Shrink AppError footprint

CHANGELOG.md

@@ -3,6 +3,13 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+## [0.21.1] - 2025-10-09
+
+### Fixed
+- Packed rarely used `AppError` context (source and backtrace slots) inside the
+  boxed inner payload so the `AppResult` alias no longer triggers Clippy's
+  `result_large_err` lint under `-D warnings`.
+
 ## [0.21.0] - 2025-10-08
 
 ### Added

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "masterror"
-version = "0.21.0"
+version = "0.21.1"
 rust-version = "1.90"
 edition = "2024"
 license = "MIT OR Apache-2.0"

README.md

@@ -73,9 +73,9 @@ The build script keeps the full feature snippet below in sync with
 
 ~~~toml
 [dependencies]
-masterror = { version = "0.21.0", default-features = false }
+masterror = { version = "0.21.1", default-features = false }
 # or with features:
-# masterror = { version = "0.21.0", features = [
+# masterror = { version = "0.21.1", features = [
 #   "axum", "actix", "openapi", "serde_json",
 #   "tracing", "metrics", "backtrace", "sqlx",
 #   "sqlx-migrate", "reqwest", "redis", "validator",

README.ru.md

@@ -67,9 +67,9 @@ MSRV зафиксирован, а родные деривы позволяют 
 
 ~~~toml
 [dependencies]
-masterror = { version = "0.21.0", default-features = false }
+masterror = { version = "0.21.1", default-features = false }
 # или с нужными фичами:
-# masterror = { version = "0.21.0", features = [
+# masterror = { version = "0.21.1", features = [
 #   "axum", "actix", "openapi", "serde_json",
 #   "tracing", "metrics", "backtrace", "sqlx",
 #   "sqlx-migrate", "reqwest", "redis", "validator",

src/app_error/core.rs

@@ -38,20 +38,25 @@ pub enum MessageEditPolicy {
 #[doc(hidden)]
 pub struct ErrorInner {
     /// Stable machine-readable error code.
-    pub code:             AppCode,
+    pub code:               AppCode,
     /// Semantic error category.
-    pub kind:             AppErrorKind,
+    pub kind:               AppErrorKind,
     /// Optional, public-friendly message.
-    pub message:          Option<Cow<'static, str>>,
+    pub message:            Option<Cow<'static, str>>,
     /// Structured metadata for telemetry.
-    pub metadata:         Metadata,
+    pub metadata:           Metadata,
     /// Policy describing whether the message can be redacted.
-    pub edit_policy:      MessageEditPolicy,
+    pub edit_policy:        MessageEditPolicy,
     /// Optional retry advice rendered as `Retry-After`.
-    pub retry:            Option<RetryAdvice>,
+    pub retry:              Option<RetryAdvice>,
     /// Optional authentication challenge for `WWW-Authenticate`.
-    pub www_authenticate: Option<String>,
-    telemetry_dirty:      AtomicBool
+    pub www_authenticate:   Option<String>,
+    pub source:             Option<Arc<dyn StdError + Send + Sync + 'static>>,
+    #[cfg(feature = "backtrace")]
+    pub backtrace:          Option<Backtrace>,
+    #[cfg(feature = "backtrace")]
+    pub captured_backtrace: OnceLock<Option<Backtrace>>,
+    telemetry_dirty:        AtomicBool
 }
 
 #[cfg(feature = "backtrace")]
@@ -156,12 +161,7 @@ mod test_backtrace_override {
 /// Rich application error preserving domain code, taxonomy and metadata.
 #[derive(Debug)]
 pub struct Error {
-    inner:              Box<ErrorInner>,
-    source:             Option<Arc<dyn StdError + Send + Sync + 'static>>,
-    #[cfg(feature = "backtrace")]
-    backtrace:          Option<Backtrace>,
-    #[cfg(feature = "backtrace")]
-    captured_backtrace: OnceLock<Option<Backtrace>>
+    inner: Box<ErrorInner>
 }
 
 impl Deref for Error {
@@ -228,13 +228,13 @@ impl Error {
                 edit_policy: MessageEditPolicy::Preserve,
                 retry: None,
                 www_authenticate: None,
+                source: None,
+                #[cfg(feature = "backtrace")]
+                backtrace: None,
+                #[cfg(feature = "backtrace")]
+                captured_backtrace: OnceLock::new(),
                 telemetry_dirty: AtomicBool::new(true)
-            }),
-            source: None,
-            #[cfg(feature = "backtrace")]
-            backtrace: None,
-            #[cfg(feature = "backtrace")]
-            captured_backtrace: OnceLock::new()
+            })
         }
     }
 

src/app_error/tests.rs

@@ -548,3 +548,12 @@ fn result_alias_is_generic() {
     assert!(matches!(default_result, Ok(value) if value == 1));
     assert!(matches!(custom_result, Ok(value) if value == 2));
 }
+
+#[test]
+fn app_error_fits_result_budget() {
+    let size = std::mem::size_of::<AppError>();
+    assert!(
+        size <= 128,
+        "AppError grew to {size} bytes; keep the Err variant lean"
+    );
+}