From b7bea6929996cf23290c74938e47cbb0a3ef5b4f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Teo=20Klestrup=20R=C3=B6ijezon?= <teo@nullable.se>
Date: Fri, 9 Jul 2021 05:06:10 +0200
Subject: [PATCH] Display the whole error stack when formatting errors

According to the format suggested in https://github.com/tokio-rs/tracing/issues/1347#issuecomment-813674313

Fixes #1347
---
 tracing-subscriber/src/fmt/format/mod.rs    | 23 ++++++++++++++++++++-
 tracing-subscriber/src/fmt/format/pretty.rs |  4 ++--
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/tracing-subscriber/src/fmt/format/mod.rs b/tracing-subscriber/src/fmt/format/mod.rs
index 7a551bee46..c28d12b22e 100644
--- a/tracing-subscriber/src/fmt/format/mod.rs
+++ b/tracing-subscriber/src/fmt/format/mod.rs
@@ -761,7 +761,10 @@ impl<'a> field::Visit for DefaultVisitor<'a> {
 
     fn record_error(&mut self, field: &Field, value: &(dyn std::error::Error + 'static)) {
         if let Some(source) = value.source() {
-            self.record_debug(field, &format_args!("{}, {}: {}", value, field, source))
+            self.record_debug(
+                field,
+                &format_args!("{}, {}.sources: {}", value, field, ErrorSourceList(source)),
+            )
         } else {
             self.record_debug(field, &format_args!("{}", value))
         }
@@ -806,6 +809,24 @@ impl<'a> fmt::Debug for DefaultVisitor<'a> {
     }
 }
 
+/// Renders an error into a list of sources, *including* the error
+struct ErrorSourceList<'a>(&'a (dyn std::error::Error + 'static));
+
+impl<'a> Display for ErrorSourceList<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_char('[')?;
+        let mut curr = Some(self.0);
+        while let Some(curr_err) = curr {
+            f.write_fmt(format_args!("{}", curr_err))?;
+            curr = curr_err.source();
+            if curr.is_some() {
+                f.write_str(", ")?;
+            }
+        }
+        f.write_char(']')
+    }
+}
+
 struct FmtCtx<'a, S, N> {
     ctx: &'a FmtContext<'a, S, N>,
     span: Option<&'a span::Id>,
diff --git a/tracing-subscriber/src/fmt/format/pretty.rs b/tracing-subscriber/src/fmt/format/pretty.rs
index ab1180823f..dedacae5da 100644
--- a/tracing-subscriber/src/fmt/format/pretty.rs
+++ b/tracing-subscriber/src/fmt/format/pretty.rs
@@ -332,12 +332,12 @@ impl<'a> field::Visit for PrettyVisitor<'a> {
             self.record_debug(
                 field,
                 &format_args!(
-                    "{}, {}{}.source{}: {}",
+                    "{}, {}{}.sources{}: {}",
                     value,
                     bold.prefix(),
                     field,
                     bold.infix(self.style),
-                    source,
+                    ErrorSourceList(source),
                 ),
             )
         } else {