Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

16 files changed, 2412 insertions, 0 deletions

diff --git a/third_party/rust/tracing-attributes/tests/async_fn.rs b/third_party/rust/tracing-attributes/tests/async_fn.rs
new file mode 100644
index 0000000000..d6d874ffd7
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/async_fn.rs
@@ -0,0 +1,488 @@
+use tracing_mock::*;
+
+use std::convert::Infallible;
+use std::{future::Future, pin::Pin, sync::Arc};
+use tracing::subscriber::with_default;
+use tracing_attributes::instrument;
+
+#[instrument]
+async fn test_async_fn(polls: usize) -> Result<(), ()> {
+    let future = PollN::new_ok(polls);
+    tracing::trace!(awaiting = true);
+    future.await
+}
+
+// Reproduces a compile error when returning an `impl Trait` from an
+// instrumented async fn (see https://github.com/tokio-rs/tracing/issues/1615)
+#[allow(dead_code)] // this is just here to test whether it compiles.
+#[instrument]
+async fn test_ret_impl_trait(n: i32) -> Result<impl Iterator<Item = i32>, ()> {
+    let n = n;
+    Ok((0..10).filter(move |x| *x < n))
+}
+
+// Reproduces a compile error when returning an `impl Trait` from an
+// instrumented async fn (see https://github.com/tokio-rs/tracing/issues/1615)
+#[allow(dead_code)] // this is just here to test whether it compiles.
+#[instrument(err)]
+async fn test_ret_impl_trait_err(n: i32) -> Result<impl Iterator<Item = i32>, &'static str> {
+    Ok((0..10).filter(move |x| *x < n))
+}
+
+#[instrument]
+async fn test_async_fn_empty() {}
+
+// Reproduces a compile error when an instrumented function body contains inner
+// attributes (https://github.com/tokio-rs/tracing/issues/2294).
+#[deny(unused_variables)]
+#[instrument]
+async fn repro_async_2294() {
+    #![allow(unused_variables)]
+    let i = 42;
+}
+
+// Reproduces https://github.com/tokio-rs/tracing/issues/1613
+#[instrument]
+// LOAD-BEARING `#[rustfmt::skip]`! This is necessary to reproduce the bug;
+// with the rustfmt-generated formatting, the lint will not be triggered!
+#[rustfmt::skip]
+#[deny(clippy::suspicious_else_formatting)]
+async fn repro_1613(var: bool) {
+    println!(
+        "{}",
+        if var { "true" } else { "false" }
+    );
+}
+
+// Reproduces https://github.com/tokio-rs/tracing/issues/1613
+// and https://github.com/rust-lang/rust-clippy/issues/7760
+#[instrument]
+#[deny(clippy::suspicious_else_formatting)]
+async fn repro_1613_2() {
+    // hello world
+    // else
+}
+
+// Reproduces https://github.com/tokio-rs/tracing/issues/1831
+#[allow(dead_code)] // this is just here to test whether it compiles.
+#[instrument]
+#[deny(unused_braces)]
+fn repro_1831() -> Pin<Box<dyn Future<Output = ()>>> {
+    Box::pin(async move {})
+}
+
+// This replicates the pattern used to implement async trait methods on nightly using the
+// `type_alias_impl_trait` feature
+#[allow(dead_code)] // this is just here to test whether it compiles.
+#[instrument(ret, err)]
+#[deny(unused_braces)]
+#[allow(clippy::manual_async_fn)]
+fn repro_1831_2() -> impl Future<Output = Result<(), Infallible>> {
+    async { Ok(()) }
+}
+
+#[test]
+fn async_fn_only_enters_for_polls() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("test_async_fn"))
+        .enter(span::mock().named("test_async_fn"))
+        .event(event::mock().with_fields(field::mock("awaiting").with_value(&true)))
+        .exit(span::mock().named("test_async_fn"))
+        .enter(span::mock().named("test_async_fn"))
+        .exit(span::mock().named("test_async_fn"))
+        .enter(span::mock().named("test_async_fn"))
+        .exit(span::mock().named("test_async_fn"))
+        .drop_span(span::mock().named("test_async_fn"))
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || {
+        block_on_future(async { test_async_fn(2).await }).unwrap();
+    });
+    handle.assert_finished();
+}
+
+#[test]
+fn async_fn_nested() {
+    #[instrument]
+    async fn test_async_fns_nested() {
+        test_async_fns_nested_other().await
+    }
+
+    #[instrument]
+    async fn test_async_fns_nested_other() {
+        tracing::trace!(nested = true);
+    }
+
+    let span = span::mock().named("test_async_fns_nested");
+    let span2 = span::mock().named("test_async_fns_nested_other");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .new_span(span2.clone())
+        .enter(span2.clone())
+        .event(event::mock().with_fields(field::mock("nested").with_value(&true)))
+        .exit(span2.clone())
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async { test_async_fns_nested().await });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn async_fn_with_async_trait() {
+    use async_trait::async_trait;
+
+    // test the correctness of the metadata obtained by #[instrument]
+    // (function name, functions parameters) when async-trait is used
+    #[async_trait]
+    pub trait TestA {
+        async fn foo(&mut self, v: usize);
+    }
+
+    // test nesting of async fns with aync-trait
+    #[async_trait]
+    pub trait TestB {
+        async fn bar(&self);
+    }
+
+    // test skip(self) with async-await
+    #[async_trait]
+    pub trait TestC {
+        async fn baz(&self);
+    }
+
+    #[derive(Debug)]
+    struct TestImpl(usize);
+
+    #[async_trait]
+    impl TestA for TestImpl {
+        #[instrument]
+        async fn foo(&mut self, v: usize) {
+            self.baz().await;
+            self.0 = v;
+            self.bar().await
+        }
+    }
+
+    #[async_trait]
+    impl TestB for TestImpl {
+        #[instrument]
+        async fn bar(&self) {
+            tracing::trace!(val = self.0);
+        }
+    }
+
+    #[async_trait]
+    impl TestC for TestImpl {
+        #[instrument(skip(self))]
+        async fn baz(&self) {
+            tracing::trace!(val = self.0);
+        }
+    }
+
+    let span = span::mock().named("foo");
+    let span2 = span::mock().named("bar");
+    let span3 = span::mock().named("baz");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone()
+                .with_field(field::mock("self"))
+                .with_field(field::mock("v")),
+        )
+        .enter(span.clone())
+        .new_span(span3.clone())
+        .enter(span3.clone())
+        .event(event::mock().with_fields(field::mock("val").with_value(&2u64)))
+        .exit(span3.clone())
+        .enter(span3.clone())
+        .exit(span3.clone())
+        .drop_span(span3)
+        .new_span(span2.clone().with_field(field::mock("self")))
+        .enter(span2.clone())
+        .event(event::mock().with_fields(field::mock("val").with_value(&5u64)))
+        .exit(span2.clone())
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let mut test = TestImpl(2);
+        block_on_future(async { test.foo(5).await });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn async_fn_with_async_trait_and_fields_expressions() {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    pub trait Test {
+        async fn call(&mut self, v: usize);
+    }
+
+    #[derive(Clone, Debug)]
+    struct TestImpl;
+
+    impl TestImpl {
+        fn foo(&self) -> usize {
+            42
+        }
+    }
+
+    #[async_trait]
+    impl Test for TestImpl {
+        // check that self is correctly handled, even when using async_trait
+        #[instrument(fields(val=self.foo(), val2=Self::clone(self).foo(), test=%_v+5))]
+        async fn call(&mut self, _v: usize) {}
+    }
+
+    let span = span::mock().named("call");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("_v")
+                    .with_value(&5usize)
+                    .and(field::mock("test").with_value(&tracing::field::debug(10)))
+                    .and(field::mock("val").with_value(&42u64))
+                    .and(field::mock("val2").with_value(&42u64)),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async { TestImpl.call(5).await });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn async_fn_with_async_trait_and_fields_expressions_with_generic_parameter() {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    pub trait Test {
+        async fn call();
+        async fn call_with_self(&self);
+        async fn call_with_mut_self(&mut self);
+    }
+
+    #[derive(Clone, Debug)]
+    struct TestImpl;
+
+    // we also test sync functions that return futures, as they should be handled just like
+    // async-trait (>= 0.1.44) functions
+    impl TestImpl {
+        #[instrument(fields(Self=std::any::type_name::<Self>()))]
+        fn sync_fun(&self) -> Pin<Box<dyn Future<Output = ()> + Send + '_>> {
+            let val = self.clone();
+            Box::pin(async move {
+                let _ = val;
+            })
+        }
+    }
+
+    #[async_trait]
+    impl Test for TestImpl {
+        // instrumenting this is currently not possible, see https://github.com/tokio-rs/tracing/issues/864#issuecomment-667508801
+        //#[instrument(fields(Self=std::any::type_name::<Self>()))]
+        async fn call() {}
+
+        #[instrument(fields(Self=std::any::type_name::<Self>()))]
+        async fn call_with_self(&self) {
+            self.sync_fun().await;
+        }
+
+        #[instrument(fields(Self=std::any::type_name::<Self>()))]
+        async fn call_with_mut_self(&mut self) {}
+    }
+
+    //let span = span::mock().named("call");
+    let span2 = span::mock().named("call_with_self");
+    let span3 = span::mock().named("call_with_mut_self");
+    let span4 = span::mock().named("sync_fun");
+    let (subscriber, handle) = subscriber::mock()
+        /*.new_span(span.clone()
+            .with_field(
+                field::mock("Self").with_value(&"TestImpler")))
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)*/
+        .new_span(
+            span2
+                .clone()
+                .with_field(field::mock("Self").with_value(&std::any::type_name::<TestImpl>())),
+        )
+        .enter(span2.clone())
+        .new_span(
+            span4
+                .clone()
+                .with_field(field::mock("Self").with_value(&std::any::type_name::<TestImpl>())),
+        )
+        .enter(span4.clone())
+        .exit(span4.clone())
+        .enter(span4.clone())
+        .exit(span4)
+        .exit(span2.clone())
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .new_span(
+            span3
+                .clone()
+                .with_field(field::mock("Self").with_value(&std::any::type_name::<TestImpl>())),
+        )
+        .enter(span3.clone())
+        .exit(span3.clone())
+        .enter(span3.clone())
+        .exit(span3.clone())
+        .drop_span(span3)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async {
+            TestImpl::call().await;
+            TestImpl.call_with_self().await;
+            TestImpl.call_with_mut_self().await
+        });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn out_of_scope_fields() {
+    // Reproduces tokio-rs/tracing#1296
+
+    struct Thing {
+        metrics: Arc<()>,
+    }
+
+    impl Thing {
+        #[instrument(skip(self, _req), fields(app_id))]
+        fn call(&mut self, _req: ()) -> Pin<Box<dyn Future<Output = Arc<()>> + Send + Sync>> {
+            // ...
+            let metrics = self.metrics.clone();
+            // ...
+            Box::pin(async move {
+                // ...
+                metrics // cannot find value `metrics` in this scope
+            })
+        }
+    }
+
+    let span = span::mock().named("call");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async {
+            let mut my_thing = Thing {
+                metrics: Arc::new(()),
+            };
+            my_thing.call(()).await;
+        });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn manual_impl_future() {
+    #[allow(clippy::manual_async_fn)]
+    #[instrument]
+    fn manual_impl_future() -> impl Future<Output = ()> {
+        async {
+            tracing::trace!(poll = true);
+        }
+    }
+
+    let span = span::mock().named("manual_impl_future");
+    let poll_event = || event::mock().with_fields(field::mock("poll").with_value(&true));
+
+    let (subscriber, handle) = subscriber::mock()
+        // await manual_impl_future
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(poll_event())
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async {
+            manual_impl_future().await;
+        });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn manual_box_pin() {
+    #[instrument]
+    fn manual_box_pin() -> Pin<Box<dyn Future<Output = ()>>> {
+        Box::pin(async {
+            tracing::trace!(poll = true);
+        })
+    }
+
+    let span = span::mock().named("manual_box_pin");
+    let poll_event = || event::mock().with_fields(field::mock("poll").with_value(&true));
+
+    let (subscriber, handle) = subscriber::mock()
+        // await manual_box_pin
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(poll_event())
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async {
+            manual_box_pin().await;
+        });
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/destructuring.rs b/third_party/rust/tracing-attributes/tests/destructuring.rs
new file mode 100644
index 0000000000..09cf1ad534
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/destructuring.rs
@@ -0,0 +1,213 @@
+use tracing::subscriber::with_default;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[test]
+fn destructure_tuples() {
+    #[instrument]
+    fn my_fn((arg1, arg2): (usize, usize)) {}
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("1"))
+                    .and(field::mock("arg2").with_value(&format_args!("2")))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn((1, 2));
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn destructure_nested_tuples() {
+    #[instrument]
+    fn my_fn(((arg1, arg2), (arg3, arg4)): ((usize, usize), (usize, usize))) {}
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("1"))
+                    .and(field::mock("arg2").with_value(&format_args!("2")))
+                    .and(field::mock("arg3").with_value(&format_args!("3")))
+                    .and(field::mock("arg4").with_value(&format_args!("4")))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(((1, 2), (3, 4)));
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn destructure_refs() {
+    #[instrument]
+    fn my_fn(&arg1: &usize) {}
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone()
+                .with_field(field::mock("arg1").with_value(&1usize).only()),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(&1);
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn destructure_tuple_structs() {
+    struct Foo(usize, usize);
+
+    #[instrument]
+    fn my_fn(Foo(arg1, arg2): Foo) {}
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("1"))
+                    .and(field::mock("arg2").with_value(&format_args!("2")))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(Foo(1, 2));
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn destructure_structs() {
+    struct Foo {
+        bar: usize,
+        baz: usize,
+    }
+
+    #[instrument]
+    fn my_fn(
+        Foo {
+            bar: arg1,
+            baz: arg2,
+        }: Foo,
+    ) {
+        let _ = (arg1, arg2);
+    }
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("1"))
+                    .and(field::mock("arg2").with_value(&format_args!("2")))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(Foo { bar: 1, baz: 2 });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn destructure_everything() {
+    struct Foo {
+        bar: Bar,
+        baz: (usize, usize),
+        qux: NoDebug,
+    }
+    struct Bar((usize, usize));
+    struct NoDebug;
+
+    #[instrument]
+    fn my_fn(
+        &Foo {
+            bar: Bar((arg1, arg2)),
+            baz: (arg3, arg4),
+            ..
+        }: &Foo,
+    ) {
+        let _ = (arg1, arg2, arg3, arg4);
+    }
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("1"))
+                    .and(field::mock("arg2").with_value(&format_args!("2")))
+                    .and(field::mock("arg3").with_value(&format_args!("3")))
+                    .and(field::mock("arg4").with_value(&format_args!("4")))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let foo = Foo {
+            bar: Bar((1, 2)),
+            baz: (3, 4),
+            qux: NoDebug,
+        };
+        let _ = foo.qux; // to eliminate unused field warning
+        my_fn(&foo);
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/err.rs b/third_party/rust/tracing-attributes/tests/err.rs
new file mode 100644
index 0000000000..485dd11961
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/err.rs
@@ -0,0 +1,306 @@
+use tracing::subscriber::with_default;
+use tracing::Level;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+use tracing_subscriber::filter::EnvFilter;
+use tracing_subscriber::layer::SubscriberExt;
+
+use std::convert::TryFrom;
+use std::num::TryFromIntError;
+
+#[instrument(err)]
+fn err() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[instrument(err)]
+fn err_suspicious_else() -> Result<u8, TryFromIntError> {
+    {}
+    u8::try_from(1234)
+}
+
+#[test]
+fn test() {
+    let span = span::mock().named("err");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::ERROR))
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err().ok());
+    handle.assert_finished();
+}
+
+#[instrument(err)]
+async fn err_async(polls: usize) -> Result<u8, TryFromIntError> {
+    let future = PollN::new_ok(polls);
+    tracing::trace!(awaiting = true);
+    future.await.ok();
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_async() {
+    let span = span::mock().named("err_async");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("awaiting").with_value(&true))
+                .at_level(Level::TRACE),
+        )
+        .exit(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::ERROR))
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || {
+        block_on_future(async { err_async(2).await }).ok();
+    });
+    handle.assert_finished();
+}
+
+#[instrument(err)]
+fn err_mut(out: &mut u8) -> Result<(), TryFromIntError> {
+    *out = u8::try_from(1234)?;
+    Ok(())
+}
+
+#[test]
+fn test_mut() {
+    let span = span::mock().named("err_mut");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::ERROR))
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err_mut(&mut 0).ok());
+    handle.assert_finished();
+}
+
+#[instrument(err)]
+async fn err_mut_async(polls: usize, out: &mut u8) -> Result<(), TryFromIntError> {
+    let future = PollN::new_ok(polls);
+    tracing::trace!(awaiting = true);
+    future.await.ok();
+    *out = u8::try_from(1234)?;
+    Ok(())
+}
+
+#[test]
+fn test_mut_async() {
+    let span = span::mock().named("err_mut_async");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("awaiting").with_value(&true))
+                .at_level(Level::TRACE),
+        )
+        .exit(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::ERROR))
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || {
+        block_on_future(async { err_mut_async(2, &mut 0).await }).ok();
+    });
+    handle.assert_finished();
+}
+
+#[test]
+fn impl_trait_return_type() {
+    // Reproduces https://github.com/tokio-rs/tracing/issues/1227
+
+    #[instrument(err)]
+    fn returns_impl_trait(x: usize) -> Result<impl Iterator<Item = usize>, String> {
+        Ok(0..x)
+    }
+
+    let span = span::mock().named("returns_impl_trait");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone()
+                .with_field(field::mock("x").with_value(&10usize).only()),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        for _ in returns_impl_trait(10).unwrap() {
+            // nop
+        }
+    });
+
+    handle.assert_finished();
+}
+
+#[instrument(err(Debug))]
+fn err_dbg() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_err_dbg() {
+    let span = span::mock().named("err_dbg");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock().at_level(Level::ERROR).with_fields(
+                field::mock("error")
+                    // use the actual error value that will be emitted, so
+                    // that this test doesn't break if the standard library
+                    // changes the `fmt::Debug` output from the error type
+                    // in the future.
+                    .with_value(&tracing::field::debug(u8::try_from(1234).unwrap_err())),
+            ),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err_dbg().ok());
+    handle.assert_finished();
+}
+
+#[test]
+fn test_err_display_default() {
+    let span = span::mock().named("err");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock().at_level(Level::ERROR).with_fields(
+                field::mock("error")
+                    // by default, errors will be emitted with their display values
+                    .with_value(&tracing::field::display(u8::try_from(1234).unwrap_err())),
+            ),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err().ok());
+    handle.assert_finished();
+}
+
+#[test]
+fn test_err_custom_target() {
+    let filter: EnvFilter = "my_target=error".parse().expect("filter should parse");
+    let span = span::mock().named("error_span").with_target("my_target");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .at_level(Level::ERROR)
+                .with_target("my_target"),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    let subscriber = subscriber.with(filter);
+
+    with_default(subscriber, || {
+        let error_span = tracing::error_span!(target: "my_target", "error_span");
+
+        {
+            let _enter = error_span.enter();
+            tracing::error!(target: "my_target", "This should display")
+        }
+    });
+    handle.assert_finished();
+}
+
+#[instrument(err(level = "info"))]
+fn err_info() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_err_info() {
+    let span = span::mock().named("err_info");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::INFO))
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err_info().ok());
+    handle.assert_finished();
+}
+
+#[instrument(err(Debug, level = "info"))]
+fn err_dbg_info() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_err_dbg_info() {
+    let span = span::mock().named("err_dbg_info");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock().at_level(Level::INFO).with_fields(
+                field::mock("error")
+                    // use the actual error value that will be emitted, so
+                    // that this test doesn't break if the standard library
+                    // changes the `fmt::Debug` output from the error type
+                    // in the future.
+                    .with_value(&tracing::field::debug(u8::try_from(1234).unwrap_err())),
+            ),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err_dbg_info().ok());
+    handle.assert_finished();
+}
+
+#[instrument(level = "warn", err(level = "info"))]
+fn err_warn_info() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_err_warn_info() {
+    let span = span::mock().named("err_warn_info").at_level(Level::WARN);
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(event::mock().at_level(Level::INFO))
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+    with_default(subscriber, || err_warn_info().ok());
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/fields.rs b/third_party/rust/tracing-attributes/tests/fields.rs
new file mode 100644
index 0000000000..c178fbb3d3
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/fields.rs
@@ -0,0 +1,160 @@
+use tracing::subscriber::with_default;
+use tracing_attributes::instrument;
+use tracing_mock::field::mock;
+use tracing_mock::span::NewSpan;
+use tracing_mock::*;
+
+#[instrument(fields(foo = "bar", dsa = true, num = 1))]
+fn fn_no_param() {}
+
+#[instrument(fields(foo = "bar"))]
+fn fn_param(param: u32) {}
+
+#[instrument(fields(foo = "bar", empty))]
+fn fn_empty_field() {}
+
+#[instrument(fields(len = s.len()))]
+fn fn_expr_field(s: &str) {}
+
+#[instrument(fields(s.len = s.len(), s.is_empty = s.is_empty()))]
+fn fn_two_expr_fields(s: &str) {
+    let _ = s;
+}
+
+#[instrument(fields(%s, s.len = s.len()))]
+fn fn_clashy_expr_field(s: &str) {
+    let _ = s;
+}
+
+#[instrument(fields(s = "s"))]
+fn fn_clashy_expr_field2(s: &str) {
+    let _ = s;
+}
+
+#[instrument(fields(s = &s))]
+fn fn_string(s: String) {
+    let _ = s;
+}
+
+#[derive(Debug)]
+struct HasField {
+    my_field: &'static str,
+}
+
+impl HasField {
+    #[instrument(fields(my_field = self.my_field), skip(self))]
+    fn self_expr_field(&self) {}
+}
+
+#[test]
+fn fields() {
+    let span = span::mock().with_field(
+        mock("foo")
+            .with_value(&"bar")
+            .and(mock("dsa").with_value(&true))
+            .and(mock("num").with_value(&1))
+            .only(),
+    );
+    run_test(span, || {
+        fn_no_param();
+    });
+}
+
+#[test]
+fn expr_field() {
+    let span = span::mock().with_field(
+        mock("s")
+            .with_value(&"hello world")
+            .and(mock("len").with_value(&"hello world".len()))
+            .only(),
+    );
+    run_test(span, || {
+        fn_expr_field("hello world");
+    });
+}
+
+#[test]
+fn two_expr_fields() {
+    let span = span::mock().with_field(
+        mock("s")
+            .with_value(&"hello world")
+            .and(mock("s.len").with_value(&"hello world".len()))
+            .and(mock("s.is_empty").with_value(&false))
+            .only(),
+    );
+    run_test(span, || {
+        fn_two_expr_fields("hello world");
+    });
+}
+
+#[test]
+fn clashy_expr_field() {
+    let span = span::mock().with_field(
+        // Overriding the `s` field should record `s` as a `Display` value,
+        // rather than as a `Debug` value.
+        mock("s")
+            .with_value(&tracing::field::display("hello world"))
+            .and(mock("s.len").with_value(&"hello world".len()))
+            .only(),
+    );
+    run_test(span, || {
+        fn_clashy_expr_field("hello world");
+    });
+
+    let span = span::mock().with_field(mock("s").with_value(&"s").only());
+    run_test(span, || {
+        fn_clashy_expr_field2("hello world");
+    });
+}
+
+#[test]
+fn self_expr_field() {
+    let span = span::mock().with_field(mock("my_field").with_value(&"hello world").only());
+    run_test(span, || {
+        let has_field = HasField {
+            my_field: "hello world",
+        };
+        has_field.self_expr_field();
+    });
+}
+
+#[test]
+fn parameters_with_fields() {
+    let span = span::mock().with_field(
+        mock("foo")
+            .with_value(&"bar")
+            .and(mock("param").with_value(&1u32))
+            .only(),
+    );
+    run_test(span, || {
+        fn_param(1);
+    });
+}
+
+#[test]
+fn empty_field() {
+    let span = span::mock().with_field(mock("foo").with_value(&"bar").only());
+    run_test(span, || {
+        fn_empty_field();
+    });
+}
+
+#[test]
+fn string_field() {
+    let span = span::mock().with_field(mock("s").with_value(&"hello world").only());
+    run_test(span, || {
+        fn_string(String::from("hello world"));
+    });
+}
+
+fn run_test<F: FnOnce() -> T, T>(span: NewSpan, fun: F) {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span)
+        .enter(span::mock())
+        .exit(span::mock())
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, fun);
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/follows_from.rs b/third_party/rust/tracing-attributes/tests/follows_from.rs
new file mode 100644
index 0000000000..a589409ded
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/follows_from.rs
@@ -0,0 +1,101 @@
+use tracing::{subscriber::with_default, Id, Level, Span};
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[instrument(follows_from = causes, skip(causes))]
+fn with_follows_from_sync(causes: impl IntoIterator<Item = impl Into<Option<Id>>>) {}
+
+#[instrument(follows_from = causes, skip(causes))]
+async fn with_follows_from_async(causes: impl IntoIterator<Item = impl Into<Option<Id>>>) {}
+
+#[instrument(follows_from = [&Span::current()])]
+fn follows_from_current() {}
+
+#[test]
+fn follows_from_sync_test() {
+    let cause_a = span::mock().named("cause_a");
+    let cause_b = span::mock().named("cause_b");
+    let cause_c = span::mock().named("cause_c");
+    let consequence = span::mock().named("with_follows_from_sync");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(cause_a.clone())
+        .new_span(cause_b.clone())
+        .new_span(cause_c.clone())
+        .new_span(consequence.clone())
+        .follows_from(consequence.clone(), cause_a)
+        .follows_from(consequence.clone(), cause_b)
+        .follows_from(consequence.clone(), cause_c)
+        .enter(consequence.clone())
+        .exit(consequence)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let cause_a = tracing::span!(Level::TRACE, "cause_a");
+        let cause_b = tracing::span!(Level::TRACE, "cause_b");
+        let cause_c = tracing::span!(Level::TRACE, "cause_c");
+
+        with_follows_from_sync(&[cause_a, cause_b, cause_c])
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn follows_from_async_test() {
+    let cause_a = span::mock().named("cause_a");
+    let cause_b = span::mock().named("cause_b");
+    let cause_c = span::mock().named("cause_c");
+    let consequence = span::mock().named("with_follows_from_async");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(cause_a.clone())
+        .new_span(cause_b.clone())
+        .new_span(cause_c.clone())
+        .new_span(consequence.clone())
+        .follows_from(consequence.clone(), cause_a)
+        .follows_from(consequence.clone(), cause_b)
+        .follows_from(consequence.clone(), cause_c)
+        .enter(consequence.clone())
+        .exit(consequence.clone())
+        .enter(consequence.clone())
+        .exit(consequence)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        block_on_future(async {
+            let cause_a = tracing::span!(Level::TRACE, "cause_a");
+            let cause_b = tracing::span!(Level::TRACE, "cause_b");
+            let cause_c = tracing::span!(Level::TRACE, "cause_c");
+
+            with_follows_from_async(&[cause_a, cause_b, cause_c]).await
+        })
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn follows_from_current_test() {
+    let cause = span::mock().named("cause");
+    let consequence = span::mock().named("follows_from_current");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(cause.clone())
+        .enter(cause.clone())
+        .new_span(consequence.clone())
+        .follows_from(consequence.clone(), cause.clone())
+        .enter(consequence.clone())
+        .exit(consequence)
+        .exit(cause)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        tracing::span!(Level::TRACE, "cause").in_scope(follows_from_current)
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/instrument.rs b/third_party/rust/tracing-attributes/tests/instrument.rs
new file mode 100644
index 0000000000..b215b8455d
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/instrument.rs
@@ -0,0 +1,252 @@
+use tracing::subscriber::with_default;
+use tracing::Level;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+// Reproduces a compile error when an instrumented function body contains inner
+// attributes (https://github.com/tokio-rs/tracing/issues/2294).
+#[deny(unused_variables)]
+#[instrument]
+fn repro_2294() {
+    #![allow(unused_variables)]
+    let i = 42;
+}
+
+#[test]
+fn override_everything() {
+    #[instrument(target = "my_target", level = "debug")]
+    fn my_fn() {}
+
+    #[instrument(level = Level::DEBUG, target = "my_target")]
+    fn my_other_fn() {}
+
+    let span = span::mock()
+        .named("my_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+    let span2 = span::mock()
+        .named("my_other_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .new_span(span2.clone())
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn();
+        my_other_fn();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn fields() {
+    #[instrument(target = "my_target", level = "debug")]
+    fn my_fn(arg1: usize, arg2: bool) {}
+
+    let span = span::mock()
+        .named("my_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+
+    let span2 = span::mock()
+        .named("my_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&2usize)
+                    .and(field::mock("arg2").with_value(&false))
+                    .only(),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .new_span(
+            span2.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&3usize)
+                    .and(field::mock("arg2").with_value(&true))
+                    .only(),
+            ),
+        )
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(2, false);
+        my_fn(3, true);
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn skip() {
+    struct UnDebug(pub u32);
+
+    #[instrument(target = "my_target", level = "debug", skip(_arg2, _arg3))]
+    fn my_fn(arg1: usize, _arg2: UnDebug, _arg3: UnDebug) {}
+
+    #[instrument(target = "my_target", level = "debug", skip_all)]
+    fn my_fn2(_arg1: usize, _arg2: UnDebug, _arg3: UnDebug) {}
+
+    let span = span::mock()
+        .named("my_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+
+    let span2 = span::mock()
+        .named("my_fn")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+
+    let span3 = span::mock()
+        .named("my_fn2")
+        .at_level(Level::DEBUG)
+        .with_target("my_target");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone()
+                .with_field(field::mock("arg1").with_value(&2usize).only()),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .new_span(
+            span2
+                .clone()
+                .with_field(field::mock("arg1").with_value(&3usize).only()),
+        )
+        .enter(span2.clone())
+        .exit(span2.clone())
+        .drop_span(span2)
+        .new_span(span3.clone())
+        .enter(span3.clone())
+        .exit(span3.clone())
+        .drop_span(span3)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(2, UnDebug(0), UnDebug(1));
+        my_fn(3, UnDebug(0), UnDebug(1));
+        my_fn2(2, UnDebug(0), UnDebug(1));
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn generics() {
+    #[derive(Debug)]
+    struct Foo;
+
+    #[instrument]
+    fn my_fn<S, T: std::fmt::Debug>(arg1: S, arg2: T)
+    where
+        S: std::fmt::Debug,
+    {
+    }
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("arg1")
+                    .with_value(&format_args!("Foo"))
+                    .and(field::mock("arg2").with_value(&format_args!("false"))),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        my_fn(Foo, false);
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn methods() {
+    #[derive(Debug)]
+    struct Foo;
+
+    impl Foo {
+        #[instrument]
+        fn my_fn(&self, arg1: usize) {}
+    }
+
+    let span = span::mock().named("my_fn");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone().with_field(
+                field::mock("self")
+                    .with_value(&format_args!("Foo"))
+                    .and(field::mock("arg1").with_value(&42usize)),
+            ),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let foo = Foo;
+        foo.my_fn(42);
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn impl_trait_return_type() {
+    #[instrument]
+    fn returns_impl_trait(x: usize) -> impl Iterator<Item = usize> {
+        0..x
+    }
+
+    let span = span::mock().named("returns_impl_trait");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span.clone()
+                .with_field(field::mock("x").with_value(&10usize).only()),
+        )
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        for _ in returns_impl_trait(10) {
+            // nop
+        }
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/levels.rs b/third_party/rust/tracing-attributes/tests/levels.rs
new file mode 100644
index 0000000000..94fc7e85a2
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/levels.rs
@@ -0,0 +1,142 @@
+use tracing::subscriber::with_default;
+use tracing::Level;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[test]
+fn named_levels() {
+    #[instrument(level = "trace")]
+    fn trace() {}
+
+    #[instrument(level = "Debug")]
+    fn debug() {}
+
+    #[instrument(level = "INFO")]
+    fn info() {}
+
+    #[instrument(level = "WARn")]
+    fn warn() {}
+
+    #[instrument(level = "eRrOr")]
+    fn error() {}
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("trace").at_level(Level::TRACE))
+        .enter(span::mock().named("trace").at_level(Level::TRACE))
+        .exit(span::mock().named("trace").at_level(Level::TRACE))
+        .new_span(span::mock().named("debug").at_level(Level::DEBUG))
+        .enter(span::mock().named("debug").at_level(Level::DEBUG))
+        .exit(span::mock().named("debug").at_level(Level::DEBUG))
+        .new_span(span::mock().named("info").at_level(Level::INFO))
+        .enter(span::mock().named("info").at_level(Level::INFO))
+        .exit(span::mock().named("info").at_level(Level::INFO))
+        .new_span(span::mock().named("warn").at_level(Level::WARN))
+        .enter(span::mock().named("warn").at_level(Level::WARN))
+        .exit(span::mock().named("warn").at_level(Level::WARN))
+        .new_span(span::mock().named("error").at_level(Level::ERROR))
+        .enter(span::mock().named("error").at_level(Level::ERROR))
+        .exit(span::mock().named("error").at_level(Level::ERROR))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        trace();
+        debug();
+        info();
+        warn();
+        error();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn numeric_levels() {
+    #[instrument(level = 1)]
+    fn trace() {}
+
+    #[instrument(level = 2)]
+    fn debug() {}
+
+    #[instrument(level = 3)]
+    fn info() {}
+
+    #[instrument(level = 4)]
+    fn warn() {}
+
+    #[instrument(level = 5)]
+    fn error() {}
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("trace").at_level(Level::TRACE))
+        .enter(span::mock().named("trace").at_level(Level::TRACE))
+        .exit(span::mock().named("trace").at_level(Level::TRACE))
+        .new_span(span::mock().named("debug").at_level(Level::DEBUG))
+        .enter(span::mock().named("debug").at_level(Level::DEBUG))
+        .exit(span::mock().named("debug").at_level(Level::DEBUG))
+        .new_span(span::mock().named("info").at_level(Level::INFO))
+        .enter(span::mock().named("info").at_level(Level::INFO))
+        .exit(span::mock().named("info").at_level(Level::INFO))
+        .new_span(span::mock().named("warn").at_level(Level::WARN))
+        .enter(span::mock().named("warn").at_level(Level::WARN))
+        .exit(span::mock().named("warn").at_level(Level::WARN))
+        .new_span(span::mock().named("error").at_level(Level::ERROR))
+        .enter(span::mock().named("error").at_level(Level::ERROR))
+        .exit(span::mock().named("error").at_level(Level::ERROR))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        trace();
+        debug();
+        info();
+        warn();
+        error();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn enum_levels() {
+    #[instrument(level = Level::TRACE)]
+    fn trace() {}
+
+    #[instrument(level = Level::DEBUG)]
+    fn debug() {}
+
+    #[instrument(level = tracing::Level::INFO)]
+    fn info() {}
+
+    #[instrument(level = Level::WARN)]
+    fn warn() {}
+
+    #[instrument(level = Level::ERROR)]
+    fn error() {}
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("trace").at_level(Level::TRACE))
+        .enter(span::mock().named("trace").at_level(Level::TRACE))
+        .exit(span::mock().named("trace").at_level(Level::TRACE))
+        .new_span(span::mock().named("debug").at_level(Level::DEBUG))
+        .enter(span::mock().named("debug").at_level(Level::DEBUG))
+        .exit(span::mock().named("debug").at_level(Level::DEBUG))
+        .new_span(span::mock().named("info").at_level(Level::INFO))
+        .enter(span::mock().named("info").at_level(Level::INFO))
+        .exit(span::mock().named("info").at_level(Level::INFO))
+        .new_span(span::mock().named("warn").at_level(Level::WARN))
+        .enter(span::mock().named("warn").at_level(Level::WARN))
+        .exit(span::mock().named("warn").at_level(Level::WARN))
+        .new_span(span::mock().named("error").at_level(Level::ERROR))
+        .enter(span::mock().named("error").at_level(Level::ERROR))
+        .exit(span::mock().named("error").at_level(Level::ERROR))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        trace();
+        debug();
+        info();
+        warn();
+        error();
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/names.rs b/third_party/rust/tracing-attributes/tests/names.rs
new file mode 100644
index 0000000000..d97dece9a1
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/names.rs
@@ -0,0 +1,63 @@
+use tracing::subscriber::with_default;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[instrument]
+fn default_name() {}
+
+#[instrument(name = "my_name")]
+fn custom_name() {}
+
+// XXX: it's weird that we support both of these forms, but apparently we
+// managed to release a version that accepts both syntax, so now we have to
+// support it! yay!
+#[instrument("my_other_name")]
+fn custom_name_no_equals() {}
+
+#[test]
+fn default_name_test() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("default_name"))
+        .enter(span::mock().named("default_name"))
+        .exit(span::mock().named("default_name"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        default_name();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn custom_name_test() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("my_name"))
+        .enter(span::mock().named("my_name"))
+        .exit(span::mock().named("my_name"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        custom_name();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn custom_name_no_equals_test() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("my_other_name"))
+        .enter(span::mock().named("my_other_name"))
+        .exit(span::mock().named("my_other_name"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        custom_name_no_equals();
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/parents.rs b/third_party/rust/tracing-attributes/tests/parents.rs
new file mode 100644
index 0000000000..7069b98ea5
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/parents.rs
@@ -0,0 +1,102 @@
+use tracing::{subscriber::with_default, Id, Level};
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[instrument]
+fn with_default_parent() {}
+
+#[instrument(parent = parent_span, skip(parent_span))]
+fn with_explicit_parent<P>(parent_span: P)
+where
+    P: Into<Option<Id>>,
+{
+}
+
+#[test]
+fn default_parent_test() {
+    let contextual_parent = span::mock().named("contextual_parent");
+    let child = span::mock().named("with_default_parent");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            contextual_parent
+                .clone()
+                .with_contextual_parent(None)
+                .with_explicit_parent(None),
+        )
+        .new_span(
+            child
+                .clone()
+                .with_contextual_parent(Some("contextual_parent"))
+                .with_explicit_parent(None),
+        )
+        .enter(child.clone())
+        .exit(child.clone())
+        .enter(contextual_parent.clone())
+        .new_span(
+            child
+                .clone()
+                .with_contextual_parent(Some("contextual_parent"))
+                .with_explicit_parent(None),
+        )
+        .enter(child.clone())
+        .exit(child)
+        .exit(contextual_parent)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let contextual_parent = tracing::span!(Level::TRACE, "contextual_parent");
+
+        with_default_parent();
+
+        contextual_parent.in_scope(|| {
+            with_default_parent();
+        });
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn explicit_parent_test() {
+    let contextual_parent = span::mock().named("contextual_parent");
+    let explicit_parent = span::mock().named("explicit_parent");
+    let child = span::mock().named("with_explicit_parent");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            contextual_parent
+                .clone()
+                .with_contextual_parent(None)
+                .with_explicit_parent(None),
+        )
+        .new_span(
+            explicit_parent
+                .with_contextual_parent(None)
+                .with_explicit_parent(None),
+        )
+        .enter(contextual_parent.clone())
+        .new_span(
+            child
+                .clone()
+                .with_contextual_parent(Some("contextual_parent"))
+                .with_explicit_parent(Some("explicit_parent")),
+        )
+        .enter(child.clone())
+        .exit(child)
+        .exit(contextual_parent)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let contextual_parent = tracing::span!(Level::INFO, "contextual_parent");
+        let explicit_parent = tracing::span!(Level::INFO, "explicit_parent");
+
+        contextual_parent.in_scope(|| {
+            with_explicit_parent(&explicit_parent);
+        });
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/ret.rs b/third_party/rust/tracing-attributes/tests/ret.rs
new file mode 100644
index 0000000000..f56c80baaf
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ret.rs
@@ -0,0 +1,307 @@
+use std::convert::TryFrom;
+use std::num::TryFromIntError;
+use tracing_mock::*;
+
+use tracing::{subscriber::with_default, Level};
+use tracing_attributes::instrument;
+use tracing_subscriber::layer::SubscriberExt;
+use tracing_subscriber::EnvFilter;
+
+#[instrument(ret)]
+fn ret() -> i32 {
+    42
+}
+
+#[instrument(target = "my_target", ret)]
+fn ret_with_target() -> i32 {
+    42
+}
+
+#[test]
+fn test() {
+    let span = span::mock().named("ret");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret);
+    handle.assert_finished();
+}
+
+#[test]
+fn test_custom_target() {
+    let filter: EnvFilter = "my_target=info".parse().expect("filter should parse");
+    let span = span::mock()
+        .named("ret_with_target")
+        .with_target("my_target");
+
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::INFO)
+                .with_target("my_target"),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    let subscriber = subscriber.with(filter);
+
+    with_default(subscriber, ret_with_target);
+    handle.assert_finished();
+}
+
+#[instrument(level = "warn", ret)]
+fn ret_warn() -> i32 {
+    42
+}
+
+#[test]
+fn test_warn() {
+    let span = span::mock().named("ret_warn");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::WARN),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret_warn);
+    handle.assert_finished();
+}
+
+#[instrument(ret)]
+fn ret_mut(a: &mut i32) -> i32 {
+    *a *= 2;
+    tracing::info!(?a);
+    *a
+}
+
+#[test]
+fn test_mut() {
+    let span = span::mock().named("ret_mut");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("a").with_value(&tracing::field::display(2)))
+                .at_level(Level::INFO),
+        )
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(2)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || ret_mut(&mut 1));
+    handle.assert_finished();
+}
+
+#[instrument(ret)]
+async fn ret_async() -> i32 {
+    42
+}
+
+#[test]
+fn test_async() {
+    let span = span::mock().named("ret_async");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .enter(span.clone())
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || block_on_future(async { ret_async().await }));
+    handle.assert_finished();
+}
+
+#[instrument(ret)]
+fn ret_impl_type() -> impl Copy {
+    42
+}
+
+#[test]
+fn test_impl_type() {
+    let span = span::mock().named("ret_impl_type");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret_impl_type);
+    handle.assert_finished();
+}
+
+#[instrument(ret(Display))]
+fn ret_display() -> i32 {
+    42
+}
+
+#[test]
+fn test_dbg() {
+    let span = span::mock().named("ret_display");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::display(42)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret_display);
+    handle.assert_finished();
+}
+
+#[instrument(err, ret)]
+fn ret_and_err() -> Result<u8, TryFromIntError> {
+    u8::try_from(1234)
+}
+
+#[test]
+fn test_ret_and_err() {
+    let span = span::mock().named("ret_and_err");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(
+                    field::mock("error")
+                        .with_value(&tracing::field::display(u8::try_from(1234).unwrap_err()))
+                        .only(),
+                )
+                .at_level(Level::ERROR),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || ret_and_err().ok());
+    handle.assert_finished();
+}
+
+#[instrument(err, ret)]
+fn ret_and_ok() -> Result<u8, TryFromIntError> {
+    u8::try_from(123)
+}
+
+#[test]
+fn test_ret_and_ok() {
+    let span = span::mock().named("ret_and_ok");
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(
+                    field::mock("return")
+                        .with_value(&tracing::field::debug(u8::try_from(123).unwrap()))
+                        .only(),
+                )
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || ret_and_ok().ok());
+    handle.assert_finished();
+}
+
+#[instrument(level = "warn", ret(level = "info"))]
+fn ret_warn_info() -> i32 {
+    42
+}
+
+#[test]
+fn test_warn_info() {
+    let span = span::mock().named("ret_warn_info").at_level(Level::WARN);
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::INFO),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret_warn_info);
+    handle.assert_finished();
+}
+
+#[instrument(ret(level = "warn", Debug))]
+fn ret_dbg_warn() -> i32 {
+    42
+}
+
+#[test]
+fn test_dbg_warn() {
+    let span = span::mock().named("ret_dbg_warn").at_level(Level::INFO);
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span.clone())
+        .enter(span.clone())
+        .event(
+            event::mock()
+                .with_fields(field::mock("return").with_value(&tracing::field::debug(42)))
+                .at_level(Level::WARN),
+        )
+        .exit(span.clone())
+        .drop_span(span)
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, ret_dbg_warn);
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/targets.rs b/third_party/rust/tracing-attributes/tests/targets.rs
new file mode 100644
index 0000000000..363f628f31
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/targets.rs
@@ -0,0 +1,97 @@
+use tracing::subscriber::with_default;
+use tracing_attributes::instrument;
+use tracing_mock::*;
+
+#[instrument]
+fn default_target() {}
+
+#[instrument(target = "my_target")]
+fn custom_target() {}
+
+mod my_mod {
+    use tracing_attributes::instrument;
+
+    pub const MODULE_PATH: &str = module_path!();
+
+    #[instrument]
+    pub fn default_target() {}
+
+    #[instrument(target = "my_other_target")]
+    pub fn custom_target() {}
+}
+
+#[test]
+fn default_targets() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(
+            span::mock()
+                .named("default_target")
+                .with_target(module_path!()),
+        )
+        .enter(
+            span::mock()
+                .named("default_target")
+                .with_target(module_path!()),
+        )
+        .exit(
+            span::mock()
+                .named("default_target")
+                .with_target(module_path!()),
+        )
+        .new_span(
+            span::mock()
+                .named("default_target")
+                .with_target(my_mod::MODULE_PATH),
+        )
+        .enter(
+            span::mock()
+                .named("default_target")
+                .with_target(my_mod::MODULE_PATH),
+        )
+        .exit(
+            span::mock()
+                .named("default_target")
+                .with_target(my_mod::MODULE_PATH),
+        )
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        default_target();
+        my_mod::default_target();
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn custom_targets() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("custom_target").with_target("my_target"))
+        .enter(span::mock().named("custom_target").with_target("my_target"))
+        .exit(span::mock().named("custom_target").with_target("my_target"))
+        .new_span(
+            span::mock()
+                .named("custom_target")
+                .with_target("my_other_target"),
+        )
+        .enter(
+            span::mock()
+                .named("custom_target")
+                .with_target("my_other_target"),
+        )
+        .exit(
+            span::mock()
+                .named("custom_target")
+                .with_target("my_other_target"),
+        )
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        custom_target();
+        my_mod::custom_target();
+    });
+
+    handle.assert_finished();
+}
diff --git a/third_party/rust/tracing-attributes/tests/ui.rs b/third_party/rust/tracing-attributes/tests/ui.rs
new file mode 100644
index 0000000000..73d7fdcef8
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ui.rs
@@ -0,0 +1,14 @@
+// Only test on nightly, since UI tests are bound to change over time
+#[rustversion::stable]
+#[test]
+fn async_instrument() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/ui/async_instrument.rs");
+}
+
+#[rustversion::stable]
+#[test]
+fn const_instrument() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/ui/const_instrument.rs");
+}
diff --git a/third_party/rust/tracing-attributes/tests/ui/async_instrument.rs b/third_party/rust/tracing-attributes/tests/ui/async_instrument.rs
new file mode 100644
index 0000000000..5b245746a6
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ui/async_instrument.rs
@@ -0,0 +1,46 @@
+#![allow(unreachable_code)]
+
+#[tracing::instrument]
+async fn unit() {
+    ""
+}
+
+#[tracing::instrument]
+async fn simple_mismatch() -> String {
+    ""
+}
+
+// FIXME: this span is still pretty poor
+#[tracing::instrument]
+async fn opaque_unsatisfied() -> impl std::fmt::Display {
+    ("",)
+}
+
+struct Wrapper<T>(T);
+
+#[tracing::instrument]
+async fn mismatch_with_opaque() -> Wrapper<impl std::fmt::Display> {
+    ""
+}
+
+#[tracing::instrument]
+async fn early_return_unit() {
+    if true {
+        return "";
+    }
+}
+
+#[tracing::instrument]
+async fn early_return() -> String {
+    if true {
+        return "";
+    }
+    String::new()
+}
+
+#[tracing::instrument]
+async fn extra_semicolon() -> i32 {
+    1;
+}
+
+fn main() {}
diff --git a/third_party/rust/tracing-attributes/tests/ui/async_instrument.stderr b/third_party/rust/tracing-attributes/tests/ui/async_instrument.stderr
new file mode 100644
index 0000000000..2c64b0c15e
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ui/async_instrument.stderr
@@ -0,0 +1,98 @@
+error[E0308]: mismatched types
+ --> tests/ui/async_instrument.rs:5:5
+  |
+5 |     ""
+  |     ^^ expected `()`, found `&str`
+  |
+note: return type inferred to be `()` here
+ --> tests/ui/async_instrument.rs:4:10
+  |
+4 | async fn unit() {
+  |          ^^^^
+
+error[E0308]: mismatched types
+  --> tests/ui/async_instrument.rs:10:5
+   |
+10 |     ""
+   |     ^^- help: try using a conversion method: `.to_string()`
+   |     |
+   |     expected `String`, found `&str`
+   |
+note: return type inferred to be `String` here
+  --> tests/ui/async_instrument.rs:9:31
+   |
+9  | async fn simple_mismatch() -> String {
+   |                               ^^^^^^
+
+error[E0277]: `(&str,)` doesn't implement `std::fmt::Display`
+  --> tests/ui/async_instrument.rs:14:1
+   |
+14 | #[tracing::instrument]
+   | ^^^^^^^^^^^^^^^^^^^^^^ `(&str,)` cannot be formatted with the default formatter
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `(&str,)`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+   = note: this error originates in the attribute macro `tracing::instrument` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: `(&str,)` doesn't implement `std::fmt::Display`
+  --> tests/ui/async_instrument.rs:15:34
+   |
+15 | async fn opaque_unsatisfied() -> impl std::fmt::Display {
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^ `(&str,)` cannot be formatted with the default formatter
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `(&str,)`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+
+error[E0308]: mismatched types
+  --> tests/ui/async_instrument.rs:23:5
+   |
+23 |     ""
+   |     ^^ expected `Wrapper<_>`, found `&str`
+   |
+   = note: expected struct `Wrapper<_>`
+           found reference `&'static str`
+note: return type inferred to be `Wrapper<_>` here
+  --> tests/ui/async_instrument.rs:22:36
+   |
+22 | async fn mismatch_with_opaque() -> Wrapper<impl std::fmt::Display> {
+   |                                    ^^^^^^^
+help: try wrapping the expression in `Wrapper`
+   |
+23 |     Wrapper("")
+   |     ++++++++  +
+
+error[E0308]: mismatched types
+  --> tests/ui/async_instrument.rs:29:16
+   |
+29 |         return "";
+   |                ^^ expected `()`, found `&str`
+   |
+note: return type inferred to be `()` here
+  --> tests/ui/async_instrument.rs:27:10
+   |
+27 | async fn early_return_unit() {
+   |          ^^^^^^^^^^^^^^^^^
+
+error[E0308]: mismatched types
+  --> tests/ui/async_instrument.rs:36:16
+   |
+36 |         return "";
+   |                ^^- help: try using a conversion method: `.to_string()`
+   |                |
+   |                expected `String`, found `&str`
+   |
+note: return type inferred to be `String` here
+  --> tests/ui/async_instrument.rs:34:28
+   |
+34 | async fn early_return() -> String {
+   |                            ^^^^^^
+
+error[E0308]: mismatched types
+  --> tests/ui/async_instrument.rs:42:35
+   |
+42 |   async fn extra_semicolon() -> i32 {
+   |  ___________________________________^
+43 | |     1;
+   | |      - help: remove this semicolon to return this value
+44 | | }
+   | |_^ expected `i32`, found `()`
diff --git a/third_party/rust/tracing-attributes/tests/ui/const_instrument.rs b/third_party/rust/tracing-attributes/tests/ui/const_instrument.rs
new file mode 100644
index 0000000000..a251e8f66b
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ui/const_instrument.rs
@@ -0,0 +1,8 @@
+#![allow(unreachable_code)]
+
+#[tracing::instrument]
+const fn unit() {
+    ""
+}
+
+fn main() {}
diff --git a/third_party/rust/tracing-attributes/tests/ui/const_instrument.stderr b/third_party/rust/tracing-attributes/tests/ui/const_instrument.stderr
new file mode 100644
index 0000000000..e76d4acad9
--- /dev/null
+++ b/third_party/rust/tracing-attributes/tests/ui/const_instrument.stderr
@@ -0,0 +1,15 @@
+error: macros that expand to items must be delimited with braces or followed by a semicolon
+ --> tests/ui/const_instrument.rs:3:1
+  |
+3 | #[tracing::instrument]
+  | ^^^^^^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the attribute macro `tracing::instrument` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: the `#[instrument]` attribute may not be used with `const fn`s
+ --> tests/ui/const_instrument.rs:3:1
+  |
+3 | #[tracing::instrument]
+  | ^^^^^^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the attribute macro `tracing::instrument` (in Nightly builds, run with -Z macro-backtrace for more info)