Merge branch 'master' into instrument-arguments

.github/dependabot.yml

@@ -0,0 +1,29 @@
+version: 2
+updates:
+- package-ecosystem: cargo
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10
+  ignore:
+  - dependency-name: opentelemetry-jaeger
+    versions:
+    - 0.12.0
+  - dependency-name: opentelemetry
+    versions:
+    - 0.13.0
+  - dependency-name: tokio-test
+    versions:
+    - 0.4.0
+  - dependency-name: matchers
+    versions:
+    - 0.1.0
+  - dependency-name: hyper
+    versions:
+    - 0.14.2
+  - dependency-name: tower
+    versions:
+    - 0.4.1
+  - dependency-name: bytes
+    versions:
+    - 1.0.0

tracing-core/src/field.rs

@@ -428,6 +428,19 @@ where
     }
 }
 
+impl<'a, T: ?Sized> crate::sealed::Sealed for &'a mut T where T: Value + crate::sealed::Sealed + 'a {}
+
+impl<'a, T: ?Sized> Value for &'a mut T
+where
+    T: Value + 'a,
+{
+    fn record(&self, key: &Field, visitor: &mut dyn Visit) {
+        // Don't use `(*self).record(key, visitor)`, otherwise would
+        // cause stack overflow due to `unconditional_recursion`.
+        T::record(self, key, visitor)
+    }
+}
+
 impl<'a> crate::sealed::Sealed for fmt::Arguments<'a> {}
 
 impl<'a> Value for fmt::Arguments<'a> {

tracing-subscriber/src/subscribe.rs

@@ -1268,14 +1268,14 @@ pub(crate) mod tests {
             .and_then(StringSubscriber2("subscriber_2".into()))
             .and_then(StringSubscriber3("subscriber_3".into()))
             .with_collector(NopCollector);
-        let subscriber =
-            Collect::downcast_ref::<StringSubscriber>(&s).expect("subscriber 2 should downcast");
+        let subscriber = <dyn Collect>::downcast_ref::<StringSubscriber>(&s)
+            .expect("subscriber 2 should downcast");
         assert_eq!(&subscriber.0, "subscriber_1");
-        let subscriber =
-            Collect::downcast_ref::<StringSubscriber2>(&s).expect("subscriber 2 should downcast");
+        let subscriber = <dyn Collect>::downcast_ref::<StringSubscriber2>(&s)
+            .expect("subscriber 2 should downcast");
         assert_eq!(&subscriber.0, "subscriber_2");
-        let subscriber =
-            Collect::downcast_ref::<StringSubscriber3>(&s).expect("subscriber 3 should downcast");
+        let subscriber = <dyn Collect>::downcast_ref::<StringSubscriber3>(&s)
+            .expect("subscriber 3 should downcast");
         assert_eq!(&subscriber.0, "subscriber_3");
     }
 }

tracing/src/lib.rs

@@ -174,6 +174,25 @@
 //! # fn main() {}
 //! ```
 //!
+//! For functions which don't have built-in tracing support and can't have
+//! the `#[instrument]` attribute applied (such as from an external crate,
+//! the [`Span` struct][`Span`] has a [`in_scope()` method][`in_scope`]
+//! which can be used to easily wrap synchonous code in a span.
+//!
+//! For example:
+//! ```rust
+//! use tracing::info_span;
+//!
+//! # fn doc() -> Result<(), ()> {
+//! # mod serde_json {
+//! #    pub(crate) fn from_slice(buf: &[u8]) -> Result<(), ()> { Ok(()) }
+//! # }
+//! # let buf: [u8; 0] = [];
+//! let json = info_span!("json.parse").in_scope(|| serde_json::from_slice(&buf))?;
+//! # let _ = json; // suppress unused variable warning
+//! # Ok(())
+//! # }
+//! ```
 //!
 //! You can find more examples showing how to use this crate [here][examples].
 //!