From fd5514454f5ca20554df35e2a373a3bbfe1ffe7c Mon Sep 17 00:00:00 2001
From: Ed Page <eopage@gmail.com>
Date: Fri, 10 Jan 2025 09:27:31 -0600
Subject: [PATCH] fix: Add key tracking for all error types

---
 src/error.rs              | 39 +++++++++++++++++++++++++++++++++++++--
 tests/testsuite/errors.rs | 10 ++++++++--
 tests/testsuite/log.rs    |  2 +-
 3 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 2d738b94..831e52b9 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -78,6 +78,16 @@ pub enum ConfigError {
         key: Option<String>,
     },
 
+    /// Custom message
+    At {
+        /// Error being extended with a path
+        error: Box<ConfigError>,
+
+        /// The key in the configuration hash of this value (if available where the
+        /// error is generated).
+        key: Option<String>,
+    },
+
     /// Custom message
     Message(String),
 
@@ -130,7 +140,15 @@ impl ConfigError {
                 key: Some(key.into()),
             },
 
-            _ => self,
+            Self::At { error, .. } => Self::At {
+                error,
+                key: Some(key.into()),
+            },
+
+            other => Self::At {
+                error: Box::new(other),
+                key: Some(key.into()),
+            },
         }
     }
 
@@ -157,8 +175,15 @@ impl ConfigError {
                 expected,
                 key: Some(concat(key)),
             },
+            Self::At { error, key } => Self::At {
+                error,
+                key: Some(concat(key)),
+            },
             Self::NotFound(key) => Self::NotFound(concat(Some(key))),
-            _ => self,
+            other => Self::At {
+                error: Box::new(other),
+                key: Some(concat(None)),
+            },
         }
     }
 
@@ -217,6 +242,16 @@ impl fmt::Display for ConfigError {
                 Ok(())
             }
 
+            ConfigError::At { ref error, ref key } => {
+                write!(f, "{error}")?;
+
+                if let Some(ref key) = *key {
+                    write!(f, " for key `{key}`")?;
+                }
+
+                Ok(())
+            }
+
             ConfigError::FileParse { ref cause, ref uri } => {
                 write!(f, "{cause}")?;
 
diff --git a/tests/testsuite/errors.rs b/tests/testsuite/errors.rs
index 8647044d..3a41d572 100644
--- a/tests/testsuite/errors.rs
+++ b/tests/testsuite/errors.rs
@@ -134,7 +134,10 @@ fn test_get_missing_field() {
         .unwrap();
 
     let res = c.get::<InnerSettings>("inner");
-    assert_data_eq!(res.unwrap_err().to_string(), str!["missing field `value2`"]);
+    assert_data_eq!(
+        res.unwrap_err().to_string(),
+        str!["missing field `value2` for key `inner`"]
+    );
 }
 
 #[test]
@@ -342,5 +345,8 @@ fn test_deserialize_missing_field() {
         .unwrap();
 
     let res = c.try_deserialize::<Settings>();
-    assert_data_eq!(res.unwrap_err().to_string(), str!["missing field `value2`"]);
+    assert_data_eq!(
+        res.unwrap_err().to_string(),
+        str!["missing field `value2` for key `inner`"]
+    );
 }
diff --git a/tests/testsuite/log.rs b/tests/testsuite/log.rs
index 29bf7eca..d8cda030 100644
--- a/tests/testsuite/log.rs
+++ b/tests/testsuite/log.rs
@@ -53,6 +53,6 @@ fn test_load_level_lowercase() {
     assert!(s.is_err());
     assert_data_eq!(
         s.unwrap_err().to_string(),
-        str!["enum Level does not have variant constructor error"]
+        str!["enum Level does not have variant constructor error for key `log`"]
     );
 }