytes left in the underlying raw
+    /// input.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let u = Unstructured::new(&[1, 2, 3]);
+    ///
+    /// assert_eq!(u.peek_bytes(0).unwrap(), []);
+    /// assert_eq!(u.peek_bytes(1).unwrap(), [1]);
+    /// assert_eq!(u.peek_bytes(2).unwrap(), [1, 2]);
+    /// assert_eq!(u.peek_bytes(3).unwrap(), [1, 2, 3]);
+    ///
+    /// assert!(u.peek_bytes(4).is_none());
+    /// ```
+    pub fn peek_bytes(&self, size: usize) -> Option<&'a [u8]> {
+        self.data.get(..size)
+    }
+
+    /// Consume all of the rest of the remaining underlying bytes.
+    ///
+    /// Returns a slice of all the remaining, unconsumed bytes.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use arbitrary::Unstructured;
+    ///
+    /// let mut u = Unstructured::new(&[1, 2, 3]);
+    ///
+    /// let mut remaining = u.take_rest();
+    ///
+    /// assert_eq!(remaining, [1, 2, 3]);
+    /// ```
+    pub fn take_rest(mut self) -> &'a [u8] {
+        mem::take(&mut self.data)
+    }
+
+    /// Provide an iterator over elements for constructing a collection
+    ///
+    /// This is useful for implementing [`Arbitrary::arbitrary`] on collections
+    /// since the implementation is simply `u.arbitrary_iter()?.collect()`
+    pub fn arbitrary_iter<'b, ElementType: Arbitrary<'a>>(
+        &'b mut self,
+    ) -> Result<ArbitraryIter<'a, 'b, ElementType>> {
+        Ok(ArbitraryIter {
+            u: &mut *self,
+            _marker: PhantomData,
+        })
+    }
+
+    /// Provide an iterator over elements for constructing a collection from
+    /// all the remaining bytes.
+    ///
+    /// This is useful for implementing [`Arbitrary::arbitrary_take_rest`] on collections
+    /// since the implementation is simply `u.arbitrary_take_rest_iter()?.collect()`
+    pub fn arbitrary_take_rest_iter<ElementType: Arbitrary<'a>>(
+        self,
+    ) -> Result<ArbitraryTakeRestIter<'a, ElementType>> {
+        let (lower, upper) = ElementType::size_hint(0);
+
+        let elem_size = upper.unwrap_or(lower * 2);
+        let elem_size = std::cmp::max(1, elem_size);
+        let size = self.len() / elem_size;
+        Ok(ArbitraryTakeRestIter {
+            size,
+            u: Some(self),
+            _marker: PhantomData,
+        })
+    }
+
+    /// Call the given function an arbitrary number of times.
+    ///
+    /// The function is given this `Unstructured` so that it can continue to
+    /// generate arbitrary data and structures.
+    ///
+    /// You may optionaly specify minimum and maximum bounds on the number of
+    /// times the function is called.
+    ///
+    /// You may break out of the loop early by returning
+    /// `Ok(std::ops::ControlFlow::Break)`. To continue the loop, return
+    /// `Ok(std::ops::ControlFlow::Continue)`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `min > max`.
+    ///
+    /// # Example
+    ///
+    /// Call a closure that generates an arbitrary type inside a context an
+    /// arbitrary number of times:
+    ///
+    /// ```
+    /// use arbitrary::{Result, Unstructured};
+    /// use std::ops::ControlFlow;
+    ///
+    /// enum Type {
+    ///     /// A boolean type.
+    ///     Bool,
+    ///
+    ///     /// An integer type.
+    ///     Int,
+    ///
+    ///     /// A list of the `i`th type in this type's context.
+    ///     List(usize),
+    /// }
+    ///
+    /// fn arbitrary_types_context(u: &mut Unstructured) -> Result<Vec<Type>> {
+    ///     let mut context = vec![];
+    ///
+    ///     u.arbitrary_loop(Some(10), Some(20), |u| {
+    ///         let num_choices = if context.is_empty() {
+    ///             2
+    ///         } else {
+    ///             3
+    ///         };
+    ///         let ty = match u.int_in_range::<u8>(1..=num_choices)? {
+    ///             1 => Type::Bool,
+    ///             2 => Type::Int,
+    ///             3 => Type::List(u.int_in_range(0..=context.len() - 1)?),
+    ///             _ => unreachable!(),
+    ///         };
+    ///         context.push(ty);
+    ///         Ok(ControlFlow::Continue(()))
+    ///     })?;
+    ///
+    ///     // The number of loop iterations are constrained by the min/max
+    ///     // bounds that we provided.
+    ///     assert!(context.len() >= 10);
+    ///     assert!(context.len() <= 20);
+    ///
+    ///     Ok(context)
+    /// }
+    /// ```
+    pub fn arbitrary_loop(
+        &mut self,
+        min: Option<u32>,
+        max: Option<u32>,
+        mut f: impl FnMut(&mut Self) -> Result<ControlFlow<(), ()>>,
+    ) -> Result<()> {
+        let min = min.unwrap_or(0);
+        let max = max.unwrap_or(u32::MAX);
+
+        for _ in 0..self.int_in_range(min..=max)? {
+            match f(self)? {
+                ControlFlow::Continue(_) => continue,
+                ControlFlow::Break(_) => break,
+            }
+        }
+
+        Ok(())
+    }
+}
+
+/// Utility iterator produced by [`Unstructured::arbitrary_iter`]
+pub struct ArbitraryIter<'a, 'b, ElementType> {
+    u: &'b mut Unstructured<'a>,
+    _marker: PhantomData<ElementType>,
+}
+
+impl<'a, 'b, ElementType: Arbitrary<'a>> Iterator for ArbitraryIter<'a, 'b, ElementType> {
+    type Item = Result<ElementType>;
+    fn next(&mut self) -> Option<Result<ElementType>> {
+        let keep_going = self.u.arbitrary().unwrap_or(false);
+        if keep_going {
+            Some(Arbitrary::arbitrary(self.u))
+        } else {
+            None
+        }
+    }
+}
+
+/// Utility iterator produced by [`Unstructured::arbitrary_take_rest_iter`]
+pub struct ArbitraryTakeRestIter<'a, ElementType> {
+    u: Option<Unstructured<'a>>,
+    size: usize,
+    _marker: PhantomData<ElementType>,
+}
+
+impl<'a, ElementType: Arbitrary<'a>> Iterator for ArbitraryTakeRestIter<'a, ElementType> {
+    type Item = Result<ElementType>;
+    fn next(&mut self) -> Option<Result<ElementType>> {
+        if let Some(mut u) = self.u.take() {
+            if self.size == 1 {
+                Some(Arbitrary::arbitrary_take_rest(u))
+            } else if self.size == 0 {
+                None
+            } else {
+                self.size -= 1;
+                let ret = Arbitrary::arbitrary(&mut u);
+                self.u = Some(u);
+                Some(ret)
+            }
+        } else {
+            None
+        }
+    }
+}
+
+/// A trait that is implemented for all of the primitive integers:
+///
+/// * `u8`
+/// * `u16`
+/// * `u32`
+/// * `u64`
+/// * `u128`
+/// * `usize`
+/// * `i8`
+/// * `i16`
+/// * `i32`
+/// * `i64`
+/// * `i128`
+/// * `isize`
+///
+/// Don't implement this trait yourself.
+pub trait Int:
+    Copy
+    + std::fmt::Debug
+    + PartialOrd
+    + Ord
+    + ops::Sub<Self, Output = Self>
+    + ops::Rem<Self, Output = Self>
+    + ops::Shr<Self, Output = Self>
+    + ops::Shl<usize, Output = Self>
+    + ops::BitOr<Self, Output = Self>
+{
+    #[doc(hidden)]
+    type Unsigned: Int;
+
+    #[doc(hidden)]
+    const ZERO: Self;
+
+    #[doc(hidden)]
+    const ONE: Self;
+
+    #[doc(hidden)]
+    const MAX: Self;
+
+    #[doc(hidden)]
+    fn from_u8(b: u8) -> Self;
+
+    #[doc(hidden)]
+    fn from_usize(u: usize) -> Self;
+
+    #[doc(hidden)]
+    fn checked_add(self, rhs: Self) -> Option<Self>;
+
+    #[doc(hidden)]
+    fn wrapping_add(self, rhs: Self) -> Self;
+
+    #[doc(hidden)]
+    fn wrapping_sub(self, rhs: Self) -> Self;
+
+    #[doc(hidden)]
+    fn to_unsigned(self) -> Self::Unsigned;
+
+    #[doc(hidden)]
+    fn from_unsigned(unsigned: Self::Unsigned) -> Self;
+}
+
+macro_rules! impl_int {
+    ( $( $ty:ty : $unsigned_ty: ty ; )* ) => {
+        $(
+            impl Int for $ty {
+                type Unsigned = $unsigned_ty;
+
+                const ZERO: Self = 0;
+
+                const ONE: Self = 1;
+
+                const MAX: Self = Self::MAX;
+
+                fn from_u8(b: u8) -> Self {
+                    b as Self
+                }
+
+                fn from_usize(u: usize) -> Self {
+                    u as Self
+                }
+
+                fn checked_add(self, rhs: Self) -> Option<Self> {
+                    <$ty>::checked_add(self, rhs)
+                }
+
+                fn wrapping_add(self, rhs: Self) -> Self {
+                    <$ty>::wrapping_add(self, rhs)
+                }
+
+                fn wrapping_sub(self, rhs: Self) -> Self {
+                    <$ty>::wrapping_sub(self, rhs)
+                }
+
+                fn to_unsigned(self) -> Self::Unsigned {
+                    self as $unsigned_ty
+                }
+
+                fn from_unsigned(unsigned: $unsigned_ty) -> Self {
+                    unsigned as Self
+                }
+            }
+        )*
+    }
+}
+
+impl_int! {
+    u8: u8;
+    u16: u16;
+    u32: u32;
+    u64: u64;
+    u128: u128;
+    usize: usize;
+    i8: u8;
+    i16: u16;
+    i32: u32;
+    i64: u64;
+    i128: u128;
+    isize: usize;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_byte_size() {
+        let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 6]);
+        // Should take one byte off the end
+        assert_eq!(u.arbitrary_byte_size().unwrap(), 6);
+        assert_eq!(u.len(), 9);
+        let mut v = vec![];
+        v.resize(260, 0);
+        v.push(1);
+        v.push(4);
+        let mut u = Unstructured::new(&v);
+        // Should read two bytes off the end
+        assert_eq!(u.arbitrary_byte_size().unwrap(), 0x104);
+        assert_eq!(u.len(), 260);
+    }
+
+    #[test]
+    fn int_in_range_of_one() {
+        let mut u = Unstructured::new(&[1, 2, 3, 4, 5, 6, 7, 8, 9, 6]);
+        let x = u.int_in_range(0..=0).unwrap();
+        assert_eq!(x, 0);
+        let choice = *u.choose(&[42]).unwrap();
+        assert_eq!(choice, 42)
+    }
+
+    #[test]
+    fn int_in_range_uses_minimal_amount_of_bytes() {
+        let mut u = Unstructured::new(&[1, 2]);
+        assert_eq!(1, u.int_in_range::<u8>(0..=u8::MAX).unwrap());
+        assert_eq!(u.len(), 1);
+
+        let mut u = Unstructured::new(&[1, 2]);
+        assert_eq!(1, u.int_in_range::<u32>(0..=u8::MAX as u32).unwrap());
+        assert_eq!(u.len(), 1);
+
+        let mut u = Unstructured::new(&[1]);
+        assert_eq!(1, u.int_in_range::<u32>(0..=u8::MAX as u32 + 1).unwrap());
+        assert!(u.is_empty());
+    }
+
+    #[test]
+    fn int_in_range_in_bounds() {
+        for input in u8::MIN..=u8::MAX {
+            let input = [input];
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(1..=u8::MAX).unwrap();
+            assert_ne!(x, 0);
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(0..=u8::MAX - 1).unwrap();
+            assert_ne!(x, u8::MAX);
+        }
+    }
+
+    #[test]
+    fn int_in_range_covers_unsigned_range() {
+        // Test that we generate all values within the range given to
+        // `int_in_range`.
+
+        let mut full = [false; u8::MAX as usize + 1];
+        let mut no_zero = [false; u8::MAX as usize];
+        let mut no_max = [false; u8::MAX as usize];
+        let mut narrow = [false; 10];
+
+        for input in u8::MIN..=u8::MAX {
+            let input = [input];
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(0..=u8::MAX).unwrap();
+            full[x as usize] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(1..=u8::MAX).unwrap();
+            no_zero[x as usize - 1] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(0..=u8::MAX - 1).unwrap();
+            no_max[x as usize] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(100..=109).unwrap();
+            narrow[x as usize - 100] = true;
+        }
+
+        for (i, covered) in full.iter().enumerate() {
+            assert!(covered, "full[{}] should have been generated", i);
+        }
+        for (i, covered) in no_zero.iter().enumerate() {
+            assert!(covered, "no_zero[{}] should have been generated", i);
+        }
+        for (i, covered) in no_max.iter().enumerate() {
+            assert!(covered, "no_max[{}] should have been generated", i);
+        }
+        for (i, covered) in narrow.iter().enumerate() {
+            assert!(covered, "narrow[{}] should have been generated", i);
+        }
+    }
+
+    #[test]
+    fn int_in_range_covers_signed_range() {
+        // Test that we generate all values within the range given to
+        // `int_in_range`.
+
+        let mut full = [false; u8::MAX as usize + 1];
+        let mut no_min = [false; u8::MAX as usize];
+        let mut no_max = [false; u8::MAX as usize];
+        let mut narrow = [false; 21];
+
+        let abs_i8_min: isize = 128;
+
+        for input in 0..=u8::MAX {
+            let input = [input];
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(i8::MIN..=i8::MAX).unwrap();
+            full[(x as isize + abs_i8_min) as usize] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(i8::MIN + 1..=i8::MAX).unwrap();
+            no_min[(x as isize + abs_i8_min - 1) as usize] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(i8::MIN..=i8::MAX - 1).unwrap();
+            no_max[(x as isize + abs_i8_min) as usize] = true;
+
+            let mut u = Unstructured::new(&input);
+            let x = u.int_in_range(-10..=10).unwrap();
+            narrow[(x as isize + 10) as usize] = true;
+        }
+
+        for (i, covered) in full.iter().enumerate() {
+            assert!(covered, "full[{}] should have been generated", i);
+        }
+        for (i, covered) in no_min.iter().enumerate() {
+            assert!(covered, "no_min[{}] should have been generated", i);
+        }
+        for (i, covered) in no_max.iter().enumerate() {
+            assert!(covered, "no_max[{}] should have been generated", i);
+        }
+        for (i, covered) in narrow.iter().enumerate() {
+            assert!(covered, "narrow[{}] should have been generated", i);
+        }
+    }
+}
diff --git a/third_party/rust/arbitrary/tests/derive.rs b/third_party/rust/arbitrary/tests/derive.rs
new file mode 100644
index 0000000000..f29d227b89
--- /dev/null
+++ b/third_party/rust/arbitrary/tests/derive.rs
@@ -0,0 +1,278 @@
+#![cfg(feature = "derive")]
+// Various structs/fields that we are deriving `Arbitrary` for aren't actually
+// used except to exercise the derive.
+#![allow(dead_code)]
+
+use arbitrary::*;
+
+fn arbitrary_from<'a, T: Arbitrary<'a>>(input: &'a [u8]) -> T {
+    let mut buf = Unstructured::new(input);
+    T::arbitrary(&mut buf).expect("can create arbitrary instance OK")
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Arbitrary)]
+pub struct Rgb {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+
+#[test]
+fn struct_with_named_fields() {
+    let rgb: Rgb = arbitrary_from(&[4, 5, 6]);
+    assert_eq!(rgb.r, 4);
+    assert_eq!(rgb.g, 5);
+    assert_eq!(rgb.b, 6);
+
+    assert_eq!((3, Some(3)), <Rgb as Arbitrary>::size_hint(0));
+}
+
+#[derive(Copy, Clone, Debug, Arbitrary)]
+struct MyTupleStruct(u8, bool);
+
+#[test]
+fn tuple_struct() {
+    let s: MyTupleStruct = arbitrary_from(&[43, 42]);
+    assert_eq!(s.0, 43);
+    assert_eq!(s.1, false);
+
+    let s: MyTupleStruct = arbitrary_from(&[42, 43]);
+    assert_eq!(s.0, 42);
+    assert_eq!(s.1, true);
+
+    assert_eq!((2, Some(2)), <MyTupleStruct as Arbitrary>::size_hint(0));
+}
+
+#[derive(Clone, Debug, Arbitrary)]
+struct EndingInVec(u8, bool, u32, Vec<u16>);
+#[derive(Clone, Debug, Arbitrary)]
+struct EndingInString(u8, bool, u32, String);
+
+#[test]
+fn test_take_rest() {
+    let bytes = [1, 1, 1, 2, 3, 4, 5, 6, 7, 8];
+    let s1 = EndingInVec::arbitrary_take_rest(Unstructured::new(&bytes)).unwrap();
+    let s2 = EndingInString::arbitrary_take_rest(Unstructured::new(&bytes)).unwrap();
+    assert_eq!(s1.0, 1);
+    assert_eq!(s2.0, 1);
+    assert_eq!(s1.1, true);
+    assert_eq!(s2.1, true);
+    assert_eq!(s1.2, 0x4030201);
+    assert_eq!(s2.2, 0x4030201);
+    assert_eq!(s1.3, vec![0x605, 0x807]);
+    assert_eq!(s2.3, "\x05\x06\x07\x08");
+}
+
+#[derive(Copy, Clone, Debug, Arbitrary)]
+enum MyEnum {
+    Unit,
+    Tuple(u8, u16),
+    Struct { a: u32, b: (bool, u64) },
+}
+
+#[test]
+fn derive_enum() {
+    let mut raw = vec![
+        // The choice of which enum variant takes 4 bytes.
+        1, 2, 3, 4,
+        // And then we need up to 13 bytes for creating `MyEnum::Struct`, the
+        // largest variant.
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
+    ];
+
+    let mut saw_unit = false;
+    let mut saw_tuple = false;
+    let mut saw_struct = false;
+
+    for i in 0..=255 {
+        // Choose different variants each iteration.
+        for el in &mut raw[..4] {
+            *el = i;
+        }
+
+        let e: MyEnum = arbitrary_from(&raw);
+
+        match e {
+            MyEnum::Unit => {
+                saw_unit = true;
+            }
+            MyEnum::Tuple(a, b) => {
+                saw_tuple = true;
+                assert_eq!(a, arbitrary_from(&raw[4..5]));
+                assert_eq!(b, arbitrary_from(&raw[5..]));
+            }
+            MyEnum::Struct { a, b } => {
+                saw_struct = true;
+                assert_eq!(a, arbitrary_from(&raw[4..8]));
+                assert_eq!(b, arbitrary_from(&raw[8..]));
+            }
+        }
+    }
+
+    assert!(saw_unit);
+    assert!(saw_tuple);
+    assert!(saw_struct);
+
+    assert_eq!((4, Some(17)), <MyEnum as Arbitrary>::size_hint(0));
+}
+
+#[derive(Arbitrary, Debug)]
+enum RecursiveTree {
+    Leaf,
+    Node {
+        left: Box<RecursiveTree>,
+        right: Box<RecursiveTree>,
+    },
+}
+
+#[test]
+fn recursive() {
+    let raw = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
+    let _rec: RecursiveTree = arbitrary_from(&raw);
+
+    let (lower, upper) = <RecursiveTree as Arbitrary>::size_hint(0);
+    assert_eq!(lower, 4, "need a u32 for the discriminant at minimum");
+    assert!(
+        upper.is_none(),
+        "potentially infinitely recursive, so no upper bound"
+    );
+}
+
+#[derive(Arbitrary, Debug)]
+struct Generic<T> {
+    inner: T,
+}
+
+#[test]
+fn generics() {
+    let raw = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
+    let gen: Generic<bool> = arbitrary_from(&raw);
+    assert!(gen.inner);
+
+    let (lower, upper) = <Generic<u32> as Arbitrary>::size_hint(0);
+    assert_eq!(lower, 4);
+    assert_eq!(upper, Some(4));
+}
+
+#[derive(Arbitrary, Debug)]
+struct OneLifetime<'a> {
+    alpha: &'a str,
+}
+
+#[test]
+fn one_lifetime() {
+    // Last byte is used for length
+    let raw: Vec<u8> = vec![97, 98, 99, 100, 3];
+    let lifetime: OneLifetime = arbitrary_from(&raw);
+    assert_eq!("abc", lifetime.alpha);
+
+    let (lower, upper) = <OneLifetime as Arbitrary>::size_hint(0);
+    assert_eq!(lower, 0);
+    assert_eq!(upper, None);
+}
+
+#[derive(Arbitrary, Debug)]
+struct TwoLifetimes<'a, 'b> {
+    alpha: &'a str,
+    beta: &'b str,
+}
+
+#[test]
+fn two_lifetimes() {
+    // Last byte is used for length
+    let raw: Vec<u8> = vec![97, 98, 99, 100, 101, 102, 103, 3];
+    let lifetime: TwoLifetimes = arbitrary_from(&raw);
+    assert_eq!("abc", lifetime.alpha);
+    assert_eq!("def", lifetime.beta);
+
+    let (lower, upper) = <TwoLifetimes as Arbitrary>::size_hint(0);
+    assert_eq!(lower, 0);
+    assert_eq!(upper, None);
+}
+
+#[test]
+fn recursive_and_empty_input() {
+    // None of the following derives should result in a stack overflow. See
+    // https://github.com/rust-fuzz/arbitrary/issues/107 for details.
+
+    #[derive(Debug, Arbitrary)]
+    enum Nat {
+        Succ(Box<Nat>),
+        Zero,
+    }
+
+    let _ = Nat::arbitrary(&mut Unstructured::new(&[]));
+
+    #[derive(Debug, Arbitrary)]
+    enum Nat2 {
+        Zero,
+        Succ(Box<Nat2>),
+    }
+
+    let _ = Nat2::arbitrary(&mut Unstructured::new(&[]));
+
+    #[derive(Debug, Arbitrary)]
+    struct Nat3 {
+        f: Option<Box<Nat3>>,
+    }
+
+    let _ = Nat3::arbitrary(&mut Unstructured::new(&[]));
+
+    #[derive(Debug, Arbitrary)]
+    struct Nat4(Option<Box<Nat4>>);
+
+    let _ = Nat4::arbitrary(&mut Unstructured::new(&[]));
+
+    #[derive(Debug, Arbitrary)]
+    enum Nat5 {
+        Zero,
+        Succ { f: Box<Nat5> },
+    }
+
+    let _ = Nat5::arbitrary(&mut Unstructured::new(&[]));
+}
+
+#[test]
+fn test_field_attributes() {
+    // A type that DOES NOT implement Arbitrary
+    #[derive(Debug)]
+    struct Weight(u8);
+
+    #[derive(Debug, Arbitrary)]
+    struct Parcel {
+        #[arbitrary(with = arbitrary_weight)]
+        weight: Weight,
+
+        #[arbitrary(default)]
+        width: u8,
+
+        #[arbitrary(value = 2 + 2)]
+        length: u8,
+
+        height: u8,
+
+        #[arbitrary(with = |u: &mut Unstructured| u.int_in_range(0..=100))]
+        price: u8,
+    }
+
+    fn arbitrary_weight(u: &mut Unstructured) -> arbitrary::Result<Weight> {
+        u.int_in_range(45..=56).map(Weight)
+    }
+
+    let parcel: Parcel = arbitrary_from(&[6, 199, 17]);
+
+    // 45 + 6 = 51
+    assert_eq!(parcel.weight.0, 51);
+
+    // u8::default()
+    assert_eq!(parcel.width, 0);
+
+    // 2 + 2 = 4
+    assert_eq!(parcel.length, 4);
+
+    // 199 is the 2nd byte used by arbitrary
+    assert_eq!(parcel.height, 199);
+
+    // 17 is the 3rd byte used by arbitrary
+    assert_eq!(parcel.price, 17);
+}
diff --git a/third_party/rust/arbitrary/tests/path.rs b/third_party/rust/arbitrary/tests/path.rs
new file mode 100644
index 0000000000..c42ec0a113
--- /dev/null
+++ b/third_party/rust/arbitrary/tests/path.rs
@@ -0,0 +1,32 @@
+#![cfg(feature = "derive")]
+// Various structs/fields that we are deriving `Arbitrary` for aren't actually
+// used except to show off the derive.
+#![allow(dead_code)]
+
+// Regression test for ensuring the derives work without Arbitrary being imported
+
+#[derive(arbitrary::Arbitrary, Clone, Debug)]
+pub struct Struct {
+    x: u8,
+    y: u8,
+}
+
+#[derive(arbitrary::Arbitrary, Clone, Debug)]
+pub struct Tuple(u8);
+
+#[derive(arbitrary::Arbitrary, Clone, Debug)]
+pub struct Unit(u8);
+
+#[derive(arbitrary::Arbitrary, Clone, Debug)]
+pub enum Enum {
+    X(u8),
+    Y(u8),
+}
+
+#[derive(arbitrary::Arbitrary, Clone, Debug)]
+struct EndingInVec(u8, bool, u32, Vec<u16>);
+
+#[derive(arbitrary::Arbitrary, Debug)]
+struct Generic<T> {
+    inner: T,
+}
author	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-07 19:33:14 +0000
committer	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-07 19:33:14 +0000
commit	36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree	105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/arbitrary
parent	Initial commit. (diff)
download	firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip