refactor!: add back Error trait

.github/workflows/ci.yml

@@ -64,16 +64,15 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust-version }}
-      - name: Run unit tests
-        if: ${{ !startsWith(matrix.os, 'windows') }}
-        run: cargo x test --no-capture
-        shell: bash
-      - name: Run unit tests (Windows)
+      - name: Adjust snapshots on Windows
         if: ${{ startsWith(matrix.os, 'windows') }}
+        run: |
+          perl -i -pe 's/\//\\/g if /at exn/' exn/tests/snapshots/*.snap
+          perl -i -pe 's/(?<!\/)\/(?!\/)/\\/g if /at examples/' examples/src/*.rs
+        shell: bash
+      - name: Run unit tests
         run: cargo x test --no-capture
         shell: bash
-        env:
-          RUSTFLAGS: --cfg windows_test
 
   required:
     name: Required

Cargo.toml

@@ -34,7 +34,6 @@ insta = { version = "1.45.1" }
 which = { version = "8.0.0" }
 
 [workspace.lints.rust]
-unexpected_cfgs = { level = "deny", check-cfg = ['cfg(windows_test)'] }
 unknown_lints = "deny"
 
 [workspace.lints.clippy]

examples/src/custom-layout.rs

@@ -17,9 +17,9 @@
 //! This example shows how to traverse the error chain and create custom
 //! formatting to match your application's needs.
 
-use std::error::Error;
 use std::fmt::Write;
 
+use exn::Error;
 use exn::Exn;
 use exn::Frame;
 use exn::Result;

examples/src/downcast.rs

@@ -21,9 +21,8 @@
 //! - Recover from specific error types
 //! - Extract structured data (HTTP codes, retry hints, etc.)
 
-use std::error::Error;
-
 use derive_more::Display;
+use exn::Error;
 use exn::Exn;
 use exn::Frame;
 use exn::Result;
@@ -119,8 +118,8 @@ mod http {
 // Retryable error, attempting retry #3
 //
 // HTTP error with status code: 503
-// Error: fatal error occurred in application, at examples/src/downcast.rs:54:24
+// Error: fatal error occurred in application, at examples/src/downcast.rs:53:24
 // |
-// |-> failed to run app, at examples/src/downcast.rs:82:35
+// |-> failed to run app, at examples/src/downcast.rs:81:35
 // |
-// |-> HTTP 503: service unavailable, at examples/src/downcast.rs:95:9
+// |-> HTTP 503: service unavailable, at examples/src/downcast.rs:94:9

exn/src/debug.rs

@@ -12,10 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error::Error;
 use std::fmt;
 use std::fmt::Formatter;
 
+use crate::Error;
 use crate::Exn;
 use crate::Frame;
 
@@ -33,7 +33,15 @@ impl fmt::Debug for Frame {
 
 fn write_exn(f: &mut Formatter<'_>, frame: &Frame, level: usize, prefix: &str) -> fmt::Result {
     write!(f, "{}", frame.error())?;
-    write_location(f, frame)?;
+
+    let location = frame.location();
+    write!(
+        f,
+        ", at {}:{}:{}",
+        location.file(),
+        location.line(),
+        location.column()
+    )?;
 
     let children = frame.children();
     let children_len = children.len();
@@ -54,55 +62,3 @@ fn write_exn(f: &mut Formatter<'_>, frame: &Frame, level: usize, prefix: &str) -
 
     Ok(())
 }
-
-#[cfg(not(windows_test))]
-fn write_location(f: &mut Formatter<'_>, exn: &Frame) -> fmt::Result {
-    let location = exn.location();
-    write!(
-        f,
-        ", at {}:{}:{}",
-        location.file(),
-        location.line(),
-        location.column()
-    )
-}
-
-#[cfg(windows_test)]
-fn write_location(f: &mut Formatter<'_>, exn: &Frame) -> fmt::Result {
-    let location = exn.location();
-    use std::os::windows::ffi::OsStrExt;
-    use std::path::Component;
-    use std::path::MAIN_SEPARATOR;
-    use std::path::Path;
-
-    let file = location.file();
-    let path = Path::new(file);
-
-    let mut resolved = String::new();
-
-    for c in path.components() {
-        match c {
-            Component::RootDir => {}
-            Component::CurDir => resolved.push('.'),
-            Component::ParentDir => resolved.push_str(".."),
-            Component::Prefix(prefix) => {
-                resolved.push_str(&prefix.as_os_str().to_string_lossy());
-                continue;
-            }
-            Component::Normal(s) => resolved.push_str(&s.to_string_lossy()),
-        }
-        resolved.push('/');
-    }
-
-    if path.as_os_str().encode_wide().last() != Some(MAIN_SEPARATOR as u16)
-        && resolved != "/"
-        && resolved.ends_with('/')
-    {
-        resolved.pop(); // Pop last '/'
-    }
-
-    let line = location.line();
-    let column = location.column();
-
-    write!(f, ", at {resolved}:{line}:{column}")
-}

exn/src/display.rs

@@ -12,9 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error::Error;
 use std::fmt;
 
+use crate::Error;
 use crate::Exn;
 
 impl<E: Error> fmt::Display for Exn<E> {

exn/src/impls.rs

@@ -12,32 +12,35 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error::Error;
 use std::fmt;
 use std::marker::PhantomData;
 use std::panic::Location;
 
+use crate::Error;
+
 /// An exception type that can hold an error tree and additional context.
-pub struct Exn<E: Error + 'static> {
+pub struct Exn<E: Error> {
     // trade one more indirection for less stack size
     frame: Box<Frame>,
     phantom: PhantomData<E>,
 }
 
-impl<E: Error + 'static> From<E> for Exn<E> {
+impl<E: Error> From<E> for Exn<E> {
     #[track_caller]
     fn from(error: E) -> Self {
         Exn::new(error)
     }
 }
 
-impl<E: Error + 'static> Exn<E> {
+impl<E: Error> Exn<E> {
     /// Create a new exception with the given error.
     ///
     /// This will automatically walk the [source chain of the error] and add them as children
     /// frames.
     ///
-    /// [source chain of the error]: Error::source
+    /// See also [`Error::raise`] for a fluent way to convert an error into an `Exn` instance.
+    ///
+    /// [source chain of the error]: std::error::Error::source
     #[track_caller]
     pub fn new(error: E) -> Self {
         struct SourceError(String);
@@ -54,9 +57,9 @@ impl<E: Error + 'static> Exn<E> {
             }
         }
 
-        impl Error for SourceError {}
+        impl std::error::Error for SourceError {}
 
-        fn walk(error: &dyn Error, location: &'static Location<'static>) -> Vec<Frame> {
+        fn walk(error: &dyn std::error::Error, location: &'static Location<'static>) -> Vec<Frame> {
             if let Some(source) = error.source() {
                 let children = vec![Frame {
                     error: Box::new(SourceError(source.to_string())),
@@ -87,7 +90,7 @@ impl<E: Error + 'static> Exn<E> {
     #[track_caller]
     pub fn from_iter<T, I>(children: I, err: E) -> Self
     where
-        T: Error + 'static,
+        T: Error,
         I: IntoIterator,
         I::Item: Into<Exn<T>>,
     {
@@ -124,7 +127,7 @@ impl<E: Error + 'static> Exn<E> {
 /// A frame in the exception tree.
 pub struct Frame {
     /// The error that occurred at this frame.
-    error: Box<dyn Error + 'static>,
+    error: Box<dyn Error>,
     /// The source code location where this exception frame was created.
     location: &'static Location<'static>,
     /// Child exception frames that provide additional context or source errors.
@@ -133,7 +136,7 @@ pub struct Frame {
 
 impl Frame {
     /// Return the error that occurred at this frame.
-    pub fn error(&self) -> &(dyn Error + 'static) {
+    pub fn error(&self) -> &(dyn std::error::Error + Send + Sync + 'static) {
         &*self.error
     }
 

exn/src/lib.rs

@@ -88,6 +88,20 @@ pub use self::option::OptionExt;
 pub use self::result::Result;
 pub use self::result::ResultExt;
 
+/// A trait bound of the supported error type of [`Exn`].
+pub trait Error: std::error::Error + Send + Sync + 'static {
+    /// Raise this error as a new exception.
+    #[track_caller]
+    fn raise(self) -> Exn<Self>
+    where
+        Self: Sized,
+    {
+        Exn::new(self)
+    }
+}
+
+impl<T> Error for T where T: std::error::Error + Send + Sync + 'static {}
+
 /// Equivalent to `Ok::<_, Exn<E>>(value)`.
 ///
 /// This simplifies creation of an `exn::Result` in places where type inference cannot deduce the
@@ -105,6 +119,6 @@ pub use self::result::ResultExt;
 ///    |         consider giving this pattern the explicit type `std::result::Result<i32, E>`, where the type parameter `E` is specified
 /// ```
 #[expect(non_snake_case)]
-pub fn Ok<T, E: std::error::Error + 'static>(value: T) -> Result<T, E> {
+pub fn Ok<T, E: Error>(value: T) -> Result<T, E> {
     Result::Ok(value)
 }

exn/src/option.rs

@@ -12,8 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error::Error;
-
+use crate::Error;
 use crate::Exn;
 use crate::Result;
 

exn/src/result.rs

@@ -12,8 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error::Error;
-
+use crate::Error;
 use crate::Exn;
 
 /// A reasonable return type to use throughout an application.
@@ -25,7 +24,7 @@ pub trait ResultExt {
     type Success;
 
     /// The `Err` type that would be wrapped in an [`Exn`].
-    type Error: Error + 'static;
+    type Error: Error;
 
     /// Raise a new exception on the [`Exn`] inside the [`Result`].
     ///
@@ -38,15 +37,15 @@ pub trait ResultExt {
 
 impl<T, E> ResultExt for std::result::Result<T, E>
 where
-    E: Error + 'static,
+    E: Error,
 {
     type Success = T;
     type Error = E;
 
     #[track_caller]
     fn or_raise<A, F>(self, err: F) -> Result<Self::Success, A>
     where
-        A: Error + 'static,
+        A: Error,
         F: FnOnce() -> A,
     {
         match self {
@@ -66,7 +65,7 @@ where
     #[track_caller]
     fn or_raise<A, F>(self, err: F) -> Result<Self::Success, A>
     where
-        A: Error + 'static,
+        A: Error,
         F: FnOnce() -> A,
     {
         match self {

xtask/src/main.rs

@@ -66,7 +66,6 @@ struct CommandTest {
 impl CommandTest {
     fn run(self) {
         run_command(make_test_cmd(self.no_capture, true, &[]));
-        #[cfg(not(windows_test))]
         run_example_tests();
     }
 }
@@ -88,7 +87,6 @@ impl CommandLint {
     }
 }
 
-#[cfg(not(windows_test))]
 fn run_example_tests() {
     let examples_dir = PathBuf::from(env!("CARGO_WORKSPACE_DIR"))
         .join("examples")