feat: introduce an "anyhow" compatibility layer feature flag (#138)

This change hides the `anyhow` compatibility layer behind an `"anyhow"`
feature flag.
In `eyre` v1.0.0 the feature is currently enabled by default.

Fixes #131

---------

Co-authored-by: Freja Roberts <ten3roberts@gmail.com>

README.md

@@ -200,7 +200,17 @@ This crate does its best to be usable as a drop in replacement of `anyhow` and
 vice-versa by `re-exporting` all of the renamed APIs with the names used in
 `anyhow`, though there are some differences still.
 
-#### `Context` and `Option`
+### Disabling the compatibility layer
+
+The `anyhow` compatibility layer is enabled by default.
+If you do not need anyhow compatibility, it is advisable
+to disable the `"anyhow"` feature:
+
+```toml
+eyre = { version = "0.6", default-features = false, features = ["auto-install", "track-caller"] }
+```
+
+### `Context` and `Option`
 
 As part of renaming `Context` to `WrapErr` we also intentionally do not
 implement `WrapErr` for `Option`. This decision was made because `wrap_err`

eyre/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 <!-- next-header -->
 
 ## [Unreleased] - ReleaseDate
+### Added
+- feature flag for `anyhow` compatibility traits [by LeoniePhiline](https://github.com/eyre-rs/eyre/pull/138)
 
 ## [0.6.11] - 2023-12-13
 ### Fixed

eyre/Cargo.toml

@@ -13,7 +13,8 @@ readme = { workspace = true }
 rust-version = { workspace = true }
 
 [features]
-default = ["auto-install", "track-caller"]
+default = ["anyhow", "auto-install", "track-caller"]
+anyhow = []
 auto-install = []
 track-caller = []
 

eyre/src/context.rs

@@ -1,5 +1,5 @@
 use crate::error::{ContextError, ErrorImpl};
-use crate::{ContextCompat, Report, StdError, WrapErr};
+use crate::{Report, StdError, WrapErr};
 use core::fmt::{self, Debug, Display, Write};
 
 #[cfg(backtrace)]
@@ -62,13 +62,15 @@ where
         }
     }
 
+    #[cfg(feature = "anyhow")]
     fn context<D>(self, msg: D) -> Result<T, Report>
     where
         D: Display + Send + Sync + 'static,
     {
         self.wrap_err(msg)
     }
 
+    #[cfg(feature = "anyhow")]
     fn with_context<D, F>(self, msg: F) -> Result<T, Report>
     where
         D: Display + Send + Sync + 'static,
@@ -78,7 +80,8 @@ where
     }
 }
 
-impl<T> ContextCompat<T> for Option<T> {
+#[cfg(feature = "anyhow")]
+impl<T> crate::ContextCompat<T> for Option<T> {
     fn wrap_err<D>(self, msg: D) -> Result<T, Report>
     where
         D: Display + Send + Sync + 'static,

eyre/src/error.rs

@@ -116,6 +116,7 @@ impl Report {
         unsafe { Report::construct(error, vtable, handler) }
     }
 
+    #[cfg(feature = "anyhow")]
     #[cfg_attr(track_caller, track_caller)]
     pub(crate) fn from_display<M>(message: M) -> Self
     where

eyre/src/lib.rs

@@ -265,7 +265,17 @@
 //! vice-versa by re-exporting all of the renamed APIs with the names used in
 //! `anyhow`, though there are some differences still.
 //!
-//! #### `Context` and `Option`
+//! ### Disabling the compatibility layer
+//!
+//! The `anyhow` compatibility layer is enabled by default.
+//! If you do not need anyhow compatibility, it is advisable
+//! to disable the `"anyhow"` feature:
+//!
+//! ```toml
+//! eyre = { version = "0.6", default-features = false, features = ["auto-install", "track-caller"] }
+//! ```
+//!
+//! ### `Context` and `Option`
 //!
 //! As part of renaming `Context` to `WrapErr` we also intentionally do not
 //! implement `WrapErr` for `Option`. This decision was made because `wrap_err`
@@ -375,18 +385,23 @@ use std::error::Error as StdError;
 
 pub use eyre as format_err;
 /// Compatibility re-export of `eyre` for interop with `anyhow`
+#[cfg(feature = "anyhow")]
 pub use eyre as anyhow;
 use once_cell::sync::OnceCell;
 use ptr::OwnedPtr;
+#[cfg(feature = "anyhow")]
 #[doc(hidden)]
 pub use DefaultHandler as DefaultContext;
+#[cfg(feature = "anyhow")]
 #[doc(hidden)]
 pub use EyreHandler as EyreContext;
 #[doc(hidden)]
 pub use Report as ErrReport;
 /// Compatibility re-export of `Report` for interop with `anyhow`
+#[cfg(feature = "anyhow")]
 pub use Report as Error;
 /// Compatibility re-export of `WrapErr` for interop with `anyhow`
+#[cfg(feature = "anyhow")]
 pub use WrapErr as Context;
 
 /// The core error reporting type of the library, a wrapper around a dynamic error reporting type.
@@ -1112,12 +1127,14 @@ pub trait WrapErr<T, E>: context::private::Sealed {
         F: FnOnce() -> D;
 
     /// Compatibility re-export of wrap_err for interop with `anyhow`
+    #[cfg(feature = "anyhow")]
     #[cfg_attr(track_caller, track_caller)]
     fn context<D>(self, msg: D) -> Result<T, Report>
     where
         D: Display + Send + Sync + 'static;
 
     /// Compatibility re-export of wrap_err_with for interop with `anyhow`
+    #[cfg(feature = "anyhow")]
     #[cfg_attr(track_caller, track_caller)]
     fn with_context<D, F>(self, f: F) -> Result<T, Report>
     where
@@ -1223,6 +1240,7 @@ pub trait OptionExt<T>: context::private::Sealed {
 ///         .ok_or_else(|| eyre!("the thing wasnt in the list"))
 /// }
 /// ```
+#[cfg(feature = "anyhow")]
 pub trait ContextCompat<T>: context::private::Sealed {
     /// Compatibility version of `wrap_err` for creating new errors with new source on `Option`
     /// when porting from `anyhow`

eyre/tests/test_context_access.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "anyhow")]
+
 mod common;
 
 use crate::common::maybe_install_handler;

eyre/tests/test_location.rs

@@ -1,6 +1,6 @@
 use std::panic::Location;
 
-use eyre::{OptionExt as _, WrapErr};
+use eyre::WrapErr;
 
 struct LocationHandler {
     actual: Option<&'static str>,
@@ -83,19 +83,22 @@ fn test_wrap_err_with() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_option_ok_or_eyre() {
     let _ = eyre::set_hook(Box::new(|_e| {
         let expected_location = file!();
         Box::new(LocationHandler::new(expected_location))
     }));
 
+    use eyre::OptionExt;
     let err = None::<()>.ok_or_eyre("oopsie").unwrap_err();
 
     // should panic if the location isn't in our crate
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_context() {
     let _ = eyre::set_hook(Box::new(|_e| {
@@ -111,6 +114,7 @@ fn test_context() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_with_context() {
     let _ = eyre::set_hook(Box::new(|_e| {
@@ -126,6 +130,7 @@ fn test_with_context() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_option_compat_wrap_err() {
     let _ = eyre::set_hook(Box::new(|_e| {
@@ -140,6 +145,7 @@ fn test_option_compat_wrap_err() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_option_compat_wrap_err_with() {
     let _ = eyre::set_hook(Box::new(|_e| {
@@ -154,6 +160,7 @@ fn test_option_compat_wrap_err_with() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_option_compat_context() {
     let _ = eyre::set_hook(Box::new(|_e| {
@@ -168,6 +175,7 @@ fn test_option_compat_context() {
     println!("{:?}", err);
 }
 
+#[cfg(feature = "anyhow")]
 #[test]
 fn test_option_compat_with_context() {
     let _ = eyre::set_hook(Box::new(|_e| {