Optional feature to wrap backtrace in an Arc to enable a full Clone impl

Cargo.toml

@@ -8,6 +8,7 @@ default = []
 backtrace = []
 extra-backtrace = ["backtrace"]
 clone-with-caveats = []
+arc-backtrace = []
 termination = ["dep:ansee"]
 
 [dependencies]

src/context.rs

@@ -10,7 +10,7 @@ use crate::report::report_write;
 
 /// Provides context furthering the explanation of *how* you got to an error.
 #[derive(Debug)]
-#[cfg_attr(feature = "clone-with-caveats", derive(Clone))]
+#[cfg_attr(any(feature = "arc-backtrace", feature = "clone-with-caveats"), derive(Clone))]
 pub struct Context {
     pub(crate) detail: Detail,
     pub(crate) extra: Vec<Detail>,
@@ -56,7 +56,7 @@ impl fmt::Display for Context {
 }
 
 #[derive(Debug)]
-#[cfg_attr(feature = "clone-with-caveats", derive(Clone))]
+#[cfg_attr(any(feature = "arc-backtrace", feature = "clone-with-caveats"), derive(Clone))]
 #[non_exhaustive]
 pub enum Detail {
     Str(&'static str),
@@ -76,7 +76,7 @@ impl Detail {
         let bt = match bt.status() {
             Disabled => Backtrace::Disabled,
             Unsupported => Backtrace::Unsupported,
-            status => Backtrace::Other(status, bt.to_string()),
+            _ => Backtrace::Other(bt.into()),
         };
         Self::Backtrace(PrivateBacktrace(bt))
     }
@@ -87,22 +87,29 @@ pub struct PrivateError(pub(crate) Arc<dyn std::error::Error + Send + Sync>);
 
 #[cfg(feature = "backtrace")]
 #[derive(Debug)]
-#[cfg_attr(feature = "clone-with-caveats", derive(Clone))]
+#[cfg_attr(any(feature = "arc-backtrace", feature = "clone-with-caveats"), derive(Clone))]
 pub struct PrivateBacktrace(pub(crate) Backtrace);
 
 // will be replaced with std::backtrace::Backtrace if and when it is Clone
 #[cfg(feature = "backtrace")]
 #[derive(Debug)]
+#[cfg_attr(feature = "arc-backtrace", derive(Clone))]
 pub(crate) enum Backtrace {
     Disabled,
     Unsupported,
-    Other(BacktraceStatus, String),
+    #[cfg(feature = "arc-backtrace")]
+    Other(Arc<std::backtrace::Backtrace>),
+    #[cfg(not(feature = "arc-backtrace"))]
+    Other(std::backtrace::Backtrace),
 }
 
-#[cfg(all(feature = "backtrace", feature = "clone-with-caveats"))]
+#[cfg(all(feature = "backtrace", feature = "clone-with-caveats", not(feature = "arc-backtrace")))]
 impl Clone for Backtrace {
     fn clone(&self) -> Self {
-        Backtrace::Disabled
+        match self {
+            Self::Unsupported => Self::Unsupported,
+            _ => Self::Disabled
+        }
     }
 }
 
@@ -117,8 +124,8 @@ impl fmt::Display for Detail {
             #[cfg(feature = "backtrace")]
             Self::Backtrace(PrivateBacktrace(Backtrace::Disabled)) => f.write_str("If you'd like a backtrace,\n  try again with RUST_BACKTRACE=1"),
             #[cfg(feature = "backtrace")]
-            Self::Backtrace(PrivateBacktrace(Backtrace::Other(status, bt))) => {
+            Self::Backtrace(PrivateBacktrace(Backtrace::Other(bt))) => {
-                f.write_str(if *status == BacktraceStatus::Captured {
+                f.write_str(if bt.status() == BacktraceStatus::Captured {
                     "Here is the backtrace:\n"
                 } else {
                     "I can't tell if backtraces are working,\n  but I'll give it a go:\n"

src/how.rs

@@ -9,7 +9,7 @@ use crate::report::report_write;
 /// By default, does not implement [`Clone`] because [`std::backtrace::Backtrace`] does not
 /// implement [`Clone`]. However, the `clone-with-caveats` feature may be used to enable a
 /// [`Clone`] impl that sets the cloned `backtrace` to [`std::backtrace::Backtrace::disabled`].
-#[cfg_attr(feature = "clone-with-caveats", derive(Clone))]
+#[cfg_attr(any(feature = "arc-backtrace", feature = "clone-with-caveats"), derive(Clone))]
 pub struct How(Box<HowInner>);
 
 struct HowInner {
@@ -119,7 +119,7 @@ impl How {
     }
 }
 
-#[cfg(feature = "clone-with-caveats")]
+#[cfg(any(feature = "arc-backtrace", feature = "clone-with-caveats"))]
 impl Clone for HowInner {
     #[inline]
     fn clone(&self) -> Self {