feat: basic backtrace propagation

eyre/src/backtrace.rs

@@ -1,8 +1,9 @@
 #[cfg(backtrace)]
-pub(crate) use std::backtrace::Backtrace;
+pub use std::backtrace::Backtrace;
 
 #[cfg(not(backtrace))]
-pub(crate) enum Backtrace {}
+#[derive(Debug)]
+pub enum Backtrace {}
 
 #[cfg(backtrace)]
 macro_rules! backtrace_if_absent {

eyre/src/compat.rs

@@ -1,4 +1,4 @@
-use crate::Report;
+use crate::{builder::ReportBuilder, Report};
 
 /// Convert this result into an eyre [`Report`](crate::Report) result
 ///
@@ -6,12 +6,7 @@ use crate::Report;
 /// [`Error`](std::error::Error) is not yet available.
 pub trait IntoEyre<T> {
     /// Convert this result into an eyre [`Report`](crate::Report) result
-    fn into_eyre(self) -> crate::Result<T>
-    where
-        Self: Sized,
-    {
-        todo!()
-    }
+    fn into_eyre(self) -> crate::Result<T>;
 }
 
 /// See: [`IntoEyre`]
@@ -19,25 +14,27 @@ pub trait IntoEyre<T> {
 /// Error type automatically implements `into_eyre` for `Result<T, E>`
 pub trait IntoEyreReport {
     /// Convert this error into an eyre [`Report`](crate::Report)
-    fn into_eyre_report(self) -> Report
-    where
-        Self: Sized,
-    {
-        todo!()
-    }
+    #[track_caller]
+    fn into_eyre_report(self) -> Report;
 }
 
 impl<T, E> IntoEyre<T> for Result<T, E>
 where
     E: IntoEyreReport,
 {
+    #[track_caller]
     fn into_eyre(self) -> crate::Result<T> {
-        self.map_err(E::into_eyre_report)
+        // Use a manual match to keep backtrace
+        match self {
+            Ok(v) => Ok(v),
+            Err(err) => Err(err.into_eyre_report()),
+        }
     }
 }
 
 #[cfg(feature = "anyhow-compat")]
 impl IntoEyreReport for anyhow::Error {
+    #[track_caller]
     fn into_eyre_report(self) -> Report
     where
         Self: Sized,
@@ -60,7 +57,13 @@ impl IntoEyreReport for anyhow::Error {
             .next()
             .expect("Error chain contains at least one error");
 
-        let report = Report::msg(head.to_string());
+        #[cfg(backtrace)]
+        let report = ReportBuilder::default()
+            .with_backtrace(self.backtrace())
+            .msg(head.to_string());
+
+        #[cfg(not(backtrace))]
+        let report = ReportBuilder::default().msg(head.to_string());
         // chai
         // eprintln!("{:?}", chain.map(|v| v.to_string()).collect::<Vec<_>>());
 

eyre/tests/test_anyhow_compat.rs

@@ -1,24 +1,64 @@
-use anyhow::Context;
-use eyre::WrapErr;
+use std::fmt::Display;
+
 use eyre::{compat::IntoEyre, Report};
 
-fn this_function_fails() -> anyhow::Result<()> {
-    anyhow::bail!("Ouch!")
+#[derive(Debug)]
+struct RootError;
+
+impl Display for RootError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "RootError")
+    }
 }
 
+impl std::error::Error for RootError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        None
+    }
+}
+
+#[cfg(feature = "anyhow-compat")]
+fn this_function_fails() -> anyhow::Result<()> {
+    use anyhow::Context;
+
+    Err(RootError).context("Ouch!").context("Anyhow context A")
+}
+
+#[cfg(feature = "anyhow-compat")]
 fn bubble() -> eyre::Result<()> {
+    use anyhow::Context;
+    use eyre::WrapErr;
     this_function_fails()
-        .context("Anyhow::context")
+        .context("Anyhow context B")
         .into_eyre()
-        .wrap_err("Eyre::wrap_err")?;
+        .wrap_err("Eyre context A")?;
 
     Ok(())
 }
 
+#[cfg(feature = "anyhow-compat")]
 #[test]
 fn anyhow_conversion() {
-    let error: Report = bubble().unwrap_err();
-    // let error = Report::msg("A").wrap_err("B").wrap_err("C");
+    use eyre::WrapErr;
+    let error: Report = bubble().wrap_err("Eyre context B").unwrap_err();
 
     eprintln!("{error:?}");
+
+    let chain = error.chain().map(ToString::to_string).collect::<Vec<_>>();
+    assert_eq!(
+        chain,
+        [
+            "Eyre context B",
+            "Eyre context A",
+            // Anyhow context
+            "Anyhow context B",
+            "Anyhow context A",
+            // Anyhow error
+            "Ouch!",
+            // Original concrete error, shows up in chain too
+            "RootError"
+        ]
+    );
+
+    // let error = Report::msg("A").wrap_err("B").wrap_err("C");
 }