From 84afb38406e769b69ba2b798abfa517e078ccb93 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Teo=20Klestrup=20R=C3=B6ijezon?= <teo@nullable.se>
Date: Thu, 10 Jun 2021 00:24:20 +0200
Subject: [PATCH] Migrate tracing-subscriber to SpanRef::scope

---
 tracing-subscriber/src/fmt/fmt_layer.rs     | 12 ++++++++----
 tracing-subscriber/src/fmt/format/json.rs   |  6 ++++--
 tracing-subscriber/src/fmt/format/mod.rs    | 13 +++----------
 tracing-subscriber/src/fmt/format/pretty.rs | 10 ++--------
 4 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/tracing-subscriber/src/fmt/fmt_layer.rs b/tracing-subscriber/src/fmt/fmt_layer.rs
index eeddabd471..451d6e6685 100644
--- a/tracing-subscriber/src/fmt/fmt_layer.rs
+++ b/tracing-subscriber/src/fmt/fmt_layer.rs
@@ -1,7 +1,7 @@
 use crate::{
     field::RecordFields,
     fmt::{format, FormatEvent, FormatFields, MakeWriter, TestWriter},
-    layer::{self, Context, Scope},
+    layer::{self, Context},
     registry::{LookupSpan, SpanRef},
 };
 use format::{FmtSpan, TimingDisplay};
@@ -804,8 +804,10 @@ where
         F: FnMut(&SpanRef<'_, S>) -> Result<(), E>,
     {
         // visit all the current spans
-        for span in self.ctx.scope() {
-            f(&span)?;
+        if let Some(leaf) = self.ctx.lookup_current() {
+            for span in leaf.scope().from_root() {
+                f(&span)?;
+            }
         }
         Ok(())
     }
@@ -864,7 +866,9 @@ where
     /// the current span.
     ///
     /// [stored data]: ../registry/struct.SpanRef.html
-    pub fn scope(&self) -> Scope<'_, S>
+    #[deprecated(note = "wraps crate::layer::Context::scope")]
+    #[allow(deprecated)]
+    pub fn scope(&self) -> crate::layer::Scope<'_, S>
     where
         S: for<'lookup> LookupSpan<'lookup>,
     {
diff --git a/tracing-subscriber/src/fmt/format/json.rs b/tracing-subscriber/src/fmt/format/json.rs
index 5cc522f6a4..c2a0ced8f4 100644
--- a/tracing-subscriber/src/fmt/format/json.rs
+++ b/tracing-subscriber/src/fmt/format/json.rs
@@ -98,8 +98,10 @@ where
         use serde::ser::SerializeSeq;
         let mut serializer = serializer_o.serialize_seq(None)?;
 
-        for span in self.0.scope() {
-            serializer.serialize_element(&SerializableSpan(&span, self.1))?;
+        if let Some(leaf_span) = self.0.lookup_current() {
+            for span in leaf_span.scope().from_root() {
+                serializer.serialize_element(&SerializableSpan(&span, self.1))?;
+            }
         }
 
         serializer.end()
diff --git a/tracing-subscriber/src/fmt/format/mod.rs b/tracing-subscriber/src/fmt/format/mod.rs
index 3950847cb8..b07bba2d15 100644
--- a/tracing-subscriber/src/fmt/format/mod.rs
+++ b/tracing-subscriber/src/fmt/format/mod.rs
@@ -7,10 +7,7 @@ use crate::{
     registry::LookupSpan,
 };
 
-use std::{
-    fmt::{self, Write},
-    iter,
-};
+use std::fmt::{self, Write};
 use tracing_core::{
     field::{self, Field, Visit},
     span, Event, Level, Subscriber,
@@ -861,9 +858,7 @@ where
             .and_then(|id| self.ctx.ctx.span(&id))
             .or_else(|| self.ctx.ctx.lookup_current());
 
-        let scope = span
-            .into_iter()
-            .flat_map(|span| span.from_root().chain(iter::once(span)));
+        let scope = span.into_iter().flat_map(|span| span.scope().from_root());
 
         for span in scope {
             seen = true;
@@ -933,9 +928,7 @@ where
             .and_then(|id| self.ctx.ctx.span(&id))
             .or_else(|| self.ctx.ctx.lookup_current());
 
-        let scope = span
-            .into_iter()
-            .flat_map(|span| span.from_root().chain(iter::once(span)));
+        let scope = span.into_iter().flat_map(|span| span.scope().from_root());
 
         for span in scope {
             write!(f, "{}", bold.paint(span.metadata().name()))?;
diff --git a/tracing-subscriber/src/fmt/format/pretty.rs b/tracing-subscriber/src/fmt/format/pretty.rs
index d98cef813d..ab1180823f 100644
--- a/tracing-subscriber/src/fmt/format/pretty.rs
+++ b/tracing-subscriber/src/fmt/format/pretty.rs
@@ -5,10 +5,7 @@ use crate::{
     registry::LookupSpan,
 };
 
-use std::{
-    fmt::{self, Write},
-    iter,
-};
+use std::fmt::{self, Write};
 use tracing_core::{
     field::{self, Field},
     Event, Level, Subscriber,
@@ -187,10 +184,7 @@ where
             .and_then(|id| ctx.span(&id))
             .or_else(|| ctx.lookup_current());
 
-        let scope = span.into_iter().flat_map(|span| {
-            let parents = span.parents();
-            iter::once(span).chain(parents)
-        });
+        let scope = span.into_iter().flat_map(|span| span.scope());
 
         for span in scope {
             let meta = span.metadata();