Update documentation of source-backtrace behavior

dtolnay · Aug 28, 2021 · 71c7ebe · 71c7ebe
1 parent 799bb53
commit 71c7ebe
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Showing 2 changed files with 6 additions and 6 deletions.
diff --git a/README.md b/README.md
@@ -137,14 +137,14 @@ pub enum DataStoreError {
   }
   ```
 
-- If a field is `#[from]` and `#[backtrace]`, the Error trait's `backtrace()`
-  method is forwarded to the `source`.
+- If a field is both a source (named `source`, or has `#[source]` or `#[from]`
+  attribute) *and* is marked `#[backtrace]`, then the Error trait's
+  `backtrace()` method is forwarded to the source's backtrace.
 
   ```rust
   #[derive(Error, Debug)]
   pub enum MyError {
       Io {
-          #[from]
           #[backtrace]
           source: io::Error,
       },

diff --git a/src/lib.rs b/src/lib.rs
@@ -161,15 +161,15 @@
 //!   # };
 //!   ```
 //!
-//! - If a field is `#[from]` and `#[backtrace]`, the Error trait's
-//!   `backtrace()` method is forwarded to the field.
+//! - If a field is both a source (named `source`, or has `#[source]` or
+//!   `#[from]` attribute) *and* is marked `#[backtrace]`, then the Error
+//!   trait's `backtrace()` method is forwarded to the source's backtrace.
 //!
 //!   ```rust
 //!   # const IGNORE: &str = stringify! {
 //!   #[derive(Error, Debug)]
 //!   pub enum MyError {
 //!       Io {
-//!           #[from]
 //!           #[backtrace]
 //!           source: io::Error,
 //!       },