7 files changed, 238 insertions, 0 deletions
diff --git a/third_party/rust/matches/.cargo-checksum.json b/third_party/rust/matches/.cargo-checksum.json
new file mode 100644
index 0000000000..27136fb6e3
--- /dev/null
+++ b/third_party/rust/matches/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"31b6fb9ee5ecddc429d13300336509fd7d199aa316375c00b581d60533b8ed43","LICENSE":"d7b49708075b5f43f8e108464f1970c8c66fa8b6afce4f9c944da3af77cc1460","README.md":"096bf8a54bac9e0fe42720d12aa40a2d3a6e78293c1bd8895f6bd9350a7fc224","lib.rs":"c6d14b7899277e45ac5f46d95f87c91ed0e5118db3b377e0914799d0e252650a","tests/macro_use_one.rs":"4f599fae16f1aef369050bf0ad74cbefec06c430b29e0c9ab0811ac9592e997a","tests/use_star.rs":"39a23b8002544f65e7a896e2cefe8e0af7404151fa65d327e748f5c1101badf8"},"package":"2532096657941c2fea9c289d370a250971c689d4f143798ff67113ec042024a5"}
+\ No newline at end of file
diff --git a/third_party/rust/matches/Cargo.toml b/third_party/rust/matches/Cargo.toml
new file mode 100644
index 0000000000..12206e91a4
--- /dev/null
+++ b/third_party/rust/matches/Cargo.toml
@@ -0,0 +1,23 @@
+# 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]
+name = "matches"
+version = "0.1.10"
+description = "A macro to evaluate, as a boolean, whether an expression matches a pattern."
+documentation = "https://docs.rs/matches/"
+readme = "README.md"
+license = "MIT"
+repository = "https://github.com/SimonSapin/rust-std-candidates"
+
+[lib]
+name = "matches"
+path = "lib.rs"
diff --git a/third_party/rust/matches/LICENSE b/third_party/rust/matches/LICENSE
new file mode 100644
index 0000000000..a7b759a49c
--- /dev/null
+++ b/third_party/rust/matches/LICENSE
@@ -0,0 +1,25 @@
+Copyright (c) 2014-2016 Simon Sapin
+
+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
+limitation the rights to use, copy, modify, merge,
+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
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+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/matches/README.md b/third_party/rust/matches/README.md
new file mode 100644
index 0000000000..543ba1b091
--- /dev/null
+++ b/third_party/rust/matches/README.md
@@ -0,0 +1,7 @@
+A macro to evaluate, as a boolean, whether an expression matches a pattern.
+
+For users who build using only Rust 1.42 and newer, consider using [`std::matches`], which
+is included in the [standard library prelude] and thus is automatically in scope.
+
+[`std::matches`]: core::matches
+[standard library prelude]: https://doc.rust-lang.org/stable/reference/names/preludes.html
diff --git a/third_party/rust/matches/lib.rs b/third_party/rust/matches/lib.rs
new file mode 100644
index 0000000000..262f8d0764
--- /dev/null
+++ b/third_party/rust/matches/lib.rs
@@ -0,0 +1,161 @@
+#![no_std]
+//! A macro to evaluate, as a boolean, whether an expression matches a pattern.
+//!
+//! For users who build using only Rust 1.42 and newer, consider using [`std::matches`], which
+//! is included in the [standard library prelude] and thus is automatically in scope.
+//!
+//! [`std::matches`]: core::matches
+//! [standard library prelude]: https://doc.rust-lang.org/stable/reference/names/preludes.html
+//!
+//! # Examples
+//!
+//! ```
+//! #[macro_use]
+//! extern crate matches;
+//!
+//! #[derive(Debug)]
+//! pub enum Foo<T> {
+//!     A,
+//!     B(T),
+//! }
+//!
+//! impl<T> Foo<T> {
+//!     pub fn is_b(&self) -> bool {
+//!         matches!(*self, Foo::B(_))
+//!     }
+//! }
+//!
+//! impl<T: core::fmt::Debug> Foo<T> {
+//!     pub fn assert_is_b(&self) {
+//!         assert_matches!(&self, Foo::B(_));
+//!     }
+//! }
+//! # fn main() { }
+//! ```
+
+/// Check if an expression matches a refutable pattern.
+///
+/// Syntax: `matches!(` *expression* `,` *pattern* `)`
+///
+/// Return a boolean, true if the expression matches the pattern, false otherwise.
+///
+/// # Examples
+///
+/// ```
+/// #[macro_use]
+/// extern crate matches;
+///
+/// pub enum Foo<T> {
+///     A,
+///     B(T),
+/// }
+///
+/// impl<T> Foo<T> {
+///     pub fn is_a(&self) -> bool {
+///         matches!(*self, Foo::A)
+///     }
+///
+///     pub fn is_b(&self) -> bool {
+///         matches!(*self, Foo::B(_))
+///     }
+/// }
+///
+/// # fn main() { }
+/// ```
+#[macro_export]
+macro_rules! matches {
+    ($expression:expr, $($pattern:tt)+) => {
+        match $expression {
+            $($pattern)+ => true,
+            _ => false
+        }
+    }
+}
+
+/// Assert that an expression matches a refutable pattern.
+///
+/// Syntax: `assert_matches!(` *expression* `,` *pattern* `)`
+///
+/// Panic with a message that shows the expression if it does not match the
+/// pattern.
+///
+/// # Examples
+///
+/// ```
+/// #[macro_use]
+/// extern crate matches;
+///
+/// fn main() {
+///     let data = [1, 2, 3];
+///     assert_matches!(data.get(1), Some(_));
+/// }
+/// ```
+#[macro_export]
+macro_rules! assert_matches {
+    ($expression:expr, $($pattern:tt)+) => {
+        match $expression {
+            $($pattern)+ => (),
+            ref e => panic!("assertion failed: `{:?}` does not match `{}`", e, stringify!($($pattern)+)),
+        }
+    }
+}
+
+/// Assert that an expression matches a refutable pattern using debug assertions.
+///
+/// Syntax: `debug_assert_matches!(` *expression* `,` *pattern* `)`
+///
+/// If debug assertions are enabled, panic with a message that shows the
+/// expression if it does not match the pattern.
+///
+/// When debug assertions are not enabled, this macro does nothing.
+///
+/// # Examples
+///
+/// ```
+/// #[macro_use]
+/// extern crate matches;
+///
+/// fn main() {
+///     let data = [1, 2, 3];
+///     debug_assert_matches!(data.get(1), Some(_));
+/// }
+/// ```
+#[macro_export]
+macro_rules! debug_assert_matches {
+    ($expression:expr, $($pattern:tt)+) => {
+        if cfg!(debug_assertions) {
+            match $expression {
+                $($pattern)+ => (),
+                ref e => panic!("assertion failed: `{:?}` does not match `{}`", e, stringify!($($pattern)+)),
+            }
+        }
+    }
+}
+
+#[test]
+fn matches_works() {
+    let foo = Some("-12");
+    assert!(matches!(foo, Some(bar) if
+        matches!(bar.as_bytes()[0], b'+' | b'-') &&
+        matches!(bar.as_bytes()[1], b'0'...b'9')
+    ));
+}
+
+#[test]
+fn assert_matches_works() {
+    let foo = Some("-12");
+    assert_matches!(foo, Some(bar) if
+        matches!(bar.as_bytes()[0], b'+' | b'-') &&
+        matches!(bar.as_bytes()[1], b'0'...b'9')
+    );
+}
+
+#[test]
+#[should_panic(expected = "assertion failed: `Some(\"-AB\")` does not match ")]
+fn assert_matches_panics() {
+    let foo = Some("-AB");
+    assert_matches!(foo, Some(bar) if
+        matches!(bar.as_bytes()[0], b'+' | b'-') &&
+        matches!(bar.as_bytes()[1], b'0'...b'9')
+    );
+}
diff --git a/third_party/rust/matches/tests/macro_use_one.rs b/third_party/rust/matches/tests/macro_use_one.rs
new file mode 100644
index 0000000000..a527a89ce7
--- /dev/null
+++ b/third_party/rust/matches/tests/macro_use_one.rs
@@ -0,0 +1,11 @@
+// https://github.com/SimonSapin/rust-std-candidates/issues/12
+#[macro_use(matches)] extern crate matches;
+
+#[test]
+fn matches_works() {
+    let foo = Some("-12");
+    assert!(matches!(foo, Some(bar) if
+        matches!(bar.as_bytes()[0], b'+' | b'-') &&
+        matches!(bar.as_bytes()[1], b'0'...b'9')
+    ));
+}
diff --git a/third_party/rust/matches/tests/use_star.rs b/third_party/rust/matches/tests/use_star.rs
new file mode 100644
index 0000000000..58a670b93e
--- /dev/null
+++ b/third_party/rust/matches/tests/use_star.rs
@@ -0,0 +1,10 @@
+//! https://github.com/SimonSapin/rust-std-candidates/issues/22
+
+extern crate matches;
+
+use matches::*;
+
+#[test]
+fn test_assert_matches() {
+    assert_matches!(4, 4)
+}