fix type inference issue in eyre macro autoderef behavior (#27)

* fix type inference issue in eyre macro autoderef behavior

* use the upstream example

* update testcase compile err output

* remove cruft

* bump version for breaking change

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "eyre"
-version = "0.4.3" # remember to update html_root_url
+version = "0.5.0" # remember to update html_root_url
 authors = ["David Tolnay <dtolnay@gmail.com>", "Jane Lusby <jlusby42@gmail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"

README.md

@@ -18,7 +18,7 @@ This crate is a fork of [`anyhow`] by @dtolnay with a support for customized
 
 ```toml
 [dependencies]
-eyre = "0.4"
+eyre = "0.5"
 ```
 
 ## Custom Report Handlers
@@ -153,7 +153,7 @@ Cargo.toml. A global allocator is required.
 
 ```toml
 [dependencies]
-eyre = { version = "0.4", default-features = false }
+eyre = { version = "0.5", default-features = false }
 ```
 
 Since the `?`-based error conversions would normally rely on the

src/kind.rs

@@ -51,9 +51,6 @@ use core::fmt::{Debug, Display};
 #[cfg(feature = "std")]
 use crate::StdError;
 
-// #[cfg(backtrace)]
-// use std::backtrace::Backtrace;
-
 pub struct Adhoc;
 
 pub trait AdhocKind: Sized {
@@ -74,21 +71,27 @@ impl Adhoc {
     }
 }
 
-pub struct Trait;
+pub struct Trait<H>(std::marker::PhantomData<H>);
 
-pub trait TraitKind: Sized {
+pub trait TraitKind<H>: Sized {
     #[inline]
-    fn eyre_kind(&self) -> Trait {
-        Trait
+    fn eyre_kind(&self) -> Trait<H> {
+        Trait(std::marker::PhantomData)
     }
 }
 
-impl<E> TraitKind for E where E: Into<Report> {}
+impl<E, H> TraitKind<H> for E
+where
+    E: Into<Report<H>>,
+    H: EyreHandler,
+{
+}
 
-impl Trait {
-    pub fn new<E>(self, error: E) -> Report
+impl<H> Trait<H> {
+    pub fn new<E>(self, error: E) -> Report<H>
     where
-        E: Into<Report>,
+        E: Into<Report<H>>,
+        H: EyreHandler,
     {
         error.into()
     }
@@ -114,3 +117,38 @@ impl Boxed {
         Report::from_boxed(error)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::eyre;
+    use std::num::ParseIntError;
+
+    struct NonDefaultHandler;
+
+    impl EyreHandler for NonDefaultHandler {
+        #[allow(unused_variables)]
+        fn default(error: &(dyn StdError + 'static)) -> Self {
+            Self
+        }
+
+        fn debug(
+            &self,
+            _error: &(dyn StdError + 'static),
+            _f: &mut core::fmt::Formatter<'_>,
+        ) -> core::fmt::Result {
+            Ok(())
+        }
+    }
+
+    fn _parse(s: &str) -> Result<i32, ParseIntError> {
+        s.parse::<i32>()
+    }
+
+    fn _throw_error() -> Result<(), Report<NonDefaultHandler>> {
+        match _parse("abc") {
+            Ok(_) => Ok(()),
+            Err(e) => Err(eyre!(e).wrap_err("try parsing an actual number")),
+        }
+    }
+}

src/lib.rs

@@ -206,7 +206,7 @@
 //!
 //! ```toml
 //! [dependencies]
-//! eyre = { version = "0.4", default-features = false }
+//! eyre = { version = "0.5", default-features = false }
 //! ```
 //!
 //! Since the `?`-based error conversions would normally rely on the
@@ -317,7 +317,7 @@
 //! [`simple-eyre`]: https://github.com/yaahc/simple-eyre
 //! [`color-spantrace`]: https://github.com/yaahc/color-spantrace
 //! [`color-backtrace`]: https://github.com/athre0z/color-backtrace
-#![doc(html_root_url = "https://docs.rs/eyre/0.4.3")]
+#![doc(html_root_url = "https://docs.rs/eyre/0.5.0")]
 #![warn(
     missing_debug_implementations,
     missing_docs,

tests/test_boxed.rs

@@ -28,13 +28,13 @@ fn test_boxed_thiserror() {
     let error = MyError {
         source: io::Error::new(io::ErrorKind::Other, "oh no!"),
     };
-    let error = eyre!(error);
+    let error: Report = eyre!(error);
     assert_eq!("oh no!", error.source().unwrap().to_string());
 }
 
 #[test]
 fn test_boxed_eyre() {
-    let error = eyre!("oh no!").wrap_err("it failed");
+    let error: Report = eyre!("oh no!").wrap_err("it failed");
     let error = eyre!(error);
     assert_eq!("oh no!", error.source().unwrap().to_string());
 }

tests/ui/no-impl.stderr

@@ -4,18 +4,18 @@ error[E0599]: no method named `eyre_kind` found for reference `&Error` in the cu
 4 | struct Error;
   | -------------
   | |
-  | doesn't satisfy `Error: eyre::kind::TraitKind`
-  | doesn't satisfy `Error: std::convert::Into<eyre::Report>`
+  | doesn't satisfy `Error: eyre::kind::TraitKind<_>`
+  | doesn't satisfy `Error: std::convert::Into<eyre::Report<_>>`
   | doesn't satisfy `Error: std::fmt::Display`
 ...
 7 |     let _ = eyre!(Error);
   |             ^^^^^^^^^^^^ method not found in `&Error`
   |
   = note: the method `eyre_kind` exists but the following trait bounds were not satisfied:
-          `Error: std::convert::Into<eyre::Report>`
-          which is required by `Error: eyre::kind::TraitKind`
+          `Error: std::convert::Into<eyre::Report<_>>`
+          which is required by `Error: eyre::kind::TraitKind<_>`
           `Error: std::fmt::Display`
           which is required by `&Error: eyre::kind::AdhocKind`
-          `&Error: std::convert::Into<eyre::Report>`
-          which is required by `&Error: eyre::kind::TraitKind`
+          `&Error: std::convert::Into<eyre::Report<_>>`
+          which is required by `&Error: eyre::kind::TraitKind<_>`
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)