1 files changed, 31 insertions, 9 deletions

diff --git a/src/error.rs b/src/error.rs
index 0971146..9f6ce8c 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -5,6 +5,8 @@ use crate::ptr::Mut;
 use crate::ptr::{Own, Ref};
 use crate::{Error, StdError};
 use alloc::boxed::Box;
+#[cfg(backtrace)]
+use core::any::Demand;
 use core::any::TypeId;
 use core::fmt::{self, Debug, Display};
 use core::mem::ManuallyDrop;
@@ -31,7 +33,7 @@ impl Error {
     where
         E: StdError + Send + Sync + 'static,
     {
-        let backtrace = backtrace_if_absent!(error);
+        let backtrace = backtrace_if_absent!(&error);
         Error::from_std(error, backtrace)
     }
 
@@ -522,6 +524,18 @@ impl Error {
     }
 }
 
+#[cfg(backtrace)]
+impl std::any::Provider for Error {
+    // Called by thiserror when you have `#[source] anyhow::Error`. This provide
+    // implementation includes the anyhow::Error's Backtrace if any, unlike
+    // deref'ing to dyn Error where the provide implementation would include
+    // only the original error's Backtrace from before it got wrapped into an
+    // anyhow::Error.
+    fn provide<'a>(&'a self, demand: &mut Demand<'a>) {
+        unsafe { ErrorImpl::provide(self.inner.by_ref(), demand) }
+    }
+}
+
 #[cfg(feature = "std")]
 #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<E> From<E> for Error
@@ -530,7 +544,7 @@ where
 {
     #[cold]
     fn from(error: E) -> Self {
-        let backtrace = backtrace_if_absent!(error);
+        let backtrace = backtrace_if_absent!(&error);
         Error::from_std(error, backtrace)
     }
 }
@@ -886,13 +900,21 @@ impl ErrorImpl {
             .as_ref()
             .or_else(|| {
                 #[cfg(backtrace)]
-                return Self::error(this).backtrace();
-                #[cfg(all(not(backtrace), feature = "backtrace"))]
+                return Self::error(this).request_ref::<Backtrace>();
+                #[cfg(not(backtrace))]
                 return (vtable(this.ptr).object_backtrace)(this);
             })
             .expect("backtrace capture failed")
     }
 
+    #[cfg(backtrace)]
+    unsafe fn provide<'a>(this: Ref<'a, Self>, demand: &mut Demand<'a>) {
+        if let Some(backtrace) = &this.deref().backtrace {
+            demand.provide_ref(backtrace);
+        }
+        Self::error(this).provide(demand);
+    }
+
     #[cold]
     pub(crate) unsafe fn chain(this: Ref<Self>) -> Chain {
         Chain::new(Self::error(this))
@@ -903,14 +925,14 @@ impl<E> StdError for ErrorImpl<E>
 where
     E: StdError,
 {
-    #[cfg(backtrace)]
-    fn backtrace(&self) -> Option<&Backtrace> {
-        Some(unsafe { ErrorImpl::backtrace(self.erase()) })
-    }
-
     fn source(&self) -> Option<&(dyn StdError + 'static)> {
         unsafe { ErrorImpl::error(self.erase()).source() }
     }
+
+    #[cfg(backtrace)]
+    fn provide<'a>(&'a self, demand: &mut Demand<'a>) {
+        unsafe { ErrorImpl::provide(self.erase(), demand) }
+    }
 }
 
 impl<E> Debug for ErrorImpl<E>